wwmt-d1s1.3-sludge and biosolids management technologies by man echo leon

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Sludge and Biosolidsanagemen ec no og es

ADB Workshop, Manila16-17 November 2011

Ms. Echo LeongAssociate Director, AECOM Asia Co. Ltd.



Outline of Presentation



Management Practices



Raw Slud e:•By-product of sewage treatment

•High organic, nitrogen and phosphorus contents

•

•May contain heavy metals in trade effluent

Primary Secondary/

Sludge



Trends in Sewage TreatmentGHG / Energy

Micro-constituents

1. Increased levels of ollutant removal What & Where?

Resource Management

2. Protection of public health

Organics Tertiary Treatment

Solids Enhanced Water Qualit

Secondary Activated Sludge

Result in increase of sludge production



Developing Countries

- PRC for exam le

on ry ons

• Total sewage sludge production of 2010 was about 9.7 M dry tons

•disposed of at landfills

• Only about 20% of the sludge is further stabilized, of which about 6% is utilized



Developed Cities

- Hon Kon for exam le

At present, landfilling isthe only means for

disposal of sewagesludge in Hong Kong.

Sludge generated fromsewage treatment

works is transported byvesse s n o aand by trucks (25% intotal) to landfills fordis osal.

About 250 dry tons ofsludge is currently

daily.



-

• Emission of greenhouse gases e.g. CH4

• Emission of odour (strong for raw sludge)

• High moisture content (70-80%), affecting landfill stability

• Occupying landfill space



Developed Countries

50%

2001

40%

2002

2003

2004

30%2006

20%

10%

0%

Land recycled Landfill Compost Incineration



Developed Countries

- . .

Year Land Application Landfilling Incineration

Class A Class B Raw Raw

1998 13% 48% 19% 20%

2002 18% 40% 25% 17%

2004* 23% 34% 23% 20%

• Class A processing has been increasing

• Class B land a lication has been decreasin

• Incineration and landfill disposal of raw sludge remaineconomical solutions for some regions

*

10

,



Drivers for New Sludge

Management Practices



Trends in Sludge Management

- Slud e reco nized as resource and utilization isa trend:

- Nutrient: land application & fertilizer

- Energy: heat and/or power - erna ve ue o n us r es

- Also, technology advancements

Sludge to Products

Sludge to FertilizerMethodBenefits

12

Sustainability



Carbon Footprint Distribution

-

Process Transport, Other, 1%,

17%

Electricity, 77%

Pumping+

Aeration

• Biosolids influences all of these parameters

• UK Water industry > 5 million tonnes CO2e

• Only the power industry emits more carbon footprint



Energy

- Energy Inflation• Oil in excess of $100/barrel 20

40

60

80

100

120

O i l P r i c e [ $ / b a r r e l ]

• Electricity up by a third between 2003 – 2010

• Gas rice doubled in same eriod

0

1998 200 0 200 2 2004 2006 2008 2 010 2012

• High volatility

-Technolo which consumes lar equantities of energy will be exposed• Drying, incineration, treatment without

di estion



Energy

- Energy Security• UK has become net importer of

1968

• Russia switching off supplies toUkraine

- Fertilizer costs closely linkedwith energy prices

Fertiliser Prices



Phosphorous

-

e m a n d

• Becoming urbanized• Changing food habits

• D

.tonnes in 3 years (equivalent to USAconsumption)

- Peak P predicted at 2035?• <100 years of easily mined P remain

• 40% of all reserves in Morocco S u p p l

• China imposed P export tax



Phosphorous- Biosolids is a good source of phosphorous……and nitrogen

• 1 tonne dr solids contains a roximatel 30 k P and 120 k N

Currently worth $50/t

- Thermal destruction does not recover this resource

- Recycling of sludge to land

• Or recovery techniques Struvite (Magnesium ammonium phosphate MgNH4PO4.6H2O),

good slow release fertilizer,

• Main technology involves addition of magnesium oxide

• Full-scale since 2006 Extraction (e.g. super critical wet air oxidation, SCWAO)



u r en or an pp ca on

- More restrictive environmental regulations,Class A

- u c percep on oppos on

- Marketable end-products- Long-term issues:

