urban wastewater reuse - treatment technologies & cost

DEPARTMENT OF CIVIL, ENVIRONMENTAL & GEOMATIC ENGINEERING

MSc DISSERTATION SUBMISSION

STUDENT NAME: CHRYSOULA SFYNIA

PROGRAMME: MSC ENVIRONMENTAL SYSTEMS ENGINEERING

SUPERVISOR: DR. LUIZA CINTRA CAMPOS

DISSERTATION TITLE:

URBAN WASTEWATER REUSE - TREATMENT TECHNOLOGIES & COST

I confirm that I have read and understood the guidelines on plagiarism, that I understand the meaning of plagiarism and that I may be penalised for submitting work that has been plagiarised.

I declare that all material presented in the accompanying work is entirely my own work except where explicitly and individually indicated and that all sources used in its preparation and all quotations are clearly cited.

Should this statement prove to be untrue, I recognise the right of the Board of

Examiners to recommend what action should be taken in line with UCL’s regulations.

Signature: Date: 06/09/2013

Urban Wastewater Reuse - treatment technologies and costs

1

EXECUTIVE SUMMARY

Arup and University College London’s (UCL), Civil, Environmental and Geomatic

Engineering Department, have launched a joint project for the design configuration of

urban water reuse networks.

This master thesis is part of the venture “Water Reuse Networks Project” and of the

ongoing research in the field with regards to wastewater treatment options for reuse

and their costs. The present study “Urban Wastewater Reuse – treatment

technologies and costs” involves a detailed review of the current trends and reuse

applications with emphasis on possible efficient scenarios.

The project is concerned how increasing pressures on the water environment

necessitate the implementation of sustainable water management practices and

regimes. It is argued that this can be achieved through the design, the application

and the optimal operation of water reuse infrastructure and management of both

supply and demand.

Wastewater reuse can be a tool of rational management of water resources. The

reasoning of the appropriate reuse of treated municipal or industrial wastewater has

intrinsic benefits associated with saving water resources and producing

environmental and economic benefits. However, the reuse of wastewater requires a

comprehensive and rational planning, taking into account possible risks and

limitations.

This study summarizes the current trends concerning urban wastewater reuse

focusing in the case of greywater reclamation. In addition, it outlines the objectives

and scope of the collaborative project. Overall, the report consists of 7 Chapters, a

glossary, an appendix and the appropriate referencing.


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The study reviews the following main issues (Chapter 4-6):

● Legislation of urban wastewater reuse

● Available technologies for greywater treatment for reuse

● Costs for these treatment schemes

Chapter 7 introduces the reader to the planning of water reuse networks. This

Chapter analyses four different possible greywater treatment scenarios that can be

implemented and have proved to be effective. These scenarios have been formed

after extensive research in literature, case studies and communication with

wastewater treatment specialists.

Finally, another significant component of this project is the discussion parts at the

end of each of the core chapters that illustrate briefly the main findings and comment

on the outcomes.


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ACKNOWLEDGEMENTS

First and foremost, I would like to thank my supervisor Dr. Luiza Cintra Campos for

giving me the opportunity to carry out this project as my master thesis together with

her invaluable guidance and support throughout the whole period. Her great

experience and professionalism inspired me to progress in my research and further

explore my capabilities. Secondly, I am also thankful to Eleni Georgiou for her

contribution and feedback review for this thesis.

Special thanks to ARUP and the WReN group for all the confidence, advice and

flexibility I was given, which ensured the smooth completion of the first part of the

collaborative project. I would also like to thank the wastewater treatment companies

that kindly provided technical and financial information of their technologies.

Last but not least, I would like to thank the “family” we created in London for all the

unconditional and endless support and help during my studies.


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To the inspiration in my life,

My father, Constantinos Sfynias,


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TABLE OF CONTENTS

EXECUTIVE SUMMARY ................................................................................................. 1

ACKNOWLEDGEMENTS ................................................................................................ 3

1. INTRODUCTION .................................................................................................... 9

1.1 Water Scarcity & Urbanization................................................................... 10

1.2 Water Use around the World ..................................................................... 12

2. AIMS & OBJECTIVES .......................................................................................... 16

3. BACKGROUND RESEARCH .................................................................................. 17

3.1 Water Reclamation & Reuse – A Sustainable Solution .............................. 18

3.2 Challenges of Water & Wastewater Reuse................................................ 19

3.3 Advantages of Water Reuse ..................................................................... 21

3.4 Types of Water Reuse Applications .......................................................... 22

3.5 Case Studies ............................................................................................. 24

4. WASTEWATER REUSE FRAMEWORK ................................................................... 28

4.1 Regulations by International Organizations ............................................... 29

4.2 Regulations by the State of California ....................................................... 38

4.3 Regulations by Other Countries ................................................................ 40

5. WASTEWATER TREATMENT FOR REUSE .............................................................. 44

5.1 Wastewater for Reuse – Greywater .......................................................... 46

5.2 Greywater Treatment Stages .................................................................... 50

5.3 Discussion................................................................................................. 71

6. WATER REUSE & COSTS .................................................................................... 72

6.1 Capital Costs ............................................................................................. 73

6.2 Operation & Maintenance Costs ................................................................ 82

6.3 Discussion................................................................................................. 86

7. SETTING UP WATER REUSE NETWORKS ............................................................. 87

7.1 Treatment Scenarios ................................................................................. 91

7.2 Discussion............................................................................................... 100

8. CONCLUSIONS & RECOMMENDATIONS .............................................................. 102

REFERENCES ......................................................................................................... 104

APPENDIX .............................................................................................................. 111


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LIST OF FIGURES

Figure 1.1: The Percent of Population with access to improved Water Sources (%) ............. 10

Figure 1.2: The Percent of Population with access to improved Sanitation (%) ..................... 11

Figure 1.3: Map of Worlds Water Stress in 1995 and in 2020 ................................................ 11

Figure 1.5: Water Use by Sector in European Countries ........................................................ 13

Figure 1.6: Agricultural water withdrawal as a percent of total withdrawal (%) ....................... 14

Figure 1.7: Industrial water withdrawal as a percent of total withdrawal (%) .......................... 14

Figure 1.8: Municipal water withdrawal as a percent of total withdrawal (%) .......................... 15

Figure 3.1: Water Reuse Applications .................................................................................... 22

Figure 3.2: Water Reuse Projects in Europe (Size & Application) ......................................... 27

Figure 4.1: California’s Warning Sign for Recycled Water ...................................................... 39

Figure 5.1: Treatment Technologies for Any Type of Reuse ................................................. 45

Figure 5.2: Sources of Household Wastewater ...................................................................... 46

Figure 5.3: Greywater Categories ........................................................................................... 47

Figure 5.4: Typical Flow Diagram of Basic System – Coarse Filtration ................................. 53

Figure 5.5: Typical Flow Diagram of Basic System – Sedimentation ..................................... 54

Figure 5.6: Typical Flow Diagram of Physical System – Sand Filter ...................................... 55

Figure 5.7: Typical Flow Diagram of Physical System – Membranes .................................... 57

Figure 5.8: Typical Flow Diagram of Chemical System – Coagulation .................................. 58

Figure 5.9: Typical Flow Diagram of Chemical System – Photobioreactor ............................ 60

Figure 5.10: Typical Flow Diagram of Biological System – SBR ............................................ 62

Figure 5.11: Typical Flow Diagram of Biological System – MBR ........................................... 64

Figure 5.12: Typical Flow Diagram of Biological System – RBC ........................................... 66

Figure 5.13: Typical Flow Diagram of Extensive Systems–Constructed Wetlands ............... 70

Figure 6.1: Typical Water & Drainage Pipelines ..................................................................... 80

Figure 6.2: Typical Pumping Station....................................................................................... 81

Figure 6.3: Breakdown of Running costs of a Wastewater Treatment Plant ......................... 82

Figure 7.1: Water Network Configuration ............................................................................... 89

Figure 7.2: Summary of Treatment Scenarios for Greywater Reclamation ............................ 90

Figure 7.3: Flow Diagram of Scenario 1- Constructed Wetland ............................................. 92

Figure 7.4: Flow Diagram of Scenario 2- RBC ....................................................................... 94

Figure 7.5: Flow Diagram of Scenario 3- SBR ........................................................................ 96

Figure 7.6: Flow Diagram of Scenario 4- MBR ........................................................................ 98

Figure 7.7: Diagram of Scenarios Costs per Equivalent Population ..................................... 101


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LIST OF TABLES

Table 3.1: Categories of Reclamation and Reused Water ...................................................... 23

Table 3.2: Worldwide Wastewater Reuse Projects in chronological order from 1912-1989 ... 24

Table 4.1: Directive Limits for Monitoring Parameters in Agriculture and Aquaculture ........... 31

Table 4.2: Health-based Targets & Helminth Reduction Targets from WHO.......................... 32

Table 4.3: Health Based Targets for Water Reuse by WHO ................................................... 33

Table 4.4: Suggested Guidelines for Urban & Agricultural Reuse .......................................... 35

Table 4.6: Suggested Guidelines for Indirect Potable Reuse ................................................. 37

Table 4.7: California’s Title 22 Pathogen Limits ...................................................................... 39

Table 4.8: Water Reuse Practices & Criteria in European Countries...................................... 41

Table 4.9: Existing Water Reuse Criteria in European Countries ........................................... 41

Table 4.10: Existing Water Reuse Criteria in the UK .............................................................. 42

Table 4.11: Reuse Criteria in Japan ........................................................................................ 43

Table 5.1: Average Greywater Yield & Demand ..................................................................... 48

Table 5.2: Summary of Greywater Characteristics .................................................................. 49

Table 5.3: Removal of various components using Membranes .............................................. 56

Table 6.1: Cost of Basic Systems ............................................................................................ 74

Table 6.2: Cost of Physical Systems ....................................................................................... 75

Table 6.3: Cost of Chemical Systems ..................................................................................... 76

Table 6.4: Cost of Biological Systems ..................................................................................... 77

Table 6.5: Cost of Extensive Systems ..................................................................................... 78

Table 6.6: Unit Cost of Water Distribution &Transmission Pipelines ...................................... 80

Table 6.7: Unit Cost of Water Transmission Pumping Station ................................................ 81

Table 6.8: Cost of Microbiological Monitoring Analysis ........................................................... 84

Table 6.9: Cost of Physicochemical Monitoring Analysis ........................................................ 85

Table 7.1: Summarized table for Scenario 1 ........................................................................... 93





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GLOSSARY

CFU Colony Forming Unit

DIY Do It Yourself

EU European Union

FAO Food and Agriculture Organisation

FC Faecal Coliforms

GAC Granular Activated Carbon

HRT Hydraulic Retention Time

MF Microfiltration

NF Nanofiltration

OECD Organisation for Economic Co-operation and Development

RO Reverse Osmosis

TC Total Coliforms

TDS Total Dissolved Solids

TSS Total Suspended Solids

UF Ultrafiltration

UN United Nations

UNDESA United Nations/Department of Economic and Social Affairs

UV Ultraviolet

WCED World Commission on Environment and Development

WHO World Health Organisation


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1. INTRODUCTION

Water has a significant importance in the creation, preservation and the development

of life in our planet and human civilization. On July 2010, through Resolution 64/292,

the United Nations recognized the “human right to water and sanitation” and

acknowledged that “clean drinking water and sanitation are essential to the

realization of all human rights” (UNDESA, 2010). Large quantities of fresh water are

needed daily in many parts of the world for domestic, agricultural, industrial use

(Eltawil, 2009).

Regarding the current situation, almost a quarter of the world’s population suffers

from inadequate fresh water supply (Fiorenza, 2003). Because of the impending

global population growth (especially in developing countries), the situation is

expected to become even worse in the next two decades (Eltawil, 2009).

The current water crisis is not subjected only to scarcity, but also to difficulties in

accessibility and unequal distribution. According to the latest statistical information

from the WHO/UNICEF Joint Monitoring Program for Water Supply and Sanitation

(JMP), released in 2013, 36% per cent of the of the world’s population, approximately

2.5 million people lack access to proper sanitation amenities and 768 million people

still consume unsafe drinking water. This dire situation results in thousands of

deaths and leads to “impoverishment and diminished opportunities” for thousands

more (WHO, 2013).

Furthermore, the pollution and uncontrolled exploitation of groundwater aquifers and

surface waters for anthropogenic activities have led to a reduction of both quantity

and quality of the available natural water resources (WHO, 2013).


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1.1 WATER SCARCITY & URBANIZATION

The planet could be called the “blue planet”, since the two thirds of its surface are

covered by water. According to several studies (Gleick, 2006), the total water volume

reaches 1.3 billion cubic kilometres. From this amount, 97% is salt water (sea), 2% is

trapped in glaciers and icebergs and the majority of the remaining 1% is bound into

great depths. So, less than 1% of fresh water is available for human consumption.

