Composting Andy Bary WSU - Puyallup

The Composting Process Heat Composting Andy Bary WSU - Puyallup Organic Matter Minerals Microorganisms Compost Pile CO 2 Organic matter, minerals, water, microbes Raw Materials Finished compost O 2 Summary: Requirements for Aerobic, Thermophilic Composting Temperature Changes in an Average Compost Pile Parameter Reasonable Range Preferred Range C:N Ratio 20:1-40:1 25:1-30:1 % Moisture 40-65% 50-60% O 2 Conc. > 5% ~10% Particle size 1-3 < 1-2 ph 5.5-8.5 6.5-8.0 Temperature 131-170 o F 131-150 o F Temperature o F 160 140 120 100 90 70 50 A B C D Time A= mesophilic B= thermophilic C= curing D= maturation Energy yielding processes include: Aerobic respiration: use of O 2 as primary oxidizing agent Anaerobic respiration: use of inorganic substances other than O 2 as oxidizing agent (e.g., nitrate) Fermentation: use of an organic compound (e.g. volatile fatty acids) as oxidizing agent Temperature range Thermophiles (function at temperatures above 113 o F (45-70 o C) Mesophiles (function at temperatures between 50-113 o F (10-45 o C) Mesophiles initiate composting process, and, as temperature increases, thermophiles take over. Mesophiles recolonize compost during curing phase. 1

Feedstock C:N Ratios Dairy Solids Nitrogen and C:N ratio Materials High C:N ratio Fall leaves Straw Wood chips or sawdust Bark Newspaper or card board Separated dairy solids Dry stack manure Materials low C:N ratio Grass clippings Raw Manure Manure with bedding 30-80 40-100 100-500 150-200 560 30-57 13-17 15-25 5-25 10-150 Bulk Density Year N, % C, % C:N Moisture lb/cu yard 2007 1.49 49 33 81 1342 2008 1.50 53 35 83 1392 2009 0.95 54 57 81 1156 2010 1.16 55 47 79 1061 2011 1.82 57 31 81 1156 2012 0.97 31 32 66 1022 2013 1.41 42 30 73 1018 average 1.33 49 33 78 1156 Moisture Range Microbes need water to carry out life functions Try to keep pile moisture content 40-65% by weight Too dry, don t have water films to move around in, can t break down organic matter Too wet, not enough O 2 for aerobic respiration, start using other molecules to breath.. produce foul odors Adapted from T. Richard Particle size and porosity effects on aeration Loosely packed, well structured Loosely packed, uniform particle size Tightly packed, uniform particle size Tightly packed, mixed particle sizes 2

Aerated Static Pile Temperatures Turned Windrow Temperatures 180 160 OFC09 OFC10 OFC11 On Farm Compost 180 160 CHKN09 CKN10 Chicken Manure Compost Temperature, F 140 120 100 PFRP Temperature, F 140 120 100 PFRP 80 80 60 0 20 40 60 80 100 120 140 Days After Initiation 60 0 10 20 30 40 Days After Initiation Process to Further Reduce Pathogens PFRP Meet temperature and time criteria For windrow method maintain >131 o F for 15 days with a minimum of 5 turns. For static aerated systems or invessel systems >131 o F for 3 days Composting methods In vessel Aerated static pile Passively aerated systems windrow Turned windrow composting Maintain temperature at 131 o F or above for 3 days after turning windrow Repeated turning of pile exposes all material to higher temperatures in pile center, and fluffs pile to increase natural aeration Must turn windrow minimum of 5x Total of 15 days > 131 o F Curing required 3

91 o F Static piles must be covered with a clean insulation layer of organic material (such as finished compost or wood chips) 147-165 108 o F 138 o F Finished Compost Porous material Raw Feed Stocks Aerated Static Pile Composting Maintains aerobic conditions Controls objectionable odors Manage pile temperatures Expedite active composting & curing Produce superior compost products Changes PFRP times Bigger piles Moisture needs to be right from the get go Potential for over-aerating (heat and moisture loss) Disposable materials Controls objectionable odors Manage pile temperatures Expedite active composting & curing Changes PFRP times Smaller piles Easier to add water Bigger composting foot print required No electricity required Turned Windrow Composting Organic nutrient management www.soils1.org Compost usage Research updates Manure Management Field day announcements Biorefinery Anaerobic Digestion Systems 4

