The effect of lignocellulosic waste on biological treatment of municipal wastewater in anaerobic digestion process

The biological purification of municipal wastewater as an organic waste with a low C/N ratio was explored in the presence of a carbon-rich lignocellulose substrate with a high C/N ratio in this study. The composition of the substrates is optimized to get the best biogas yield while maintaining reactor stability. The best composition was modeled and determined using response surface methods and mixture design. The findings revealed that anaerobic co-digestion of municipal wastewater with high C/N ratio substrates like sugarcane plants and wasted black tea improves biogas generation. This behavior was observed in reactors with more than 70 % w/w cane waste in this study’s testing. Spent black tea as a co-substrate is suitable for co-digestion with municipal wastewater. But the presence of this substance with a high percentage in combination due to the antibacterial properties of polyphenol and tannins in it leads to the loss of useful microorganisms of anaerobic digestion and reduces biogas production yield. The best substrate composition contains 25 % w/w of the lignocellulose waste of sugar cane, 34 % w/w spent black tea, and 41 % w/w municipal wastewater, which produced 239 mL/g VS of biogas.