Sludge Treatment Facilities - Association of …aesnet.com.hk/wp-content/uploads/hkie-seminar_14mar09...4 Sludge Treatment Facilities (STF) Current Situation At present, landfilling

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MAUNSELLMAUNSELL

Sludge Treatment FacilitiesSludge Treatment FacilitiesPresented byPresented byIrIr Echo LeongEcho LeongMetcalf & Eddy Ltd.Metcalf & Eddy Ltd.

Sludge Treatment Facilities (STF)

Presentation OutlinePresentation Outline

Current SituationCurrent SituationNeed for the STFNeed for the STFAlternative Treatment OptionAlternative Treatment OptionSiteSite LocationLocationEIAEIA StudyStudyProgrammeProgramme

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Mainly includeSCISTW & other 10regional large STWs

Sources of SludgeSources of Sludge

CEPT & SecondaryTreatment


Shek Wu HuiYuen LongSan Wai

Tai Po

Stonecutters IslandPillar Point

Shatin

Sham Tseng

Siu Ho Wai

Stanley

Sai Kung

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Sludge Production ForecastSludge Production Forecast

Wet tonnes/dayWet tonnes/day

YearYear

1,5401,5401,4301,4301,1601,160800800

20162016201420142012201220020088


Sludge ContributionSludge Contribution

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CurrentCurrent SituationSituationAt present, landfilling isthe only means fordisposal of sewage sludgein Hong Kong.

Sludge generated fromsewage treatment worksis transported by vessels(75% in total) and bytrucks (25% in total) tolandfill sites for disposal.

About 800 tonnes ofsludge were disposed ofat landfill sites in 2008.


Sludge Landfilling IssuesSludge Landfilling Issues

Increase in Sludge Production:Increase in Sludge Production:Commissioning of HATS Stage 2A andCommissioning of HATS Stage 2A andexpansion / upgrading of some existingexpansion / upgrading of some existing STWsSTWsIncreased from 800Increased from 800 tpdtpd at presentat present toto overover 11,,400400tpdtpd by 2014by 2014

As a result, the current disposal ratio of 1:10As a result, the current disposal ratio of 1:10(sludge : MSW / construction waste)(sludge : MSW / construction waste) cannotcannotbe maintainedbe maintained

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Need forNeed for the STFthe STF

The current practice of disposing of dewateredThe current practice of disposing of dewateredsludge at landfill is not sustainable:sludge at landfill is not sustainable:

CoCo--disposal problem : The current safe codisposal problem : The current safe co--disposal ratiodisposal ratio1:10 cannot be maintained1:10 cannot be maintained

Limited landfill life: Existing landfills would only last untilLimited landfill life: Existing landfills would only last untilearly to mid 2010 decade, there is an urgent need toearly to mid 2010 decade, there is an urgent need toprolong the landfill lifeprolong the landfill life

International trend: Disposal of biodegradable waste atInternational trend: Disposal of biodegradable waste atlandfill is not in line with international trendlandfill is not in line with international trend

Urgent need for Alternative Sludge Disposal MeanUrgent need for Alternative Sludge Disposal Meanss


AlternativeAlternative TreatmentTreatment OptionOptionDevelopmentDevelopment

Sludge Treatment and Disposal Strategy Study (STDSS)Sludge Treatment and Disposal Strategy Study (STDSS)Completed in 1999Completed in 1999Recommended all HK's dewatered sewage sludge to be treated inRecommended all HK's dewatered sewage sludge to be treated inan incineration facilityan incineration facility

Advisory Council on the Environment (ACE)Advisory Council on the Environment (ACE)Consulted in Dec 1999Consulted in Dec 1999Agreed that incineration would be the right directionAgreed that incineration would be the right direction

Preliminary Project Feasibility Study (PPFS)Preliminary Project Feasibility Study (PPFS)Completed in 2001Completed in 2001Concluded that fluidized bed incineration is a feasible technoloConcluded that fluidized bed incineration is a feasible technologygyfor sewage sludge in Hong Kongfor sewage sludge in Hong Kong

Sludge Treatment Facilities (STF)Sludge Treatment Facilities (STF)Commenced in 2004Commenced in 2004

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International PracticesInternational Practices

Japanese ExperienceJapanese ExperienceOverOver 8800% of Japan% of Japan ssludge isludge is iincineratedncinerated

