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Performance and Environmental Impact Evaluations of Alternative Waste Conversion Technologies in California


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Title: Performance and Environmental Impact Evaluations of Alternative Waste Conversion Technologies in California

  • Performance and Environmental Impact Evaluations
    of Alternative Waste Conversion Technologies in
  • Public Workshop
  • April 14, 2004

  • California Integrated Waste Management Board
  • Fernando Berton Project Coordinator

  • CIWMB Background Fernando Berton
  • University of California Project Overview
  • Tom Durbin
  • Feedstocks Tom Durbin, Rob Williams
  • Processes and Products
  • Tom Durbin, Rob Williams
  • Environmental Impacts Bill Welch
  • Conclusions
  • Tom Durbin, Rob Williams, Bill Welch

Materials Being Landfilled
  • 1989 legislation goal 50 diversion by 2000
    (currently 47)
  • Organics (biogenic and fossil derived)
  • Divert 10-13 million tons
  • Landfill about 30 million tons
  • Paper /cardboard largest category
  • Recycle 4-5 million tons, Landfill 11 million
  • Inorganic Components 8 million tons

CIWMB Programs
  • Dec 1999 Colloquy Started Dialogue
  • May 2001 Conversion Technology Forum
  • Lack of political leadership
  • Statutory constraints
  • Lack of funding
  • Economics and markets
  • Lack of data
  • Feedstock access
  • Public perception understanding
  • Regulatory

CIWMB Actions
  • May 2001 Directed work in 5 areas
  • Interagency coordination
  • Follow-up workshops/symposia
  • Leveraging Fed/State
  • Legislative proposal for small-scale grants and
    lifecycle analysis research
  • Assist applicants in permit process

CIWMB Strategic Plan
  • Conversion technologies could be major tool
    towards zero waste
  • harnessing the energy potential in waste by
    using new and clean technology to convert the
    material directly into green fuel or gas to
    produce electricity.
  • Strategic Plan Goals Objectives
  • Environmentally preferable technologies
  • Promoting new technologies and processes
  • Alternative means of diversion, including
    technologies that result in electricity and fuel

CIWMB Policy Recommendations
  • Adopted April 2002
  • Conversion Technology Definition
  • Conforming definition to transformation
  • Findings
  • Level of credit
  • Regulatory and Permitting

AB 2770 Penultimate Version
  • Administration-sponsored
  • Definition, findings, level of credit
  • Conforming changes for counting diversion
  • Provisions on CEQA, testing residue, etc.
  • RD program
  • Lifecycle costs/benefits
  • Feedstock amenability with different
  • Small-scale grant/RD program

AB 2770 Chaptered Version
  • Gasification Definition
  • Lifecycle and market impacts - RTI
  • Technical evaluation UC contract
  • Risk assessment issues OEHHA contract
  • Report to Legislature

Performance and Environmental Impact Evaluations
of Alternative Waste Conversion Technologies in
California University of California,
Riverside College of Engineering Center for
Environmental Research and Technology University
of California, Davis Sponsored by California
Integrated Waste Management Board
Technology Identification/Evaluation
  • Definitions
  • Analysis of performance characteristics
  • Technical limitations
  • Commercial status
  • Types of feedstocks and quality (moisture)

Processes Evaluated
  • Thermochemical Processes
  • Gasification
  • Pyrolysis
  • Catalytic Cracking
  • Plasma Arc
  • Biochemical Processes
  • Fermentation
  • Digestion
  • Hydrolysis

Product Evaluation
  • Types of Products (e.g., electricity, fuels or
  • Environmental impacts of products
  • Processing steps
  • Determine potential value of products that could
    be produced from MSW electricity petroleum

Environmental Impacts
  • Emissions and emissions sensitivity to feedstocks
  • Residues (hazardous and non-hazardous)
  • Nuisance factors (noise, dust, traffic)
  • Other environmental impacts

Initial Work
  • Initial work created a database (contract
    IWM-C0172 )
  • Report
  • Solid Waste Conversion A review and database of
    current and emerging technologies
  • Interactive Data Base is available at
  • http//
  • Including downloading of complete db

