Investigation of the Effects of Supplementing a Biodegradable Municipal Solid Waste Anaerobic Digester with Maize Cobs.

Abstract

A study was carried to determine the effects of supplementing a municipal solid waste (MSW) anaerobic digester with maize cobs. This was an effort aimed at making biodegradable MSW anaerobic digestion more reliable by producing continuous and adequate gas for the intended applications. The study was carried out in a laboratory using protein rich MSW and carbohydrate rich maize cobs in a mesophillic digester for a period of 10 days. The nutrient composition of the feedstock was determined through proximate and ultimate analysis. The results showed varying nutrient composition for maize cobs and municipal solid waste. The co- digestion of MSW and maize cobs resulted in the determination of the optimum mixing ratio for maximum gas yields and quality of gas. The MSW and maize cobs were digested at the ratios of 3:1, 2:1 and 1:1 while the independent digestion of MSW and maize cobs served as the control. It was also noted that the Carbon: Nitrogen(C: N) which is a key component of anaerobic digestion was greatly improved with co-digestion. The comparison of biogas yields from the independent digestion of the feedstock and the yield from co-digestion indicates that, it is beneficial to use a fraction of maize cobs and MSW in an attempt improve the digestion conditions. It was also noted that the composition of final product (biogas) is affected by the type and composition of feedstock. A mixture of MSW and maize cobs at the ratio of 2:1 proved to yield the highest quantity of gas.