Despite the technological development, the stocks of renewable fresh water will be

only 0.3% of global water (Eltawil, 2009).

Increasingly in recent years, the problem of water shortage is becoming an actuality.

The views can be characterised as ranging from extremely scaremongering to

extremely optimistic and reassuring.

The maps below (Figures 1.1, 1.2) were published in 2013 by the United Nations and

highlight the accessibility of the population to improved water sources and sanitation,

respectively.

FIGURE 1.1: THE PERCENT OF POPULATION WITH ACCESS TO IMPROVED WATER SOURCES (%)

(FAO, 2012)


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FIGURE 1.2: THE PERCENT OF POPULATION WITH ACCESS TO IMPROVED SANITATION (%)

(FAO, 2012)

According to estimates, in 2025, when the Earth's population will be approaching or it

will have exceeded 10 billion people, one in three inhabitants of the planet, - 3.5

billion people- will live in water scarcity conditions or will be directly threatened by it.

This trend is being illustrated in Figure 1.3, which shows the freshwater scarcity of

1995 and that of 2025.

FIGURE 1.3: MAP OF WORLDS WATER STRESS IN 1995 AND IN 2025 (WMO, 1996)


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In addition, water is projected to become a cause of conflicts in neighbouring

countries, since about 40% of Earth's inhabitants live in more than 200 transnational

river basins, from which they share water resources (Eltawil, 2009).

According to all the above statistics and owing to the foreseen growth of the world‘s

population (especially in the developing countries), the problem is expected to

become more and more critical over the next two decades (Eltawil, 2009), bringing

water shortage to the top of the international agenda.

1.2 WATER USE AROUND THE WORLD

Large quantities of fresh water are needed every day in many parts of the world for

domestic, agricultural, industrial use (Eltawil, 2009). However, the distribution of

water in these three activities depends on the extent and type of development in

every country. At the same time it is influenced by both the climatic conditions and

the type of crops cultivated, which determine the irrigation requirements of the

country.

FIGURE 1.4: TYPICAL BREAKDOWN OF FRESHWATER USE (FAO, 2012)


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Worldwide, it is estimated that 70% of fresh water is consumed for irrigation needs

(FAO, 2012), but in countries like India, Mexico, Iran and Greece the figure is even

higher (FAO, 2013). In Japan, agriculture does not contribute significantly to the

economy of the country but the amount of water needed for agricultural use is vast as

all of its crops are based on irrigation. The different allocation of water use which

characterizes the U.S., Poland, UK and Germany’s irrigation policies not only

indicates greater water consumption by the industry, but also that the agriculture is

depended on the rainfalls.

FIGURE 1.5: WATER USE BY SECTOR IN EUROPEAN COUNTRIES (Aquarec, 2006)

In industrially developed countries, such as England and Germany, the largest

percentage of disposable water is being distributed into the industry (Figure 1.5).

Conversely, in countries where the developed agriculture is based on irrigated crops,

more water goes to agriculture. A visual impression is provided in the following maps

(Figure 1.6, 1.7) where it is shown the amount of water withdrawn by the agricultural

and the industrial sector, respectively.


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FIGURE 1.6: AGRICULTURAL WATER WITHDRAWAL AS A PERCENT OF TOTAL WITHDRAWAL (%)

(FAO, 2012)

FIGURE 1.7: INDUSTRIAL WATER WITHDRAWAL AS A PERCENT OF TOTAL WITHDRAWAL (%)

(FAO, 2012)

Generally, the consumption of water for domestic use is proportional to the living

standards of a country. Higher living standards and higher income per person implies

higher consumption of water (larger homes, better conditions of cleanliness and

hygiene, lifestyle change, etc.). However, this is not the rule, as in modern countries


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where the state and the communities have realised the importance of saving water

resources, serious efforts have been made to reduce the use of household level. This

also follows from the calculations of FAO, which states that the U.S. consumes far

more water for domestic uses (210 m3/person per year), whereas the United

Kingdom is an exception and consumes 35 m3/person per year (FAO, 2013). A map

of the municipal water withdrawal globally is displayed below in Figure 1.8.

FIGURE 1.8: MUNICIPAL WATER WITHDRAWAL AS A PERCENT OF TOTAL WITHDRAWAL (%)

(FAO, 2012)

According to Shiklomanov (1999), the three main sectors mentioned that consume

water will become more demanding in the near future. Specifically, the percentage of

irrigated surfaces is projected to increase by one third in 2010 and by 50% by 2025,

while water for industrial and domestic use is growing at twice the rate of the

population growth. The water consumption is observed that since 1900 has sevenfold

in total, as the water demand doubles every 20 years (Shiklomanov, 1999).

Under these circumstances, an increased trend towards the reclamation and reuse of

wastewater is observed around the world as a means to reduce current or future

water scarcity.


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2. AIMS & OBJECTIVES

Arup and University College London (UCL) have entered into a collaborative project

to investigate and develop a methodology for the design configuration of wastewater

reuse networks of sub-municipal scale. This project aims to provide an optimum

configuration of these networks, taking into consideration the input and output water

quality, the treatment schemes and their costs.

“Urban Wastewater Reuse – treatment technologies and costs” is a review of the

water reuse framework and the current urban wastewater treatment options

combined with the costs involved that can be used as a guide for water reuse

network designing. This study has three overarching aims:

● Assess the urban wastewater treatment technologies

● Evaluate the economic factor of wastewater technologies

● Develop efficient possible wastewater treatment scenarios

The objectives have been accomplished with the following:

● Collection and recording of the existing water reuse framework

● Understanding of the wastewaters nature (quality and quantity)

● Determination of water reuse applications and final recipients

● Evaluation of existing wastewater treatment systems

● Calculation of the wastewater treatment costs (literature and companies)


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3. BACKGROUND RESEARCH

The continuous population growth, pollution and the continuing deterioration of both

surface and groundwater aquifers, the unequal distribution of water resources and

periodic droughts have necessitated the exploration and development of new water

sources (Metcalf & Eddy, 1991). In industrialized countries the problems associated

with ensuring water supply and disposal of urban and industrial waste have been

intensified. In contrast, in developing countries and especially in arid or semi-arid

regions, there is a need for affordable technology in order to increase the exploitable

quantities of water, along with the protection of the environment and the natural

resources.

It is estimated that the use of "marginal" water could decisively contribute to the

sustainable use of water resources through the implementation of integrated water

resources management plans, where the recycled water will be considered an

essential component for increasing the availability and control of pollution (Angelakis

et al., 2002).

In the path for water sustainability, a key concern of the international community is

finding alternative water sources. In this direction, the practice of reclaiming and

reusing municipal waters wins more territory and is the objective of several academic

projects. Thus, the necessity for establishing criteria for wastewater recycling and

reuse has been widely recognised in many countries of the world. Development of

criteria to minimize the microbial health risks associated with wastewater recycling

and reuse should take into account other water related exposures such as through

the food-chain, drinking water and contact with water in recreational areas.


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3.1 WATER RECLAMATION & REUSE – A SUSTAINABLE SOLUTION

The new environmental practice around the world is based on the five «Rs» which

represent the basic principles of environmental protection; Reclamation, Recycle,

Reuse, Renewable and Reduce (Paranichianakis et al, 2009). Under this prism, a

few hundred thousand cubic meters of liquid waste generated worldwide could be

reclaimed, reused, thus creating a form of recycling, which will result in the reduction

of the amount of fresh water used in various fields, creating a renewable source of

water.

In this context, reclaimed and reusable water promotes an alternative reliable water

source. “Reusing treated wastewater basically compresses the hydrological cycle

from an uncontrolled global scale to a controlled local scale” (Durham et al., 2005).

Water reclamation and reuse: Definitions (Durham et al., 2005)

Reclaimed water: Wastewater that has been treated to meet specific water quality standars with

the intention to be used for a series of purposes.

Water Reuse: The use of appropriately treated wastewater.

Non-potable reuse (NPR): The use of reclaimed water for purposes other than drinking water

(e.g. irrigation).

Direct potable reuse (DPR): The use of reclaimed water directly into drinking water after

advanced treatment.

Greywater: Used water discharged from homes, business, industry, and agricultural facilities.


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3.2 CHALLENGES OF WATER & WASTEWATER REUSE

The effective planning and operation of water reuse projects as well as the safe use

of treated wastewater implies the understanding of the challenges of this practice.

Some of these issues are briefly addressed below (USEPA, 2004; Bixio, 2006).

Establishment of criteria

An important issue is the need for the establishment of a legislative framework that

enhances water and wastewater reuse. This framework should take into

consideration all risks that may arise (health and environment), including

microbiological and physicochemical quality parameters and proposing strategies for

motivation and public acceptance.

Public health protection

The reclaimed and treated water should not pose any risk to public health. So in this

direction, regulations set limits on the amount of pathogenic microorganisms. Also

special emphasis should be given to the frequent monitoring of the water quality

reused. Finally, some guidelines suggest protective measures to be in place for the

safety of the public that may be exposed directly or indirectly with the treated water

(see Chapter 4).

Environmental cost

The reuse of wastewater should be done with respect to the natural environment.

The protection of ecosystems, the flora and fauna, the avoidance of further

degradation of the natural resources are main targets. The calculation of the

environmental footprint and the potential impact would be very useful at a preliminary

level.


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Economic factors

The economic factor is one of the most important challenges in the issues of water

and wastewater reuse. Financing such projects is possibly the main obstacle for the

wider use of treated water. However, researchers are working on new technologies

that may reduce the capital, the operation and the maintenance costs.

Public acceptance & opinion

The authorities responsible for the distribution of reclaimed water (local communities,

councils, organizations) should not only make sure of the safety of the provided water

but also need to build trust and credibility with the public. This can be achieved with

water reuse campaigns, educational programs or further motives.

Aesthetics

In some cases and also for aesthetic reasons, reusable water should be colourless

and odourless (e.g. for irrigation in gardens or parks, recreation areas). Also,

attention should be given in harmonising the treatment process, chosen for the

wastewater treatment, with the landscape and the environment.


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3.3 ADVANTAGES OF WATER REUSE

The reclamation and reuse of treated wastewater is shown to have significant

advantages (Durham, 2005):

i. The development of a new water resource

ii. The protection of water resources, particularly in coastal areas with saltwater

intrusion in aquifers

iii. The policy development of water resources, with emphasis on preserving

resources and the environment

iv. The protection of public health and the environment

v. The reduction of the water cost

vi. The reliability of water supply, specifically in rural areas


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3.4 TYPES OF WATER REUSE APPLICATIONS

Throughout the centuries, water and wastewater reuse has developed from a simple

disposal method of polluted water to an advanced process of reclamation providing

agricultural, industrial, urban and even domestic reuse.

The most common form of reuse is for non-potable purposes such as agricultural and

urban water supply, for industrial uses (e.g. cooling), for fire fighting and others (Bixio

et al., 2006). These require adequate treatment of the effluent in order to correspond

to quality obligations upon the intended use. A schematic description of the

applications is shown in Figure 3.1 (Asano, 1989).

FIGURE 3.1: WATER REUSE APPLICATIONS (Asano, 1989)

Water reuse can be direct or indirect. In recent years it has attracted more and more

interest in the indirect reuse field even for indirect potable use (Leverenz et al., 2011).

In the first case, water is reclaimed from wastewater transported from the treatment

units for irrigation of agricultural land and recreational areas without the mediation of

natural water sources or other aquatic formations. In the second case, indirect water

reuse happens after the reclaimed water is mixed with surface or underground water

resources that can be used as drinking water sources (Leverenz et al., 2011).


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The improvements in technology for wastewater and drinking water treatment have

ensured that a range of new and emerging challenges from both microbial and

chemical contaminants are met. Hence, the indirect recycling developed in many

parts of the world for many years is demonstrated to be safe (UKWIR 2004).

Table 3.1 summarizes the fields for reclaimed water use and the applications that

treated water can have in these fields.

TABLE 3.1: CATEGORIES OF RECLAMATION AND REUSED WATER (USEPA, 2004)

Categories Characteristics

Agricultural use

Irrigation of food crops Other type of irrigation livestock, plant nurseries, lawn

Urban & Recreational use

Irrigation in areas open to the public: parks, schools, fountains, fire protection, cooling, toilet cleaning Irrigation in areas with limited access: golf courts, cemeteries, motorways Restricted use fishing, boating

Industrial use cooling, boiler feed, process water

Environmental use maintain / increase watercourses flow, strengthening natural wetlands, aquaculture, enrichment of underground aquifers

Domestic use garden irrigation, car washing, toilet flushing, cooling

Drinking use

Direct

Indirect mixing with surface or underground drinking water sources


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3.5 CASE STUDIES

The reuse of wastewater, particularly for irrigation, has been practiced for centuries

and seems to have originated from the ancient Greek civilizations (Angelakis et al.,

2005). In Europe, the use of sullage was a common practice in Germany since the

16th century (De Turk et al., 1978) and in England since the 18th century (Wolman,

1977). In USA the reuse of water was reported to have started in 1870 (Rafter, 1899).

