Anaerobic Co-digestion of Biomass for Methane Production : Recent Research Achievements
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Transcript of Anaerobic Co-digestion of Biomass for Methane Production : Recent Research Achievements
Anaerobic Co-digestion of Anaerobic Co-digestion of Biomass for Methane Biomass for Methane
Production : Recent Research Production : Recent Research Achievements Achievements
Wei Wu Wei Wu CE 521 CE 521
Introduction Introduction
Anaerobic Digestion Anaerobic Digestion Anaerobic digestion (AD)Anaerobic digestion (AD)
Organic Matter + HOrganic Matter + H22O + BacteriaO + Bacteria
CHCH44 + CO + CO22 + NH + NH33 + H + H22S S TraditionallyTraditionally
Single substrate and single purpose Single substrate and single purpose Manure was digested to produce energy Manure was digested to produce energy Sewage sludge should be stabilizedSewage sludge should be stabilized Industrial waste water should be pre-treatedIndustrial waste water should be pre-treated
Recently Recently Co-digestion of two or more substrate and multi-Co-digestion of two or more substrate and multi-
purpose purpose
Co-digestion Co-digestion Co-digestion Co-digestion
Two or more substrates Two or more substrates Major amount of a main basic substrates Major amount of a main basic substrates
(e.g. manure or sewage sludge) + Minor (e.g. manure or sewage sludge) + Minor amount of a singe, or a variety of additional amount of a singe, or a variety of additional substratessubstrates
Multi-purpose process serving at the Multi-purpose process serving at the same timesame time
Waste upgradingWaste upgrading Energy production Energy production Improvement of fertilizer qualityImprovement of fertilizer quality
Co-digestion—Cont.Co-digestion—Cont. Factors impact the production of biogasFactors impact the production of biogas
The type of waste being digestedThe type of waste being digested Its concentration Its concentration Its temperatureIts temperature The presence of toxic materialsThe presence of toxic materials The pH and alkalinityThe pH and alkalinity The hydraulic retention timeThe hydraulic retention time The solids retention timeThe solids retention time The ration of food to microorganism The ration of food to microorganism The rate of digester loadingThe rate of digester loading The rate at which toxic end products of The rate at which toxic end products of
digestion are removed digestion are removed
Manure
Low C/N ratio– high ammonia High alkalinity
Rich in macro/micronutrient
Benefits of Co-digestion Benefits of Co-digestion Improved nutrient balance and Improved nutrient balance and
digestion performance digestion performance A nutrient ratio of TOC:N:P = 300:5:1 to A nutrient ratio of TOC:N:P = 300:5:1 to
achieve optimal digestion performance achieve optimal digestion performance Crop or Crop residues
High C/N ratio– high carbon contentLow alkalinity
Lack of macro/micronutrient
Improve the C/N ratio, buffering capacity and more biodegradable substrate
Benefits of Co-digestionBenefits of Co-digestion Effective utilization of digester volumes Effective utilization of digester volumes
Help to utilize the availability of free Help to utilize the availability of free capacitiescapacities
Co- digestion of energy crops and manure Co- digestion of energy crops and manure resulted in the doubling of the plant capacity resulted in the doubling of the plant capacity from 500 kW to 1000 kW retaining the digester from 500 kW to 1000 kW retaining the digester volume (Lindorfer et al., 2007)volume (Lindorfer et al., 2007)
The wide distribution of sewage treatment The wide distribution of sewage treatment plants minimizes transportation costsplants minimizes transportation costs
Equalization of particulate, floating, Equalization of particulate, floating, settling, acidifying etc. wastes, through settling, acidifying etc. wastes, through dilution by manuredilution by manure
Co-digestionCo-digestion
Thermophilic ADThermophilic AD Exceed 55 ° CExceed 55 ° C Retention time Retention time
ofof 12-14 d 12-14 d
Types of digesterTypes of digester Mesophilic ADMesophilic AD
Approximately 30-35Approximately 30-35° C° C Retention time of Retention time of 15 – 30 d15 – 30 d
Continuously stirred tank reactors (CSTRS) under mesophilic conditions
Co-digestionCo-digestion Source of organic waste streams can be Source of organic waste streams can be
co-digested with manure co-digested with manure Food Industry Food Industry
Waste from potato, sugar beet, meat, and dairy Waste from potato, sugar beet, meat, and dairy processing processing
Grain Industry Grain Industry Damaged grainDamaged grain
Paper Industry Paper Industry Newspaper and recycled paperNewspaper and recycled paper
Domestic Wastes Domestic Wastes Livestock Wastes Livestock Wastes Crop ResiduesCrop Residues
Corn stover and switchgrassCorn stover and switchgrass
Case 1 Case 1
Lehtomaki et al., 2007
Cow manure alone
Cow manure alone
Cow manure alone
Manure + 30% sugar beet tops
Manure + 30% grass
Manure + 30% oat straw
Increased by 65 %
Increased by 58 %
Increased by 16 %
Case 2 Case 2 Whey co-digestion with diluted poultry Whey co-digestion with diluted poultry
manure manure For an hydraulic retention time of 18 For an hydraulic retention time of 18
days at 35 days at 35 ° C and organic loading rate of ° C and organic loading rate of 4.9 g COD/L4.9 g COD/L
Biogas production increased by 40% Biogas production increased by 40%
Gelegenis et al., 2007
Case 3 Case 3 Co-digestion of solid slaughter house Co-digestion of solid slaughter house
waste, fruit-vegetable wastes, and waste, fruit-vegetable wastes, and manure manure Possibility to treat combined waste of Possibility to treat combined waste of
Manure (cattle and swine)Manure (cattle and swine) Solid slaughterhouse wastes (rumen, paunch Solid slaughterhouse wastes (rumen, paunch
content, and blood from cattle and swine)content, and blood from cattle and swine) Fruit-vegetable wastes Fruit-vegetable wastes
Alvarez et al., 2007
Drawbacks of Co-digestion Drawbacks of Co-digestion Increased digester effluent chemical Increased digester effluent chemical
oxygen demand (COD)oxygen demand (COD) Additional pretreatment requirementsAdditional pretreatment requirements Increased mixing requirementsIncreased mixing requirements Wastewater treatment requirementsWastewater treatment requirements High utilization degree required High utilization degree required
Conclusion Conclusion Co-digestion offers several possible Co-digestion offers several possible
ecological, technological, and economical ecological, technological, and economical advantagesadvantages
There is very limited research, specifically in the U.S., that characterizes the digestibility of a number of the waste streams
The potential economic impact of fully utilizing alternative waste streams with AD of manure seems to be great, but economic analysis must be done to quantify this information