Bio-gas from Dairy Scum — A Case Studyof Vidya Dairy

摘要

The low density semi-solids, which float in the fat trap unit of the effluent treatment plant contains fats, proteins, packing materials etc. They are called 'dairy effluent scum' and are removed manually. The current practice is to either dump them in drying beds/landfills or pass it to soap manufacturers. Studies carried out at Sardar Patel Renewable Energy Research Institute (SPRERI) Gujarat has shown that biomethanation of the dairy effluent scum is an attractive alternative for milk processing industries in terms of energy generation for captive use, besides resulting in significant reduction of the organic pollutant load and environmental pollution. The main solid waste generated during the treatment of the effluent in milk processing industryis the dairy effluent scum. It has been reported that 50-100 ke of scum is producedfor every lakh litres of milk processed. It contains around 80-90% moisture and 70-80% of volatile matter in terms of total solids depending up on the product processed in the dairy plant. Dairy effluent scum is rich in organic content, which makes it amenable for bio-methanation.Based on the findings at SPRERI, a demonstration plant of 500 kg d"' capacity has been installed in M/s Vidya Dairy — an instructional milk plant of Anand Agricultural University, Anand, Gujarat — for recovery of methane rich bio-gas. The bio-gas produced is used for replacing piped natural gas (PNG) in their canteen to meet their partial cooking energy demand. This conversion and utilization has resulted in significant reduction in organic pollutant load on the ETP along with generation of renewablegaseous fuel in the form of methane gas which has improved the economics of the milk processing industry.