In addition, increased interest in the use of recycled water for agricultural purposes

began to occur in developed countries during the decade 1980-1990 mainly due to

the capabilities and advantages that it presents. Table 3.2 shows some big scale

reclamation and reuse of wastewater projects in chronological order of development.

TABLE 3.2: WORLDWIDE WASTEWATER REUSE PROJECTS IN CHRONOLOGICAL ORDER FROM 1912-1989 (Angelakis et al., 1995)

Year Location Capacity

[m3/d]

Water Reuse Type

1912 Golden Gate Park,

San Francisco, USA

Landscape irrigation

Recreational ponds

(Metcalf & Eddy, 1991)

1926 Grand Canyon National

Park, Arizona, USA

Landscape irrigation

WC cleaning

Water cooling & heating

1929 City of Pomona, California,

USA

Landscape and garden irrigation

1942 City of Baltimore, Maryland,

USA

Cooling in metal and steel

industry (Bethlehem Steel

Company)

1960 City of Colorado springs,

Colorado,USA

Irrigation of golf courts, parks,

cemeteries & sidewalks

1961 Irvine Ranch Water District,

California,USA

60,000 Irrigation

Industrial use

WC cleaning in high buildings

1962 Soukra, Tunisia Irrigation of citrus fruits

Reduction of aquifer salinisation

1968 City of Windhoek,Namibia 21,000 Drinking water after mixing


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1969 City of Wagga Wagga,

Australia

10,000 Irrigation of public spaces

WC cleaning

1970 Sappi Pulp and Paper

group, Enstra,South Africa

Paper industry reuse

1975 Valley o river Salt, Arizona,

USA

10,000 Enrichment of aquifers with

effluents of secondary treatment

1976 Orange County Water

District,California, USA


direct injection (Nellor et al.,

1985)

1977 Dan Region Project,

Tel-Aviv, Israel


filtration ponds

1977 City of St. Petersburg,

Florida, USA

150,000 Irrigation of golf courts, parks,

school yards & public spaces

1984 Tokyo Metropolitan

Government, Japan

Large scale WC cleaning

1985 City of El Paso, Texas, USA 38,000 Enrichment of aquifers

1987 Monterey Regional Water

Pollution Control Agency

Monterey Wastewater,

California, USA

5,500 Irrigation of agriculture spaces

1989 Shoal haven Heads,

Australia

120,000 Irrigation of gardens

WC cleaning

1989 Consorci de la Costa Brava,

Girona,Spain

Irrigation of golf courts

The reclamation and reuse of wastewater seems to be a rapidly growing practice

mainly in arid and semi-arid regions. Similar projects of increased number and extent

are being programmed and implemented each year in several countries, particularly

in the U.S., Australia, Israel, Japan, the countries of the Maghreb and South Africa

(Paranichianakis et al., 2009).


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Because of its wealthy water resources and the existing differences between the

member countries, the EU has not particularly dealt so far with reclamation and reuse

water. However, the recent drought in Spain, Greece and other countries has posed

serious questions for the crucial issue of water recycling.

The most experienced country in reclamation and reuse of municipal wastewater is

the U.S.A. In the 70s, 216 million cubic meters of treated wastewater were annually

used (Asano & Tchompanoglous, 1991), while today this quantity has reached 555-

715 million cubic meters, which are distributed in more than 4,800 applications. Israel

has a similar experience (Fine et al., 2006), where it is estimated that 20% of the

needs are covered today with the use of reused wastewater. Moreover, Spain uses

recycled water for four types of uses: watering golf courses, irrigation of crops,

enhance aquifer of coastal areas to prevent the inflow of seawater and flow increase

of rivers in order to protect riverside ecosystems (Castro, 2010). In Italy today treated

wastewater is used to irrigate about 4000 hectares, whereas in Southern Italy the

irrigation areas that use untreated wastewater is undefined (Barbagallo, 2001).

Belgium is another example of water recycle for industrial purposes, as 38%

(expected 60% in near future) of the wastewater is used in industrial operations.

In the UK, treatment and recycling of waste water is limited. The recycled water is

used mainly to maintain river levels and protect their ecosystems. It is also used to

irrigate golf courses, parks and wash cars.

Figure 3.2 shows the geographic distribution of recorded water reuse projects in

conjunction with their capacity and reuse in applications. It is observed that the

majority of these projects are large scale (> 5∙106 m3/s) with applications in

agriculture.


27

FIGURE 3.2: WATER REUSE PROJECTS IN EUROPE (SIZE & APPLICATION) (Bixio, 2006)


28

4. WASTEWATER REUSE FRAMEWORK

A specific quality of water is required for every beneficial use of treated wastewater

effluent in order to minimize the potential public health risks and environmental

impacts. This ultimately determines the required treatment processes and

technologies to be implemented and the costs involved. Therefore, each type of

reuse requires special legislative criteria.

In recent years, the reclamation and reuse of wastewater effluents is a matter of

priority and one of the main activities of the water and wastewater managing bodies

at international, European and national level. Many countries in the developed world

and international organizations have established criteria for reclamation and reuse of

wastewaters effluents, including the U.S. (State of California), Israel, Australia, the

Food and Agriculture Organization of the UN (FAO), the World Health Organization

(WHO) and the Environmental Protection Agency of the USA (US EPA). However, it

is worth noting the absence of legislation in European Union on the required quality

for reuse of treated wastewater. A general reference to the issue is in the Directive

91/271 (EU, 1991) of the EU (Article 12 paragraph 1), while many European

countries have set their own criteria for the reuse of wastewater effluent.

The purpose of this chapter was to describe the established criteria for the reuse of

wastewater from countries and organizations within and outside the European Union.

Particular emphasis was given to cases in which the standards have been the basis

of several other criteria worldwide, such as the criteria by the World Health

Organisation, the State of California, the US EPA and Australia. Also, there are

comments on the prevailing trends and innovations in this field.


29

4.1 REGULATIONS BY INTERNATIONAL ORGANIZATIONS

At international level, Directives and/or regulations for reclamation and reuse of

wastewater effluents is based on two main "philosophies"; that of WHO, FAO and

World Bank and that of the State of California. These are currently used as standards

to establish criteria for the reuse of treated wastewater, even though they incorporate

basic differences and to some extent they are contradictory.

The revised guidelines by WHO (WHO, 2006) provide a new method of risk

assessment for public health and the environment by setting quality levels similar to

that used for drinking water. In addition, the revised guidance of the Environment

Agency of the United States (US EPA, 2004) and California (State of California, 2004)

give particular emphasis to uses such as irrigation, the underground aquifers

enrichment and indirect potable uses.

● WHO

In 1973, World Health Organization proposed the first criteria and treatment methods

for various water reuse applications. The criteria established for the crop irrigation,

have been characterised as particularly severe (100 FC/100 ml for unrestricted

irrigation) and were based on the philosophy of “zero risk” (WHO, 1973).

In 1989 the organization reviewed the directive and issued a new set of criteria,

mainly of microbiological quality that emphasized on the type of irrigated crops.

Irrigation is separated into two categories with the following limits (WHO, 1989):

∞ Unrestricted (crop irrigation, garden and recreational areas watering)

200 FC/100 ml


30

∞ Restricted (irrigation of crops not eaten raw).

1 helminth egg per litter

In addition, the WHO directive takes in account, for the first time, the methods of

wastewater treatment, the irrigation system and the exposed human groups. So, it

recommends additional specific precautions such as using special clothing, high

levels of hygiene, careful cooking, special washing facilities, control of human

exposure, promoting of sanitation (WHO, 1989).

In 2006, the Organization issued the third edition of the directives for safe wastewater

reuse that replaced the previous two editions (Table 4.1). The main purpose of the

new Directive is to protect the health of people that may come directly or indirectly in

contact with the treated water. In this direction, WHO developed further information

on issues relating with:

∞ Diseases of the population that contacts with the reclaimed wastewater

∞ Risk Analysis

∞ Risk managing strategies (quantification of safety measures)

∞ Chemical compounds in wastewater, whose acceptable limits are summarized in

Appendix F.

∞ Strategies for the implementation of the Directives

The current water quality parameter limits are described in Table 4.1 together with

the proposed application.


31

TABLE 4.1: DIRECTIVE LIMITS FOR MONITORING PARAMETERS FOR WASTEWATER REUSE IN

AGRICULTURE AND AQUACULTURE (WHO, 2006).

Activity / Exposure Water Quality Parameters

Agriculture E.coli per 100 ml Helminth eggs per litre

Unrestricted irrigation

Root crops 103 1

Leaf crops 104

Drip irrigation, high-growing crops 105

Restricted irrigation

Labour-intensive, high-contact agriculture 104 1

Highly mechanized agriculture 105

Septic tank 106

Aquaculture

Produce consumers

Pond 104 Not detected

Wastewater 105 Not detected

Excreta 106 Not detected

Workers, Local communities

Pond 103 No viable eggs

Wastewater 104 No viable eggs

Excreta 105 No viable eggs

For the establishment of the appropriate legislation to protect public health, experts

have defined specific levels of protection according to the type of exposure (health

based targets). These levels are based on the fact that any disease that results from

the use of reclaimed wastewater should not cause a "loss" greater than 10-6 DALYs

(Disability - Adjusted Life Years) per person per year, as shown in Table 4.2 (WHO,

2006).


32

TABLE 4.2: HEALTH-BASED TARGETS & HELMINTH REDUCTION TARGETS FROM WHO

Irrigation type Target for viral, bacterial

& protozoan pathogens

Microbial reduction target for

helminth eggs

Unrestricted 10-6

DALY per person per year 1 per litre

Restricted 10-6

DALY per person per year 1 per litre

Localized

(e.g. drip irrigation)

10-6

DALY per person per year Low-growing crops

1 per litre

High-growing crops

No recommendation


33

Finally, WHO proposes a series of measures to protect consumers, workers, their

families and local communities, as presented in Table 4.3.

TABLE 4.3: HEALTH BASED TARGETS FOR WATER REUSE BY WHO (WHO, 2006)

Exposed

group Hazard

Health-based

targets

Quality parameters Health protection

measures E.coli/100 ml Viable

trematode/l

Consumers,

workers & local

communities

Excreta-related

diseases

10-6

DALY

per person per

year

104

(consumers)

103

(contact)

Not detected

- Wastewater treatment -Excreta treatment -Health & hygiene promotion -Chemotherapy & immunization

Consumers

Excreta-related

diseases

10-6

DALY

per person per

year

104 Not detected

-Produce restrictions -Waste application timing -Depuration -Food handling -Produce washing/disinfection -Cooking foods

Foodborne

trematodes

Absence of

trematode

infections

Chemicals Tolerable daily intakes [CAC]

Workers & local

communities

Excreta-related

diseases

10-6

DALY

per person per

year

103

(contact)

-Access control -Use of protective equipment -Disease vector control -Intermediate host control -Access to clean drinking water & sanitation -Redusing vector contact

Skin irritants Absence of skin disease

Schistosomiasis Absence of schistosomiasis

No viable schistosome

eggs

Vector-borne

diseases

Absence of vector-borne disease


34

● US Environmental Protection Agency

The US EPA issued its first directive on the reuse of municipal wastewater in 1980.

The Directive was revised in 1992 and recently in 2004 in order to include more

information and the advanced technologies (US EPA, 2004).

US EPA revised Guidelines for Water Reuse published in 2004 contains updated

information on water use and water reuse practices in the United States (USEPA,

2004). The revised guidelines propose treatment processes, safety distances,

monitoring frequencies and define the limits of water quality parameters for each

intended use of the output (Tables 4.4-4.6). Faecal coliforms (FC) are adopted as

indicators to assess the microbiological quality of the treated wastewater and

concentration limits for BOD and turbidity are also set. Furthermore a minimum level

of disinfection for all purposes is recommended to avoid effects from accidental

contact.

Generally, for the majority of the applications the expected turbidity, TSS and pH are

2 NTU, 30 and 6-9, respectively, whereas BOD values vary due to the sensitivity

of each recipient (Tables 4.4, 4.5). As shown in Table 4.6 emphasis is given on the

categories related to indirect potable reuse taking into account the findings of recent

research studies which suggest groundwater recharge and surface water

augmentation with treated wastewater. As expected, these standards are very strict

with no detected coliforms, low turbidity ( 2 NTU) and mean pH values (6.5-8.5).