FluidFluid bbeded iincinerationncineration ppredominatesredominates

((overover 161600 plants)plants)

Other treatments including heat drying/compostingOther treatments including heat drying/compostingfor sludge reuse and landfillingfor sludge reuse and landfilling



U.S. ExperienceU.S. ExperienceMainly reuse for lMainly reuse for landand aapplicationpplication

IncinerationIncineration rrepresentsepresents about 20about 20%%

(over 250 plants)(over 250 plants)

Landfilling isLandfilling is ddecreasingecreasing

FFluidized bed incinerators rluidized bed incinerators replacingeplacing mmultipleultiplehhearthearth incineratorsincinerators

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European ExperienceEuropean ExperienceLandfillLandfilling is ding is decreasingecreasing (about 15%)(about 15%)IncinerationIncineration is iis increasing (ncreasing (about 40about 40%%))

DenmarkDenmarkItalyItalyGermanyGermanyU.K.U.K.

FluidizedFluidized bbeded incineration pincineration predominateredominatessLandLand aapplication willpplication will rremainemain sstable (table (aboutabout 45%)45%)


International PracticesInternational PracticesSummarySummary

Incineration is a proven technology and is beingIncineration is a proven technology and is beingincreasingly used in Japan and Europeincreasingly used in Japan and EuropeMany major US cities plan to continue to useMany major US cities plan to continue to useincinerationincinerationHeat drying and composting are the key technologiesHeat drying and composting are the key technologiesfor sludge reusefor sludge reuseLandfilling is decreasing in Japan, U.S., and EuropeLandfilling is decreasing in Japan, U.S., and EuropeLand application including soil conditioners and fertilizersLand application including soil conditioners and fertilizersand need to meetand need to meet US EPA Part 503 Class AUS EPA Part 503 Class A

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HKHK SludgeSludge

High chloride content due to seawaterHigh chloride content due to seawaterflushingflushingExceptExcept sludge generated insludge generated in ShekShek Wu HuiWu HuiSTW and Sai Kung STWSTW and Sai Kung STWCurrent demandCurrent demand of recycled sludgeof recycled sludge isislimitedlimitedSeparate studySeparate study conductedconducted by EPDby EPD


Options for Volume ReductionOptions for Volume Reduction

Updated review of sludge treatmentUpdated review of sludge treatmenttechnologiestechnologies

Options consideredOptions consideredCoCo--incineration with MSWincineration with MSW

Heat DryingHeat Drying

FluidizedFluidized--Bed IncinerationBed Incineration

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CoCo--IncinerationIncinerationMix sludge with municipal solid waste (MSW)Mix sludge with municipal solid waste (MSW)Moisture contentMoisture content

Sludge :Sludge : 70 to 80 percent70 to 80 percentSolid waste : 20 to 30 percentSolid waste : 20 to 30 percent

Primary differences between sludge incinerators and MSWPrimary differences between sludge incinerators and MSWincineratorsincinerators

Residence timeResidence timeGrate designGrate design

MSW incineratorsMSW incineratorsShort retention timeShort retention timeGrates are designed with openings to permit the introduction ofGrates are designed with openings to permit the introduction of airairOpenings can permit unburned sludge particles to fall throughOpenings can permit unburned sludge particles to fall through


CoCo--IncinerationIncinerationRequirements for complete combustion of sludgeRequirements for complete combustion of sludge

Limiting the amount of sludge introduced to the MSW incineratorsLimiting the amount of sludge introduced to the MSW incinerators andanddistributing sludge evenly with the MSWdistributing sludge evenly with the MSWMSWMSW--toto--Sludge rate : 15 to 30 : 1Sludge rate : 15 to 30 : 1

Typical problems encountered with coTypical problems encountered with co--incinerationincinerationPoor mixing of the sludge and MSWPoor mixing of the sludge and MSWToo thick a layer of sludgeToo thick a layer of sludgeToo low a ratio of MSWToo low a ratio of MSW--toto--SludgeSludge

These factors result in only partially burned sludge and airThese factors result in only partially burned sludge and airand heat balance problems. The partially dried, unburnedand heat balance problems. The partially dried, unburnedsludge is discharged along with the incinerator ash causingsludge is discharged along with the incinerator ash causingpotential odour problemspotential odour problems

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Heat DryingHeat DryingDescriptionDescription

