to digest or incinerate sludgethat is the question · pdf fileohio wea‐awwa 2014 technical...
TRANSCRIPT
© 2014 O’Brien & Gere
ToDigestorIncinerateSludge…ThatistheQuestion
Ohio WEA‐AWWA 2014 Technical Conference & Expo, Columbus, Ohio, August 29, 2014
MarkGreene,O’Brien&Gere
© 2014 O’Brien & Gere
Today’s Presentation
To Digest or Incinerate Sludge…That is the Question
Statistics
Incineration Basics
Anaerobic Digestion Basics
SWOT
Moving Forward
© 2014 O’Brien & Gere
Energy Usage Distribution By Treatment Process Train
© 2014 O’Brien & Gere
Energy Usage Distribution Within Solids Handling Stream
3.7% of WWTP total
© 2014 O’Brien & Gere
US Biosolids Disposal Practices
© 2014 O’Brien & Gere
Ohio Sludge Disposal Practices
2002– OhioEPAestablishessewagesludgeregulations OhioAdministrativeCoderule3745‐40
2005– OhioEPAreceivesEPAdelegationforthesewagesludgeprogram. 1ofonly7States
2011revisedrules2003‐2009biosolidsreports 30%offacilitiesprocess90%ofthebiosolids
© 2014 O’Brien & Gere
Ohio Biosolids Generation (2004‐2009)
© 2014 O’Brien & Gere
Ohio Biosolids Disposal Practices (2004‐2009)
© 2014 O’Brien & Gere
Ohio Biosolids Disposal Practices (2004‐2009)
Beneficial reuse requires
sludge stabilization
© 2014 O’Brien & Gere
How to Stabilize?
• Dewater cake to 20%+ solidsAnaerobic Digestion
• Produce inorganic ash, use as landfill cover
Incinerate Sludge
• Dewater cake plus add lime, 25%+ solids
Chemical Stabilization
• Sludge drying• Other methodsCombination
• Digestion and IncinerationFocus of this presentation
© 2014 O’Brien & Gere
Solids Handling Operating Costs
Fuel/Electricity0%
Chemical17%
Landfill Fees64%
Labor/Benefits19%
Anaerobic Digestion
Fuel/Electricity25%
Chemical16%
Landfill Fees3%
Labor/Benefits56%
Incineration
© 2014 O’Brien & Gere
INCINERATION
© 2014 O’Brien & Gere
Sewage Sludge Incinerators
~170SSIplantsinoperationinUS
Threemaintypesofincineratorsareused
>80%areofthemultiplehearthdesign
~15percentarefluidizedbedcombustors
3percentareelectric
MostlocatedintheEasternUnitedStates
AlsoasignificantnumberontheWestCoast
NewYorkhasthelargestnumberoffacilities(33)
Pennsylvania(21)andMichigan(19)havethenext‐largestnumbersoffacilities
Ohiohas~10plantswithSSI’sSource: AP-42, Compilation of Air Pollutant Emission Factors, EPA, 2012
© 2014 O’Brien & Gere
Incineration Practices in Ohio
© 2014 O’Brien & Gere
Other Biosolids Practices in Ohio
© 2014 O’Brien & Gere
Maximum Achievable Control Technology (MACT)
Incinerationnolongerfallsunder“domesticsewageexclusion”provisionoftheCleanWaterAct,butunderSection129oftheCleanAirAct
CompliancedateisMarch21,2016 SSIclassificationdeterminationisnecessary Emissionstestingisrequired
Additional/NewControlsmayberequired Mercuryscrubbingsystem Causticadditiontowetscrubberventuris
› SulfurdioxidecomplianceandimprovedHClemissions Additionofwetelectrostaticprecipitator
› Cadmium,lead,andparticulatescompliance SelectiveNonCatalyticReductionsystem
› InjectammoniainexhaustgasexitforNOxreduction
© 2014 O’Brien & Gere
Incineration
StrengthsTurn on/off as needed
Ash residual (solids reduction)
Proven Technology
Operator familiarity
Lower initial capital cost
WeaknessesMore fossil fuel (higher utility cost)
Larger carbon foot print
Limited grant potential
Not "Green"
Odor from sludge handling
Higher operation cost
Limited tipping fee potential
© 2014 O’Brien & Gere
Incineration
Opportunities
Merchant Facility: Accept outside sludge
