Anaerobic co-digestion is one of the most promising auxiliaries for treating waste because of the high energy redemption. Bio-digester is designed and apparatus installed for anaerobic co-digestion of cow waste with crop residue in order to manufacture biogas. Gas production is measured by using water displacement method. The experimental results show that 1 kg of cow dung can produce about 15 to 30 L of biogas per day. By the addition of wheat straw, it yielded 20 to 60 L per day of gas. Bio-digester slurry consists of a blend of cow dung, crop residue, and inoculum in the ratio of 50:30:20 (50 kg cow dung: 30 kg wheat straw: 20 kg inoculums) by weight. Experimental analysis for measuring the different parameters affecting the processes like chemical oxygen demand, temperature and pH levels was carried out. Semi-flow through process was applied throughout the process of production in order to manage feedstock and effluent. The University of the Punjab annually produces 1670 kg/acre of crop residue and 1946 kg/day of cow dung, whereas, the total crop produce is 4130 kg/acre/annum. The result shows that by effectively utilizing the crop residue which is available seasonally as 20 to 60 L of bio gas yield per day, this can provide methane gas to laboratories of Punjab University.
Key words: Bio-digester, anaerobic, co-digestion.
GDP, Gross development production; CO, carbon monoxide; NO, nitrogen oxide; SO2, Sulphur dioxide; COD, chemical oxygen demand; BOD, Biological oxygen demand; pH, potential hydrogen; ASTM, American Society for Testing and Materials.