Report of the overseas training program on

DEWATS

(Decentralized Wastewater Treatment Systems)

03-08 October 2010

Venue – Nagorkot, Nepal

Training Conducted by

ENPHO

Environment and Public Health Organization

Submitted to

Department of Local Government

Eastern Province

Sri Lanka

Prepared By- Eng.A.J.A.H.Jowsi , Municipal Engineer –Kalmunai Municipal Council

Acknowledgement

My Heartfelt Gratitude Goes to the UN-Habitat for sponsoring my training

program .I wish to express my special thanks to Dr. Fahmy Islmail ,National

Technical Advisor of UN-Habitat Sri Lanka for motivating me to participate in the

Training

Secondly I am very much thankful to Hon. Governor, The Chief Secretary and the

Commissioner of Local Government of Eastern Province for granting official duty

leave and to Hon.Mayor and Commissioner of Kalmunai Municipal council for

releasing me for the Training.

My Sincere thanks go to the Trainers, Mr. Rajesh Pai and Ms.Susmita Sinha , from

CDD , Mr. Bipin Dangol from ENPHO and my colleagues who supported and

contributed to successfully complete this valuable Training .

Contents

1.0 Background

2.0 Key Learning

3.0 Application of DEWATS in Local Sri Lankan Context

4.0 Recommendations

5.0 Annexes

01. Background

The training program was organized by ENPHO and Supported by various

organizations such as UN-HABITAT , CDD and BORDA . The title of the training

was “International Engineers’ Training on DEWATS”

Participants from countries from Nepal , India, Pakistan ,Bhutan , Malaysia and

Mongolia attended the training .

The training started on 03-10-2010 (Sunday) with the Introduction to Wastewater

Characteristics and Presentations by the participants on experience on Sanitation

Projects. On the second day onwards until the third day afternoon it continued to

cover design of the conveyance system and comparison in between centralized

systems and the de-centralized systems, subsequent to that design calculations

for different DEWATS modules were explained. On the third and fourth days a

concept designs was prepared for three cases. Participants were divided in to

three groups and three cases were considered to develop DEWATS. (Community

project, a Hotel and the training center) Field visits were performed and

presentations were made on the each group work. On the fifth day excursion

was made to sites, which are in operation and under construction . On the sixth

day; construction, commissioning, maintenance and monitoring aspects were

covered.

Brief Introduction about DEWATS

DEWATS stands for “Decentralized Wastewater Treatment Systems”. DEWATS is a

technical approach rather than merely a technology package.

DEWATS applications are based on the principle of low-maintenance since most

important parts of the system work without technical energy inputs and cannot

be switched off intentionally.

Main DEWATS modules for physical and biological wastewater

treatment:

1. Settler 2. Anaerobic Baffled Reactor 3. Anaerobic Filter 4. Planted

Gravel Filter

Advantages of DEWATS

Providing treatment for domestic and industrial wastewater

Low primary investment costs as no imports are needed

Efficient treatment for daily wastewater flows up to 1000m3

Modular design of all components

Tolerant towards inflow fluctuations

Reliable and long-lasting construction design

Expensive and sophisticated maintenance not required

Low maintenance costs

2.0 Key learning

Design of the Modules of the DEWATS

Design calculations were made individually then the results were

discussed and compared. Indian standards were used to calculate the

water demand, and other design parameters.

Construction and Maintenance aspects.

Techniques adopted for the construction of Bio-Gas reactors and

Planted Gravel Filters (PGF) were greatly discussed. Maintenance

aspects such as de-sludging , replacing the filter media at Anerobic

Filters and PGF were understood .

Concept design for community, hotel and Government Institutions

A concept design was prepared for the Hotel called “Hotel –Country

Villa “ as per my Group exercise. We made site inspection to collect

data and to Identify the issues .

We collected the relevant data such as Water usage , existing disposal

practices , future expansions of the hotel , the availability of the land

and the re-use options .

Group design exercise was done , a concept design for the Hotel was

prepared . There has been power point presentations made on each

concept design.

Field Visit to DEWATS under construction

ENPHO has designed a DEWATS for an orphanage in the vicinity of

Kathmandu. Practical aspects of construction of DEWATS was explained

at the site .

Field Visit to the Existing Systems

a. Site-1 . Community wastewater treatment

This project was funded by UN-Habitat and implemented by the

community based organization in Collaboration with the Municipality of

the area concerned . It is designed to cover 200 units , and at present

135 units have already been connected . The facility has been running

for one year .