Technical Survey
  • Overall technical evaluation vendors surveyed
    but no evaluation of specific technologies/vendors
    was performed
  • Database of nearly 400 technologies/Vendors
  • Initial UCD database, CIWMB database, Juniper
    report, other sources
  • About 70 responses received
  • 18 pyrolysis, 22 gasification, 11 biological, 10
    plasma arc, 9 catalytic cracking or other
  • 70 addressed survey questions
  • Variety of systems and responses made it
    difficult to make apples to apples comparisons

Purpose of Workshop
  • Present and explain preliminary findings
  • Discuss potential advantages/liabilities of
    alternative conversion technologies
  • Provide a question and answer period
  • Obtain feedback from stakeholders
  • Discuss needs for additional data/information

Project Timing
  • Public Workshop discuss preliminary findings
  • Working Draft sent to Technical Advisory Board
  • Comments expected by end of April
  • Completed final draft reported by early May and
    provided to Board for May meeting
  • Posted on CIWMB website by early May
  • Peer-review and public comments through late May
  • Final report and responses to comments targeted
    for completion by June for Board Review
  • Release of Final Report will be delayed to July
    Board meeting if comments remain to be addressed

Feedstocks for Alternative Conversion Technologies
MSW Diversion in California
  • California landfills approximately 37.5 million
    tons of waste annually (U.S. 231.9 million tons
  • 1990 Integrated Waste Management Act (AB 939) set
    goals to cut waste disposal by 25 by 1995 and 50
    by 2000
  • Diversion Rates have increased considerably from
    10 in 1989 to 47 currently

1999 Waste Stream Characterization
Waste Distribution Mass/Energy
Energy Equivalence
  • 2370 MW of electrical power
  • 5 of states capacity and 6 of consumption
  • 60 million barrels of crude oil
  • _at_ 37 barrels ----- 2.2 billion

Diversion Efforts for Misc. Organics
  • 170 compost and Process facilities
  • Composting, mulch, landfill cover, biomass to
  • Handle 6-7 million tons of organic materials
  • 2 million wet tons (1.6 MBDT) urban wood waste
    consumed in several of the states 30 biomass
    power plants
  • Approximately 15 million wet tons ( 8 MBDT) of
    organics sent to landfill (CD wood, green waste,
    food waste, and other)

Diversion Efforts for Paper
  • Paper recycling represents 4-5 million tons
  • Cardboard boxes recycle rate 52
  • Old newspaper recycle rate 59
  • 10 million tons of paper to landfill
  • 25 million tons of organic materials still sent
    to landfill

Diversion Efforts for Plastics
  • Overall recycling rates for plastics are
    relatively low and in the 2-4 recovery range
  • PETE (soda bottle) recycling rates were over 70
    in California in 1994 up from 4 in 1988
  • HDPE (milk jug) recycling rates were 25
  • Recycling rates for plastic films and other
    plastics which make up a predominant portion of
    the waste remain below 3, however

Waste Reduction
  • Packaging and containers
  • 32 of MSW generated, 28 of disposed MSW
  • European Policies
  • 1994 EC Directive to take measures to reduce
    package waste
  • 1991 German Extended Producer Responsibility
  • Manufacturers take back container packaging
  • Individual companies or central system
  • US2.25 per month
  • Packaging 90 recovered and 80 recycled
  • Uncertain how readily such programs could be
    implemented in California

MSW Combustion aka incineration
  • 130 million tons worldwide at over 600 facilities
  • Roughly 75 of waste in Japan
  • 167 large facilities in US ---- 2/3rds on east
  • 3 in California
  • Poor perception by public
  • Incinerators have decreased emissions

Feedstocks for Alternative Conversion Technologies
  • Thermochemical processes can accept nearly all
  • Biochemical processes generally accept only
    biodegradable feedstocks
  • Some high solids reactors can accept more
    inhomogeneous waste with the no biodegradable
    components exiting as digestate
  • Effects of metals in pigments, etc.
  • PVC and chlorine containing materials can
    contribute to dioxin/furan formation in
    thermochemical processes

Waste Distribution Mass/Energy
Biochemical Process Feedstocks
  • Biodegradable components of the landfill stream
  • Food wastes
  • Leaves, grass, trimmings
  • Paper/cardboard
  • Wood waste
  • Biodegradation varies in rate and degree