• a ogen regrow

• Contaminants of concern

Energy from Sludge - Rising energy costs

- A promising option to reduce GHGemission, renewable incentives

-

- Using advanced digestion to increasebiogas production

- Co-digestion

- Closure to energy intensive facilities



Technologies



Raw Sludge (Thickened)

DewateringDewatering Dewatering

AnaerobicDigestion

AnaerobicDigestion

Dewatering

TreatmentComposting

Dewatering

Drying Composting

Stabilized and Sterilized Sludge for Land Application



Raw Sludge (Thickened)

Dewatering Dewatering DewateringDewatering

HeatDrying

ThermalHydrolysis

AnaerobicDigestion

IncinerationAnaerobicDigestion

HeatDrying

Pyrolysis/ Gasification

HeatDrying

Dewatering

Dewatering

Heat Recovery, Biogas or Alternative Fuel for Power Generation

Residual Disposed to Landfill or Land Application



Option 1 – Raw Incineration

Thermal Hydrolysis



v v . v



Gasification

• Operation: 700-1000oC

condition• Converting carbon to

Syngas

Flue gas

syngas, nc u ng , 2

and CH4，high energy

recovery efficiency• Limited installations, mainly

located in Germany, Japanand Switzerland

AirBottom ash

• High cost



Considerations in

Selection of Technology



What are

What areFeasible SludgeApplications?

the ProjectObjectives?

reatmentPractices?

What is the

Current

RecommendSludge

Management

Situation? Strategy



What should be considered inthe Development of a Sludge

as er an

us a na eSludge Master



disposal- Study for PRC (for example)

TR Identification: 9 core treatment technologies with 15 TRs

1) landfilling of partially dried sludge

2) anaerobic digestion (AD) + utilization of biogas and digested sludge

3) thermal hydrolysis pre-treatment (THP) + AD + biogas and digested

sludge utilizationme sta zat on + an app ca on

5) incineration + heat recovery

6) thermal drying + pellets applied to land

8) thermal drying + substitution of coal in cement kilns/ power plants

9) composting of dewatered sludge



1 Landfilling of partially dried sludge

a …without LFG recoveryTR: Thickenin + Dewaterin 80% MC + Heat Dr in 60% MC + Landfill

b …with LFG recoveryTR: Thickening + Dewatering (80% MC) + Heat Drying (60% MC) + Landfill

2 Anaerobic di estion (AD) with bio as recover and di ested slud e

a …applied to landTR: Thickening + AD (Biogas Recovery) + Dewatering (80% MC) + Land

Application

b …composted and applied to landTR: Thickening + AD (Biogas Recovery) + Dewatering (80% MC) + Composting + Land Application

…

TR: Thickening + AD (Biogas Recovery) + Dewatering (80% MC) + Landfill

d …to landfill without LFG recoveryTR: Thickening + AD (Biogas Recovery) + Dewatering (80% MC) + Landfill



3 Thermal hydrolysis pretreatment (THP) followed by AD with biogas recoveryand digested sludge…

a …applied to land TR: Thickening + Dewatering (84% MC) + THP + AD (Biogas Recovery) + Dewatering (80% MC) + Land Application

b …heat dried as coal substitute for cement kiln or power stationTR: Thickening + Dewatering (84% MC) + THP + AD (Biogas Recovery) +

4 Lime stabilization, application of stabilized sludge to land

TR: Thickening + Dewatering (80% MC) + Lime Treatment (65% MC) + Land Application

5 Incineration with heat recovery

Disposal



6 Heat drying of sludge with pellets applied to land

TR: Thickening + Dewatering (80% MC) + Heat Drying (40% or 65% MC) + Land pp ca on