What is a Biorefinery? An upgrade to a traditional waste handling or waste treatment facility What types of facilities? Agricultural operations, such as dairy farms Municipal composting facilities Municipal waste water treatment facilities What is a Biorefinery? An upgrade to a traditional waste handling or waste treatment facility What types of upgrades? Onsite biofuel production Onsite bioproduct production, such as biofertilizers and biochar Onsite treatment and reuse of water Why is it important to develop a Biorefinery? Case study: traditional dairy manure management Air quality Air quality What is the core technology of a Biorefinery? Anaerobic Digestion (AD) the conversion of organic mater via microbial activity into methane and carbon dioxide Field Application Soil nutrient overload quality The Biorefinery can address Air, Soil, and quality Why is anaerobic digestion alone not enough? Updated case study: The Dairy Waste Biorefinery Updated case study: dairy manure management with AD Biogas Air quality Air quality Field Application Soil nutrient overload quality More technology is needed to address Air, Soil, and quality 5

Highlighted components of a Biorefinery Types of anaerobic digesters Types of anaerobic digesters Advantages of Co-digestion (maximize biogas production) Solids separation (value added products) Nutrient recovery (reduce air, soil, and water quality ) treatment (on-site reuse) Anaerobic digestion is performed in a sealed and selfcontained reactor Allows for controlled mixing and constant temperature Typical hydraulic retention time (HRT) can range from 10 to 30 days (22-28 days common for manure) Common temperature ranges include 35 o C (mesophilic) and 55 o C (thermophilic) Types of anaerobic digesters Advantages of Co-digestion Manure alone has rather low energy content because the cow has already digested the organic material Co-digestion typically uses organic waste material that retains higher energy content Biogas production can be enhanced 25% to 400% over manure only digestion Basic AD reactor designs for complex, heterogeneous municipal and farm-based wastewaters. Modified from AgSTAR s fact sheet AD 101: Anaerobic Digesters (EPA 2014a). Advantages of Co-digestion Advantages of Co-digestion 6

Biorefinery Overview 1. Primary Solids Separation We will briefly define four process units within the biorefinery concept: Biogas 1. Primary Solids Seperation Fiber 2. Advanced Solids Seperation Phosphorus Nitrogen Phosphorus 3. Nutrient 4. 4. Treatment Treatment Clean Technology: Mature and in widespread use Equipment: Slope screens, rotary screens and screw presses ~40% removal of TS in effluent : Digested fibrous solids used as animal bedding or value-added soil amendment Opportunity: Estimated use of 50% for on-farm bedding with remainder value-added product Challenges: Finding a market A B C (A) Separated AD fiber (photo Craig Frear); (B) Cows bedding on AD fiber (photo DVO Inc.); (C) Value-Added from AD Fiber (photo Magic Dirt) 10-20% TN 10-20% TP $12-18/cow/yr $45-60/cow 9-12 yard 3 /cow/yr $70-120/cow/yr 2. Advanced Solids Separation 3. Nutrient Technology: Mature but relatively new on the dairy Equipment: Centrifuges, belt presses, dissolved air flotation (DAF) Polymer/coagulant additions are common ~97% removal of TSS in effluent : Suspended solids associated with the majority of Phosphorus Challenges: Important considerations include, electrical usage, O/M costs, total Phosphorus removal, and final product form (drying) A B (A) DAF System, George DeRuyter and Sons Dairy, WA; A (B) DAF Effluent B C 30-35% TN 70-90% TP $30-55/cow/yr $130-200/cow 1 dry ton/cow/yr $100/cow/yr Struvite Crystallization Nitrification/Denitrification Ammonia Stripping Algal Systems Vermiculture 40 Struvite Crystallization Nitrification/Denitrification Technology: Mature but relatively new on the dairy : Struvite is a slowrelease crystalline fertilizer containing roughly 10%, 6%, and 13% by mass magnesium, nitrogen and phosphorus Opportunity: High quality product ready for market Challenges: Requires relatively dilute wastewater to avoid concerns with solids Struvite crystallizer and product, Massey MD, photo A courtesy MultiForm B Harvest C ~10% TN 70-80% TP $80-100/cow/yr $100-200/cow 0.1 dry ton/cow/yr $60/cow/yr Technology: Mature for municipal facilities but challenging to implement on the dairy Equipment: Large dual reactor system: both aerobic and anaerobic steps : N2 gas (value added product?) Challenges: Limited applications to dairy wastewater, more common pilot and commercial systems with swine manure Post AD and solids separation, the majority of the remaining nitrogen (~80%) is in ammonia form Bimodal approach, simplified NDN for ammonia removal but not water clean-up or complex (membrane, partial nitrification processes, etc.) for combined ammonia removal and clean up NDN system on swine farm in North Carolina, USA (image A courtesy of extension.com) B C 70-80% TN 20-50% TP $15-50*/cow/yr $400-600/cow NA NA 7