Biochemical Process Feedstocks
  • Biodegradation is not complete
  • Lignin fraction will not degrade anaerobically
  • Lignin amounts
  • Wood (20-30)
  • Food wastes (5-20)
  • Paper (1 25)
  • Practical systems can not completely degrade the
    non-lignin components, due to time, volume,
    energy, and expense limitations

Biochemical Process Feedstocks
Biogas Potentials
  • Laboratory studies to determine Biomethane
    Potential (BMP)
  • analogous to BOD assays for waste water
  • Sample is digested under ideal AD conditions
    until no more biogas is produced (4-8 weeks)

Biochemical Process Feedstocks
Biomethane Potential (BMP) of some
feedstocks Energy in Biogas per wet pound of
Sources Chynoweth,, (1993) Owens and
Chynoweth (1993) Eleaser,,
(1997) Tchobanoglous,, (1993)
LCA/ Marketing study
  • Examined impacts of alternative conversion
    technologies on recycling
  • Most of results related to additional
    preprocessing needed for conversion technologies
  • No effects on recycling of paper
  • Plastics recycling would increase for biochemical

  • Improve characterization of waste in conjunction
    with waste characterization studies
  • Proximate, ultimate, and elemental analysis
  • Ash, metals, toxic congeners
  • Higher heating values (HHV)
  • Characterize protein, carbohydrates, and fats in
    typical food wastes

Alternative Conversion Technologies Processes
and Products
Conversion Processes to Evaluate
  • Physicochemical
  • Biodiesel
  • Distillation

(No Transcript)
  • Full Oxidation of fuel for production of heat at
    elevated temps w/o generating commercially useful
    intermediate gases, liquids, or solids.
  • Referred to as Incineration.
  • Flame temp 1500 - 3000ºF
  • Heat mass transport, progressive pyrolysis,
    gasification, ignition, burning, with fluid
  • Usually employs excess oxidizer to ensure max.
    fuel conversion
  • Recoverable Heat is only useful product.

  • Thermally degrade material w/o the addition of
    any air or oxygen
  • Similar to gasification can be optimized for
    the production of fuel liquids (pyrolysis oils),
    with fewer gaseous products (but leaves some
    carbon as char)
  • Pyrolysis oil uses (after appropriate post
    treatment) liquid fuels, chemicals, adhesives,
    and other products.
  • A number of processes directly combust pyrolysis
    gases, oils, and char
  • Temp. range 750-1500oF.

  • Emphasis is to form energetic gaseous products
    with fewer liquids / solids residues
  • Conversion via direct internal heating provided
    by partial oxidation using substoichiometric air
    or oxygen.
  • Also indirect heating methods (externally fired
    burners) or autothermal methods (exothermic
    reducing reactions )
  • Temp. Range 1300 - 1500ºF.
  • Utilizes a reactant
  • Often used with pyrolysis to complete
    gasification of pyrolytic oils and chars

Process Parameters
  • Product composition can be changed by temp,
    pressure, speed of process, and rate of heat
  • Lower temp./fast pyrolysis temps -- more liquid
  • High temperatures produce more gases
  • Higher pressures can increase reaction rates/
  • Pyrolyzing/gasifying media can be varied by using
    hydrogen and/or steam.
  • Hydrogen
  • Enhances chemical reduction processes
  • Suppresses oxidation of carbon in feedstock
  • Inhibits formation of dioxins and furans
  • Water or steam
  • Increase porosity of char-activated carbon
  • Change the resultant gases and vapors.
  • Can use lower temperatures but higher pressures
    than dry processes.

