The effect of the substrate to inoculum ratio (SIR) on the anaerobic digestion (AD) of the liquid fractions (LFs) of co-hydrothermally treated mixed biomass (sewage sludge (SS) and the organic… Click to show full abstract
The effect of the substrate to inoculum ratio (SIR) on the anaerobic digestion (AD) of the liquid fractions (LFs) of co-hydrothermally treated mixed biomass (sewage sludge (SS) and the organic fraction of municipal solid waste (MSW)) was evaluated. The impact of SS + MSW-hydrochar was also studied at different hydrochar concentrations (0, 1, 5, 10, 15, 20 and 25 ghydrochar/L), in two of the LFs studied. The SIR had a significant impact on methane yield (YCH4) and organic matter degradation, with low methane production (4-44 NmLCH4/g tCODadded) observed for all LFs at SIR = 1:3. Hydrochar significantly improved YCH4 and specific methane production rate. Compared with the AD without hydrochar, the YCH4 improved up to 1.95 times at 15 g/L. Hydrochar doses from 1 to 10 g/L shortened the lag phase, while higher concentrations (15 to 25 g/L) showed an increment with respect to the control reactor without hydrochar.
               
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