Batch anaerobic co-digestion of OFMSW (organic fraction of municipal solid waste), TWAS (thickened waste activated sludge) and RS (rice straw): Influence of TWAS and RS pretreatment and mixing ratio

• BMP of OFMSW, TWAS and RS co-digestion was investigated.
• TWAS and RS pre-treatments improved biogas yield.
• The optimal mixing ratio of OFMSW, TWASthrmo-NaOH and RSH2O2RSH2O2 was 3:0.5:0.5.
• Highest biogas yield and VS removal reached 558.5 L/kgVSadded and 76.9%, respectively.
• Kinetic model parameters of the batch experiment were analyzed.

The biochemical methane potential of co-digestion of OFMSW (organic fraction of municipal solid waste), TWAS (thickened waste activated sludge) (thermal and thermo-alkaline pretreated) and RS (rice straw) (NaOH and H2O2 pretreated) were investigated in this paper. The batch experiments were conducted at three different OFMSW/TWAS/RS (volume basis) ratios of 1:1.5:1.5, 1:0.5:0.5, and 3:0.5:0.5, respectively. In addition, to predict the biogas yield and evaluate the kinetic parameters, modified Gompertz model was introduced. A 3:0.5:0.5 ratio of OFMSW mixed with thermo-alkaline-treated TWAS and H2O2-treated RS produced the highest biogas production (558.5 L/kgVSadded) and the highest VS (volatile solids) removal efficiency (76.9%) due to the synergistic effect. The modified Gompertz model (R2: 0.868–0.998 and 0.910–0.999 for mono- and co-digestions, respectively) showed a good fit to the experimental results and the estimated parameters indicated that the pretreatments and co-digestion of substrates markedly improved the biogas production rate.