General Gasifier
Source Carbona Coporation
Gasification Schematic
Gasifier (IGCC)
Source Carbona Coporation
Other example (BRI)
Patent 5,821,111 (1998) Bioengineering Resources,
Gas-Phase Products
  • CO, H2, CH4, O2, N2, H20, CO2 more minor
  • Majority of processes surveyed utilize
    post-combustion of gaseous for electricity/heat
  • Post combustion of gaseous products will produce
    products similar to those found in typical
    combustion (NOx, CO, hydrocarbons, etc.)
  • Easier to clean than typical combustion
  • Exhaust volumes are smaller (less/no O2/air)
  • Pyrolysis oil formation 80, less than 20
  • Low molecular weight species (CH4 power plants,
    CH4 or H2 engines)
  • Cl, SO2, metals scrubbed prior to combustion

Synthesis Gas
  • Mixture of CO and H2 that can be produced from a
    variety of sources
  • The use of different reactants and process
    conditions in gasification allows the gas phase
    composition or the CO and H2 ratio to be varied
  • Can be used to produce fuels, chemical products,
    feed gas for low temperature biochemical
  • Direct process exhaust is essentially eliminated
  • Synthesis gas should be scrubbed prior to
    secondary processing

Catalytic Cracking
  • Pyrolysis with catalytic cracking of oils
  • Utilized in oil refineries on polymeric wastes to
    produce liquid fuels
  • Plastic Energy, LLC is siting a facility in
    California using same technology as Zabrze,
    Poland facility (established in 1997)
  • Ozmotech (Australia) installing similar
    facilities in Spain and Australia

Catalytic Cracking
Plastic Energy LLC Facility
  • Planning to process waste plastics (numbers
    2,4,5, and 6).
  • 95 will be film plastics (resins 2 and 4 or
    HDPE and LDPE)
  • PVC and PET will be hand sorted at MRF

Catalytic Cracking
Plastic Energy LLC Facility
  • Baled plastic delivered from MRF
  • Washed in mechanically stirred flotation tank
    (any inadvertent PVC should sink)
  • Cleaned plastic is melted 365 ºF
  • Flows to reactor and introduced to catalyst,
    heated to 600 ºF
  • Crude oil is formed which is distilled to
    gasoline and very low sulfur diesel component
  • Gasoline used onsite for process energy,
  • Diesel product sold

Catalytic Cracking
Plastic Energy LLC Facility
Source Larry Buckle Plastic Energy, LLC
Catalytic Cracking
Plastic Energy LLC Facility
Plasma Arc Systems
  • Heating Technique using electrical arc
  • Developed for treating hazardous feedstocks
  • Contaminated soils
  • Low-level radioactive waste
  • Medical waste
  • Used in some metals processing
  • Good for creating molten ash (slag), so is used
    for incinerator ash melting and stabilizing in
  • One Commercial scale facility for treating MSW in

Plasma Arc Systems
  • Can be used in pyrolysis, gasification, or
    combustion systems
  • Depends on amount of reactive oxygen or hydrogen
    fed to reactor
  • Air or inert gas is passed through electric arc
    creating ionized plasma
  • The plasma can reach temperatures of 9,000
  • Gas temperature in the reactor chamber (outside
    of the arc itself) can reach 1,700 2,200ºF and
  • The molten slag is typically around 3,000ºF.
  • Will create producer/synthesis gas if operated as
  • Plasma systems can require large amounts of

Plasma Arc Systems
RCL Plasma Recoverable Energy Estimates No
air/oxygen used in gasifier
Plasma Arc Systems
  • Hitachi Metals/Westinghouse Plasma
  • Commercial scale plant at Utashinai Japan
  • 200 tons per day feed input
  • 50 is MSW
  • 50 Auto shredder residue (ASR)
  • Energy for Plasma torches is less because
  • ASR is more energetic fuel
  • Operates with air injection to reactor in amount
    40 of stoichiometric requirements
  • This is a plasma assisted air blown gasifier

Plasma Arc Systems
Utashinai Plant Emissions
(reported by Westinghouse Plasma)
Thermochemical Products
  • Fuel gases
  • Internal/external combustion engines
  • Fuel cells
  • Other prime movers
  • Liquid Fuels
  • Methanol
  • Fischer-Tropsch (FT) liquids
  • Hydrogen
  • Synthetic ethanol

Thermochemical Products
  • Chemicals
  • Ethylene (recycling of plastics)
  • Ammonia based fertilizers
  • Substitute petroleum products
  • Adhesives and resins
  • Food flavorings
  • Pharmaceuticals
  • Fragrances
  • Gas phase components for Biochemical Processes