35

Reuse Category & Description

Treatment Reclaimed Water Quality

Reclaimed Water Monitoring Setback Distances

Urban Reuse

Unrestricted Secondary

(4)

Filtration(5)

Disinfection

(6)

pH=6.0-9.0 ≤10mg/l BOD

(7)

≤2 NTU(8)

No detectable faecal coliform/100ml

(9,10)

1mg/l Cl2 residual (min) (11)

pH – weekly BOD – weekly Turbidity – continuous Faecal coliform – daily Cl2 residual – continuous

50 ft (15 m) to potable water supply wells; increase to 100 ft (30 m) when located in porous media

(18)

Restricted Secondary

(4)

Disinfection(6)

pH=6.0-9.0 ≤30mg/l BOD

(7)

≤30mg/l TSS ≤ 200 faecal coliform/100ml

(9,13,14)


pH – weekly BOD – weekly TSS – daily Faecal coliform – daily Cl2 residual – continuous

300 ft (90 m) to potable water supply wells

100 ft (30 m) to areas accessible to the public (if spray irrigation)

Agricultural Reuse

Food Crops Secondary

(4)

Filtration(5)

Disinfection

(6)

pH=6.0-9.0 ≤10mg/l BOD

(7)

≤2 NTU(8)


(9,10)


pH – weekly BOD – weekly Turbidity – continuous Faecal coliform – daily Cl2 residual – continuous

50 ft (15 m) to potable water supply wells; increase to 100 ft (30 m) when located in porous media

(18)

Processed Food Crops Non-Food Crops

Secondary(4)

Disinfection

(6)

pH=6.0-9.0 ≤30mg/l BOD

(7)

≤30mg/l TSS ≤ 200 faecal coliform/100ml

(9,13,14)


pH – weekly BOD – weekly TSS – daily Faecal coliform – daily Cl2 residual – continuous

300 ft (90 m) to potable water supply wells

100 ft (30 m) to areas accessible to the public (if spray irrigation)

TABLE 4.4: SUGGESTED GUIDELINES FOR URBAN & AGRICULTURAL REUSE (USEPA, 2012)


36


Treatment Reclaimed Water Quality Reclaimed Water

Monitoring Setback Distances

Impoundments

Unrestricted

Secondary

Filtration

Disinfection

pH=6.0-9.0

≤10mg/l BOD

≤2 NTU


1mg/l Cl2 residual (min)

pH – weekly

BOD – weekly

Turbidity – continuous

Faecal coliform – daily

Cl2 residual – continuous

500 ft (150 m) to potable water supply wells (min) if bottom not sealed.

Restricted Secondary

Disinfection

≤30mg/l BOD

≤30mg/l TSS

≤ 200 faecal coliform/100ml


pH – weekly

TSS – daily



500 ft (150 m) to potable water supply wells (min) if bottom not sealed.

Environmental Reuse

Environmental Reuse Variable

Secondary and disinfection(min)

Variable, but not to exceed:

≤30mg/l BOD

≤30mg/l TSS



BOD – weekly

SS – daily



Industrial Reuse

Once-through Cooling Secondary

pH=6.0-9.0

≤30mg/l BOD

≤30mg/l TSS



pH – weekly

BOD – weekly

TSS – daily



300 ft (90 m) to areas accessible to the public.

Recirculation cooling towers

Secondary

Disinfection (chemical

coagulation and filtration may be needed)

Variable, depends on recirculation ratio:

pH=6.0-9.0

≤30mg/l BOD

≤30mg/l TSS



300 ft (90 m) to areas accessible to the public. May be reduced if high level of disinfection is provided.

Groundwater Recharge – Nonpotable Reuse

Site specific and use dependent

Primary (min.) for spreading

Secondary (min) for injection

Site specific and use dependent

Depends on treatment and use Site specific

TABLE 4.5: SUGGESTED GUIDELINES FOR ENVIRONMENTAL & INDUSTRIAL REUSE (USEPA, 2012)


37


Treatment Reclaimed Water Quality

Reclaimed Water Monitoring Setback Distances

Indirect Potable Reuse

Groundwater Recharge by Spreading into Potable Aquifers

Secondary

Filtration

Disinfection

Soil aquifer treatment

Includes, but not limited to, the following:

No detectable total coliform/100ml

pH=6.5-8.5


pH=6.5-8.5

≤2 NTU

≤2 mg/l TOC of wastewater origin

Meet drinking water standards after percolation through vandose zone


pH – daily

Total coliform – daily


Drinking water standards – quarterly

Other – depends on constituent

TOC – weekly


Monitoring is not required for viruses and parasites: their removal rates are prescribed by treatment requirements

Distance to nearest potable water extraction well that provides a minimum of 2 months retention time to the underground.

Groundwater Recharge by Injection into Potable Aquifers

Secondary

Filtration

Disinfection

Advanced wastewater treatment



pH=6.5-8.5


pH=6.5-8.5

≤2 NTU

≤2 mg/l TOC(7)

of wastewater origin

Meet drinking water standards


pH – daily

Total coliform – daily


Drinking water standards – quarterly

Other – depends on constituent

TOC – weekly


Monitoring is not required for viruses and parasites: their removal rates are prescribed by treatment requirements

Distance to nearest potable water extraction well that provides a minimum of 2 months retention time to the underground.

Augmentation of Surface Water Supply Reservoirs

Secondary

Filtration

Disinfection

Advanced wastewater treatment



pH=6.5-8.5


pH=6.5-8.5

≤2 NTU

≤2 mg/l TOC(7)

of wastewater origin

Meet drinking water standards

Site specific – based on providing 2 months retention time between introduction of reclaimed water into a raw water supply reservoir and the intake to potable water treatment plant.

TABLE 4.6: SUGGESTED GUIDELINES FOR INDIRECT POTABLE REUSE (USEPA, 2012)


38

4.2 REGULATIONS BY THE STATE OF CALIFORNIA

Today, the applicable criteria in the state of California include four categories of

recycled water quality (Table 4.7) (State of California, 2003). The criteria for reuse

apart from the determination of limits of pathogens, the turbidity and the processes

requirements include standards for the reliability of the treatment.

These standards indicate backup power and security systems, multiple or redundant

process units, storage or disposal of treated wastewater in emergency situations,

advanced monitoring mechanisms and automation functions. Furthermore the

proposed additions to the reuse criteria include the following distance security

requirements (State of California, 2003):

i. Irrigation is prohibited with wastewater discharges which have not been

disinfected within 50 m of any drinking water wells,

ii. The accepted distance for secondary treatment effluents which have not been

disinfected is 30 m,

iii. The accepted distance or tertiary treatment effluents (secondary, filtration and

disinfection) the distance should be 15 m and finally;

iv. The storage of treated wastewater that has been under tertiary treatment is

prohibited in less than 30 m from residences or places, where the risk of

accidental exposure is high.

(State of California, 2003)


39

TABLE 4.7: CALIFORNIA’S TITLE 22 PATHOGEN LIMITS (State of California, 2003)

Water Quality Total Coliform [MPN]

Disinfected Tertiary recycled water < 2.2 per 100 ml

Disinfected Secondary – 2.2 recycled water 2.2 -23 per 100 ml

Disinfected Secondary – 23 recycled water < 23 per 100 ml

Direct beneficial Use (no disinfection) -

Other space control measures include the reduction of runoffs while using recycled

water, the protection of recreational places of human contact, the placement of

warning signs like: "Recycled water–Non potable" and others.

The state of California has also established criteria of the enrichment of underground

aquifers (directly and indirectly) with treated wastewater since 1974, which were

recently revised. More details on the allowable uses for recycled water according to

the State of California can be found in Appendix G.

FIGURE 4.1: CALIFORNIA’S WARNING SIGN FOR RECYCLED WATER (State of California, 2003)


40

4.3 REGULATIONS BY OTHER COUNTRIES

4.3.1 EUROPEAN COUNTRIES

One of the major factors that have limited the reuse of wastewater in Europe and

especially in the Mediterranean region is the absence of a unified, international or

even regional, legislative framework. Noteworthy is the absence of legislation on the

reuse of treated wastewater in the EU as the only reference which is quite generic

was made in Directive 91/271/EC where in Article 12, § 1 states that " treated

wastewater should be reused whenever appropriate” (EU, 1991). Specifically for the

European Countries, one other important aspect for the lack of unified framework is

the variations in the availability of water resources and their uses in the northern,

central and southern parts.

However, the reuse of treated wastewater for irrigation is already a widely applied

practice, especially in Mediterranean countries. Most of these countries, promote the

establishment of criteria, but often not in the form of specific, national law, but with

the form of guidelines. Table 4.8 summarises the water reuse trends and the criteria

in several European countries, whereas Table 4.9 indicates the specific criteria in the

countries where there is an existing framework.


41

TABLE 4.8: WATER REUSE PRACTICES & CRITERIA IN EUROPEAN COUNTRIES (Angelakis et al., 2002)

Country

Urban

use

Unlimited

Agricultural &

Industrial use

Restricted

Agricultural

use

No

Recycling

Established

Criteria

Criteria

pending

No

Criteria

Albania

Belgium

Croatia

Cyprus

France

Greece

Italy

Malta

Monaco

Spain 1

UK

1: Only in certain regions (Andalucía, Balearic & Catalonia)

TABLE 4.9: EXISTING WATER REUSE CRITERIA IN EUROPEAN COUNTRIES (Bixio et al., 2006)

Country Type of Criteria Notes

Belgium Aquafin proposal to the Government (2003)

Based on Australian EPA Guidelines

Cyprus Provisional Standards

TC < 50/100 ml in 80% of the

cases on a monthly basis and < 100/100

ml always

France Art. 24 décret 94/469 3 1994 Circulaire DGS/SD1.D./91/n°51

Based on WHO standards

Italy Decree of Environmental Ministry 185/2003

-

Regional authorities: Sicily, Emilia Romagna & Puglia

Guidelines Based on WHO standards and Title 22,

respectively

Spain Law 29/1985, BOE n.189, 08/08/85 Royal Decree 2473/1985

Based on California’s Title 22

Regional authorities: Andalucía, Balearic & Catalonia

Guidelines Based on WHO standards


42

In the UK, British Standards has published BS8525-1: 2010 for greywater systems.

These recently published standards provide tables with the water quality

requirements for reuse purposes and include guidelines for the designing, the

implementation and the maintenance of greywater treatment systems. Table 4.10

describes these water quality requirements.

TABLE 4.10: EXISTING WATER REUSE CRITERIA IN THE UK (BSi, 2010)

Parameter Spray application Non-spray application

Escherichia coli /100 ml Not detected 250

Intestinal enterococci/ 100 ml Not detected 100

Legionella pneumophila / 100 ml 10 N/A

Total coliform / 100 ml 10 1000

Turbidity [NTU] <10 <10

pH 5-9.5 5-9.5

Residual chlorine [mg/l] <2 <2

Residual bromine [mg/l] 0 <5

4.3.2 OTHER COUNTRIES

In addition to all the above mentioned legislation which exists in Europe at local level,

other countries have established strict water reuse criteria in order to enhance water

reclamation techniques in them.

● Australia

Since 1984, the Environmental Policy Agency of the State New South Wales (NSW)

has established a council to develop guidelines and promote the reclamation and

reuse of treated wastewater. Recent studies estimate that in the area of Sidney

approximately 1.3 Mm3/d are being treated of which 0.031 Mm3/d are being reused

(NSW, 2008).


43

The initial Australian EPA guidelines provided criteria for three categories of reuse of

secondary treated water after disinfection for agricultural and industrial use, with the

following quality criteria:

i. Category A: < 300 cfu/100 mL FC, after 30 days storage

ii. Category B: <750 cfu/100 mL FC , after 20 days storage

iii. Category C: <2.000 cfu/100 mL FC, after 10 days storage

A couple of years later, the same organization established criteria for urban and

unlimited use of wastewater effluents, with the following qualitative characteristics:

FC <1/100 mL, TC <10/100 mL, viruses <5/50 L, parasites <1/50 L (NSW, 2008).

● Japan

In Japan, unlike other countries in arid or semi-arid areas, the main categories in

wastewater reuse are based on the enhancement of the environment, toilet cleaning,

industrial use and snow production (Nagasawa, 2009). The quality requirements

seem to be strict (Table 4.11) as they are the same for all reuse purposes (Jefferson

et al., 1999).

TABLE 4.11: REUSE CRITERIA IN JAPAN (Jefferson et al., 1999)

Total coliforms/

100 ml

Faecal coliforms/ 100

ml

BOD5

[mg/l] Turbidity [NTU] pH

< 10 < 10 10 5 6-9


44

5. WASTEWATER TREATMENT FOR REUSE

The urban wastewater belongs to the broader category of wastewaters. Wastewater

is characterised by types of water which has undergone a change of physical,

chemical and biological properties due to human activities (Metcalf & Eddy, 1991). It

is therefore impossible to be used for the same purposes because it may cause

adverse health or environmental problems. Wastewaters can be defined according to

their origin, in the following categories (Metcalf & Eddy, 1991); Domestic

wastewater (from residential areas that mainly comes from household activities and

functions of the human organism, Commercial wastewater (from commercial

activities, such as restaurants and hotels), Industrial wastewater (from premises

used for any industrial or commercial activity), Surface water runoff (Rainwater

along with the road materials).

