Grantee Research Project Results
Final Report: Advanced Manure Management for Small Dairy Farms
EPA Contract Number: EPD08018Title: Advanced Manure Management for Small Dairy Farms
Investigators: Roberts, T. Guy
Small Business: Avatar Alternative Energy Inc. d.b.a. Avatar Energy, LLC
EPA Contact: Richards, April
Phase: I
Project Period: March 1, 2008 through August 31, 2008
Project Amount: $70,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2008) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Animal Waste and Waste to Energy
Description:
Avatar’s R&D personnel have spent the past 5 years working to design, build and operate first a prototype and now a pilot-scale plug-flow anaerobic digester with an effluent treatment system that is suitable for small dairy farms. The pilot digester is located on the Foote Farm, a 160-head dairy located in Charlotte, Vermont. The pilot digester incorporates modular design features that allow the system to be scaled to fit on dairy farms ranging in size from 80 to 600 head. This pilot system has been producing biogas since June 2007 and has been using this biogas to generate hot water to pre-heat the manure substrate and maintain digester hull temperature. Avatar’s commercial goal is to create cost-effective, self-sustaining modular digester systems for small farms that reimburse the farmer with value-added by-products from manure. These by-products include biogas which can power a generator, provide heat, and reduce odor and pathogens. A “screw-press” separator receives the digester effluent to produce a fibrous digested solid fraction and a digested liquid fraction. This liquid fraction is sent to an aerobic trickling filter to nitrify ammonium in the effluent stream and to create a phosphorus-rich sludge.Summary/Accomplishments (Outputs/Outcomes):
One objective of our Phase I work plan was to evaluate the performance of the aerobic trickling filters units. Shortly after beginning Phase I work, the separator, a key piece of equipment, failed, leaving us unable to supply digested liquids to the trickling filters. The separator could not be replaced until October 3, 2008, but is now functioning perfectly. A more extensive evaluation of the trickling filter is now proposed for the Phase II work plan.
Our other Phase I objectives were to calculate the mass-balance for the digester system and to develop a cost-benefit analysis that could be used as the system develops. Both of these objectives required the creation of process flow and piping and instrumentation diagrams. These diagrams were completed by Avatar’s engineering team. In addition the team prepared schematics for each stream in the Avatar pilot digester and effluent treatment system. These schematics indicate the specifications for each component of the hydronic heating lines and biogas handling equipment. From these diagrams a complete parts list has been made for a 200-head capacity ‘AnD’ model commercial digester. This information has gone into making a Cost/Benefit spreadsheet for configurations of the AnD model digester hull for 80 to 300 head dairy operations.
Conclusions:
Thermal calculations validated that even the 80-head pilot digester should produce excess heat for the digester. They also show that if the biogas is used to fuel a “combined heat and power” generator, then the heat recovered from the generator will satisfy the requirements of the digester in ambient temperatures below freezing. These calculations assume, however, that heat transfer and insulation are installed effectively. Lower than anticipated operating temperatures signaled that our pilot system did not have adequate insulation. These thermal studies provided a guide to selecting a more thermally and cost-effective means of installing insulation and heating lines to maintain digester hull temperature. Insulation and heating lines are being upgraded in October 2008 to achieve specifications.
Avatar’s trickling filter design has been re-evaluated, as well, leading to design changes in the structure of the air exchange surfaces, representing an overall simplification of design and reduction in materials cost. The trickling filters are not designed to be operated during the winter months, to avoid potential ice build-up on the filter media. The manure separator will remain operational throughout the winter to continue to provide digested manure solids for bedding material. The liquid fraction of the digester effluent will be stored in the manure lagoon during winter months and land applied in the spring. Design changes to the trickling filters will be completed this winter and the upgrades can be completed within the first 2 months of Phase II. The operation of the trickling filters will resume in April 2009; in time for the performance evaluations.
Supplemental Keywords:
small business, SBIR, EPA, anaerobic digester, animal waste, waste to energy, effluent treatment system, dairy farm, manure management, modular digester, simple assembly, scalable, plug flow architecture, solids separator, digested manure, liquid fraction, solid fraction, nitrogen, phosphorus, greenhouse activities, sustainable industry/business, scientific discipline, RFA, technology for sustainable environment, sustainable environment, environmental engineering, anaerobic digester, agriculture, alternative energy source, waste to fuel conversion, dairy farms, digester, anaerobic, plug flow, scalable, modular, trickling filter, nutrient management, sustainable agriculture , RFA, Scientific Discipline, Sustainable Industry/Business, Sustainable Environment, Technology for Sustainable Environment, Environmental Engineering, waste to fuel conversion, animal waste, agriculture, alternative energy source, dairy farmsThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.