Pyrolysis Oils
  • Complex mixtures of hydrocarbons
  • Alcohols, aldehydes, ketones, esters, water, etc
  • Can be combusted on site in boilers and engines
  • Lower heating values depending on feedstock
  • Chemical uses
  • Phenol species, acetaldehyde, formaldehyde,
    aromatic chemicals
  • Wood waste fragrances, adhesives, resins, food
    flavorings, pharmaceuticals
  • Dioxins and Furans can concentrate in pyrolytic
  • 80-90 of total dioxins/furans
  • Scrubbing 99.84 in removal of Cl prior to
  • Still examining some data in this area

Commercial Status
  • Thermochemical processes more widely applied to
    MSW in Europe and Japan
  • Large-Scale thermochemical processes used since
    the 1800s
  • Many techniques developed for coal processing
  • TyssenKrupp Uhde has 100 gasifiers most for coal
  • Most Waste facilities operate below 200 tons per
  • Some will have higher capacity

Commercial Status II
  • SVZ facility at Schwarze Pumpe in Germany
  • one of the largest facilities
  • 450k tpy solid waste 55 tpy liquid waste.
  • Mitsui Takuma (licensees Siemens gasif.
  • Plants operating since 1990s, others planned or
  • Nippon Steel
  • Dozen plants 80 to 450 tpd, most operational.
  • Two plants 100 and 450 tpd capacities since late
  • Ebara/Alstom
  • 450 tpd facility in place.
  • 7 plants either operating, commissioning, and
  • 1,500 tpd plant in Kuala Lumpur, Malaysia May

Commercial Status III
  • A number of Identified Plants did have issues in
    commissioning, operating or financially
  • Brightstar
  • Fürth, Germany plant had accident
  • Siemens abandoned the European market
  • Karlsruhe, Germany facility - Thermoselect

Pre-Conclusions -Thermochemical
  • Pyrolysis/gasification appears to be technically
    viable for electricity production
  • Recommend CIWMB further investigate/evaluate
    processes using synthesis gas for fuel or
    chemical production where post combustion is not
  • Use of thermochemical processes seems to be
    expanding but process validation is important
  • Suggest AB2770 definition for gasification be
    modified to be more scientifically correct
  • Did not examine costs

Biochemical Conversion
  • Biochemical conversion-
  • lower temperature and slower rates compared to
    thermochemical methods
  • Generally, higher moisture feedstocks are
  • Biodegradable components only
  • None of the current waste plastic stream
  • Lignin components of biomass are not degradable

Biochemical Conversion
  • Aerobic (with oxygen)
  • Composting operates primarily in this mode
  • Stabilizes/degrades material faster than if
  • Only biochemical mode for lignin degradation (and
    is very slow)
  • Anaerobic (without Oxygen)
  • Principal biological process occurring in

Biochemical Conversion
  • Anaerobic decomposition
  • Biodegradable material only (lignin does not
    degrade anaerobically)
  • Polymer carbohydrate needs to be broken up into
    simpler molecules (sugars). Hydrolysis
    accomplishes this
  • Facultative and Fermentive bacteria/yeasts
  • Biogas ( 50-65 methane, balance CO2, small
    amounts of impurities) Anaerobic Digestion -
  • Ethanol (and/or other chemicals) Fermentation

Biochemical Conversion
  • Fermentation route to ethanol and other chemicals
  • For sugars and starches is fully commercial
    (wine, beer, corn (grain) derived ethanol)
  • Not yet commercial for cellulosic biomass (most
    MSW biomass is cellulosic)
  • Because of expense and difficulty of Hydrolysis
  • Must Hydrolyze cellulose/hemicellulose to sugars
    and organic acids
  • Then yeast ferments the sugars

Biochemical Conversion
  • Hydrolysis Methods
  • Hydrothermal
  • Hot water, maybe high pressure
  • Steam or Ammonia explosion
  • Enzymatic
  • Cellulase enzymes to de-polymerize the cellulose
  • Currently expensive but believed to be most
    economical route in future
  • Intensive research and engineering of microbes
    ongoing in public and private institutions world
  • Acid
  • Dilute or Concentrated Technologically mature
  • Currently more economical than enzymatic

Concentrated Acid Hydrolysis
Acid/sugar separation
Source http//
Biochemicals (fermentative route)
Source Arkenol
  • After Hydrolysis
  • Carbohydrate Cell mass ? Ethanol CO2
    More cell mass
  • Under best circumstances, mass yield of Ethanol
    is 51 of mass of input carbohydrate
  • Accounting for microbe cell growth, best yield in
    practical systems is 46 (mass basis)
  • Recall, the lignin component does not participate

Fermentation of components of MSW
  • Using Hydrolysis to yield sugars and organic
  • Masada
  • Arkenol
  • Waste to Energy (Genahol)
  • And others
  • Using Thermal gasification to depolymerize the
  • BRI
  • Novahol
  • And others?

