A new method for the simultaneous enhancement of methane yield and reduction of hydrogen sulfide production in the anaerobic digestion of waste activated sludge

- An approach was used to enhance the CH4 yield while decreasing the H2S production.
- Characteristic APS reductase and sulfite reductase were detected in this study.
- Alkaline fermentation had an adverse impact on the abundance of SRB.
- Alkaline fermentation made the acetotrophic methanogens more dominant.

The biogas generated from anaerobic digestion (AD) also includes undesirable by-product such as hydrogen sulfide (H2S), which must be removed before the biogas can be used as a clean energy source. Therefore, it is necessary to find an appropriate strategy to simultaneously enhance the methane yield and reduce H2S production. An efficient strategy-pretreating sludge at pH 10 for 8 d and adjusting the system at neutral pH to produce methane for 20 d-is reported for the synchronous enhancement of methane production and reduction of H2S production during AD. The experimental results showed that the cumulative methane yield was 861.2 ± 6.1 mL/g volatile solids (VS) of sludge pretreated at pH 10 in semi-continuous stirred anaerobic reactors for 84 d, an increase of 49.6% over the yield in the control. Meanwhile, the cumulative production of H2S was 144.1 × 10−4 mL/g VS, 54.2% lower than that in the control.

188