Co-production of biohydrogen and biomethane from food waste and paper waste via recirculated two-phase anaerobic digestion process: Bioenergy yields and metabolic distribution.

Graphical abstract Highlights • Successful co-production of bioH 2 and bioCH 4 was achieved by R-TPAD process. • The R-TPAD process was feasible to treat OFMSW (FW + PW) with PW content ≤50%. • Increasing PW favored H 2 yields by enriching H 2 -producing bacteria in the process. • The major cellulose-degrading bacteria grew only in the mesophilic phase (2nd stage). • The H 2 -producers were recirculated to the 1st phase after growing in the 2nd phase. Abstract To achieve the co-production of H 2 and CH 4 , co-digestion of food waste (FW) and paper waste (PW) was performed on the recirculated two-phase anaerobic digestion (R-TPAD). The PW content in the feedstock increased from 0% to 20%, 40% and 50% (in total solids) with FW as the rest. The results showed that bioH 2 and bioCH 4 were simultaneously and stably produced in the long-term operation. With the increasing PW content, the removal efficiency of volatile solids decreased slightly from 84.9% to 78.4%; the bioH 2 yields increased from 50 to 79 NL-H 2 /kg-VS fed while the bioCH 4 yields decreased from 426 to 329 NL-CH 4 /kg-VS fed. With the fixed amount of FW, adding PW could significantly increase the total bioenergy yields. The relative abundance showed that the key H 2 -producing bacteria, Caproiciproducens and Thermoanaerobacterium , increased after PW addition. The microbial distribution suggests that the H 2 -producers were recirculated to the first stage after proliferating in the second stage. [ABSTRACT FROM AUTHOR]