Masada OxyNol
  • Middletown, N.Y., Permitted (start construction?)
  • Unit operations include
  • MRF
  • Feedstock Preparation (shredding and drying)
  • Acid Hydrolysis Unit (single stage)
  • Fermentation and Distillation Units
  • Focusing on MSW feedstocks

Masada OxyNol
Middletown Facility
  • 230,000 tons per year MSW
  • 70,000 dry tons per year Biosolids
  • Products
  • Ethanol (25 -35 gallons per wet ton feedstock)
  • CO2
  • Recyclables (from up-front separation)
  • Gypsum
  • majority of revenue stream for a typical OxyNol
    facility comes from tipping fee, not products
    produced from waste

  • Develops Biorefineries
  • Cellulose to ethanol via concentrated acid
    hydrolysis (2-stage)
  • Commercial scale plant in Japan using waste wood
  • 67 gallons ethanol per dry ton of feedstock
    (equivalent to Masada yield on wet basis)

Waste to Energy w/ Genahol
  • 2-Stage Dilute Acid Hydrolysis
  • Brelsford Engineering Proc.
  • Attempting validation plant in Santa Maria, CA
  • MRF residue
  • Biomass to ethanol
  • Lignin Plastics thermal CT for heat and power
  • Expect Similar Yields

Anaerobic digestion block diagram
Source Brelsford Engineering, Inc
BRI Energy, LLC
  • Bioreactor ferments waste and synthesis gases
  • Ethanol
  • Hydrogen
  • Proposing to gasify biomass and other components
    in MSW and fermenting the producer gas to ethanol

BRI Energy, LLC
Source patent 5,821,111 (Gaddy, 1998).
Bioengineering Resources, Inc
BRI Energy, LLC
  • Yield from biomass feedstock is potentially
    greater than acid/enzymatic hydrolysis because
    lignin is converted in gasifier (Claim 75
    gallons ethanol/dry ton)
  • Because of bacteria and bioreactor
    characteristics, fermentation stage is quick
  • Claim material is gasified and fermented to
    ethanol in less than 1 hour. (Std. sugar
    fermentation 36-48 hrs.)
  • Plastics, tires, waste oils can be processed to
    ethanol in this system

  • Also promoting ethanol from fermentation of
    synthesis gas
  • Focusing on wood waste right now (wood from bark
    beetle infestation)

Anaerobic Digestion producing Biogas
  • Principle process occurring in Landfills
  • Many waste water treatment plants use AD
  • Extensive development and use of this technology
    in Europe
  • Policies GHG reduction, Total Organic Carbon
    restrictions in Landfill stream.

Anaerobic Digestion Block Diagram
Adapted from Mata-Alvarez, J. (2003)
Anaerobic Digestion producing Biogas
  • Systems can be classified
  • Low or High Total Solids
  • LSlt 15 TS or gt 85 moisture (wet systems)
  • HS range between 20-30 TS or 70-80 moisture
    (dry systems)
  • Single Stage digester
  • Two or multi-stages
  • Batch
  • Optimum Temperatures
  • Mesophilic (85 95 ºF)
  • Slower reaction longer retention times
  • Thermophilic (120- 150 ºF)
  • Faster but requires more heat energy

