Effect of substrate-to-inoculum ratio on anaerobic digestion of treated and untreated cotton textile waste

Abstract

Anaerobic digestion is a promising technology for biogas recovery from cotton textile waste. However, limited studies have focused on anaerobic digestion of cotton textile waste. This study evaluated the effect of different SIRs of 0.5, 1.0, 1.5, and 2.0 using treated and untreated cotton substrate in a batch anaerobic digestion process under mesophilic condition for 15 days. The cotton textile waste was treated with 0.5 M Na2CO3 at 150 °C for 3 h. The highest methane yield of 366.76 mL/g VS, which is equivalent to anaerobic degradability of 89.67%, was observed from SIR of 0.5 for untreated substrate. However, for treated substrate, SIR of 1.0, 1.5, and 2.0 shows an increased methane yield and anaerobic degradability of more than 50% when compared to untreated substrate. Furthermore, for treated substrate, higher substrate loading of SIR 1.0 produced a comparable yield of 306.73 mL CH4/g VS, which is equivalent to anaerobic degradability of 75%. The Gompertz model fitted with the experimental data with R2 value of 0.96-0.99, which was an improvement over the first-order kinetic model.