Stimulatory effect of magnesium supplement on anaerobic co-digestion of food waste and domestic wastewater

Abstract

This study investigated the synergistic effect of anaerobic co-digestion (ACoD) of food waste (FW) and domestic wastewater (DWW) together with the magnesium (Mg2+) supplement on biogas production and organics removal. An upflow anaerobic sludge blanket (UASB) reactor was operated at 35 °C under an intermittent feeding mode (48 h feed and 48 h no feed) while batch experiments were performed for the effect of Mg2+ supplement on ACoD. In terms of chemical oxygen demand (COD) removal and methane recovery, the best performance was at 150 mg/L Mg2+ supplement where COD removal efficiency and methane content reached 83.1 ± 1.1 % and 61.4 ± 0.6 %, respectively, 13.06 % and 10.63 % higher compared to the control without Mg2+ supplement. In addition, a lower ammonia-nitrogen accumulation (661.1 ± 53.0 mg/L) was observed compared to the control (811.0 ± 44.5 mg/L), showing the Mg2+ supplement also stimulatory to the ammonia-nitrogen removal, further reducing the inhibitory effect of ammonia on the ACoD performance. Results imply a promising strategy for the successful implementation of the use of ACoD technology to the treatment of FW and DWW for the resource recovery.