This project focuses in the case of reclamation and reuse of greywater, which is part

of domestic wastewater. Greywater has considerable advantages in that it is a large

resource of low organic content (Pidou, 2007).

The growing importance given to the protection and conservation of water resources

has led to the development and implementation of wastewater treatment techniques,

from which the uncontrolled disposal is one of the main causes of water resources

degradation. The particular conditions of each region (temperature, climate), the

nature of wastewater (high or low load, with or without toxic substances) and the

problems encountered in the implementation of various methods led to the

development of various wastewater treatment systems.


45

The purpose of wastewater treatment is to return the water in nature with acceptable

quality characteristics that are compatible with the desired uses, in order to protect

public health and natural ecosystems, preserve the environment and avoid depletion

of water resources, which despite their apparent abundance, are not inexhaustible in

front of the growing human population and multiple needs (Metcalf & Eddy, 1991).

The following figure (5.1) demonstrates that wastewater reclamation technologies

have progressed to such an extent, that the produced treated water can be of higher

quality than that of drinking water .

FIGURE 5.1: TREATMENT TECHNOLOGIES FOR ANY TYPE OF REUSE (USEPA, 2012)


46

5.1 WASTEWATER FOR REUSE – GREYWATER

Understanding the wastewater nature is a key parameter in the sizing, configuration

and operation of environmental engineering systems for the collection, treatment and

disposal of used water.

Greywater is a “reflection of the household activities and its characteristics are

strongly dependent on living standards, social and cultural habits, number of

household members and the use of household chemicals” (FBR, 2013). One of the

most interesting and understandable approaches of greywater nature was made by

Prof. Cedo Maksimovic (2012), which illustrated that greywater consists of bath,

shower, washing machine and dishwasher discharges (Figure 5.2), whereas,

blackwater consists of wastewater from toilets and kitchen sinks.

FIGURE 5.2: SOURCES OF HOUSEHOLD WASTEWATER (Maksimovic, 2012)


47

In addition, greywater is divided in two categories according to its load, as high load

greywater needs a different type of treatment than low load greywater. Figure 5.3,

describes the two types of greywater loading.

FIGURE 5.3: GREYWATER CATEGORIES (FBR, 2013)

Specifically, greywater corresponds to up to 70% of the total domestic consumed

water (44% in the UK) but contains only 30% of the organic fraction and 9-20% of the

nutrients (Pidou et al., 2007). However, greywater has several other characteristics,

considering the quantity and quality, which are described further in the following

section (5.1.1).


48

5.1.1 GREYWATER CHARACTERISTICS

The quantity of greywater discharged from households in the UK is calculated by the

British Standards (2010) with the use of “Water Efficiency Calculator” developed by

the Communities and Local Government (CLG). This tool determines easily the

average greywater yield and the demand for the sizing of treatment plants. Below,

Table 5.1 provides some typical greywater quantities linked with certain occupancies

that may describe from single households to small towns.

TABLE 5.1: AVERAGE GREYWATER YIELD & DEMAND (BSi, 2010)

Occupancy Yield [litres] Demand

WC Laundry Other uses 1

1person 50 25 15 10

2 people 100 50 30 20

4 people 200 100 60 40

8 people 400 200 120 80

10 people 500 250 150 100

15 people 750 375 225 150

20 people 1,000 500 300 200

30 people 1,500 750 450 300

50 people 2,500 1,250 750 500

100 people 5,000 2,500 1,500 1,000

150 people 7,500 3,750 2,250 1,500

200 people 10,000 50,000 3,000 2,000

500 people 25,000 12,500 7,500 5,000

1000 people 50,000 25,000 15,000 10,000

10000 people 500,000 250,000 150,000 100,000

1: For instance, garden watering or car washing


49

As far as greywater quality is concerned, the main polluting parameters are:

Suspended Solids (TSS) - Organic load (COD, BOD5) - Nitrogen and Phosphorus

compounds - Dissolved solids (DS) and the microbes (coliforms, bacteria, viruses,

protozoa). Table 5.2, summarizes the physicochemical characteristics of greywater,

as found in literature (Metcalf & Eddy, 1991).

TABLE 5.2: SUMMARY OF GREYWATER CHARACTERISTICS (Metcalf & Eddy, 1991)

Parameters Units Value

pH - 6.4 - 8.1

Conductivity μC/cm 82 - 1845

Turbidity NTU 0 - 240

TSS mg/L 48 - 435

Raw COD mg/L 100 – 795

Filtered mg/L 82 – 472

DO mg/L 0 – 176.9

BOD5 mg/L 50 – 539

NT mgN/L 3.8 – 17

PT mgP/L 0.1- 2

Anionic Surfactant mg/L LSS 9 – 86

E.Coli CFU/100 mL 0 – 2.51∙107

Fecal Enterococci CFU/100 mL 0 – 2.51∙105


50

5.2 GREYWATER TREATMENT STAGES

The main stages of greywater treatment are (Darakas, 2010):

Pre-treatment in which materials, such as cloths, gravels, sand particles,

small pieces of wood or plastic, oil, grease, etc. are being removed because

they usually cause damage to the mechanical equipment and problems in the

maintenance/operation of the system.

Primary treatment in which part of the suspended solids and organic

substances are being removed.

Secondary treatment in which the biodegradable organic substances, the

suspended solids and the nutrients (nitrogen and phosphorus) are being

removed with the use of biological and chemical processes. Noted that

disinfection is also included in the standard definition of conventional

secondary treatment.

Tertiary treatment in which the remaining suspended solids from the

secondary treatment are being removed, typically using filtration means.

Advanced treatment for the removal of suspended and dissolved

substances of the waste those remain after the usual biological treatment

when this is required in various applications of water reuse.


51

Research on greywater treatment and reuse has been observed in literature since

1970 (Hall et al., 1974; Hypes et al., 1975; Arika et al., 1977). The primary

technologies investigated were physical based treatment schemes, such as coarse

filtration and membranes, usually followed by disinfection. These technologies were

implemented and tested years later, initially in single houses (Brewer et al., 2000).

Between 1990-2000 more advanced biological treatment options were studied for

greywater treatment, such as rotating biological contactors (Nolde, 1999), biological

aerated filters (Surendran and Wheatley, 1998) and aerated bio-reactors (Shin et al.,

1998; Brewer et al., 2000). Later researches have suggested the use of more

complex technologies like membrane bioreactors (MBRs) (Friedler, 2005; Liu et al.,

2005) and in lieu of these expensive options, natural treatment systems such as

constructed wetlands (Shrestha et al., 2001; Dallas et al., 2004; Gross et al., 2007).

As far as chemical based greywater treatment options are concerned, only three are

mentioned in literature; conventional coagulation (Sostar-Turk, 2005), electro-

coagulation (Lin et al., 2005) and photocatalysis (Parsons et al., 2000).

The choice of the appropriate treatment highly depends on the reuse application and

the influent flow rate. Overall greywater treatment systems can be categorised

according to their treatment type as follows (Pidou, 2007):

● Basic systems (coarse filtration, sedimentation and disinfection)

● Physical systems (sand filter, adsorption and membranes)

● Biological systems (biological aerated filter, rotating biological contractor

and membrane bioreactor)

● Chemical systems (conventional coagulation, electro-coagulation and

advanced oxidation methods)

● Extensive systems (ponds and reed beds)


52

In the extensive systems physical, chemical and biological processes take place. The

main distinction is that treatment in extensive systems flows naturally, thus in slow

velocities, whereas in conventional systems treatment is being done rapidly, because

of the imposed artificial conditions.


53

5.2.1 BASIC SYSTEMS

Basic greywater treatment systems provide elementary level of treatment for not

demanding water reuse applications. Usually basic systems are preferred in small

scale projects, such as a house or a limited number of houses. They are generally

two-phase systems based on coarse filtration or sedimentation, coupled with

disinfection (Figure 5.4, 5.5). According to literature these systems are not as

efficient as the average removal of pollutant indicators (Darakas, 2010).

TSS: 40-50% COD: 70% BOD5: 25-30% Turbidity: 50%

● Coarse Filtration

The purpose of coarse filtration is the removal of the sizeable materials or particles

that greywater may contain (sand, pieces of wood, plastic, branches, rags, etc.), in

order to eliminate the suspended solids. However, it provides only a restricted

treatment in terms of organics and solids (Pidou, 2007). Nevertheless, it is a simple

filtration system which can be easily installed in households by anyone with even

limited DIY skills.

FIGURE 5.4: TYPICAL FLOW DIAGRAM OF BASIC SYSTEM – COARSE FILTRATION (Pidou, 2007)


54

● Sedimentation

The aim of sedimentation is to separate the substances that float and the ones that

precipitate from greywater (Metcalf and Eddy, 1991). It is a physical separation

process of the suspended particles based on gravity, of which the specific weight is

greater than that of water (d>100 μm and C>50 mg/L). The widespread

implementation of sedimentation systems is due to the simplicity of the method,

despite the complications often occurred in sedimentation tanks, and the low energy

consumption.

FIGURE 5.5: TYPICAL FLOW DIAGRAM OF BASIC SYSTEM – SEDIMENTATION (Pidou, 2007)


55

5.2.2 PHYSICAL SYSTEMS

Physical schemes for greywater treatment can be classified in two groups; sand

filters and membranes. Sand filters can be applied alone or together with adsorption

techniques, with or without disinfection (Hypes et al., 1975; Pidou, 2007).

● Sand Filters

Sand filters are used for the removal of suspended particles, turbidity and bacteria

from greywater. The basic principle of filtration through a bed of sand (and in some

cases a combination of sand and anthracite) is already adopted by nature (Darakas,

2010). Sand filters usually offer high speeds of filtering and can have an increased

lifetime when properly maintained through frequent backwashing. Thus, their

implementation has low operation and maintenance costs (Pidou, 2007).

However, when used alone sand filters offer coarse filtration, which means weak

treatment levels, so they are often combined with disinfection (Hypes et al., 1975).

Hypes et al. (1975) reported good removal of total coliforms but inadequate removal

of suspended solis and turbidity. The addition of an adsorption technique, like

activated carbon, interestingly may not provide considerable improvement to the

results (Pidou et al., 2007). A typical flow diagram of a sand filter system is illustrated

in Figure 5.6 below.

FIGURE 5.6: TYPICAL FLOW DIAGRAM OF PHYSICAL SYSTEM – SAND FILTER (Pidou, 2007)


56

● Membranes

The application of membranes in advanced water and wastewater treatment is a new

and promising technology in that it is increasingly attracting interest from

environmental researchers. The main disadvantage of this technology is the high

cost and energy consumption. Despite this, literature shows surprisingly positive

results (Tsonis, 2004), concerning the efficiency of the method (Table 5.3):

TABLE 5.3: REMOVAL OF VARIOUS COMPONENTS USING MEMBRANES (Tsonis, 2004)

Parameters MF UF NF RO

Biodegradable Organic Compounds -

TDS - -

TSS - -

Heavy Metals - -

Hardness - -

Nitric ions - -

Synthetic Organic Compounds - -

Priority Organic Compounds -

Bacteria

Protozoa, Helminth eggs

Viruses - -

Membranes are usually made of cellulose acetate (rayon) or proprietary polymers

such as polyamides (Judd and Jefferson, 2003). Each membrane presents best

performance values in a certain range of temperature, pH and qualitative

characteristics of the liquid, which requires experimental data for the selection. In

Figure 5.7, a flow diagram of a typical membrane physical treatment is illustrated,

where MF, UF, NF or RO membranes can be implemented.


57

FIGURE 5.7: TYPICAL FLOW DIAGRAM OF PHYSICAL SYSTEM – MEMBRANES (Pidou, 2007)

The main advantages of using membrane technologies for greywater treatment are

the excellent removal capacity of dissolved and suspended solids and the good

removal of organic compounds. On the other hand, limitations in membrane

implementation include the high operation and maintenance costs, which are mainly

due to the large energy consumption needed to achieve the required overpressure,

the demands for regular replacement or cleaning of the membranes and the disposal

of the produced concentrate (Sostar-Turk, 2005; Pidou, 2007).


58

5.2.3 CHEMICAL SYSTEMS

As far as chemical based treatment options are concerned, only three are mentioned

in literature for greywater reuse.

● Coagulation - Electro coagulation

Chemical coagulation in wastewater treatment is the process in which flocculants of

the suspended matter are created in colloidal dimensions. This process is necessary

in order to allow the precipitation of these substances which precipitate with a very

slow pace because of their small size (10-3

μm – 1 μm). Therefore the flocculants

generated during the process, which are larger and denser, facilitate and accelerate

sedimentation alongside easing filtration (Gregory, 2013).

