Changes in Concentrations of Malodorous Compounds From Fresh and Aged Dairy Manure During Controlled Aeration Composting

 

D L ELWELL (1), D C Borger (2), D V Blaho (2), J K Fahrni (1), H M Keener (1), L B Willett

 

(1) Food, Agr., and Env. Eng., (2) Animal Sci., The Ohio State Univ./OARDC, USA

 

Effects of composting on odorous chemicals in dairy manure were investigated in replicated pilot-scale studies.  Three 16-day composting trials were conducted, using 205 L vessels.  Fresh or 10-day-aged manure (83kg), from lactating cows, was mixed with sawdust (3:1 w/w).  Vessels were either aerated continuously with high (2.3 kg/hr)/low (0.8 kg/hr) airflow controlled by thermostats or intermittently on a 5 min high air flow/55 min off clock controlled cycle.  Six vessel replicates were conducted on each manure/airflow treatment combination.  Temperatures, airflow, O(2) consumption, and CO(2) production were recorded every 10 minutes. Trapped NH(3) emissions were determined daily.  Exhaust air was passed through water-cooled condensers, and condensate volume, pH, and volatile fatty acids (VFAs) were quantified at 12 or 24 hr intervals.  Solids were collected from each vessel initially, at remix on day 7, and at the end of each trial for anaysis of moisture, pH, ash, C/N, VFAs and phenolics.  Phenolics were captured by head-space analysis or extracted with ethyl ether.  VFAs were recovered with pH 2.0 water.  Analysis was by flame or mass selective detection gas chromatography.  Fresh manure/sawdust mixes contained approximately 5,000 ppm of acetate, with proportionately le propionate (0.1), isobutyrate (0.01), and isovalerate (0.01).  Aged manure mixes contained acetate (1.82), propionate (0.55), isobutyrate (0.04), butyrate (0.51), isovalerate (0.57), valerate (0.07) as well as a number of C(11) to C(17) fatty acids.  Phenol, p-cresol, and skatol were present in fresh and aged manures and concentrations varied with analytical method. Temperatures increased most rapidly in continuously aerated vessels with all exceeding 60 C by 24 hr, and returning to near ambient by day 16.  VFAs in condensate were generally not detectable after day 5.  By day 7, only acetate remained in fresh manure mixes with low concentrations at day 7 and 16 in the aged manure compost.  These composting conditions were effective in destruction of the odorous chemicals studied.

 

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Biofiltration for Ammonia Gas From Dairy Manure Composting

 

JIHYUNG HONG, Keumjoo Park,  Wonchun Choi

 

Dept. of Agricultural Machinery Engineering, Sunchon National University, 540-742 South Korea, South Korea

 

The effects of various biofilters from dairy manure composting were examined for the ammonia removal efficiency . The effects of the depth of the biofilters were also examined. The composting and biofiltration experiments consisted of five series of tests. Dairy manure amended with crop and forest residues was composted in 605 L pilot-scale reactor using continuous air flow for 20 days. Three pilot-scale biofilters with three kinds of media levels of 0.2, 0.4, 0.6 m in depth and 0.3 m in diameter were built to clean compost odor, respectively. The ammonia odor reductions was measured by cumulative ammonia concentrations at the inlet and the outlet biofilter media. Results indicated that removal efficiency varied according to biofiter  media depth. Based on  ammonia removal efficiency and biofilter media depth, biofilter with 50% wood chips and 50% manure compost by weight mixture showed 100% removal efficiency at a media depth in the range of 40 to 60 cm for ammonia odor removal from composting.

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Effects of Dairy Manure Amendments On Composting Process Kinetics.

 

PECCHIA, J.A., Keener, H.M., and Michel Jr., F.C.

 

Food, Agricultural and Biological Engineering, The Ohio State University-OARDC, Wooster, Ohio 44691, USA

 

Dairy operations utilize different bedding materials based on availability, costs and animal comfort.  Not only can the bedding material affect the comfort of the cow, but it also plays a significant factor in manure handling and composting of the materials.  The different characteristics of the bedding material can affect the water holding capacity and the porosity of the compost, thereby affecting the decomposition rate and oxygen levels within the compost.  An understanding of the effects that bedding material plays in dairy manure composting will help farmers minimize costs associated with utilizing these amendments.  In this study, dairy manure was amended with either straw or hardwood sawdust and composted in windrows over a four month period.  Both the straw and sawdust amended dairy manures showed considerable dry matter loss over the composting period.  The straw amended dairy manure had the most noticeable changes in dry bulk density and volume reduction.   Compost oxygen concentrations were consistently lower in the sawdust amended windrows than the straw amended windrows.  Composting temperature trends varied between the two windrows, however, both achieved the sustained high temperatures needed to kill weed seeds and pathogens.