Production of Methane from Food Waste Using Microwave Radiation: Investigating the Effects of Power, Exposure Time and Kinetics Process

Background and Energy recovery from waste is an appropriate method for waste management and energy production from food waste. Energy production through waste incineration produces significant emission which is a critical threat for environment. Anaerobic digestion of the waste is a suitable way to produce clean energy. This study aimed to investigate the anaerobic digestion from food waste using microwave pretreatments in different levels of power and time that eventually increase anaerobic digestion and produce methane.
The food waste was collected from the restaurant in Bu-Ali Sina University and microwave (MW) treatment was performed before feeding reactor. Pretreatment process of the food waste was done by a domestic MW (P= 450 and 630 W) in different radiation times (100, 200 and 300 s). Reactors at mesophilic temperature (37°C) were launched for 15 days and SCOD and TCOD values were measured before loading and at the end of the tests. Using MATLAB software, the cumulative methane values were fitted on exponential, modified Gompertz and logistic models and the best model was determined in terms of the highest R2 and lowest RMSE and SSE amounts.
Based on the results, the best performance of anaerobic digestion, the maximum percentage of AWT IMAGE and the highest rate of methane production were obtained in 630 W microwave power and 300 s exposure time. Also, cumulative methane production was fitted using exponential, modified Gompertz and logistic models.
Increasing the power and exposure time enhanced solubility and the AWT IMAGE of the food waste. By increase in AWT IMAGE the daily biogas and methane productions also increase. The TSremoved and VSremoved values increase when the microwave power and exposure time increased. Also, the modified Gompertz model is a comprehensive and flexible model that is well fitted the experimental data and modified Gompertz model results in the highest R2 value and the lowest RMSE and SSE.