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Ohio WEA‐AWWA 2014 Technical Conference & Expo, Columbus, Ohio, August 29, 2014

To Digest or Incinerate …That is the Question

Mark Greene, O’Brien & Gere

© 2014 O’Brien & Gere To Digest or Incinerate Sludge…That is the Question

Today’s Presentation

Statistics

Incineration Basics

Anaerobic Digestion Basics

SWOT

Moving Forward

© 2014 O’Brien & Gere Usage Distribution By Treatment Process Train

© 2014 O’Brien & Gere Energy Usage Distribution Within Solids Handling

3.7% of WWTP total

© 2014 O’Brien & Gere US Disposal Practices

© 2014 O’Brien & Gere Ohio Sludge Disposal Practices

 2002 – Ohio EPA establishes sludge regulations  Ohio Administrative Code rule 3745‐40  2005 – Ohio EPA receives EPA delegation for the program.  1 of only 7 States  2011 revised rules  2003‐2009 biosolids reports  30% of facilities process 90% of the biosolids

© 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 requires sludge stabilization

© 2014 O’Brien & Gere How to Stabilize?

Anaerobic •Dewater cake to 20%+ solids Digestion

Incinerate • Produce inorganic ash, use as Sludge cover

Chemical •Dewater cake plus add lime, Stabilization 25%+ solids

• Sludge drying Combination •Other methods

Focus of this •Digestion and presentation

© 2014 O’Brien & Gere Solids Handling Operating Costs

Anaerobic Digestion Incineration /Electricity 0%

Chemical Labor/Benefits 17% 19% Fuel/Electricity 25%

Labor/Benefits 56% Chemical Landfill Fees 16% 64%

Landfill Fees 3%

© 2014 O’Brien & Gere INCINERATION

© 2014 O’Brien & Gere Sewage Sludge Incinerators

 ~170 SSI plants in operation in US

 Three main types of incinerators are used

 >80% are of the multiple hearth design

 ~15 percent are fluidized bed combustors

 3 percent are electric

 Most located in the Eastern United States

 Also a significant number on the West Coast

 New York has the largest number of facilities (33)

 Pennsylvania (21) and Michigan (19) have the next‐largest numbers of facilities

 Ohio has ~10 plants with SSI’s Source: AP-42, Compilation of Air 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)

 Incineration no longer falls under “domestic sewage exclusion” provision of the Clean Act, but under Section 129 of the Clean Air Act  Compliance date is March 21, 2016  SSI classification determination is necessary  Emissions testing is required  Additional/New Controls may be required  scrubbing system  Caustic addition to wet venturis › dioxide compliance and improved HCl emissions  Addition of wet electrostatic precipitator › , , and compliance  Selective Non Catalytic Reduction system › Inject in exit for NOx reduction

© 2014 O’Brien & Gere Incineration

Strengths Weaknesses

Turn on/off as needed More (higher utility cost) Larger carbon foot print Ash residual (solids reduction) Limited grant potential

Proven Technology Not "Green"

Odor from sludge handling Operator familiarity Higher operation cost

Lower initial capital cost Limited tipping fee potential

© 2014 O’Brien & Gere Incineration

Opportunities Threats

Utilize original/rebuilt incinerators

Merchant Facility: Accept outside sludge Future cost to replace for revenue

Potential changes in air emission regulations

© 2014 O’Brien & Gere ANAEROBIC DIGESTION

© 2014 O’Brien & Gere Anaerobic Digestion

 Primarily for solids stabilization as part of an overall solids handling system  Mesophilic digestion is most prevalent  95º to 98ºF (35º to 37ºC)

© 2014 O’Brien & Gere Mesophilic Digestion

 Features of a ‐designed and well‐operated mesophilic digestion process

 Uniform feed of screened and de‐gritted raw solids › semi‐continuous/continuous

 Automatic removal (positive control) of floatables, scum, and foam

 Complete mixing

 Adequate heating

 Improved pre‐thickening of feed

© 2014 O’Brien & Gere Anaerobic Digestion

Strengths Weaknesses

"Green"/ sustainable technology Biological process Reduced carbon footprint

Tipping fee generation Capital cost

Proven Technology Operational skill (new skill set/training required) Closed vessel/no

No incinerator stacks Residual sludge/ Grant potential disposal

© 2014 O’Brien & Gere Anaerobic Digestion

Opportunities Threats

Grant potential Sour digester if not property operated

Tipping Fees Odors if not operated properly

Rate stabilization Third party performance contracting Public Relations ‐ Community Overfeed/underfeed/loading Good Neighbor Future SSO & Market competition for outside regulations/ fee sources –new mind set

© 2014 O’Brien & Gere Digeste YES, Incinerate NO

 Dairy whey  Salad dressing  Fats, , and grease   Outdated beer and soda  Pulverized waste Small particles, no contamination, no grit

© 2014 O’Brien & Gere Municipal Solids Waste to Landfill

© 2014 O’Brien & Gere Future Sludge Management Options

Anaerobic Incineration Digestion •Business as •New sources usual of revenue •Uncertain •Operating Long Term cost Solution reduction

© 2014 O’Brien & Gere Benefits of Anaerobic Digestion

Anaerobic • Good neighbor Digestion technology

High Strength •Can be treated by this Waste technology

Revenue • Tipping fees Potential

Cost • Electricity purchase Avoidance

© 2014 O’Brien & Gere Harvest Carbon or Waste Carbon?

 Sludge  Incineration  75% VS before digestion  Destroys virtually all of the carbon and volatile solids  60% VS after digestion   Anaerobic Digestion Remaining Ash  Mostly inert, inorganic  Removes some carbon material during the 20 day process  Suitable to be used as daily  Converts it to carbon cover at the landfill dioxide and  Remaining Carbon  Still in the sludge cake  Hauled to composting or the landfill

© 2014 O’Brien & Gere Hub and Spoke

Small Plant Small Plant Sludge Sludge

Medium Plant Anaerobic Digester

Small Plant Small Plant Sludge Sludge

© 2014 O’Brien & Gere One Size Fits All?

 The decision to digest or incinerate sludge must be done on a case‐by‐case basis  Not cost effective to digest or incinerate sludge at small plants  Maybe cost effective to digest sludge at medium size facilities, but not cost effective to incinerate  Possibly cost effective to digest and incinerate sludge at large facilities

© 2014 O’Brien & Gere Mark Greene, [email protected], (315) 956‐6271

© 2014 O’Brien & Gere Ohio WEA‐AWWA 2014 Technical Conference & Expo, Columbus, Ohio, August 29, 2014

To Digest or Incinerate Sludge…That is the Question

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© 2014 O’Brien & Gere © 2014 O’Brien & Gere