Sostar- Turk (2005), proposes coagulation coupled with a sand filter and activated

carbon for the treatment of high load greywater, with impressive results in the

removal of suspended solids (100%) and satisfying removal of COD and BOD, 93%

and 95% respectively. These results can be found in more detail in the summarised

tables in Appendix C.

FIGURE 5.8: TYPICAL FLOW DIAGRAM OF CHEMICAL SYSTEM – COAGULATION (Darakas, 2010)


59

The electrochemical flocculation or electro coagulation is an advanced and efficient

electrochemical technology for removal of organic and inorganic contaminants from

wastewaters (Lin et al., 2005). This method differs from the conventional chemical

coagulation in the fact that the coagulants (Al(OH)3, Fe(OH)3 and Mg(OH)2) are not

added into the wastewater but are being generated in situ due to electro dialysis of

the anodes of Al, Fe or Mg (Tsonis, 2004). This method has been tested for low load

greywater in Taiwan by Lin at al. (2005), showing good levels of treatment.

● Photocatalysis

Photocatalysis (PCD) is an advanced oxidation method which is becoming

increasingly important in wastewater treatment especially in cases when greywater

contains small quantities of refractory organic substances (Mills et al., 1997). This

method is based in the ability of the UV light to extract constantly electrons from TiO2

and create pairs of holes (h+) and electrons (e) that with the combination of water

create hydroxyl radicals (OH-). Hydroxyl radicals are one of the most powerful

oxidants, which react and degrade all harmful organic compounds in greywater

(Tsonis, 2004). This technique can be applied in special photobioreactors installed in

greywater treatment plants. A detailed flow diagram is illustrated in Figure 4.8.

Parsons (2004) tested the efficiency of a bench scale system that used

photobiorector (TiO2/UV) that showed interesting findings which can be found in

Appendix C.


60

FIGURE 5.9: TYPICAL FLOW DIAGRAM OF CHEMICAL SYSTEM – PHOTOBIOREACTOR

(Parsons, 2004)


61

5.2.4 BIOLOGICAL SYSTEMS

There are a variety of biological based treatment schemes for greywater as these

seem to achieve a very good treatment level with an exceptionally good removal of

organic compounds (Pidou et al., 2007). Each biological system meets differently the

performance and cost requirements, as according to the desirable scale simple

biological systems or more advanced ones can be chosen. Systems such as

membrane bioreactors (MBRs), sequencing batch reactors (SBRs), fixed film

reactors, rotating biological contractors, anaerobic filters and biological aerated filters

(BAFs) have already been reported in literature for greywater treatment. These

systems are usually coupled with other treatment options (disinfection,

sedimentation, and screening) in order to meet the quality demands (Pidou, 2007).

Pidou et al. (2007) in their publication, state that biological systems are “the type of

treatment most commonly seen” in big scale treatment projects. In fact, these

schemes have been reported to treat greywater generated in multi-storey buildings

(Nolde, 1999) and student accommodation (Brewer, 2000).

This Section demonstrates the three most applied systems, as these seem to be very

promising and differ significantly among them.


62

● Sequencing Batch Reactor (SBR)

This system, which can also be applied to large settlements, is particularly attractive

in the case of small settlements, because of its simplicity and its ability to respond

very well to flow and pollutant load frequent fluctuations (MEECC, 2012). The system

is characterised by the high level of organic load removal, which can exceed 95%

(Shin et al., 1998).

One of the main features of the system is the combination, in a common reservoir, of

activated sludge bioreactor functions and these of secondary sedimentation. An SBR

has three basic alternating operating phases (2, 3, and 4) as demonstrated in Figure

5.10. The main difference with a conventional activated sludge system lies in the fact

that in the SBR reactor the distinction of biochemical reactions and sedimentation is

not spatial but temporal (Darakas, 2010).

FIGURE 5.10: TYPICAL FLOW DIAGRAM OF BIOLOGICAL SYSTEM – SBR (MEECC, 2012)


63

The main advantages of this system are (Shin et al., 1998; Darakas, 2010):

Good removal of organic load expressed as BOD5.

Satisfactory removal of nitrogen and phosphorus.

Small area requirement.

Relative simplicity of the system. Absence of sedimentation tanks, pipes for

handling wastewater and pump stations.

Minimum staff requirement, because operation phase is easily automated.

Sludge bulking problems are almost nonexistent, and in any case can be

easily controlled.

The main disadvantages of an SBR are:

High construction and operation costs (generally lower than conventional

activated sludge and extended aeration systems).

High energy consumption.

Advanced electrical equipment and automation systems.

Construction of equalization tank.


64

● Membrane Bioreactors (MBRs)

Membrane Bioreactors is a relatively recent development in the field of wastewater

treatment. This method is essentially a combination of the classical and widespread

method of activated sludge with filtration (MF or UF), thus eliminating the use of

sedimentation tank as a means of final effluent clarifier and sludge condenser

(MEECC, 2012).

Specifically, the novelty of the method lies in the use of special new technology

membrane films which are submerged in the stream and through which the influent is

moving (Darakas, 2010). The flow diagram of the bioreactor is presented below in

Figure 5.11.

The high concentration of biomass in the bioreactor, results in the accomplishment of

full decomposition of the organic matter (small amount of excess sludge) and

nitrification within 3 hours. The method can be an autonomous process, after a

simple pretreatment, as literature provides very promising results about the efficiency

of the system.

FIGURE 5.11: TYPICAL FLOW DIAGRAM OF BIOLOGICAL SYSTEM – MBR (MEECC, 2012)


65

MRB presents the following advantages (MEECC, 2012):

High outflow quality (removal of organic load expressed as BOD5 > 95%).

Presents no problems of sludge sedimentation

Reduced volume system requirements

Works perfectly even as a decentralized wastewater treatment system with

great flexibility depending on the population served

Needs limited but skilled personnel

It can fit perfectly with the natural environment

Causes minimal disturbance

Among the major drawbacks of MBR are (MEECC, 2012):

High fixed costs of membranes

High operating costs (due to the need of regular membrane replacement)

Limited application (relatively modern technology)

Require delicate screening upstream of the membranes to avoid fouling

problems

Requires an equalization tank


66

● Rotating Biological Contactors (RBCs)

Rotating biological contactor is a system that combines many of the advantages of

traditional activated sludge systems (small area requirement) and these of biological

filters (simplicity of operation, low operational costs). The rotation of the biological

discs provides effective ventilation and sufficient contact with the effluent and

biomass so as to achieve high organic load removal and in some cases nitrification

(Darakas, 2010).

FIGURE 5.12: TYPICAL FLOW DIAGRAM OF BIOLOGICAL SYSTEM – RBC (MEECC, 2012)

An RBC has the following advantages:

High removal of organic load

Small area requirement

Simplicity of operation

Low operating cost

Easy biomass and effluent separation

Stability of both hydraulic and organic load fluctuations

System flexibility

Denitrification potential using appropriate devices


67

The main disadvantages of RBCs are:

May encounter operational problems, mainly in the support and rotating

mechanism of the filters

Require to be combined with sedimentation tanks

Odour problems

Appendix D includes a detailed table with the performance data of the biological

based systems found in literature.


68

5.2.5 EXTENSIVE SYSTEMS

Extensive or natural systems for greywater treatment make use of different

physical, chemical and biological processes that occur in nature. All of these

processes in natural systems take place in an "ecosystemic" reactor (Tsonis,

2004). One of the main characteristics of these systems is the low velocities of

biochemical processes (which in any case are lower than that of the mechanical

systems). As seen in literature, the most common practice for greywater

treatment in extensive systems is constructed wetlands, such as reed beds and

ponds (Shrestha et al., 2001; Dallas et al., 2004; Gross et al., 2007). Extensive

systems are commonly used in low flow rates.

● Reed beds

These systems are usually soils flooded with an amount of shallow water (<0.6 m), in

which specific flora is being cultivated for treatment reasons. There is a variety of

plants that may be used for this process in reed beds such as Phragmites australis

(Shrestha et al., 2001), Coix lacryma-jobi (Dallas et al., 2004) and many other

hydrophilic species.

The vegetation is the substrate for the bacteria growth that assists in filtering and

adsorbing the components of waste, transports the oxygen in the water mass and

reduces the growth of algae by controlling the amount of solar radiation (Darakas,

2010). Both artificial and natural wetlands are used for greywater treatment.

Reed beds are a simple and effective solution for small treatment units, to serve even

until 2,000 inhabitants, when the required output has low organic load (BOD5 <5mg /

l) and solids (TSS <10mg /l).


69

The advantages of reed beds are summarised below (Tsonis, 2004):

Low construction, operation and maintenance costs

Resistance in hydraulic and pollution load fluctuations

Easy to customise it with the surrounding ecosystem and aesthetics of the area

Enhances “green” technology

Some disadvantages include:

Low nitrogen and phosphorus removal.

Odour and insect problems.

Large areas requirement

Strong dependence on climatic factors

Inability to treat greywater with high organic load.

● Ponds

The most common natural scheme for greywater treatment systems are the systems

of artificial ponds (Gross et al., 2007). It is usually earthen basins used for the

treatment of municipal sewage and rarely for industrial wastewater. Ponds are

classified depending on the frequency of evacuation they undergo. Despite this

classification, they are divided in categories according to their depth and biological

processes (Tsonis, 2004). So, ponds may be aerobic, anaerobic or aerated.

The advantages of artificial ponds are (Tsonis, 2004):

The low manufacturing and operation costs.

The possibility to adjust the effluent flow rate.

The stability in the fluctuations of the organic load, due to dilution.


70

The disadvantages of ponds are:

Requirement for large areas.

Possible odours (especially where anaerobic decomposition takes place).

The high concentration of suspended solids in the effluent (due to high

concentrations of algae) (Gross et al., 2007).

Strong dependence on climatic factors.

A typical flow diagram of constructed wetlands is shown in Figure 5.13 and a detailed

table with the literature findings on the performance of these systems in included in

Appendix E.

FIGURE 5.13: TYPICAL FLOW DIAGRAM OF EXTENSIVE SYSTEMS–CONSTRUCTED WETLANDS

(Pidou, 2007)


71

5.3 DISCUSSION

The literature review indicates that sand filters and simple technologies have been

shown to attain a limited treatment of the greywater, whereas membranes have been

reported to provide great elimination of the solids but could not deal with the organic

fraction efficiently. On the other hand, extensive and biological schemes can

accomplish a reliable general treatment of greywater with a significant removal of the

organics. However, the most proficient by and large performances were reported

within the schemes that combined different approaches to guarantee efficient

treatment of all the fractions. Finally, all the above technologies cannot be completely

evaluated without an investigation of their economic feasibility, which can be found in

the next chapter.


72

6. WATER REUSE & COSTS

In a period when energy and financial resources are limited, an engineer or

otherwise the decision maker should, in the context of sustainable development,

select technical solutions that meet the environmental and social constraints, have

lower energy requirements and minimum cost.

As part of the effort to achieve the environmental and social goals, the engineer can

choose between a variety of technological schemes, as analysed in Chapter 5. The

range, however of this choice is restricted, by several factors, of which the most

important is cost.

The aim of this Chapter was to provide a comparative evaluation of the total costs

(construction, operation and maintenance) of some of the most important greywater

treatment systems, suitable for a range of units (from domestic to municipal) and

costs of wastewater treatment plant that may implement these technologies. The

findings of this Chapter followed a long term literature research and communication

with wastewater treatment companies and specialists.

This Chapter can be useful for the preliminary assessment of these systems, but also

constitute the basis for estimates and other options.


73

6.1 CAPITAL COSTS

The most important elements of the capital costs for a wastewater treatment plant for

reuse can be broadly categorised as follows (NRC, 2012):

Plant type, size and location

Tanks and other structures of concrete or steel

Equipment installed

Buildings and insulation

Transmission and pumping

Electromechanical equipment and control systems

The first five elements generally correspond to 85% of the total capital expenditures

(Andreadakis et al., 1992). However, the structure costs together with the building

and insulation costs are not included in this study as the study focuses on the

treatment costs.


74

6.1.1 COST OF TREATMENT SCHEMES

The construction and operating costs depend on the treatment system and therefore

the analysis of the methodology varies according to the main characteristics of the

systems. However, there is not sufficient data for all the systems individually, as

usually they are implemented in combination for better performances.

● Basic systems

Basic systems are “marketed and promoted as being simple to use with low

operational costs” (Pidou et al. 2007). Usually these systems are coupled with

disinfection in order to provide a satisfactory treatment level. For this reason there is

no economical data for individual basic systems. However, there are three case

studies that provide costs (Table 6.1) for complete treatment systems that include

coarse filtration or sedimentation (Brewer et al. 2000; Hills et al., 2001; March et al.,

2004).