EvaporateEvaporate wwaterater uusingsing llowow ttemperatureemperature eevaporationvaporationeequipmentquipmentProven technologyProven technologyIfIf uuse asse as iincinerationncineration pprere--treatment,treatment, fflexibility islexibility is ggainedainedDirectDirect ddryers (ryers (ssludgeludge ccontactsontacts ddryingrying aair)ir)IndirectIndirect ddryers (ryers (hheatedeated jjackets/ackets/sshells)hells)

IssuesIssuesHigh energy consumptionHigh energy consumptionAirAir ppollutionollution ccontrolontrol nneededeededMarketing ofMarketing of hhighigh ssaltalt ccontentontent ssludge will beludge will be ddifficultifficult


Fluidized Bed IncinerationFluidized Bed IncinerationDescriptionDescription

Proven in large plantsProven in large plantsLarge volume reductionLarge volume reductionTime,Time, ttemperature,emperature, tturbulenceurbulence>> 850850 ooCC & 2 sec& 2 sec

IssuesIssuesTrained PersonnelTrained PersonnelConcern on air emission e.g. dioxinConcern on air emission e.g. dioxinUSEPAUSEPA considers regular monitoringconsiders regular monitoringof dof dioxinioxin eemissionmission from mfrom municipalunicipalsewage ssewage sludgeludge iincineratorsncinerators is notis notrequiredrequired

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Recommend OptionRecommend Option

SludgeReceiving

Incineration

Flue Gas Treatment

Ash & ResidueStorage

Landfilling

Emission


Potential Site LocationsA site search study was conducted to identify potential suitable sitesand 9 sites were short-listed for detailed assessment.

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Site Selection Assessment CriteriaSite Selection Assessment CriteriaCumulativeCumulative eenvironmentalnvironmental iimpactmpactEngineeringEngineering ffeasibilityeasibilityOperationalOperational cconvenienceonvenienceFinancialFinancial iissuesssuesStrategicStrategic pplanninglanning iissuesssues

The assessment concludes that the ash lagoonThe assessment concludes that the ash lagoonat Tsang Tsui near Nim Wan, Tuen Mun is theat Tsang Tsui near Nim Wan, Tuen Mun is themost technically viable locationmost technically viable location


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Existing Condition of Proposed SiteExisting Condition of Proposed Site


Sludge Transportation RoutesSludge Transportation Routes

StonecuttersIsland STW

ProposedProposedSludgeSludge

TreatmentTreatmentFacilitiesFacilities

Siu Ho Wan STW

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• Sludge Reception & Storage• Incinerators & Flue Gas

Treatment System & Stack• Flue Gas Residuals Silos, Ash Silos,

Chemical/ Fuel Storage

• Administration Building & VisitorCentre

• Maintenance Workshop• Desalination Plant• Sewage Treatment Plant

Key Components


GreenGreen Design for the STFDesign for the STF• Compliance with the most stringent emission standard• Sustainable development – 90% reduction in volume of waste

disposal of at landfill• Renewable energy from incineration can be used to generate

electricity for daily operation• Effluent reuse for on-site cleaning and irrigation• Water supply by desalination of seawater• Rain water collection and reuse

Based on the green design concept, STF will be a self-sustainable facilityand compliance with both stringent air emission and water dischargestandard.

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Air Emission StandardAir Emission Standard

--11 1010--77Dioxins & FuransDioxins & Furans (c)(c)

--0.50.5 (b)(b)Total Heavy MetalsTotal Heavy Metals

--0.050.05 (b)(b)Total Cadmium & ThalliumTotal Cadmium & Thallium

--0.050.05 (b)(b)MercuryMercury

400400200200Nitrogen Oxides (NONitrogen Oxides (NOXX) as Nitrogen Dioxide (NO) as Nitrogen Dioxide (NO22))

1001005050Carbon Monoxide (CO)Carbon Monoxide (CO)

2002005050Sulphur Dioxide (SOSulphur Dioxide (SO22))

4411Hydrogen Fluoride (HF)Hydrogen Fluoride (HF)

60601010Hydrogen Chloride (Hydrogen Chloride (HClHCl))

20201010Organic CompoundsOrganic Compounds

30301010ParticulatesParticulates (d)(d)

HalfHalf -- HourlyHourlyDailyDaily

Target Emission Limits (mg/mTarget Emission Limits (mg/m33)) (a)(a)

Air PollutantAir Pollutant

(a) Emission limits are reference to 0oC and 101.325 kPa.(b) Average values over a sampling period of a minimum of 30 minutes and a maximum of 8 hours. Including Sb, As, Pb, Co, Cr, Cu, Mn, V and Ni.(c) The unit is I-TEQ (The emission limit is equal to 0.1 ng I-TEQ m-3), according to the BPM 12/1, the averaging time for dioxin is 6 to 8 hours.(d) The particulate emission limit is assumed to be RSP.