Single Stage Low Solids AD (Waasa Process)
Biogenic fraction of MSW
10-15 TS
Inoculation loop
Heat addition
Make-up water
Water treatment
Recycle process water
Hydrolysis, acetogenesis, and methanogenesis
occur in a single vessel.
Adapted from Mata-Alvarez, J. (2003)
Single Stage High Solids Reactors
Less pre-treatment, though high solids pumps cost
more Some systems can accept Unsorted MSW
(requires some size reduction and removal of
large items) though yield suffers Plug Flow
reactors, therefore require method to inoculate
fresh feed
Adapted from Mata-Alvarez, J. (2003)
2-Stage AD Schematic
Opportunity to optimize hydrolysis and methane
production separately First Stage can be Low or
High Solids, continuous or batch loading Second
stage is generally Low Solids
Adapted from Mata-Alvarez, J. (2003)
Anaerobic Phased-Solids Digester
High Solids Hydrolysis stages operate in Batch
Mode Timing is phased for uniform methane
production rate Second stage is generally Low
Solids Best with source separated biogenic
fraction of MSW
Source Professor Ruihong Zhang
Anaerobic Phased-Solids Digester
Model results for lab-scale APS digester
Methane production due to individual phased batch
hydrolysis reactors. Overall methane production
is smoother. This system is being piloted.
Source Karl Hartman, UCD
AD in Europe
  • 86 facilities larger than 3300 ton per year
  • Total installed capacity of 2.8 million tons
    waste per year
  • Spain will be treating 7 of biodegradable
    components of MSW by end of 2004 (13 facilities,
    average 70,000 tons per year).

AD Capacity in Europe
Solid Waste Anaerobic Digester Capacity in Europe
Facilities with gt 10 of feedstock coming from
MSW components. Many co-feed with animal manures,
biosolids 90 of capacity is composed of Single
Stage systems
Data were projected for 2004
De Baere, L. (2003).
Biochemical Conversion
Biochemical ConversionPre-Conclusions
  • Technically viable for some components of waste
  • Costs (and perhaps low public awareness) impede

Alternative Conversion Technologies
Environmental Impacts
Present Situation
  • Landfills produce mainly CH4, CO2
  • Trace gas constituents (BTX, H2S, vinyl chloride)
  • Landfills largest source of GHG methane
    emissions --- roughly 1/3rd of total
  • 3,000 landfills in California, 311 active
  • 51 convert gas to energy currently 211 MW
  • Another 26 planning to use energy 29 MW
  • 70 landfills flare landfill gas (66 MW eq.)
  • Remainder (164) vent to atmosphere (31 MW eq.)

Thermochemical Process Emissions
  • Intermediate gases/oils may contain CO, VOCs,
    HCl, H2S, dioxins/furans
  • Many processes surveyed use intermediate gas
    combustion for electricity/heat production
  • Post combustion of gaseous products will produce
    products similar to those found in typical
    combustion (NOx, CO, hydrocarbons, etc.)
  • Easier to clean than typical combustion
  • Intermediate gas volumes are smaller (less/no
  • Low molecular weight species (CO, H2, CH4)
  • Cl, S, PM can be scrubbed prior to combustion

Dioxin/Furans I
Dioxin/Furans-Formation II
  • Poor gas-phase mixing
  • Low combustion temperatures
  • Oxygen-starved conditions
  • Temperatures 480ºF to 1290ºF
  • Formation from Wastes
  • Feedstocks with high levels of Cl and Cu
  • Oxygen content of feedstock 25-45

  • Weber and Sakurai, Chemosphere, 45, 1111-1117
  • Industrial Light Shredder (5 Cl) Refrigerator
    shredder (1 Cl), w/ 3-6 Cu
  • 90 PCDD/F in pyrolysis oils (1,500-10,000 ng/g)
  • Mohr et al., Chemosphere, 34, 1053-1064
  • Feedstock contained chloro-benzenes, phenols,
  • PCDD/F 1,983 ng/g in oil for 3,485 ng/g feedstock
  • Miranda et al., Polymer Degrad Stability
  • Vol. 73, pp 47-67, 2001
  • Commingled plastics with PVC (7.9)
  • Cl volatilized at 680 ºF to HCl
  • NaOH scrubber removed 99.84
  • Resulting pyrolysis oil contained 12 ppm Cl

Pollution Controls
  • Cold-quenching dioxins/furans, acid gases
  • Baghouse, ESP particulate matter
  • Catalytic/thermal incineration - dioxins/furans,
    VOCs, CO
  • Flame temperature control/catalytic reduction
  • Scrubber Acid gases
  • Carbon filters, carbon injection, duct sorbent
    injection dioxins/furans, VOCs

