Anaerobic fermentation of agricultural residues: potential for improvement and implementation. Twelfth quarter progress report, 16 March 1979-15 June 1979 and Addendum describing project activities, 16 June 1979-15 October 1979

Abstract

Five different types of anaerobic fermentor reactor designs were operated, with the majority of effort focused on two full scale reactors (both about 35m/sup 3/), each designed to process the manure residues from up to 65 dairy cows. Three pilot units (5m/sup 3/ volume) are being operated to determine the limits of operation variables - temperature, labor inputs, mixing, and bedding composition. The low-cost full scale plug flow reactor has now been operated for more than one year, including the winter with the lowest temperature for the longest period recorded for the northern New York area. During the twelfth quarter the full scale plug flow and conventional control reactors were tested in parallel at new conditions of 15 days and 10 days HRT, 35/sup 0/C and 10 to 12% TS manure feed. Steady state results for the 15 day HRT condition once more indicated a more efficient solids conversion with the plug flow design (34.1% TVS destruction efficiency) than with the completely mixed full scale system (27.8% TVS destruction efficiency) when operated on dairy manure (13% TS) at 35/sup 0/C. No serious operational problems have been encountered with either full scale reactor during the twelfth quarter. Thermal data from themore » plug flow reactor has now been obtained for a full year cycle. The apparent overall efficiency of the boiler and reactor heating systems varied between 40 and 55%. In order to translate the temperature and operating data of the plug flow unit into a comprehensible energy balance, a computer model for the prediction of energy production and for the description of conducted heat losses and feed heating requirements was developed. Data analysis and the development of certain sections of the final report were given considerable attention throughout the twelfth quarter. The preparation of the farmer's feasibility manual was also initiated during this period.« less