EIA StudyEIA Study

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Objective of EIA StudyObjective of EIA Study

To provide information on the nature andTo provide information on the nature andextent of environmental impacts arising fromextent of environmental impacts arising fromthe construction and operation of the Projectthe construction and operation of the Projectand related activities that take placeand related activities that take placeconcurrentlyconcurrently

To apply for Environmental Permit beforeTo apply for Environmental Permit beforeconstruction and operation ofconstruction and operation of STFSTF


Scope of EIAScope of EIA StudyStudy

Air QualityAir QualityHuman Health RiskHuman Health RiskEcologyEcologyWaste ManagementWaste ManagementWater PollutionWater PollutionNoiseNoiseLandscape and VisualLandscape and VisualLandfill Gas HazardLandfill Gas Hazard

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583m

420m

394m

375m

Tuen Mun TownCentre

Air QualityAir Quality

Ridge

ButterflyEstate

Lung KwuTan

310m

320m269m

281m200m

160m


Tuen MunTown Centre

Air QualityAir Quality

ButterflyEstate

LungKwu Tan

Proposed WENTLandfill Extension

Black PointPowerPlant

ExistingWENTLandfill

Green IslandCement

EcoParkShiu WingSteel Mill

Tuen MunIndustrial Area

Castle PeakPower Plant

Target emission limits for STF are equivalent toHong Kong BPM for Municipal WasteIncineration and EC’s Waste IncinerationDirective

Emissions from other sources are based onmaximum allowable emission in SP licence

Five years average monitoring data recorded atYuen Long Station adopted as background airpollution concentrations

Proposed SludgeTreatment Facilities

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Air Pollution ControlAir Pollution Control

Air pollution control and stack monitoring systemAir pollution control and stack monitoring systemto ensure STF stack emissions meet the stringentto ensure STF stack emissions meet the stringenttarget emission limitstarget emission limits

Sludge reception hall and sludge hopper systemSludge reception hall and sludge hopper systemare enclosed to control odour emissionsare enclosed to control odour emissions

Potential odour emissions from STF will bePotential odour emissions from STF will becollected and destroyed by incineration processcollected and destroyed by incineration processor ventilated to deodorizer before dischargeor ventilated to deodorizer before discharge


Human Health RiskHuman Health Risk

Cancer risk associated with STF emissions isCancer risk associated with STF emissions ispredicted to comply with risk guidelinepredicted to comply with risk guideline

Cumulative acute and long term nonCumulative acute and long term non--carcinogenic health impact are found to becarcinogenic health impact are found to beinsignificant when compared to local andinsignificant when compared to local andoverseas guideline levelsoverseas guideline levels

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EcologyEcology

The identified habitats in the Assessment AreaThe identified habitats in the Assessment Areahave low to moderate ecological value,have low to moderate ecological value,including:including:

East Lagoon Breeding ground for Little GrebeSecondary woodland


EcologyEcologyMitigation MeasuresMitigation Measures

Thorough inspections before construction to confirm noThorough inspections before construction to confirm nobreeding activitiesbreeding activitiesIf breeding activities are found in East Lagoon:If breeding activities are found in East Lagoon:

Erect hoarding and provide buffer area around breeding groundErect hoarding and provide buffer area around breeding groundRestriction of access to breeding siteRestriction of access to breeding site

Erect a barrier with climbing plant between East andErect a barrier with climbing plant between East andMiddle Lagoon to provide screening effectMiddle Lagoon to provide screening effect

Enhancement MeasuresEnhancement MeasuresNative tree planting within project siteNative tree planting within project siteCreation of pond habitat within project siteCreation of pond habitat within project site

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Waste ManagementWaste ManagementDuring Construction PhaseDuring Construction Phase

To avoid offTo avoid off--site disposal, excavated PFA wouldsite disposal, excavated PFA wouldbe totally reused as filling material within the STFbe totally reused as filling material within the STFsite areasite area

