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:
In cooperation with industry and University scientists, evaluated a third-generation full-scale swine manure treatment system (obj. 1a). Phase I (a 1,200-sow Farrow to Feeder operation and a 12,960 Feeder to Finish operation) was completed and a report submitted to NC Clean Water Management Trust Fund. This third-generatioin treatment system incorporated a decanting step that made it more economical and efficient the treatment for swine farms that use flush systems and produce diluted manure. Conducted deammonification experiments that combined anammox and partial nitrification using a single-tank process (obj. 1c). The new process is being tested with swine effluents from anaerobic digesters. It offers three major advantages over previous biological N removal systems: 1) it does not require carbon for N removal, so all the manure carbon can be used to produce bio-energy; 2) it reduces 58% of the aeration needs for N removal; and 3) a single-tank approach reduces equipment costs. Conducted experiments for phosphorus recovery from hen manure solids using the ‘quick wash’ technology developed by ARS-Florence scientists (obj. 1e). Ammonia and greenhouse gases were measured from two bird houses in Arkansas (one control and one in-house litter composting). Research work included measuring gas fluxes and pathogen sampling from litter compost piles (obj. 1g). Conducted pyrolysis of animal manure blended with plastic mulch waste (obj. 2c). Small amounts of swine solids, chicken litter and plastic mulch were pyrolyzed in a batch bench-scale reactor system. Optimal temperatures and reaction time for these feedstocks were measured by thermogravimetric analysis. Also 150 pounds of each swine solids, chicken litter, compost, and the mixtures of manures and used agricultural plastic mulch were pyrolyzed using Aemerge’s 150 lb/hr pyro/gasification system. The measure of denitrification enzyme activity and nitrous oxide emission in riparian buffers contiguous to beef pastures, row crops with poultry applications, and row crops with swine wastewater application continued into the second years sampling (3a). The potential denitrification increased from the field edge to the stream. Nitrous oxide emissions were measured, but they were not exceptionally high. Determined contaminant sorption capacities of biochars and hydrochars (obj. 4a). Ammonia adsorption capacities of activated and non-activated biochars (hard wood and chicken litter) were determined on location. University collaborators determined adsorption isotherms of hydrochar with atrazine (USC) and ammonia (NCA&T). Studies were conducted using designer biochars produced from blends of animal manure and pine chips (obj. 2d). These feedstocks were pelletized prior to pyrolysis to obtain a more cohesive product. Both pelletized and dust-size biochars were mixed into a hard setting soil to determine their effect on improving water infiltration and plant root penetration (obj. 4b). For some biochar treatments, plant growth was reduced because of soil fertility imbalances as a result of high application rates. Biochars applied as dust caused significant increase in water infiltration.
1. Recovered ammonia from poultry litter using flat gas-permeable membranes. This recovery of gaseous ammonia from poultry litter benefit bird health and productivity while reducing environmental concerns of emissions from poultry production. Scientists at ARS-Florence, South Carolina, investigated the potential use of gas-permeable membranes as components of a new process to capture and recover ammonia in poultry houses. This new process (U.S. Patent Application 61314683) includes the passage of gaseous ammonia through a micro-porous hydrophobic membrane, capture with a circulating dilute acid on the other side of the membrane, and production of a concentrated ammonium salt. Bench- and pilot-scale prototype systems using flat expanded polytetrafluoroethylene membranes and a sulfuric acid solution consistently reduced headspace ammonia gas concentrations from 70 to 97% and allowed recovery of 88 to 100% of the ammonium volatilized from poultry litter. The potential benefits of this technology include cleaner air inside poultry houses, reduced ventilation costs, and a concentrated liquid ammonium salt that can be utilized as a plant nutrient product.
2. Animal manures converted to biochars via pyrolysis for waste treatment provide an alkaline, phosphorus-dense, carbon-based soil amendment. Utilizing plant or wood-based biochars alone may increase soil organic matter and water retention but cannot provide sufficient soil nutrients. However, much of the manure biochar applied to low organic matter, Southeastern Coastal Plain soils can lead to excessive soil phosphorus concentrations as well as significant changes in soil pH. Thus, finding a singular biochar to suit all soil issues is difficult. Scientists at ARS-Florence developed a novel concept that biochars can be designed to fit the needs of soil –increased organic matter, nutrient and water retention. Extensive studies showed that specific feedstocks, their blends and pyrolysis conditions can be manipulated to produce biochar with custom compositional properties. From these results, ARS-Florence scientists developed guidelines to manufacture designer biochars tailored to improve specific soil issues. For manure biochars, it is recommended to blend manures with plant or wood materials, pelletize, and then pyrolyzed at lower temperatures. This creates a biochar suitable for soils with higher levels of nutrients. Utilization of these guidelines should allow farmers and the public to make more effective use of biochar as a soil amendment while, also, improving crop productivity.
3. Microbial community structure across a wastewater-impacted riparian buffer zone in the southeastern Coastal Plain. Riparian buffer zones serve a critical function of recycling nitrogen via denitrification in agricultural systems. Those located next to fields receiving high nitrate-loads are of particular importance because riparian buffers may have a higher propensity for incomplete denitrification leading to nitrous oxide emissions, a potent greenhouse gas. In order to better understand denitrification and nitrous oxide emissions in riparian buffers soils receiving high loads of nitrate, ARS scientists in Florence, South Carolina, studied the microbial community composition of these riparian buffer soils. The study characterized the microbial populations found in riparian buffer zone soils and determined if microbial community structure could be linked to the bacterial process of denitrification. A riparian buffer zone located downstream of a pasture irrigated with swine lagoon effluent was examined utilizing DNA sequencing of the bacterial 16S rRNA gene, and quantitative Real-Time PCR of three denitrification genes. Proteobacteria was identified as the dominant bacterial group, followed by the Acidobacteria. Analysis of quantitative Real-Time PCR results identified spatial relationships between soil series, site location, and gene abundance, which could be used to infer propensity of riparian buffer soils to incomplete denitrification and help their management to minimize off-site impacts of manure applications to crops and pastures.
Ro, K.S. 2012. Thermochemical conversion technologies for production of renewable energy and value-added char from animal manures. In: He, Z., editor. Applied Research of Animal Manure: Challenges and Opportunities Beyond the Adverse Environmental Concerns. Hauppauge, NY:Nova Publishers. p. 63-81.