4/13/2009. Farm Scale Composting: Environmental Benefits, Challenges, and Economics OUTLINE

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1 Farm Scale Composting: Environmental Benefits, Challenges, and Economics Frederick C. Michel, Jr., Harold M. Keener, Jerome Rigot, Tom Wilkinson, Sukhbir Grewal, John Pecchia, Zhongtang Yu, Linda SifS Saif, Sandra Tirado, Jing Chen, Lingling Wang, S. Sreevatsan, Mark Morrison Food, Agricultural and Biological Engineering, The Ohio State University OARDC, Wooster, OH OUTLINE Farm Scale Composting Systems Results from On farm Dairy Manure Composting Economics of a Dairy Manure Composting System Environmental Benefits of Composting Pathogen destruction (dairy+swine) Antibiotic resistance gene destruction (beef+swine) Nitrogen immobilization (dairy) Conclusions 1

2 Bedded Pack Systems Separated Manure Kaldor Composting Farms Dairy and Reuse COMPOSTING Gradients of Temperature Oxygen, Moisture 2

3 Windrow Composting Permeable Compost covers Used to reduce water infiltration Windrow Turners Windrow Turners Self propelled Trench Systems Trench systems with automatic turners 3

4 4/13/29 An agitated bed system used for dairy manure composting. Turners operate on the top of 8 ft high concrete walls. An inclined conveyor lifts and mixes the material, breaking preferential air pathways and moving the composting material along the channel. The turner moves the product 12 ft to 24 feet with each pass. Source Transform Compost High Rise Hog House with Aerated Floor for Composting/Drying Hoop House System Farm Scale Windrow Composting of Swine Manure from a HRHB Fresh Aire Farms, Ohio ref. Harmon, J.D., M.S.Honeyman. Hoop Structures- Research in Performance and Operation. Iowa State University. Compost cover 4

5 RESEARCH OBJECTIVES Compare the effects of the two most commonly used compost amendments (hardwood sawdust and wheat straw) and the use of sand bedding on the decomposition rate and mass, volume, carbon and nitrogen losses during the composting of dairy manure. Develop design parameters for manure composting systems. Estimate costs for dairy manure compost systems. Bedding Types used by Ohio Cows (% of cows) Sawdust 36% Sand 22% Sand use equaled.22 kg/kg manure Other/Combo 14% Straw 28% Treatments 1. Straw bedded dairy manure amended with sawdust 2. Straw bedded dairy manure amended with straw 3. Sand bedded dairy manure amended with sawdust 4. Four replicate windrows made in May, August, early September, late September. Treatments Straw or sawdust amendments added to give an initial moisture content of approximately 65% Sand bedded manure amended with sawdust to give an ash free moisture content of 65% (51% wb). Composting Process Design Measurements Temperature Oxygen Concentration Pathogen Survival Initial and Final Volume Initial and Final Weight Water loss Bulk Density and Porosity Nitrogen losses Initial Compost Properties Total Total C:N Bulk Compost Moisture Carbon N Ratio Density ID (% wet) (%) (%) (g/g) (wet kg/m ) DM/Sawdust DM/Straw DM/Sand/SD

6 Initial Windrow Manure Density (kg manure per m of windrow length) Sawdust + Dairy Manure Straw + Dairy Manure 1. Sawdust amended dairy manure compost 1 kg manure/m 2. Straw amended dairy manure compost 377 kg manure/m 3. Sand bedded dairy manure with sawdust 935 kg manure/m Temp (C) Composting Temperatures Sawdust DM/SD1 DM/SD2 DM/SD3 DM/SD Day PFRP and Organic Guideline Temp (C) Composting Temperatures Straw 8 DM/ST1 DM/ST2 DM/ST3 DM/ST Day PFRP and Organic Guideline e (C) Temperature Composting Temperatures Sand bedded + sawdust Mix Turn Moisture Content 51% 55% 61% 65% Day PFRP and Organic Guideline Oxygen Concentrations during composting 6