During Operation PhaseDuring Operation PhaseThe incinerator ash (bottom ash and fly ash) andThe incinerator ash (bottom ash and fly ash) andflue gas cleaning residue will be disposed of atflue gas cleaning residue will be disposed of atthe landfill after checked for compliance with thethe landfill after checked for compliance with theproposed incineration residue pollution controlproposed incineration residue pollution controllimitslimits


Water PollutionWater PollutionDuring operation phase, allDuring operation phase, allgenerated wastewater willgenerated wastewater willbe discharged to the onbe discharged to the on--sitesitewastewater treatment plantwastewater treatment plant

The treated effluent will beThe treated effluent will bereused in the STFreused in the STF

There would be noThere would be nowastewater effluentwastewater effluentdischarged to the coastaldischarged to the coastalwaters of Deep Baywaters of Deep Bay

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Noise ImpactNoise Impact

No existing or planned noise sensitiveNo existing or planned noise sensitivereceivers identified within 1km from the projectreceivers identified within 1km from the projectsite boundarysite boundaryAll noise generating activities of STF would beAll noise generating activities of STF would beenclosed within building structuresenclosed within building structuresOffOff--site road traffic noise impacts generatedsite road traffic noise impacts generatedfrom STF were assessed and would not resultfrom STF were assessed and would not resultin significant impactin significant impact


Landscape and VisualLandscape and Visual

PROPOSED STF

WENT LANDFILL

RESIDENTIAL AREA OF HA PAKNAI

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Landscape and VisualLandscape and VisualPROPOSED STF

RESIDENTIAL AREA OF LUNGKWU TAN


Landscape and VisualLandscape and Visual

View from Ha Pak Nai

View from Lung Kwu Tan

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Landscape and VisualLandscape and VisualConstruction phase measures:Construction phase measures:

Compensatory plantingCompensatory plantingControl of nightControl of night--time lightingtime lightingErection of decorative screen hoardingErection of decorative screen hoarding

Operation phase measures:Operation phase measures:Aesthetic design of faAesthetic design of faççade, chimneys of STF andade, chimneys of STF andassociated structures to harmonize with the surroundingassociated structures to harmonize with the surroundingsettingssettingsShrub and climbing planting to soften structuresShrub and climbing planting to soften structuresTree planting to screen STFTree planting to screen STF


Aesthetic Design of IncineratorsAesthetic Design of IncineratorsOverseas ExamplesOverseas Examples

Crossness, UK Osaka, Japan

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Landfill Gas HazardLandfill Gas Hazard

Risk of landfill gas hazard assessed byRisk of landfill gas hazard assessed bysourcesource--pathwaypathway--target analysistarget analysisOverall risk level associated with:Overall risk level associated with:

Existing WENT Landfill = LowExisting WENT Landfill = LowProposed WENT Landfill Extension = MediumProposed WENT Landfill Extension = Medium

With implementation of protection measures,With implementation of protection measures,no adverse impact of landfill gas hazard onno adverse impact of landfill gas hazard onthis Project is anticipatedthis Project is anticipated


Conclusion of EIA StudyConclusion of EIA Study

The EIA has determined the likely nature andThe EIA has determined the likely nature andextent of environmental impacts predicted toextent of environmental impacts predicted toarise from the Projectarise from the Project

With the recommended mitigation measuresWith the recommended mitigation measuresapplied, the Project would be environmentallyapplied, the Project would be environmentallyacceptable and no unacceptable residualacceptable and no unacceptable residualimpacts are anticipated.impacts are anticipated.

Approved EIA Report available at EPDApproved EIA Report available at EPDwebsitewebsite

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TentativeTentative ProgrammeProgramme

Apr 2009Apr 2009Public Works SubcommitteePublic Works Subcommittee(PWSC)(PWSC)

End 2012End 2012CommissioningCommissioning

May 2009May 2009Finance Committee (FC)Finance Committee (FC)

FebFeb 20092009EIAEIA ReportReport ApprovalApproval

DateDateDescriptionDescription

MAUNSELLMAUNSELL

Sludge Treatment FacilitiesSludge Treatment FacilitiesThank youThank you

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Sludge Treatment Facilities - Association of …aesnet.com.hk/wp-content/uploads/hkie-seminar_14mar09...4 Sludge Treatment Facilities (STF) Current Situation At present, landfilling