Biogas generation from anaerobic co-digestion of tofu liquid waste and tapioca flour liquid waste at various initial pHs

Tofu liquid waste (TLW) and tapioca flour liquid waste (TFLW) are the two abundant wastewaters in Indonesia. The current research had a goal to examine the influence of the mixing ratio of TLW:TFLW=0:100, 50:50, 100:0v/v, and initial pHs of 5-8 on biogas production from TLW and TFLW. At an initial pH of 7, the TLW:TFLW ratios of 0:100, 50:50, and 100:0 resulted in biogas yields of 143.99, 341.13, and 93.00 mL/g-CODadded,respective-ly. It means that anaerobic co-digestion (AcoD) generated a higher biogas yield than anaerobic mono-digestion (AmoD). In addition, the biogas from AcoD contained a higher methane content (44.1-48.1%) than that from AmoD of TLW or TFLW. Furthermore, AcoD of TLW:TFLW=50:50 at initial pHs of 5, 6, 7, and 8 resulted in biogas yields of 187.76, 296.02, 341.13, and 165.21 mL/g-CODadded,respectively. Hence, an initial pH of 7 provided suitable conditions for microbes so biogas could be generated in a large amount. Initial pHs of 7 and 8 generated biogas with standard methane content (44.1-55.5%). The highest COD removal (55%) was achieved at AcoD (50:50) with an initial pH of 7. Therefore, the best condition was AcoD with an initial pH of 7. Based on the kinetic analysis, AcoD (50:50) with an initial pH of 7 had the highest biogas potential and the lowest adaptation time. The findings of the current study supported the hypothesis that the AcoD generated higher biogas yield and methane content than the AmoD, as well as the initial pH of 7 generated the highest biogas yield.