7 Heat drying of sludge with pellets applied to land

TR: Thickenin + Dewaterin 80% MC + Heat Dr in 10% MC + Gasification (Syngas) + Tar/Ash for Disposal

8 Heat drying of sludge used as coal substitute in cement kiln or power station

: c en ng + ewa er ng + ea ry ng + oa u s u e

9 Composting of dewatered sludge with sludge compost applied to land

TR: Thickening + Dewatering (80% MC) + Composting + Land Application



disposal- Study for PRC (for example)

Assessment and comparison of TRs based on the followingframework

Criteria Sub-criteria

Engineering Feasibility

Flexibility; compatibility; reliability; side-stream effects; trackrecords; implementation feasibility; occupational safety.

nv ronmen a Efficiency

omp ance w oca env ronmen a sc arge s an ar s;potential for beneficial sludge utilization (resource recovery);risk of secondary pollution; carbon footprint (CFP)

Acceptance

-

customers; nearby communities; general public

Financial Life-cycle costs; capital investment; O&M costs; financing and



Estimation of the relative carbon footprint (CFP) of the 15 TRs:- UK Water Industry Research (UKWIR) and its Carbon Accounting

or oo s w up a es

- Primary greenhouse gas (GHG) - carbon dioxide, methane and nitrousoxide

- “ 2 p.a.)”

- Relative CFP assessment of different TRs based on the followingassumptions:

Population served: 250,000 to 300,000 persons Wastewater treated: approximately 100,000 m 3 per day

Dewatered sludge cake produced: 80 wet tons per day (80% MC)

Total annual production of sludge: 5,840 tons dry solids



Carbon Footprint Assessment

1,2951,295



Carbon Footprint Assessment

TRs 2a, 2b, 2c, 3a, 3b and 8

-Low CFP with energy recovery

- c eve, or are c ose o ac ev ng, car on neu ra y

-Energy recovery in sludge processing as a means of reducing CFPTRs 1b, 2d, 4, 5, 7, and 9

- e um , some s w t ow cap ta cost

-Results are sensitive to the assumptions made and particular local circumstances

TRs 1a, 6a and 6b- g ue to energy- ntens ve ry ng process w t no energy recovery , or t rougfugitive emissions from landfill gas

Summary

-The wide range of CFPs suggests that CFP is a key factor in selecting sludge TRs

-CFP results for a given TR will vary due to local factors - a project by project basiswith assum tions and values ad usted to the local situation



2 Anaerobic digestion with biogas recovery and digested sludge…

2a …applied to land

TR: Thickening + Anaerobic Digestion (Biogas Recovery) + Dewatering (80% MC)+ Land Application

- 2

-Nutrient and energy recovery

- Low capital and operation costs

- AD is a well-developed and common technology used in other

Weaknesses -Not pathogen and odour-free, restricting land application- Biogas production depends on the organic content of sludge

- Medium land requirement for sludge treatment

- s requ rement or operat ng an system

Suggestion -Should be promoted – take into account sludge characteristicsand sludge product marketability



2 Anaerobic digestion with biogas recovery and digested sludge…

2b …composted and applied to land

TR: Thickening + Anaerobic Digestion (Biogas Recovery) + Dewatering (80% MC)+ Composting + Land Application

--Compost sludge is usually pathogen and odour-free forunrestricted land application

-Nutrient and energy recovery

- Low ca ital and o eration costs- AD and composting are well-developed and common technologiesused in other countries

Weaknesses -Potential odour concern-

- High land requirement for sludge treatment- Skills requirement for operating an AD system

Suggestion -Should be promoted; take into account sludge characteristics



3 Thermal hydrolysis pretreatment (THP) followed by Anaerobic

…

3a …applied to landTR: Thickening + Dewatering (84% MC) + THP + Anaerobic Digestion (Biogas Recovery) + Dewatering (80% MC) + Land Application

Strengths -Near carbon neutrality（CO2e: 211tons/yr）-Enhanced nutrient and energy recovery- Pathogen and odour-free product for unrestricted land application

- Lower land requirement- e um cap ta an operat on costs

Weaknesses -THP is a proprietary process with limited vendors and itsperformance under the conditions of the PRC will be subject forreview.