for revenue
Threats
Utilize original/rebuilt incinerators
Future cost to replace
Potential changes in air emission regulations
© 2014 O’Brien & Gere
ANAEROBIC DIGESTION
© 2014 O’Brien & Gere
Anaerobic Digestion
Primarilyforsolidsstabilizationaspartofanoverallsolidshandlingsystem
Mesophilicdigestionismostprevalent 95ºto98ºF(35ºto37ºC)
© 2014 O’Brien & Gere
Mesophilic Digestion
Featuresofawell‐designedandwell‐operatedmesophilicdigestionprocess Uniformfeedofscreenedandde‐grittedrawsolids
› semi‐continuous/continuous
Automaticremoval(positivecontrol)offloatables,scum,andfoam
Completemixing
Adequateheating
Improvedpre‐thickeningoffeed
© 2014 O’Brien & Gere
Anaerobic Digestion
Strengths"Green"/ sustainable technology
Reduced carbon footprint
Tipping fee generation
Energy recovery
Proven Technology
Closed vessel/no odors
No incinerator stacks
Grant potential
Weaknesses
Biological process
Capital cost
Operational skill (new skill set/training required)
Residual sludge/digestate disposal
© 2014 O’Brien & Gere
Anaerobic Digestion
Opportunities
Grant potential
Tipping Fees
Rate stabilization
Third party performance contracting
Public Relations ‐ Community Good Neighbor
Future SSO waste & regulations/compost fee
Threats
Sour digester if not property operated
Odors if not operated properly
Toxicity
Overfeed/underfeed/loading
Market competition for outside sources – new mind set
© 2014 O’Brien & Gere
Digeste YES, Incinerate NO
Dairywhey Saladdressing Fats,oils,andgrease Manure Outdatedbeerandsoda Pulverizedfoodwaste
Smallparticles,nocontamination,nogrit
© 2014 O’Brien & Gere
Municipal Solids Waste to Landfill
© 2014 O’Brien & Gere
Future Sludge Management Options
Incineration
•Business as usual
•Uncertain Long Term Solution
Anaerobic Digestion
•New sources of revenue•Operating
cost reduction
© 2014 O’Brien & Gere
Benefits of Anaerobic Digestion
• Good neighbor technology
Anaerobic Digestion
• Can be treated by this technology
High Strength Waste
• Tipping feesRevenue Potential
• Electricity purchaseCost Avoidance
© 2014 O’Brien & Gere
Harvest Carbon or Waste Carbon?
Sludge 75%VSbeforedigestion 60%VSafterdigestion
AnaerobicDigestion Removessomecarbonduringthe20dayprocess
Convertsittocarbondioxideandmethane
RemainingCarbon Stillinthesludgecake Hauledtocompostingorthelandfill
Incineration Destroysvirtuallyallofthecarbonandvolatilesolids
RemainingAsh Mostlyinert,inorganicmaterial
Suitabletobeusedasdailycoveratthelandfill
© 2014 O’Brien & Gere
Hub and SpokeSmall Plant Sludge
Small Plant Sludge
Small Plant Sludge
Small Plant Sludge
Medium Plant
Anaerobic Digester
© 2014 O’Brien & Gere
One Size Fits All?Thedecisiontodigestorincineratesludgemustbedoneonacase‐by‐casebasis
Notcosteffectivetodigestorincineratesludgeatsmallwastewaterplants
Maybecosteffectivetodigestsludgeatmediumsizefacilities,butnotcosteffectivetoincinerate
Possiblycosteffectivetodigestandincineratesludgeatlargefacilities
© 2014 O’Brien & Gere
To Digest or Incinerate Sludge…That is the Question
NOTICE Thismaterialisprotectedbycopyright.Nootheruse,reproduction,ordistributionofthismaterialoroftheapproachesitcontains,isauthorizedwithoutthepriorexpresswrittenconsentofO’Brien&Gere.
©Copyright,2014O’Brien&GereEngineers,Inc., AllRightsReserved
Ohio WEA‐AWWA 2014 Technical Conference & Expo, Columbus, Ohio, August 29, 2014
All materials printed on recycled paper.
© 2014 O’Brien & Gere