TABLE 6.1: COST OF BASIC SYSTEMS

Location Structure System HRT/

Flow rate

Capital

Costs O&M Costs

UK1 House

Filtration +

Disinfection N/A £ 1195 £50/year

UK2

Houses Coarse filtration +

Disinfection 28 m

3 /day £ 1625 £49/year

Spain3 Hotel

Screening +

Sedimentation +

Disinfection

38 hours £11,500 £0.50/m3

1: Brewer et al. 2000, 2: Hills et al., 2001, 3: March et al., 2004

From literature, only the system located in Spain was observed to be cost effective

as it had savings of “£0.75/m3 and a payback period of 14 years” (Pidou, 2007).


75

● Physical systems

Physical systems, as analysed in Chapter 4, seem to incorporate promising

technologies in the case of greywater reclamation, as they provide an excellent

treatment level. The economical data concerning these systems was provided from

wastewater treatment companies in the UK and from one case study, summarised in

Table 6.2.

TABLE 6.2: COST OF PHYSICAL SYSTEMS


Flow rate

Capital

Costs O&M Costs

UK1 Houses Sand filter N/A £ 45–350 /m3 5% of capital

Slovenia2

Houses Activated carbon filter 200 m3/day £ 0.11 /m3 £ 0.4 /m3

Slovenia2

Houses

Membrane plant

UF/RO 200 m3/day £ 0.63 /m3 £ 0.72 /m3

1: Xylem UK Ltd, 2013 , 2: Sostar-Turk et al., 2005

When comparing the costs of the above schemes, the filters coupled with activated

carbon seem to be cost effective and with high pollutants removal rates, at the same

time (Sostar-Turk, 2005). However, membrane plants are a more sustainable option,

“because only 25% of effluent water ends in the environment and about 75% is

recycled” ((Sostar-Turk, 2005). This means that larger amounts of water are recycled

annually, thus more money is being saved. Nevertheless, site specific scenarios

should be studied because even though the percentage of the recycled water may be

high the membranes cost is still 50% higher than that of GAC.


76

● Chemical systems

As far as the chemical systems are concerned, there are some costs data in

literature (Table 6.3) from already tested wastewater treatment plants, yet evidence

of photobioreactor costs is not available.

TABLE 6.3: COST OF CHEMICAL SYSTEMS

Location System HRT/

Flow rate

Capital

Costs

O&M

Costs

Slovenia1

Coagulation +

Sand filter + GAC 40 min £ 0.07/ m3

£ 0.27/ m3

Taiwan2

Electro-coagulation +

Disinfection 28 m

3/day £ 0.04/ m3 £ 0.10/ m3

1: Sostar-Turk et al., 2005, 2: Lin et al., 2005


77

● Biological systems

The biological schemes that can be implemented for greywater reclamation are

usually coupled with other treatment schemes and an although expensive option can

also be effective (Pidou et al., 2007). A summary of the cost data for biological

systems can be found in Table 6.4.

TABLE 6.4: COST OF BIOLOGICAL SYSTEMS


Flow rate Capital Costs O&M Costs

UK1

Student hall

Screening +

Aerated bio filter+

GAC

N/A £ 1720 £ 128 /year

UK2

Student hall

Biological reactor+

Sand filter+ GAQ+

disinfection

0.65 m3/day £ 30,000 £ 611/year

Australia3

House Biofilm +

UV disinfection N/A £ 2514-3325 N/A

Germany4

Houses Modular biological

system 0.6m

3day £ 4300 £ 17-20/year

UK5

Houses Membrane bioreactor

(coated fibre membrane) 125 m

3/day

£ 80/m2

(membrane area

needed 1.92 m2/m

3)

>£ 20/m3

UK5


(Al flocs on substrate) 4,000 m

3/day

£ 35/m2

(membrane area

needed 0.292 m2/m

3)

£ 17-21/m3

UK5


(polypropylene membrane) 3,750 m

3/day

£30-40/m2

(membrane area

needed 0.72 m2/m

3)

£ 12/m3

USA6

House SBR N/A £ 5500 -7700 £ 160-260/year

1: Surendran et al., 1998, 2: Brewer et al., 2000, 3: Pidou et al., 2007, 4: Nolde, 2005,

5: Visvanathan et al., 2000, 6: Obropta, 2005


78

● Extensive systems

Apart from being considered as sustainable technologies, extensive or natural

systems are also regarded as low cost options for greywater recycle. In fact,

literature has provided some interesting data concerning the costs of constructed

wetlands, compiled in Table 6.5. In addition, further cost data are shown in the

following table, for modular reed beds, gathered from a wastewater treatment

company that specializes in natural treatment systems.

TABLE 6.5: COST OF EXTENSIVE SYSTEMS


Flow rate Capital Costs

O&M

Costs

Costa Rica1

3 Houses 2 Reed beds +

Pond

>10 days

0.76 m3/day

£ 531 £ 12/year

Nepal2

House Sedimentation +

Reed bed 0.5 m

3/day £ 230 Negligible

Sweden3

Student hall 3 Ponds +

Sand filter 1 year £ 240 /person N/A

Ireland4

- Vertical flow reed beds 0.1–0.3

m3/day

£ 1300 N/A

Ireland4

- Horizontal flow reed

bed

0.1–0.3

m3/day

£ 950 N/A

1: Dallas et al., 2004, 2: Shrestha et al., 2001, 3: Gunther, 2000, 4: Herr Ltd., 2013

The only economic constraint of constructed wetlands is the cost of the substrate

media which may be 50% of the total construction costs, thus raising significantly the

budget for small scale treatment plants (USEPA, 1999).

http://www.sciencedirect.com/science/article/pii/S0925857404000965#bib31


79

6.1.2 TRANSMISSION & PUMPING

The construction of wastewater treatment facilities depends not only on the treatment

processes of the unit, but also on the supporting water network and pipes, which

should also be completed in order to create a functional plant. In addition, costs can

also differ significantly for varied landscapes, when the wastewater treatment plant is

situated at “lower elevations and the recipients are in the higher elevations”, thus

requiring pumping stations (Figure 6.2) (NRC, 2012).

These expenditures have been found to account for 35% to 50% of the total

construction costs (Metcalf and Eddy, 1995) and are demonstrated in Tables 6.6 and

6.7, in relation to pipes diameter and the capacity of water transmission, respectively.

Usually water pipelines (Figure 6.1) are ductile cast iron due to their resistance to

corrosion and centrifugal pumps are being used for water transmission (COSTwater,

2013).


80

TABLE 6.6: UNIT COST OF WATER DISTRIBUTION &TRANSMISSION PIPELINES (COSTwater, 2013)

Diameter of water pipes

mm

Frost areas

£/ m

Non frost areas

£/ m

150 143.2 91.2

200 140.6 96.3

250 152.8 111.1

300 165.0 125.9

350 210.0 159.3

400 254.3 193.3

450 284.5 227.3

500 314.0 260.7

600 319.8 298.0

750 373.7 373.7

900 539.4 539.4

1050 745.6 745.6

>1050 and <1500 800.2 800.2

>1500 and <2100 1103.3 1103.3

>2100 and <2250 1116.1 1116.1

>2250 and < 2400 1251.0 1251.0

>2400 and <3000 1326.7 1326.7

>3000 1819.3 1819.3

FIGURE 6.1: TYPICAL WATER & DRAINAGE PIPELINES (NRC, 2012)


81

TABLE 6.7: UNIT COST OF WATER TRANSMISSION PUMPING STATION (COSTwater, 2013)

Water transmission capacity

m3/d

Unit Cost

£/ m3/d

3785 77.1

7570 60.4

18925 43.7

37850 34.0

75700 26.3

189250 19.3

378500 14.8

FIGURE 6.2: TYPICAL PUMPING STATION (COSTwater, 2013)


82

6.2 OPERATION & MAINTENANCE COSTS

The analysis of operational and maintenance costs include the factors listed below

which are also displayed in Figure 6.3, as percentages of their contribution to the

expenses.

Employee salaries

Energy requirement for operation.

Chemicals and other requirements

Water application and sludge disposal

Replacement program.

Material required for repairs.

The personnel needed of each treatment plant depend on its size and complexity.

The replacement costs apply to those design elements that have shorter lifetime than

the planned period and should therefore be replaced sooner (e.g. membranes).

Replacement cost is the same as the original cost of the items (Metcalf and Eddy,

1995).

FIGURE 6.3: BREAKDOWN OF RUNNING COSTS OF A WASTEWATER TREATMENT PLANT (adapted from COSTwater, 2013)

18%

26%

6% 13%

18%

9%

10% Water discharge fee

Electric fee

Chemical fee

Sludge transport and disposal

Staff cost

Administration cost

Maintenance & Replacement cost


83

6.2.1 COST OF ENERGY REQUIREMENTS

“Energy is needed in many stages of the reclaimed water production cycle, including:

wastewater treatment, transmission to the water reclamation plant, advanced

treatment, and possible distribution to the recipient” (NRC, 2012). However, the

energy cost may differ among areas and depend on the size and the type of the

wastewater treatment plant. For instance natural systems require low energy

resources, whereas an SBR consumes big amounts of electricity.

Generally, the energy requirements of reclaimed water treatment may vary from 0.4

to 1.53 kWh/m3 (or 1.4 to 5.5 MJ/m3) (NRC, 2012).


84

6.2.2 COST OF QUALITY CONTROLS

As already mentioned, the reuse of treated wastewater should not pose any risks to

public health and the environment. For this reason apart from the treatment

processes quality monitoring should also be taken into account within the

maintenance costs. During monitoring two types of parameters are being analysed;

microbiological (Table 6.8) and physicochemical (Table 6.9). The following tables

provide the costs of these analyses individually. In the case of physicochemical

parameters, monitoring frequency is also provided, as some parameters need to be

monitored in a regular basis (daily/weekly) whereas others do not need frequent

analysis.

● Microbiological Parameters

TABLE 6.8: COST OF MICROBIOLOGICAL MONITORING ANALYSIS (adapted from Salgot et al., 2006)

Parameter Cost per analysis

Legionella £170

E.coli and similar £5

Enterococci (Salmonela) £5 - £17

Nematode eggs £17 - £50

Taenia £17 - £50

Giardia and Cryptosporidium £50 - £170

Bacteriophage £5 - £17

Enterovirus £50 - £170


85

● Chemical & Physicochemical Parameters

TABLE 6.9: COST OF PHYSICOCHEMICAL MONITORING ANALYSIS (adapted from Salgot et al., 2006)

Parameter Indicators Costs

per analysis

Monitoring

frequency1

Physico-

chemical pH, EC, Turbidity, TSS £5

Organic matter COD, BOD, DO, AOX £5 - £17

Nutrients Total –N, NH4+-N, Total-P £5 - £17

Minerals NO3-, SO4

2+, CN-, F-, Cl- £5 - £17

Residual

chlorine

Cl2 (if chlorination)

Disinfection products

£5 - £17

£170

(Heavy) metals

As, Cd, Cr, Hg, Pb, B, Al, Ba,

Be, Co, Cu,

Fe, Li, Mn, Mo, Ni, Se, Sn,

Th, V, Zn

£17 - £50

£17 - £50

Organic micro-

pollutants

Surfactants

Mineral oil

Pesticides

EDTA

Chloride solvents

Aldehyde

Aromatic organic solvents

PAHs

Phenols

Pharmaceuticals

£17 - £50

£17 - £50

£50 - £170

£50 - £170

£50 - £170

£17 - £50

£50 - £170

£50 - £170

£17 - £50

£170

1: Frequency: (permanently-weekly), (monthly – once a year), (once per 1-

5 years)


86

6.3 DISCUSSION

The cost information provided in this Chapter is an initial level of details and can be

useful for basic financial evaluations, as it does not include building construction and

water disposal system costs.

However, demonstrates cost trends concerning the capital, the operational and the

maintenance costs. Primarily, energy requirements of the plant seem to determine

the operating expenses. As far as the treatment schemes are concerned, they show

many economical variations. In brief, it is observed that natural processes (e.g. reed

beds) that do not require mechanical equipment and large amounts of energy are

generally the most economical option. Whereas advanced treatment schemes (e.g.

MRB) have high capital and operational costs. Gratziou (2005) used mathematical

modelling in order to rank the cost of some schemes according to the equivalent

population as shown in Table 6.10.

TABLE 6.10: RANKING OF TREATMENT SCHEMES ACCORDING TO THEIR COST (Gratziou, 2005)

Equivalent Population [E.P]

100-5000 5000-8000 8000

Constructed Wetlands Constructed Wetlands Constructed Wetlands

SBR SBR MBR

RBC MBR RBC

MBR RBC SBR

In any case the overall and the running costs of greywater treatment plants depend

on of the type and capacity of the unit thus is difficult to evaluate their cost-

effectiveness.


87

7. SETTING UP WATER REUSE NETWORKS

Setting up water reuse networks is the following step of the previous analysis, which

is essential in order to provide a complete study for urban water reclamation.

