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United States Department of Agriculture

Agricultural Research Service

2009 Annual Report

1a.Objectives (from AD-416)
Develop and evaluate algal systems for the treatment of dairy and swine manure effluents with respect to: a) capturing N and P from raw and anaerobically digested dairy manure effluents; b) utilization of the algal biomass as an organic fertilizer; and c) overall system nutrient uptake efficiency, operational costs, and potential returns of integrated farm-scale systems. Determine levels and biological effects of oxytetracycline and chlorotetracycline in manure from treated animals on biological treatment processes. Determine levels of antibiotic resistant bacteria in treated manures from animals treated with oxytetracycline and chlorotetracycline. Develop technology and management practices that improve anaerobic digestion of dairy and other animal manure by: a) increasing yield of methane gas; b) increasing energy efficiency of the conversion system; and c) reducing cost. Develop technology to increase the efficiency with which the methane is used to economically meet the energy needs of the farm.

1b.Approach (from AD-416)
Laboratory and pilot-scale field studies will be used to evaluate treatment efficiency and cost of microalgal-based treatment technologies at different loading rates of raw and anaerobically digested manure effluents. Dried algal biomass from manure treatment will be tested in growth chamber studies to evaluate the value of the biomass as an organic fertilizer capable of meeting plant nutrient requirements. Laboratory-scale composting, soil incubation, and anaerobic digestion studies will be used to determine the fates of the antibiotics oxytetracycline, chlorotetracycline, and antibiotic-resistant bacteria in manures from therapeutically treated beef calves. Laboratory and pilot-scale field studies will be used to quantitate effects on methane yield of co-digesting dairy manure with agricultural and industrial by-products. Additional studies will focus on use of cold tolerant microbial consortia to improve the rate and yield of methane production during anaerobic digestion of dairy manure at 10-25 C.

3.Progress Report
Although composting is an effective practice for stabilizing manure nutrients prior to land application, a large fraction of manure nitrogen is volatilized as ammonia during typical composting operations. The effectiveness of an inorganic amendment to reduce ammonia volatilization from composted poultry litter was investigated. Studies were initiated using a photoacoustic gas analyzer for measuring ammonia, methane, carbon dioxide, and nitrous oxide emissions from composting dairy manure. Reducing dependency on fossil energy and using available, renewable, and sustainable energy feedstocks is a national concern. It is estimated that 43.5 million dry tons of animal manure could be available for conversion to energy. Though some farmers do convert manure to energy, success varies, largely because current processes tend to be expensive and unreliable, are primarily used for odor and water pollution control, and do not effectively capture the energy potential of the manure. Research is needed to develop anaerobic digestion strategies that enhance methane production to meet on-farm energy requirements. Dry anaerobic digestion (> 15% total solid) of three animal manure-switchgrass mixtures was studied in order to characterize biogas production. Biogas production from the anaerobic digestion of pulped food wastes was also evaluated.

1. Increasing biogas production by digestion of manure switchgrass in high-solids reactors. Although small dairy farms (less than 1000 animals) do not generate enough manure for electrical production from biogas, there are significant opportunities to combine other byproducts with the manure to increase biogas production significantly. ARS scientists in Beltsville, Maryland, anaerobically digested mixtures of three animal manure (swine, poultry, and dairy) and switchgrass to determine which mixture yielded the most biogas. Biogas yields were very low using high-solids reactors containing a 1 to 5 ratio of dry switchgrass mixed with either dairy manure or diluted poultry litter. However, biogas production was relatively high from reactors using a comparable swine manure-switchgrass mixture. In these reactors, approximately 80% of biogas production was attributable to degradation of the switchgrass. Although these experiments are only a first step in the process, the results suggest that switchgrass could be a useful biomass resource for high-solids digestion.

2. Determining the concentrations of hormones in biosolids and poultry litter. The presence of natural hormones and the synthetic hormone ethinylestradiol was monitored in lime-treated biosolids and poultry litter samples in order to determine the likely potential of these compounds to run off from fields treated with these materials as soil amendments. These hormones exist in their free form and as chemical conjugates requiring more sophisticated measurement techniques such as liquid chromography triple quadrupole mass spectrometry. Estrone, estrone sulfate, and progesterone were found most frequently in the samples, with the concentrations in biosolids typically less than 10 ng/g and the concentrations in poultry litter were somewhat higher. Estriol, estradiol, ethinylestradiol, and testosterone were seldom detected. This information will be used to help managers better regulate the release of these compounds when they are applied to agricultural fields in soil amendments.

