Effect of Thermal and Thermo-chemical Pretreatments on Food Waste in Anaerobic Digestion and Methane Production in Batch Leach Bed Reactor with Down Flow at Thermophilic Temperature

Energy recovery from waste is a proper way to waste management and energy production from foods waste. Anaerobic digestion of the waste is a suitable way to produce clean energy. This study aimed to investigate the anaerobic digestion of food waste and methane production by thermal and thermo-chemical pretreatments at a temperature of thermophilic (55 ˚C) in the Batch Leach Bed Reactor with Down Flow reactor (LBR DF).
In the present study, the food waste collected from Restaurant of Bu-Ali Sina University and autoclaving and microwave pretreatment was performed before feeding LBR DF. In the thermal pretreatments, homogeneous mixture of food waste pretreated using autoclave and microwave. In the thermo-chemical pretreatments, initially, food waste pretreated using NaOH 5N for 60 minutes and then pretreated using autoclave and microwave. LBR DF was launched at thermophilic temperature and SCOD, TCOD, TS and VS values were measured before loading and at the end of tests. By using MATLAB software, the cumulative methane was fitted on modified Gompertz model and B0, Rm and values were determined for all experiments.
According to the results, the best results was in microwave along with NaOH 5N pretreatment that SCOD / TCOD value increased to the amount of 82.25%, methane production to the amount of 39.98 l, TSremoved and VSremoved to the amounts of 6.01% and 7.1% respectively. In addition, lowest of value and highest of Rm value was observed in microwave along with NaOH 5N pretreatment to the amounts of 3.38 (day) and 1.8 (l/day) respectively.
Generally, thermo-chemical pretreatment have the better performance than the thermal pretreatment and without pretreatment. Thermo-chemical pretreatment causes more damage the compounds of food waste and thereby increases the amount of SCOD / TCOD%, TSremoved, VSremoved and methane production.