- Requires specially trained staff for operationSuggestion -Should be promoted – consider sludge characteristics, financial

capability, and sludge product marketability.



3 Thermal hydrolysis pretreatment (THP) followed by Anaerobic…

3b …heat dried as coal substitute for cement kiln or power stationTR: Thickening + Dewatering (84% MC) + THP + Anaerobic Digestion (Biogas Recovery) + Dewatering (80% MC) + Heat Drying (10% MC) + Coal Substitute

Strengths - At carbon neutrality (CO2e: -543tons/yr）- Enhanced nutrient and energy recovery- Pathogen and odour-free product, wider application

- Feasibility depends on the reliability of product users-

Weaknesses - THP is a proprietary process with limited vendors and itsperformance under the conditions of the PRC will be subject toreview.

- .

Suggestion - Suitable for large cities with strong financial capability and with acement kiln or power station nearby for utilization

- Not recommended for small and medium-sized cities



8 Heat drying of sludge used as coal substitute in cement kiln or power

TR: Thickening + Dewatering (80% MC) + Heat Drying (10% MC) + Coal Substitute

Strengths - Near carbon neutrality (CO2e: 1,295tons/yr）-Small land requirement for sludge treatment-Relative low capital cost compared to other energy recovery options

Weaknesses -High operation cost-Feasibility depends on the reliability of product users

Suggestion -Suitable for cities with limited available land for beneficial uses andwith cement kiln or power station nearby



Case StudCase Stud -- Hon Kon Slud e Mana ement PracticeHon Kon Slud e Mana ement Practice

• Sludge quantity: will increase from about 900 wet tpd in 2010 to 1,500 wet

tpd in 2014/2015

• Current practice: landfilling

• Practice after 2013:

•

with heat recovery

• DBO contract

• Under construction• nc u e n sewage c arge

• Community facilities e.g. SPA

• About 260,000 tonnes

GHG reduction per year



Conclusions

Conclusion



Conclusion

n eve op ng oun r es…

1)Drivers for a modern approach to sludge management:

- rapidly increasing sludge production due to stricter legislation, populationncrease, more ur an za on

- growing scarcity of landfill resources- Energy is becoming increasingly expensive

- ,

- Advanced digestion processes especially thermal hydrolysis

- Alternative uses for biogas

-

2)Sludge management developed in line with government policy:

- Sustainable means for utilization or disposal

- orrespon ng s

- Recovery of resources and energy

- Low carbon solutions

Conclusion



Conclusion

e ec on….

1)Where land application is viable, sludge utilization is likely to give the best balance ofenvironmental benefit and cost. Most of the TRs for land application are with AD as

.

2)Thermal hydrolysis is becoming more popular to enhance the performance of thedownstream processes for energy recovery or dewaterability

,explored

4)Where landfilling is necessary, pre-treatment should precede the landfilling process for

energy recovery and volume reduction. But, landfill cost is rising sharply in developedcountries and these trends will quite likely happen in developing countries too.

Conclusion



Conclusion

e ec on….

1)No “one solution fits all”

2)CFP a key factor in selecting TRs

-Low CFP: options with energy recovery

-High CFP: options involving thermal drying without energy recovery, or landfilling withoutlandfill gas management/ utilization

3)Other factors: land, sludge volume and quality, financial and technical capacities, qualityassurance and public acceptance

…

Increase awareness of the benefits of sludge utilization and adoption of low carbonsolutions



Thank You

Contact:c o. eong aecom.com

wwmt-d1s1.3-sludge and biosolids management technologies by man echo leon

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