Methane production from cheese whey

Abstract

Cheese whey was treated in a 17·5-litre laboratory-scale up-flow anaerobic sludge blanket reactor operated over a range of hydraulic retention times and organic loading rates. The reactor performance was determined in terms of methane production, volatile fatty acids conversion and chemical oxygen demand reduction. At a constant influent strength, the methane production rate (litres CH 4g −1 COD day −1) decreased with decreasing hydraulic retention time. At constant hydraulic retention time the methane production rate increased as the influent strength was increased up to a concentration of 28·8 g COD litre −1. The methane production rate was similar for two influent concentrations studied at hydraulic retention times longer than 10 days. The effect of short hydraulic retention times on methane production rate was more pronounced for the higher influent concentration than for the lower influent concentration. The highest methane production rate of 9·57 litres CH 4 litre −1 feed day −1 was obtained at a loading rate of 5·96 g −1 COD litre −1 and an influent concentration of 28·8 g COD litre −1. A high treatment efficiency in terms of chemical oxygen demand reduction was obtained. In general, over 98% removal of chemical oxygen demand was achieved. The results indicated that anaerobic digestion of cheese whey using an up-flow sludge blanket reactor could reduce pollution strength and produce energy for a cheese plant.