1a. Objectives (from AD-416):
Development and evaluation of manure treatment systems. Specific objectives: (1) Develop treatment technologies and management practices to reduce the concentrations of pharmaceutically active compounds (antibiotics and natural hormones) in manures, litters, and biosolids utilized in agricultural settings; (2) Develop management practices and technologies to minimize greenhouse gas (GHG) emissions from manure and litter storage and from composting operations by manipulating the biological, chemical, and physical processes influencing production and release of ammonia and greenhouse gases during composting; (3) Develop technology and management practices that improve the economics and treatment efficiency of anaerobic digestion of animal manures and other organic feedstocks (e.g. food wastes, crops/residues) for waste treatment and energy production.
1b. Approach (from AD-416):
Modern livestock production involves the use of large amounts of nutrient inputs as well as antibiotics. Untreated manure is either stored or immediately applied to farmland as a fertilizer. When manure is applied to fields, manure components (nutrients, microorganisms, and remaining antibiotic residues) may reach surface water by volatilization, run-off or leaching. The goal of this research is to improve our basic understanding of two common manure treatment practices (composting and anaerobic digestion) so as to maximize their benefits and minimize their economic and environmental costs. The first objective is to evaluate the efficacy of a series of minimal management options for composting manure and poultry litter on-farm to reduce concentrations of ten widely used pharmaceutically active compounds. Treatments are designed to span a range of practical management options – from the current practice of stockpiling the manure/litter to amending it with straw (to increase aeration) and adding insulating layers of straw. The second objective seeks to reduce the environmental footprint of composting by reducing methane, nitrous oxide, and ammonia emissions during composting. Greenhouse gas and ammonia emissions will be measured using replicate pilot-scale compost piles composed of manure/bedding from the BARC dairy and food/green wastes from local food processors. The first set of treatments will test the timing and frequency of compost mixing and turning. Subsequent experiments will measure and compare gas emissions from replicate piles constructed at initial bulk densities and from piles covered with 7-30 cm layers of finished compost. The third objective involves an evaluation of a relatively low-cost anaerobic digestion system that has significant potential for use on small farms. Six replicate pilot-scale plug-flow digesters, with two operational designs will be studied to provide long-term research on a system that has not been fully explored. Treatment efficiency, capital and operational costs, and gas utilization strategies will be evaluated for each type of system. Costs and benefits of different treatment strategies will be compared to existing manure management practices.
3. Progress Report:
Progress was made on all three objectives, all of which fall under National Program 214, and focus on improving our basic understanding of two common manure treatment practices (composting and anaerobic digestion). Under objective 1, technologies and practices to reduce concentrations of pharmaceutically active compounds in manures, litters, and biosolids, we made progress in developing methods for analysis of five of the pharmaceutically active compounds of interest in poultry litter. Under objective 2, practices and technologies to minimize greenhouse gas (GHG) emissions from manure storage and composting operations, we made significant progress in determining the effect of delaying compost mixing on GHG emissions. Under objective 3, we made progress toward completing construction of replicate pilot-scale anaerobic digesters. Construction was delayed by unexpected failure of the digester bag material. More durable digester bags have now been installed. Additional insulation and more efficient heat exchangers are also being installed.
1. Greenhouse gas emissions from dairy manure composting operations. Manure management practices are widely regarded to significantly affect greenhouse gas (GHG) emissions from livestock operations. Unfortunately, there is relatively little specific information regarding the effect of different management practices on GHG emissions that is useful to producers. Manure composting is thought to reduce total GHG emissions relative to emissions from untreated manure. The objective of this study was to characterize emissions from pilot-scale dairy manure compost piles. Results from two separate trials showed that total methane emissions decreased significantly as the date of first mixing was delayed. Ultimately, decisions to delay compost turning to reduce GHG emissions will have to be balanced against the schedule required for pathogen reduction.
Varel, V.H., Wells, J., Shelver, W.L., Rice, C., Armstrong, D.L., Parker, D.B. 2012. Effect of anaerobic digestion temperature on odour, coliforms and chlortetracycline in swine manure or monensin in cattle manure. Journal of Applied Microbiology. 112:705-715.