The resource recovery potential of blackwater and foodwaste: anaerobic co-digestion in serial semi-continuous stirred tank reactors

The sustainable management of household food waste (FW) and household blackwater (BW) is becoming more challenging. This research investigated three different semi-continuous stirred tank reactor (CSTR) performances for digestion of the mixture of BW and FW; for producing biogas. Through the application of the serial semi-CSTR digestion (35 °C), the produced biogas from the BW-FW (1:1 proportion) offered to be higher than the single semi-CSTR 55 °C (25%) and that of the single semi-CSTR 35 °C (31%). The serial semi-CSTR higher biogas volume production was attributed to the extra biogas generated from the residual organic matter and residual volatile fatty acids decomposition existing in the digestate of the first reactor and further utilized in the second-step methanogenic reactor chamber. The serial semi-CSTR physicochemical parameters showed stable performance with total chemical oxygen demand reduction efficiency of 97%, and without inhibition at the pH value of 8.5 ± 0.9. The serial semi-CSTR 35 °C digestion offered the advantages for improving the worth of resources recovered from FW and the BW to accomplishing a higher biogas percentage and enhanced sludge stabilization for water resources and waste management.