Applied Microbiology: Open Access
Open Access

Abstract

Effect of Seasonal Variation on Anaerobic Treatment of Organic Municipal Solid Waste-II: Population Dynamics of Bacteria and Archaea Communities

Ogbonna CB, Stanley HO and Abu GO

This study was designed to investigate the effect of seasonal variation on population dynamics of bacteria and archaea communities during anaerobic treatment of organic municipal solid waste. The waste was subjected to anaerobic treatment inside one-stage 250 L-capacity batch-type mesophilic poly-tank reactors with used volume of 230 L, substrate concentration of 5.53% total solids, rumen juice as the source of microbial inoculum and a retention time of 84 days. The first Anaerobic Digestion (AD_H) treatment was conducted during the dry season (between February and April, 2016) while the second Anaerobic Digestion (AD_C) treatment, a repeat of the first process, was conducted during the rainy season (between July and October, 2016). To monitor performance of the anaerobic treatment process, populations of selected bacteria and archaea groups and biodegradation of the feed where estimated with time using standard methods. Inside the AD_H system, the population of Acetoclastic Methanogens (AMA), Hydrogenotrophic Methanogens (HMA), Strict Anaerobic Bacteria (SAB) and Facultative Anaerobic Bacteria (FAB) ranged from not-detected to 8.76 × 10⁶ CFU/ml, not-detected to 7.93 × 10⁶ CFU/ml, 1.45 × 10⁶ CFU/ml to 4.18 × 10⁷ CFU/ml and 1.2 × 10⁶ MPN/ml to 7.5 × 10⁷ MPN/ml respectively with time. Inside the AD_C system, the population of AMA, HMA, SAB and FAB ranged from not-detected to 1.46 × 10⁶ CFU/ml, not-detected to 1.05 × 10⁶ CFU/ml, 9.2 × 10⁵ CFU/ml to 1.85 × 10⁷ CFU/ml and 2.4 × 10⁶ MPN/ml to 1.2 × 10⁸ MPN/ml respectively with time. Biodegradation of the feed inside the AD_H system and the AD_C system, increased to 97.21% and 75.86% respectively after 84 days. Microbial populations inside the AD_H-system increased significantly more than the microbial populations inside the AD_C-systems with time, leading to a significantly (p<0.05) better performance of the AD_H-system than the AD_C-system with respect to biodegradation of the feed. Therefore, seasonal variation appears to have influenced the population dynamics of microbial communities during anaerobic degradation of the waste.