Ammonia Stripping Algal Systems Technology: Developing Equipment: Contact tower to harvest ammonium gas Post-AD effluent advantageous for ammonia stripping higher ph, supersaturated CO2 and excess thermal energy : Liquid or solid ammonium sulfate (ammonium salt fertilizer) Opportunity: Utilization of carbon dioxide stripping can reduce chemical input costs with additional research/demonstration on ion exchange or membrane systems Challenge: Operations cost Ammonia stripping and ammonium sulfate recovery towers post-ad, Byosis B C 50-75% TN NA $60-130/cow/yr $250-300/cow 0.2 dry ton/cow/yr $50/cow/yr Technology: Active research Equipment: Both openair/raceway and photobioreactor systems in development and in pilot testing Opportunity: While considerable work still needed in regard to algal biofuel viability, algal production, as part of a wastewater system, holds more short-term promise Challenge: No mature markets presently exist for a dry algal product A (A) Algal raceway; (B) dried turf algae biomass (photos courtesy USDA ARS) B 50-80% TN 50-80% TP $250-330/cow/yr $400-500/cow 0.65 dry ton/cow/yr $80/cow/yr Vermiculture 4. Treatment Technology: Active research/developing Equipment: Passive aerobic bioreactors (~filter tank) While most focus on solids treatment via vermi-compost, several dairies have/are installing worm-based filtration systems aimed at ammonia removal Post-AD effluent or non-ad lagoon wastewater, although solids control and temperature can be concerns Opportunity: Some potential for value-added sales of castings as well as worms. Vermifiltration system in California (photo courtesy of Biofiltro) 70-90% TN 5-10% TP $15-20/cow/yr $250-300/cow 0.13 dry ton/cow/yr $13/cow/yr Membranes Evaporation 46 Membranes Evaporation Technology: Mature but relatively new on the dairy Equipment: Various sequential membranes with decreasing poresize (MF, UF, RO) and multiple passes/recycles can be used to produce discharge/process water from the wastewater : Typical performance yields 50-60% clean water, with rest of volume as water with removed solids, and dilute RO concentrate. Challenges: Solids control, appropriate choice of membranes, acid treatment/ammonia control, multiple RO passes, high pressure losses/electrical cost, and O/M costs are concerns Pilot membrane system at US dairy, photo courtesy of McLanahan ~96% TN ~100% TP $125-175/cow/yr $350-450/cow 0.56 dry ton/cow/yr $138/cow/yr Technology: Active research/developing Opportunity: With sufficient thermal energy, system can evaporate considerable wastewater, producing ~ 50% of volume as dilute concentrate which can be further treated with R/O. Challenges: As before, solids control, acid/ammonia control, multiple stage processing and O/M are concerns alongside thermal energy need Data from Drosg et al., 2015; Hoop et al., 2011; Frear et al., 2015 with O/M assuming that 100% of thermal need supplied by AD, yielding a roughly 50% concentration effect (Drosg et al., 2015) Process chart of evaporative processing of manure wastewater (Drosg et al., 2010) ~40% TN ~90% TP $225-300/cow/yr $200-250/cow 0.58 dry ton/cow/yr $104/cow/yr 8

Comparison review Primary Solids Separation Advanced Solids Separation 10-20% TN 30-35% TN 10-20% TP 70-90% TP $12-18/cow/yr $30-55/cow/yr $45-60/cow $130-200/cow 9-12 yard 3 /cow/yr 0.8 dry ton/cow/yr $70-120/cow/yr $100/cow/yr Nutrient Struvite Crystallization Nitrification/Denitri fication Treatment Treatment Ammonia Stripping Membranes Algal Systems Evaporation ~96% TN ~40% TN ~100% TP ~90% TP $125-175/cow/yr $225-300/cow/yr $350-450/cow $200-250/cow 0.56 dry ton/cow/yr 0.58 dry ton/cow/yr $138/cow/yr $104/cow/yr Vermiculture ~10% TN 70-80% TN 50-75% TN 50-80% TN 70-90% TN 70-80% TP 20-50% TP NA 50-80% TP 5-10% TP $80-100/cow/yr $15-50*/cow/yr $60-130/cow/yr $250-330/cow/yr $15-20/cow/yr $100-200/cow $400-600/cow $250-300/cow $400-500/cow $250-300/cow 0.1 dry 0.65 dry NA 0.2 dry ton/cow/yr ton/cow/yr ton/cow/yr 0.13 dry ton/cow/yr $60/cow/yr NA $50/cow/yr $80/cow/yr $13/cow/yr 49 Off-dairy Organics Off-dairy Woody Biomass Biogas Anaerobic Digester Bedding Future Bio-Refinery Concept Pyrolysis Heat Solids Separation Fiber Biochar Bio-Fertilizers Nutrient Storage Lagoon Field Animal Drinking Treatment Dairy Waste Bio-refinery Organic Waste Bio-refinery 9