Evaluation of biogas production from whey at laboratory scale

Abstract

This research aims is to evaluate the production of biogas with whey, starting with the characterization of the raw materials (manure and whey) to determine their chemical composition. The following experiments, in total six, with three compositions of different concentrations of whey, were observed and the data evaluated for 20 days, measuring the average production rate of gas. The composition with the best results concerning the productions rate of gas was used to charge the bio-digester up to a scale of 31.1 l for 31 days at service. During this time, the heat transfer between the gas butane and the biogas that has been produced was determined. It showed that boiling water enters in less time with butane than biogas, suggesting that biogas is less efficient than butane. The proposed precondition for the technology of producing biogas (water + manure) indicates that the production costs per liter of the mixture add up to $0.36 in case of whey and $0.20 for water. Nevertheless, the output for biogas with whey amounts 243.16 l per month, whereas the output with water only sums up to 74 l per months, which implies that the use of whey is much cheaper.