PROFILING ANAEROBIC DIGESTION STAGES FROM CAFETERIA FOOD WASTE FOR PRODUCTION OF BIOGAS

Abstract

Population growth in Malaysia has led to a rise in waste production. Soon, the capacity of the sanitary landfill will not be sufficient to accommodate the daily garbage production. Therefore, biogas plants are one of the finest answers to this issue. There has been numerous research on the use of food waste (FW) to make biogas, which can then be transformed into renewable energy. Food waste constitutes the largest percentage of municipal solid waste in Malaysia (MSW). In this study, the acclimatization process was conducted to profile the stages in this process for 27 days using cafeteria food waste (CFW) as a substrate. During the process, the pH sample and biogas production was recorded. The results showed that the hydrolysis stage occurred during day 0-1, indicated by a drop in pH from 7 to 2. This was followed by the acidogenesis stage from day 2-14, with the pH remaining within the acidic range of 3.5-6.5. The acetogenesis stage took place from day 15-18, maintaining a similar acidic pH range. Lastly, the methanogenesis stage occurred during day 19-27, characterized by a significant increase in biogas production. Methanogenic archaea converted the produced acetate, hydrogen, and carbon dioxide into methane gas. Different total solid (TS) contents of CFW: 10%, 15%, and 20%, were investigated. The highest biogas production was observed with a TS content of 20%, resulting in an accumulated biogas volume of 360 ml over seven days of fermentation. Conversely, the lowest biogas production was observed with a TS content of 10%, yielding a biogas volume of 170 ml. This study demonstrates that biogas production increases with higher total solids (TS) content. Finally, this study proves that food waste is a potential feedstock for biogas production that can help to reduce the current issues of waste disposal.