Bio-gas produced at the treatment facility is supplied to 6 houses and

the income generated from that is used for the payment of the

caretaker of the treatment facility.

Treated effluent is discharged to the nearby stream , the samples at the

outlet were collected to ensure the BOD is within the limit.

b. Site-2 Community wastewater treatment

In this site , wastewater is flowing through a Settling tank and through

two PGFs , horizontal and vertical . A bio gas system is to be augmented

to the existing system and it was already constructed.

This treatment plant is working for four years ..the treated effluent is

allowed to flow through the drainage canal.

c. Site –c Eco-House .

One house belongs to one of the executive officer of ENPHO was visited

It has rainwater harvesting, Bio-gas using organic waste and Worm-

composting .

The house portrays and ideal model of ECO-house .

Interaction with counterpart engineers and sharing of the experience.

This training program enabled a sharing platform amongst the participants .

Group works , games in the training , Entertaining programs in the evenings

and visit to the sun-rise scene .

Experiences of various country situations were discussed . For example

about the Extreme cold weather conditions in Mongolia and the techniques

adopted .

3.0 Application of DEWATS in Srilanka context

Suitability of the DEWATS in Eastern Province

• DEWATS applications provide treatment for both, domestic and industrial sources

• DEWATS applications provide treatment for organic wastewater flows from 1-1000 m3

per day

• DEWATS applications are reliable, long lasting and tolerant towards inflow fluctuation

• DEWATS applications do not need sophisticated maintenance

Without considering facilities for necessary chemical pre-treatment of wastewater from

industries, DEWATS applications are based on four basic technical treatment

Modules which are combined according to demand:

• Primary treatment: sedimentation and floatation

• Secondary anaerobic treatment in fixed-bed reactors: baffled upstream reactors or anaerobic

filters

• Tertiary aerobic treatment in sub-surface flow filters

• Tertiary aerobic treatment in polishing ponds

DEWATS applications are designed and dimensioned in such a way that treated water meets

requirements stipulated in environmental laws and regulations.

Some Benefits

Bio-gas can be generated and it can be utilized to cover some portion of

operations cost .

Treated water can be re-used , the systems can be designed to get the Quality of

the treated for the different applications such as irrigation , toilet flushing ect.

Apart from it there some other benefits ,

� Ecologically Balanced – It helps in bringing tourists more and hence helps

more earnings

� Environment improved

� Social Encouragement

� Water sources are protecte

Potential areas to Implement DEWATS in Kalmunai

1.0 Tsunami Housing schemes – There are three major housing schemes in

Sainthamaruthu, Kalmunai Kudy and Maruthamunai which were constructed

on the reclaimed land. In these area there is a need to construct the

wastewater collection system as the infiltration of the soil is very low. During

the rainy seasons ground water rises to the surface level and making a

greater discomfort.

2.0 Hospitals - AMH hospital already has the wastewater treatment facility in

place. In future Sainthamaruthu and Maruthamunai Hospitals are to be

provided with proper wastewater disposal .

3.0 Commercial institutions. Hotels , factories discharge wastewater to ground or

water resources this must be stopped .

4.0 City Residential area – In the long term run .the entire city of Kalmunai need

sewer system .specially the Sainthamaruthu and Kalmunaikudy area need

within 2-5 years .

Constraints ( as specific to Kalmunai MC in applying DEWATS)

• Need significantly large area for the Planted Gravel filters .

• Flat land feature – need to pump the water , which may need additional

Operational cost . A service charge is to be collected from the community.

4.0 Recommendations

Community Consultation Programs

It is important build consensus on Wastewater treatment based on decentralized

options , support of the community is vital in the following aspects .

a. Cost of Operation and Maintenance of the system is to be covered from

the community . House hold fee for service is to be introduced . The cost

will be high if it is difficult to maintain the gravity flow so pumping is most

the significant part of the operation .

b. At certain location pipes and the necessary structures such as manholes to

be constructed in the properties as per the design.

Planning and Implementing wastewater management schemes

Employing professionals to study and propose DEWATS OPTIONS for the city (As

the apprentice for my professional review under the IESL ( Institute Of Engineers

Sri Lanka ) , I wish to work on the design of the DEWATS System under the ISESL

recommended mentor. )

Preparing the proposal and seeking financial assistance.

City Development plan

It is important to know the population characteristics of the city , Population

density , Zones of development or Land use plan , to be prepared in

collaboration with the UDA.

5.0 Annexes .

1.0 Certificate of Training

2.0 Pictures