1a. Objectives (from AD-416):
1. Develop improved treatment technologies to better manage manure from swine, poultry and dairy operations to reduce releases to the environment of odors, pathogens, ammonia, and greenhouse gases as well as to maximize nutrient recovery. 2. Develop renewable energy via thermochemical technologies and practices for improved conversion of manure into heat, power, biofuels, and biochars. 3. Develop guidelines to minimize nitrous oxide emissions from poultry and swine manure-impacted riparian buffers and treatment wetlands. 4. Develop beneficial uses of manure treatment technology byproducts.
1b. Approach (from AD-416):
This research will take a synergistic approach towards developing innovative and effective animal manure treatment practices and holistic systems. This research will pursue four complementary bioresource management approaches. First, improved treatment technologies to better manage manure from swine, poultry, and dairy operations will be developed to reduce releases into the environment of odors, pathogens, ammonia, and greenhouse gases as well as to maximize nutrient recovery. These technologies include improved solid liquid separation, enhanced biological nitrogen treatment by anaerobic ammonia oxidation, recovery of ammonia from manure using gas permeable membranes, recovery of phosphorus from solid manure, wastewater treatment using constructed wetlands, in-house composting of poultry litter, and their integration into systems of treatment technologies. Second, investigations will be conducted to develop thermochemical technologies and practices for improved conversion of manure into heat, power, biofuels, and biochars. Manure based feedstocks for thermochemical conversion will be evaluated. Improved methods to condition manures for biochar and combustible gas production using pyrolysis will be determined. An efficient carbonization process for production of manure biochars with specific composition and properties for beneficial use will be developed. Third, research will be conducted to develop guidelines to more effectively manage and minimize nitrous oxide emissions from poultry and swine manure impacted riparian buffer zones and treatment wetlands. Fourth, we will develop beneficial uses for manure byproducts. These include the use of manure biochars as adsorbants for gaseous and aqueous contaminants, as soil amendments to improve physical and chemical properties, and as fertilizer source for crop production. Results from this project will advance the state of the science for more effective animal waste treatment and implementation of environmentally safe alternatives to traditional land application.
3. Progress Report:
Laboratory tests were carried out to recover phosphorus from sludge using the quick wash process developed by ARS-Florence scientists (objective 1e). Results indicate that the quick wash process can selectively extract more than 80% of the phosphorus content from sludge. The process can produce biosolids low in phosphorus while it recovers the extracted phosphorus as a concentrated calcium phosphate salt. Conducted study on microbial community composition in four anaerobic lagoons using next generation DNA sequencing through deep 16S rDNA analysis of water columns (objective 1f). Preliminary results revealed distinct microbial communities for each lagoon that remained consistent throughout the depth of each water column. Three of the four lagoons were dominated by anaerobic bacteria, mostly Peptostreptococcus, Clostridium, and sulfur reducing bacteria. One lagoon had a large number of aerobic Mycobacteria indicating slightly oxidative conditions of the water column. Completed study to identify microbial markers in the water column of a swine lagoon fed with treated water from a second generation wastewater treatment system. The study included two adjacent lagoons, one fed with treated aerated water and the other one maintained anaerobic. Monthly samples were collected, and DNA extracted for downstream molecular analysis to identify organisms contained within each lagoon. This study assesses whether liquid from reclaimed lagoons can be safely used for irrigation free of pathogens (objective 1h). Completed study on effects of blending and pelletizing poultry litter with plant material feedstocks on biochar production by pyrolysis and chemical characteristics (objective 2a). Biochars were analyzed for their structural qualities, individual pellet strength, energy content and chemical composition. Results from this study show marked improvements on the energetic and chemical composition of biochars from poultry litter blended with switchgrass or pine chips. Field sampling was performed in transects across edge of the field and riparian buffer manure-impacted soils on five farm sites in North and South Carolina. This study is assessing nitrous oxide emissions and denitrification enzyme activity to provide guidelines to minimize nitrous oxide emissions from manure-influenced Coastal Plain soils (objective 3a). A laboratory microcosm experiment was conducted using manure-based designed biochars to test the effect of feedstock blend and particle size on both water storage and phosphorus movement through well- and poorly-drained sandy Coastal Plain soils (objective 4b). Poultry litter and swine solids were blended with plant materials, pelleted, and pyrolyzed to generate biochar. Data revealed that after three leaching events over 90 days, feedstock blend and biochar particle size of designed biochars can control the availability of phosphorus. Greenhouse experiments were conducted to test agronomic value of manure biochar (objective 4c). Two trials were completed using biochars made from manures that were added as phosphorus fertilizer sources to pots planted to cotton and soybean. The biochars performed as well as chemical fertilizer.