The ultimate selection of the appropriate series of greywater treatment technologies

will be governed by the Treatment Scenarios. The Treatment Scenarios need to be

designed to take into account a wide range of selection criteria as it is imperative that

these consider technological, environmental as well as financial key factors within the

scope of the project and within a reasonable timeframe. Primary input elements to

consider when selecting the appropriate sequence of technologies are (Siraj, 2012):

● Wastewater origin and quantity

The composition and origin of wastewater (domestic, commercial, industrial) should

be determined. In the case of greywater, it can be characterised as “low or high load”

greywater. In addition, the quantity (flow) of the produced greywater will determine

the area footprint of the treatment facility and the selection of treatment processes

that need to be employed.

● Desired quality performance

This is determined by the final recipients of the reclaimed water, which may have

quality requirements for specific reuse applications, always in accordance to the

legislation.

● Legislation

The regulatory determinants and discharge standards for the quality of treated

effluents in accordance with the regional and national standards and guidelines that

must be met for the end use of the reclaimed wastewater.


88

● Economic factors

Economic affordability of the various treatment processes used in wastewater

reclamation should be taken into consideration, with the analysis of the capital,

operational and maintenance costs.

● Environmental conditions

These may include the land availability, geography and climate.

● Location

The availability of local skills for design, construction as well as operation and

maintenance may dictate the technical acceptability of the various treatment options.

Unlike in developed and industrialised countries, capital is scarcely found in poor and

developing countries and therefore, available treatment options tend to be less

automated and energy intensive.

Furthermore, setting up water reuse networks requires not only the understanding of

the network connections, but also the correlation between the suggested treatment

schemes in the processing stages. Figures 7.1 and 7.2 were designed in order to

ease this understanding and are the basis of Treatment Scenarios (Section 7.1).


89

These diagrams illustrate the user configuration of the network with water transfer

between the supplier and the recipients. In details, Figure 7.1a, is the central supply

core, in which a group of suppliers deliver their outputs after treatment to other users.

On the other hand, Figure 7.1b represents a network of individual users, in which the

supplier is also the user after recirculation. Finally, the third diagram, Figure 7.1c,

illustrates the demand relationship of “one to many and many to one”.

FIGURE 7.1: WATER NETWORK CONFIGURATION (adapted from Arup, 2012)

Figure 7.2 shows the summarised figures of all the suggested greywater treatment

schemes (Chapter 5) organised in the relevant treatment stages in order to support

the design of the networks treatment scenarios.


90

FIGURE 7.2: SUMMARY OF TREATMENT SCENARIOS FOR GREYWATER RECLAMATION (adapted from Tilley et al., 2008)


91

7.1 TREATMENT SCENARIOS

This section aims to investigate four (4) potential scenarios for greywater treatment,

which have been selected after extensive research in order to meet both the

legislative and the economic standards.

In the first part, four flow diagrams, one for each scenario describe the stages of the

treatment processes selected. The second part presents the relevant summarizing

tables for the quality performance and cost effectiveness of these scenarios.

The flow diagrams include solid lines that illustrate the core treatment stages and

dashed lines that describe the optional steps. The corresponding tables on the other

hand incorporate three main subjects; systems performance, legislative criteria and

costs.

Scenario 1 - Constructed wetland system, combines a natural treatment system with

primary sedimentation (basic system), leading the effluent into UV disinfection before

storage or distribution.

Scenario 2 – Rotating Biological Contactors system employs two sedimentation

processes before and after the RBC, with a final disinfection stage.

Scenario 3 – Sequencing Batch Reactor system includes a pre-treatment stage with

a sieve filter and then introduces the effluent in the SBR system and the UV

disinfection tank.

Scenario 4 – Membrane Bioreactor system, unlike all the above systems is a one

stage treatment that may need only disinfection.


92

7.1.1 SCENARIO 1 – CONSTRUCTED WETLAND

FIGURE 7.3: FLOW DIAGRAM OF SCENARIO 1- CONSTRUCTED WETLAND


93

TABLE 7.1: SUMMARIZED TABLE FOR SCENARIO 1

Scenario 1 – Constructed Wetland

Quality Parameters Legislative criteria1 System Performance

2 Design Capacity System Costs

3

BOD5 < 10 mg/l < 17 mg/l 0.1–0.3 m3/day £ 950 - 1200

TSS < 30 mg/l < 13 mg/l 0.5 m

3/day £ 800

COD N/A < 50 mg/l 0.75 m

3/day £ 1000

Turbidity < 10 NTU < 10 NTU

Faecal Coliform < 250 CFU /100ml < 102 CFU /100 ml

Escherichia coli < 250 CFU /100ml < 102 CFU/100 ml

1: (BSi, 2010; USEPA, 2012) , 2: (EPA, 2000), 3: (Herr Ltd, 2013)


94

7.1.2 SCENARIO 2 – RBC SYSTEM

FIGURE 7.4: FLOW DIAGRAM OF SCENARIO 2- RBC


95


Scenario 2 – RBC

Quality Parameters Legislative criteria1 Systems Performance

2 Design Capacity Systems Costs

3

BOD5 < 10 mg/l < 8 mg/l Hydraulic load

TSS < 30 mg/l < 13 mg/l 0.01 m

3/day /m

2 £ 1,625,000

COD N/A < 40 mg/l

Turbidity < 10 NTU < 2 NTU

Faecal Coliforms < 250 CFU /100ml > 1 CFU /100 ml

1: (BSi, 2010; USEPA, 2012) , 2: (Pidou, 2007) 3: (Ovivo, 2013)


96

7.1.3 SCENARIO 3 – SBR SYSTEM

FIGURE 7.5: FLOW DIAGRAM OF SCENARIO 3- SBR


97


Scenario 3 – SBR

Parameters Legislative criteria1

Systems Performance2

Design Capacity

[m3/day]

Systems Costs3

[£]

BOD5 < 10 mg/l

10 mg/l 45.4 61,100

TSS < 30 mg/l

10 mg/l 56.8 89,050

Turbidity < 10 NTU

N/A 3785.4 220,350

Total Nitrogen N/A

5 - 8 mg/l 5299.6 263,250

Phosphorus N/A

1 - 2 mg/l 5526.7 263,250

7570.8 366,600

16088.0 474,500

18927 760,500

1: (BSi, 2010; USEPA, 2012) , 2: (Pidou, 2007) 3: (EPA, 1999; COSTwater, 2013)


98

7.1.4 SCENARIO 4 – MBR SYSTEM

FIGURE 7.6: FLOW DIAGRAM OF SCENARIO 4- MBR


99


Scenario 4 – MBR

Quality Parameters Legislative criteria 1

Systems Performance 2

Typical Design Flux Systems Costs

3

[£]

BOD5 < 10 mg/l < 2.0 mg/l 25 LMH (l/m2 /hour)

TSS < 30 mg/l < 2.0 mg/l 36 40,131 – 114,660

COD N/A < 45 mg/l 360 401,310 – 1,146,600

Turbidity < 10 NTU < 1 NTU 3600 5,000,000-6,032,000

Faecal Coliform < 250 CFU /100ml < 2.2 CFU/100 ml 36000 36,800,000-40,300,000

Total Nitrogen N/A < 10.0 mg/l

NH3 N/A < 1.0 mg/l

Phosphorus N/A < 1.0 mg/l

1: (BSi, 2010; USEPA, 2012) , 2: (Pidou, 2007; Nalco, 2013) 3: (COSTwater, 2013)


100

7.2 DISCUSSION

The above Treatment Scenarios constitute four possible greywater treatment

systems which were selected after extensive literature research and personal

communication with wastewater treatment companies. However, Figure 7.2 can be

used to form other possible scenarios, as part of supplementary future studies in the

field.

From the findings analysis, it is shown that all the selected systems comply with the

standards, concerning the quality parameters. This means that they accomplish very

good removal levels of the organic load and solids found in greywater. It is worth

noting that for the performance evaluation, the strictest legislative limits were chosen,

in order to show the performance for demanding applications (BSi, 2010; USEPA,

2012).

From the analysis of the systems costs, it is observed that these vary according to

the capacity and scale of the treatment system, with the most expensive choice this

of Membrane bioreactor, following the Rotating biological contactor, the Sequencing

batch reactor and the Constructed wetland.

Furthermore, Gratziou (2005) has developed a mathematical model that calculated

the cost of treatment systems according to the equivalent population. Figure 7.7

illustrates the results for our scenarios and it is shown that increased systems

capacities correspond to lower costs per m3 of wastewater per capita. This means

that large scale reuse projects may be more cost effective than these of domestic

scale.


101

FIGURE 7.7: DIAGRAM OF SCENARIOS COSTS PER EQUIVALENT POPULATION

0.0

1000.0

2000.0

3000.0

4000.0

5000.0

6000.0

7000.0

8000.0

9000.0

0 500 1000 1500 2000 2500

Syste

m C

osts

[£/c

ap

ita]

Equivalent Population [E.P]

Constructed wetland

RBC

SBR

MBR


102

8. CONCLUSIONS & RECOMMENDATIONS

Within the framework of sustainable development, one of the key concerns of the

international community is the discovery of alternative water sources. In this direction,

the practice of reclamation and reuse of wastewater should be recognised as

common practice and an essential protection method for the environment and

economies. Significant amounts of water can be saved while favouring all segments

“of the human centric water cycle”. Crop irrigation, urban spaces irrigation, industrial

cooling, reuse for environmental purposes, even indirect potable uses are some of

the application categories of treated wastewater that have already gained worldwide

acceptance.

The rational management of water resources requires a serious and responsible

planning at many levels. Several parameters should be taken into consideration, from

which the most important is the protection of public health and ecosystems. This can

be accomplished not only with the establishment of quality standards and the

protection measures, but also with the responsible monitoring programs of the

reused waters.

As far as the technical and financial issues of the project are concerned, greywater

reclamation is a feasible and sustainable practice that incorporates a variety of

treatment schemes and costs. Greywater treatment plants size and costs may vary,

offering reuse options from single households to municipal range projects. However,

the production of clear conclusions, and in particular a precise hierarchy of the

greywater treatment options reviewed, in the form of a selection guide is an attractive

idea but poses serious risks of failure. This is not only because it was impossible to

analyse all the existing and developing systems in the present study but also for the


103

reason that the advantages, disadvantages and limitations of each option had

different weighting and degree of importance in each individual reuse project.

For these reasons it was considered appropriate that this work should focus on the

registration of the legislation, the treatment options and their costs, aiming that a

review of the reuse trends will provide ideas for further advances.

This study covered the fields and objectives set in the beginning of the project,

regarding greywater treatment systems and costs. However, there are still many

fields that could be investigated in urban water reuse networks. Some suggestions of

further research are as follows:

● Conduct the same technical and economical research for commercial or industrial

wastewater for urban reuse applications.

● Investigate the case of reusing reclaimed waters for indirect or even direct

potable use.

● Research the technical and economical feasibility of other Treatment Scenarios.

Finally, the problem of adequacy, quality and management of water resources needs

to be perceived from local as well as international perspectives. It is a complex issue

with various social and economical dimensions and conflicting views. The issue of

water intersects the relationship between society, nature and ecological balance, the

relationship of production and economy, the relationship of society with political and

social values, thus water is and should be considered as a collective good.

“The world has enough for everyone's need, but not enough for everyone's greed.”

Mahatma Gandhi

http://www.goodreads.com/author/show/5810891.Mahatma_Gandhi


104

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APPENDIX

APPENDIX A: Data of Basic Systems

APPENDIX B: Data of Physical Systems

APPENDIX C: Data of Chemical Systems

APPENDIX D: Data of Biological Systems

APPENDIX E: Data of Extensive Systems

APPENDIX F: WHO Regulation - Maximum permissible concentration for chemical

compounds

APPENDIX G: California Title 22 - Allowable uses for Recycled water


112

APPENDIX A: Data of implemented Basic Systems (Pidou et al. 2007)


113

APPENDIX B: Data of implemented Physical Systems (Pidou et al. 2007)


114

APPENDIX C: Data of implemented Chemical Systems (Pidou et al. 2007)


115

APPENDIX D1: Data of implemented Biological Systems (Pidou et al. 2007)


116

APPENDIX D2: Data of implemented Biological Systems (Pidou et al. 2007)


117

APPENDIX E: Data of implemented Extensive Systems (Pidou et al. 2007)


118

APPENDIX F: WHO Regulation - Maximum permissible concentration for toxic

chemical compounds (WHO, 2006)


119

APPENDIX G: California Title 22 - Allowable uses for Recycled water

(State of California, 2003)

urban wastewater reuse - treatment technologies & cost

Documents

reuse of wastewater

reuse costs

reuse applications

wastewater treatment

industrial wastewater

water environment

treatment schemes chapter

saving water resources