Innovative Biosystems and Bioengineering (Oct 2018)
Technological Solution of Biogas Output Increasing at Grain Distillery Spent Wash Fermentation
Abstract
Background. Distillery spent wash is the main waste of the alcohol industry. This is highly concentrated wastewater, which is characterized by high chemical oxygen demand (COD) values – up to 60–120 g O2/dm3 – and low pH values – up to 3.7. It makes its processing a complicated task. One of the methods of its utilization is anaerobic fermentation with the production of biogas. Inert carriers for microorganism immobilization or granulation are used to intensify the process of anaerobic treatment and increase sludge concentration. Due to the high concentration of anaerobic microorganisms in granules, compared to the number of microorganisms in free-floating active sludge, the process of methanogenesis is more intensive with a high yield of biogas and a decrease in COD. Objective. To determine the possible centres of anaerobic sludge granulation in highly concentrated waste of alcohol production to increase biogas output in the process of waste treatment. Methods. Activated carbon, modified carbon on which surface calcium ions were precipitated, FeCl3, silica gel based sorbent, talc based sorbent were used to form pellets as the centres of microorganism accumulation. Results. Pellets have not been formed with the use of activated carbon; modified carbon with calcium ions; silica gel based sorbent and ferrum compounds. Pellets of activated sludge were received with the use of talc based sorbent – formation of initial biofilm on a carrier was observed on the third day of fermentation and then it was growing in pellets. Conclusions. It was demonstrated that for highly concentrated waste effluents of a distillery (grain distillery spent wash), which after co-fermentation with poultry manure contain volatile fatty acids in concentration 800–2000 mg/dm3, it is needed to use sorbents to receive microorganism pellets as a centre of granulation. Sorbents must contain donors and proton acceptors. It was established that the use of granular activated sludge for the distillery waste purification improves the efficiency of COD and Biochemical Oxygen Demand removal by 15–17%, increases biogas output by 26 ± 2% and biogas methane content by 8 ± 1%.
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