Effects of freezing–thawing pretreatment on anaerobic digestion of wheat straw and its kinetics analysis

In this study, freezing–thawing (FT) pretreatment of different freezing time and temperatures was investigated to find the effect on anaerobic digestion (AD) wheat straw (WS). The temperature gradient is − 10 °C, 20 40 °C 80 12 h, 24 48 h 96 h. Total methane production exhibited a mere distance among all samples. Morphology change sculptured by SEM showed method broke structure WS leaving fragments pores in varying degrees. Three kinetic models were performed represent behavior experimental data. Kinetic model parameters total lag phase that logistic function had best fit, followed modified Gompertz model, yet transfer lost efficacy experiment. Logistic then used reveal influence caused temperature, results implied FT can shorten AD, providing 21.39% improvement under optimal conditions analysis response surface regression shows has more than time. Warmer do better time, which be achieved most cold regions, so treatment occur naturally such area without additional energy input.