Recipient Organization
UNIVERSITY OF ARKANSAS
(N/A)
FAYETTEVILLE,AR 72703
Performing Department
Biological & Agr Engineering
Non Technical Summary
Arkansas is ranked #2 in poultry production in the nation, which generate about 1.3 million metric tons of litter annually. Up to this date, there are virtually no cost-effective methods available to deal with this waste stream environmentally and resourcefully other than land application, which, over the years, is linked to environmental issues in many places in the state due to the saturation of nutrients (nitrogen and phosphorus) in the soil receiving the litter application, increasing the potential of surface and ground water pollution caused by nutrients runoff and/or leaching from overloaded soils. To safeguard the environment, effective technologies are needed to treat poultry litter in order to reduce its polluting power and at the same time recover its additional values other than being used solely as cropland fertilizer. The ultimate goals of this research will be to protect the soil and water and natural resources in Arkansas, and in the nation as well, by reducing the volume of wastes produced and maximizing the value-added products production and environmental benefits so the agricultural production can be sustained in a long run.
Animal Health Component
30%
Research Effort Categories
Basic
30%
Applied
30%
Developmental
40%
Goals / Objectives
Engage collaborators from the needed broad range of disciplines, institutions, and stakeholder groups to catalyze conceptual and quantitative synthesis, collaboration, and data sharing
Facilitate organization, synthesis, and integration of component-based research findings and supporting data and
Discover (or reveal), substantiate, and interpret the broader impacts of component-level modifications to animal-production systems.
Project Methods
A series of well-designed experiments will be carried out for this project including co-digestion poultry litter with other animal wastes, the effect of carbon to nitrogen ratio, temperature, and pH on digestion efficiency, the effect of hydraulic retention times and organic loading rates, water cleaning techniques to lower ammonia concentration, etc. For each group of factors, multiple levels of each influencing factor will be studied and statistical designs of experiments will be used for comparing different treatments and optimizing the treatment system. The research information will be delivered to the public via major available means such as publications, websites, teaching/extension materials, extension and outreach, and experiential learning opportunities. Evaluations of the project success will rely on surveys from theproducers as to the extent of them havingbeen educated by the new technology and havingindicated their willingness to adopt the developed technology.Since there are fivemajor research objectivesin this project, the methods will be presented based on the specific objectives.Objective 1: Co-digesting poultry litter with other animal wastes In this project, different mixing ratios of poultry litter with either liquid swine or dairy manure will be investigated to determine the feasibility of this technology based on biogas production, methane content in biogas, volatile solids destruction, COD and BOD reduction.Objective 2: The effect of carbon/nitrogen ratio, temperature, and pH In this study, four C/N ratios will be investigated, i.e., 15/1, 20/1, 25/1, and 30/1 to determine the optimal C/N ratio for biogas production and reduction in COD and BOD. With varying C/N ratios, a range of three pH values (6.5, 7.0, and 7.5) will also be investigated at the same time, which comprises a 3x4 experimental design. Batch tests will be employed using 1 L flasks as digesters and the total volume of biogas produced will be measured using the water displacement method. The methane and CO2 content of the biogas will be determined using a gas chromatograph. All the experiments will be carried out under mesophilic temperature condition (37oC).Objective 3: The effect of hydraulic retention time (HRT) and organic loading rate (OLR) A continuous, lab-scale anaerobic sequencing batch reactor (ASBR) system will be built to investigate the effect of HRT and OLR on the co-digestion performance of poultry litter. Four HRT (3, 6, 9, and 12 days) will be examined with 3-4 OLRs to determine the optimal running parameters in terms of pH, HRT, C/N ratio, and OLR for the methane ASBR to produce methane continuously and efficiently. Information obtained can be used to design a scale-up reactor that can be transferred into a pilotscale system for farm use.Objective 4: Solid state digestion of poultry litter The basic idea is to extract the ammonia, which is detrimental to the digestion process, before digestion. There are a number of methods to extract ammonia from poultry litter including using water, chemicals, and even ammonia strippers. However, soaking poultry litter in water to solubilize ammonia initially present is a simple but potentially more applicable method that has not been extensively examined. The solids digestion after ammonia extraction needs more research to determine the maximal solids level that the digestion process can handle. The outcomes from this project may lead to an applicable technology for on-farm treatment of poultry litter cost effectively.Objective 5: Beneficial use of the solid fraction of the digestates Experiments will be designed to examine two fungi species, Pleurotus ostreatus and Agrocybe aegerita, for breaking down lignocellulosic residues in the digestate to produce mushroom. Rice straw (RS) will be chopped to 5 cm pieces and then mixed with the digestate solids (DS) at different levels (RS/DS: 100, 85, 70, 55, 40, 25, 10, 0). A single factor randomized design with eight levels of the factor combinations will be adopted for this study. Each substrate combination will be replicated in four bags and a random sample will be taken from each bag for a total of 32 experimental units. Mushroom yields, lignocellulosic enzyme production and substrate utilization, and mushroom fruit body production in relation to lignocellulosic enzyme activity will be the variables to be investigated.