A Comparative Study of Biogas Yield from Various Brewery Wastes and Their Blends with Yam Peels

Abstract

A study was undertaken to determine biogas yield (% methane) from various local brewery wastes and their blends with yam peels (YP). The wastes investigated were Kunu chaff (KC), Burukutu (BKT) and spent grain (SG). The wastes were in two blends A and B. The blend A was SG:BKT:KC = 40:30:30 and blend B was SG:BKT:KC:YP = 40:20:20:20. All the waste types and their blends were bio-digested in an anaerobic digester in replicates for 20 days at ambient temperature experiment. The N, TS, VS, C, C:N, pH of the feedstocks were determined by standard methods. The gas yield was obtained by downward displacement of water. ANOVA at p ≤ 0.05 was used to determine if there was any significant difference in the biogas yield from the waste types. The gas yield were of the order blend B > KC > blend A > SG > BKT > YP. Blend B which had the highest yield of 75.6% had the highest C:N of 27;1 while YP which had the least of yield 52.3% had the least C:N of 10:1.The results obtained indicate good prospects for generation of biogas while managing the wastes generated from various brewing activities in Nigeria both for small- and large-scale applications.

Keywords: Comparative, biogas, local brewery wastes, anaerobic digester, spent grain, yam peels, blends.