Biomethanation of acidic pH wastewater with acid stressed microorganisms

Abstract

The aim of the research was to study the biomethanation of brewery wastewater under acidic condition with acid stressed bacteria.  Acid was used to inactivate the methane producing archaea from brewery digester sludge.  The acid treated microorganisms prepared were used as inocula.  Prior to use, the microorganisms was acclimated with glucose and nutrient solution along with the brewery wastewater. The initial pH of the brewery wastewater was adjusted to be acidic and the pH of the fermentation medium was recorded at pH levels of 5.3, 5.7, 6.2 and 7.0.  The experiments were conducted in batch mode at 35±1°C in serum bottles. Gas collection was based on the water displacement.  The CH₄ yield obtained was 155, 158, 172 and 190 ml at STP/g COD degraded at initial pH of the fermentation medium of 5.3, 5.7, 6.2 and 7, respectively.  This study found that biomethanation in the acidic fermentation medium with acid stressed bacteria was succeeded when the microbial system was maintained at an optimal pH 7 and was acclimated with the long period of 30 days.