1. Measuring gas emissions from animal waste treatment lagoons is both important and an exceptional challenge. The lagoons are typically located in non-ideal locations that usually interfere with ideal airflow; i.e., trees and crops. ARS-Florence scientists documented an improved measurement method, the inverse-dispersion technique for measuring gas emissions from treatment lagoons. The verification used a floating gas emission source positioned on a lagoon surface to deliver known emission rates of methane gas. Although the tested lagoon setting did not strictly meet the ideal assumptions of the technique, the results showed an overall accuracy level of 88%. This finding is particularly encouraging for researchers and regulatory agencies studying agricultural gas emissions. Accordingly, the inverse-dispersion technique presents a simple and economical measurement tool for gas emissions from complex lagoon scenarios.
2. Biochars produced from plant residues and poultry litter as effective bioenergy sources. Plant and manure feedstocks can be made into energy dense char products by undergoing thermochemical conversion via pyrolysis. Effective conversion of plant and manure feedstocks into char is dependent on ash content and their composition of elements such as chlorine, potassium, silica, sodium, and sulfur, which in excessive amounts can dramatically reduce char conversion efficiency and foul pyrolysis equipment. Scientists at ARS-Florence characterized the elemental composition in several plant (bagasse, peanut hulls, pecan shells, pine chips, switchgrass) and manure (poultry litter) feedstocks and their biochar counterparts to determine how individual elements may influence pyrolysis conversion efficiency. Plant-based chars had better thermal energy contents and lower ash contents than poultry litter implying efficient thermal conversion. Instead, poultry litter char had medium heating values and substantial amounts of chlorine and sulfur, which could promote equipment corrosion during thermal energy processing. This study indicates that energy conversion of poultry litter and the integrity of thermal processing equipment can be greatly improved by blending it with plant residue feedstocks.
3. Use of hydrothermal carbonization products as sorbent of environmental contaminants. Hydrothermal carbonization is an aqueous thermal process that converts organic wastes into a product called hydrochar. ARS-Florence scientists working with university collaborators discovered that the hydrochar made from chicken litter and swine manure showed excellent sorption capacity of environmental contaminants such as endocrine disrupting chemicals, herbicides, and polyaromatic hydrocarbons. This high sorption capacity toward these compounds was attributed to the hydrochar’s diverse surface chemistry as evidenced by advanced solid carbon nuclear magnetic resonance analyses. In addition, it was found that hydrochar surface chemistry can be easily modified with activating compounds to produce more stable hydrochar products. For example, hydrochar activated with citric acid resulted in a more stable hydrochar in soil environments. These findings suggest that hydrochar can be used as an effective environmental sorbent for various contaminants.
4. Encapsulation of anammox bacteria in polymer pellets for enhanced bio-treatment of ammonia contained in swine wastewater. The use of the anaerobic ammonium oxidation (anammox) as a new pathway to biologically remove ammonia significantly reduces over 50 percent of aeration needs and cost of treatment. However, due to the low growth rate of anammox bacteria, one of the main challenges for effective implementation of the anammox process is to develop methods that increase the bacterial cells’ retention inside the reactors. In this research we immobilized anammox bacteria NRRL B-50286 (Brocadia caroliniensis) by encapsulation in polymer gel pellets of polyvinyl alcohol using a freezing method (cryogels). The pellets were added to stirred reaction tanks to remove ammonia from wastewater. They were successfully tested achieving more than 93 percent ammonia removal efficiency. The pellets removed the nitrogen pollutants at a rate of 3 grams per kilogram of pellet per day. They could be used in the treatment tanks at a proportion of 20 to 30 percent (w/v) to more effectively treat swine wastewater using the anammox process.
5. Partial nitrification of swine wastewater. In this research we evaluated a more economical biological nitrogen removal process based on partial nitrification-anammox (anaerobic ammonia oxidation). This approach requires about half the aeration required by nitrification-denitrification, which significantly lowers operational costs of treatment. Novel strains or mixtures of microorganisms discovered and patented by USDA-ARS were used in the research: A high performance nitrifying sludge mix, and a novel anammox isolate Brocadia caroliniensis. Using sequential batch reactors (SBR) at bench scale, the research optimized the partial nitrification step and provided a balanced intermediate effluent for anammox using swine wastewater containing more than 1000 parts per million of ammonia nitrogen. A balanced intermediate effluent was successfully produced. Further, the intermediate effluent was effectively tested with anammox in a second SBR reactor. The results obtained provided key information on the production of partially nitrified effluent suitable for the anammox process. This information is needed for scaling-up the process to develop a more economical biological nitrogen removal system for livestock producers.
Cantrell, K.B., Martin, J.H. 2012. Stochastic state-space temperature regulation of biochar production Part I: Theoretical development. Journal of the Science of Food and Agriculture. 92:481-489.