Effect of pretreatment and anaerobic co-digestion of food waste and waste activated sludge on stabilization and methane production

• Pretreatment enhanced stabilization of food waste and waste activated sludge.
• Co-digestion is effective in food waste stabilization and methane production.
• Ultrasonic treatment and co-digestion of food waste and waste activated sludge gave the highest methane yield.

The effect of pretreatment and anaerobic co-digestion of food waste (FW) and waste activated sludge (WAS) was assessed by the reductions of total suspended solids (TSS), volatile suspended solids (VSS), COD removal and methane production. Thermal treatment and anaerobic digestion reduced VSS up to 43.4% (FW) and 43.1% (FW + WAS) by increasing the solubilization of the feedstock. Methane yields of ultrasonic treatment reached 206.4 (FW) and 326.3 (FW + WAS) mL CH4 g−1 VSS removed which were 50.5 and 56.2% higher than that of the control. Results showed that each pretreatment gave distinctive effect on different feedstocks due to dissimilar composition. Co-digestion conferred superior result than mono digestion with FW or WAS. Estimated parameters (methane production potential and the rate) with Gompertz equation also inferred that co-digestion increased methane production significantly.