3. Increasing biogas production by digestion of manure and pulped food wastes. There is growing interest in diverting organic wastes from landfills to minimize landfill methane emissions. However, such diverted wastes must be utilized quickly and carefully to maximize their resource value and to minimize potential negative environmental effects such as odors. ARS scientists anaerobically digested mixtures of dairy manure and pulped food wastes (provided by a CRADA partner) to determine how biogas yields were affected by increasing amounts of food wastes. Results showed that reactors containing manure and 5% food waste produced about 20% more biogas than comparable reactors containing only 1% food waste. In addition to increased biogas yield, on-farm digestion of food wastes with manure may provide opportunities for additional revenue through avoided tipping fees and carbon credits.

4. Determining the fate of antimicrobials in agricultural lands receiving biosolids. The antimicrobial pesticides, triclosan and triclocarbon, are often found in soap, detergents, and antiseptics and have been found in biosolids from waste water treatment facilities. These compounds, which are highly toxic to aquatic organisms, are strongly sorbed to biosolids but can be released to the environmental when the biosolids are applied to agricultural fields. Studies were conducted to determine the likely concentrations of triclosan and triclocarban in biosolids by examining their sorption to biosolids during treatment of waste water and then following their fate in land applied biosolids which is a major (60%) disposal practice in the U.S. Concentrations in fresh biosolids averaged 16 and 18 mg/Kg, respectively for triclosan and triclocarbon; the half life of triclosan after biosolids application was more than 100 days and many times longer for triclocarban. Thus, a better understanding of the factors controlling the release of these compounds from land-applied biosolids and their potential transport offsite is needed to minimize negative effects to surrounding ecosystems.

5. ARS participates in interagency task force on pharmaceuticals in the environment. An interagency report, “Pharmaceuticals in the Environment: An Interagency Research Strategy” was completed with ARS as a work group member. This report was commissioned by the Committee on the Environment and Natural Resources, Office of Science and Technology Policy. The purpose of this report was to summarize federal research in this area and to develop an integrated interagency strategy for conducting investigations on priority research needs identified by the work group. Outcomes from this planning document are being implemented:.
1)Coordinate animal feeding operation studies to examine the contribution of pharmaceuticals to the environment combined with exposures from Waste Water Treatment Plant discharges;.
2)Organize an analytical user’s group; and.
3)Highlight the stewardship activities in USDA and coordinate CSREES granting efforts into the research plan.

6.Technology Transfer

Number of Active CRADAs1

Review Publications
Mulbry III, W.W., Kondrad, S.L., Pizarro, C. 2007. Biofertilizers from Algal Treatment of Dairy and Swine Manure Effluents: Characterization of Algal Biomass as a Slow Release Fertilizer. Journal of Vegetable Science. 12(4):107-125.

Mulbry III, W.W., Kondrad, S.L., Pizarro, C., Westhead, E.K. 2008. Treatment of Dairy Manure Effluent Using Freshwater Algae in Outdoor Pilot-Scale Raceways: Algal Production and Nutrient Recovery. Bioresource Technology. 99:8137-8142.

Mulbry III, W.W., Ingram, S.K., Buyer, J.S. 2008. Treatment of Dairy and Swine Manure Effluents Using Freshwater Algae: Fatty Acid Content and Composition of Algal Biomass at Different Manure Loading Rates. Journal of Applied Phycology. 20:1079-1085.

Arikan, O., Mulbry III, W.W., Rice, C. 2008. Management of Antibiotic Residues from Agricultural Sources: Use of Composting to Reduce Chlortetracycline Residues in Beef Manure from Treated Animals. Journal of Hazardous Materials. 164:483-489.

Arikan, O., Mulbry III, W.W., Ingram, D.T., Millner, P.D. 2009. Minimally Managed Composting of Beef Manure at the Pilot Scale: Effect of Manure Pile Construction on Pile Temperature Profiles and the Fate of Oxytetracycline and Chlorotetracycline. Bioresource Technology. 100:4447-4453.

Last Modified: 3/30/2015
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