7 Total Mass (kg/au/yr) 22, 2, 18, 16, 14, 12, 1, 8, 6, 4, 2, Total Weight Dairy Manure + Sawdust Compost Manure weight Initial Compost Final Compost DM/SD1 DM/SD2 DM/SD3 DM/SD4 Final Compost (assuming 4% moisture) Total Mass (ton/au/yr) Total Mass (kg/au/yr) 22, 2, 18, 16, 14, 12, 1, 8, 6, 4, 2, Total Weight Dairy Manure + Straw Compost Manure weight Initial Compost Final Compost DM/ST1 DM/ST2 DM/ST3 DM/ST4 Final Compost (assuming 4% moisture) s (ton/au/yr) Total Mas Total Mass (kg/au/yr) Total Weight Dairy Manure + Sand + Sawdust Compost 22, 2, 18, 16, 14, 12, 1, 8, 6, 4, 2, Manure weight (w sand) DM/S/SD1 DM/S/SD2 DM/S/SD3 DM/S/SD4 Initial Compost Final Compost Final Compost (assuming 4% moisture) Losses during composting (% of initial compost) Compost Volume Wet Volatile ID loss Weight Solids DM/Sawdust DM/Straw DM/Sand/SD % 83% 76% 4% 57% 46% 36% 49% 55% 33% 41% 48% 93% 83% 81% 65% 27% 58% 86% 48% 8% 71% 2% 63% 8% 22% 24% 19% 32% 36% 23% 32% 48% 24% 24% 42% N Losses during composting (% lost of initial amount) Ammonia loss during composting versus liquid manure storage 4% y = -.89x R 2 =.5872 N loss (% of initial) 3% 2% 1% % Initial CN ratio 7

8 Conclusions Part 1 o Dairy manure composting led to extensive reductions in manure volume and weight even after considering the weight of the added amendments. o Sawdust amended windrows (with and without sand) contained 935 to 1 (kg manure/m) while the straw amended windrows contained 377 (kg manure/m) requiring a greater pad area. o Sawdust amended composts without sand reached temperatures >55 C in less than 1 days and met pathogen and weed seed destruction guidelines. o Straw amended and sand bedded composts did not reach pathogen guidelines of >55º C for 15 days. Increasing windrow size may solve this problem. o Moisture management was critical for manure weight reductions during composting. Once compost is stable, self heating is not available to fuel evaporation of excess moisture. o There was a negative correlation between initial C:N ratio and nitrogen loss (R 2 =.59). Therefore to minimize nitrogen loss during dairy manure composting a C:N ratio of 4:1 to 5:1 may be necessary. Cost Estimate for a 7 Cow Dairy Composting Facility 7 Cows 7,721 ton manure/yr 3, ton amendment/yr $ 2. Compost Value/yd Acre concrete pad, 1/1 covered Operating Costs Labor (1 foreman/equipment operator, 2 collectors) 11, $ yr $ yr Maintenance (2% of equipment cost) 1, $ yr Fuel (diesel$1.5/gal) 1,5 1. $ Amendments (wood) 135,993 $ yr $ yr Total Operating 257,493 Capital Costs Land Acquisition $ - Concrete Pad, Site preparation, drainage, storage area $ 1,525,774 Roofed dbuilding $ 113,855 Turning Machine $ 7, Front End Loader $ 6, Truck $ 5, Misc $ 2, Total Capital $ 1,839,629 Interest Rate (8% fixed).8 11 year depreciation equipment, 16 year depreciation buildings $ 197,459 yr Total Costs (Capital and Operating) $ 454,951 yr Total Return (Compost sales at $2/yd 3 ) $ 411,931 yr Profit/(Loss) $ (43,2) yr Current cost ($7/cow/yr) $ (49,) yr Current cost ($15/cow/yr) $ (15,) yr Comparison of Pathogen Persistence in Composted and Liquid Stored Manures Compost Price $5/yd 3 $25/yd 3 Fertility Value 8

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12 A U A 18 US 126 T I A AR B AR C AR AR M AR AR R M M C E A T R B S M L S A C M AC G RP nt Bacteria Antibiotic Resistan (CFU/g) 1.E+9 1.E+8 1.E+7 1.E+6 1.E+5 1.E+4 1.E+3 1.E+2 1.E+1 erythromycin Swine Manure (day ) Liquid Stored (25 C, 5 d) Composted (55 C, 5 d) tetracycline P A R G P D C C 2 4 A Swine Composted Lagoon Upflow Manure Swine Samples Bioreactor Manure 12

13 O C Composting addresses many unaccounted for negative impacts of liquid manure systems. Pathogen destruction. Antibiotic resistance genes destruction. Nitrogen loss and odors. Transportation effects on Infrastructure Estimated dairy manure composting costs can be competitive with paying to haul manure off farm. Composting economics are positive when compost can be sold for greater than $2/yd3 and amendments are available at low costs. A USDA IFAF OWDA OSU OARDC R E C G NCSU A W M C 13