Improvements in Air Pollution Control
Emissions Data
Emissions Data II
Solid Waste Data
Environmental Impact Summary
  • All waste disposal methods carry environmental
  • Proper design of waste conversion processes must
    address air emissions, liquid and solid residues
  • Characterization and pre-sorting of feedstocks
    can reduce emissions
  • Process and pollution control technologies can
    minimize environmental impacts, but must be
    carefully designed and operated
  • Overall environmental impacts of well-designed
    alternative waste conversion technologies are
    equal to or less than current practice of

Conclusions for Alternative Conversion
Problem at Hand?
  • Non-sustainable environment of landfilling of 37
    million tons of material annually
  • Landfill gas impacts other factors
  • Landfill expansion becoming more difficult and
    not beneficial to society
  • Source reduction, recycling, alternative
    conversion technologies

Available Feedstocks
  • 2370 MWe or 60 million barrels of oil
  • Paper and Cardboard
  • Landfill 10 million tons, Recycle 4-5 million
    tons (30)
  • 44 of energy value
  • Plastics
  • 2nd high energy content 30 of total
  • 11 of landfilled mass and 22 of landfilled
  • Growing rapidly and recycling rates are
    relatively low
  • Only thermochemical can process
  • Biochemical Feedstocks
  • Food waste
  • Green/paper waste
  • Contaminants
  • Chlorine containing materials (PVC)
  • Pigments in paper, other metal contaminants

Thermochemical Processes
  • Pyrolysis - Thermally degrade material w/o the
    addition of any air or oxygen
  • Can be used to maximize oil production
  • Many processes use post-combustion for
  • Gasification - Conversion via direct internal
    heating provided by partial oxidation using
    substoichiometric air or oxygen (Hydrogen or
  • Indirect heating methods (externally fired
    burners) or autothermal methods (exothermic
    reducing reactions )
  • Can be utilized to produce synthesis gases
  • Synthesis gas produce chemical/fuel without
  • Combust for electricity -produce gaseous products
    similar to combustion
  • Lower exhaust volumes
  • Lower molecular weight species
  • Scrubbing prior to full combustion or use in

Thermochemical Processes II
  • Have the greatest potential to process the whole
    MSW organic stream
  • More commercial in Japan and Europe
  • Some plants have experienced problems
    Technology must be proven sound
  • Study did not cover economic viability
  • Suggest AB2770 definition for gasification be
    modified to be more scientifically correct
  • More formal vendor should be conducted
  • Need to consider possibility of fuels/chemical
    instead of electricity perhaps work in this
  • Synthetic ethanol, F-T diesel, hydrogen
  • Ethylene, fertilizers, petroleum products,
  • Pyrolysis Oils fragrances, adhesives, resins,

Biochemical Processes
  • Fermentation, anaerobic aerobic digestion
  • Carried out at lower temps. reaction rates
  • Utilize biodegradable feedstocks

Environmental Conclusions
  • Air Emissions Thermochemical process
  • Can use synthesis gas for fuel/chemical w/o
  • Post-combustion similar products to combustion
  • Little for no oxygen/air reducing environment
  • Small air volume
  • Low molecular weight species cleaner to combust
  • Less costly but similar emissions control
  • Solid Waste
  • Thermochemical processes concentrate but do not
    create metallic species
  • Liquid Waste
  • Spent acids from biochemical processes, spent
    scrubber solutions

Socio-economic Impacts
  • Full Life Cycle Analysis should be used in
    comparing benefits/liabilities
  • Potential Resource 60 million barrels oil or
    2370 MW electrical power
  • Provide diversity of product markets
  • Extension of landfills
  • Impacts on recycling
  • Environmental impacts

  • Formal vendor evaluation
  • Improve Characterization of MSW
  • Elemental analysis, heating value, biochemical
  • Improve estimates of waste generation
  • Collect emissions data for Thermochemical
  • Investigate legislation for further increase in
    landfill diversion
  • Co-fund alternative conversion projects
  • Study future landfill costs
  • Study the feasibility of zero waste through
    recycling or source reduction
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