Batch influences of exogenous hydrogen on both acidogenesis and methanogenesis of excess sludge

Methane (CH4) recovery from excess sludge plays an important role in wastewater treatment aimed at achieving carbon neutrality. Besides pretreatment for excess sludge, exogenous CO2 and even H-2 have already been tested in enhancing CH4 production from anaerobic digestion (AD). However, exogenous H-2 injected into AD might simultaneously influence both upstream acidogenesis and downstream methanogenesis. In this study, a series of batch tests were conducted to ascertain the influences of hydrogen partial pressure (P-H2) on these two processes. Interestingly, the batch tests demonstrated that injecting exogenous H-2 into AD at the beginning of each batch cycle can both stimulate acidogenesis (organic conversion rate) and enhance methanogenesis (both CH4 and biogas productions) at an appropriate P-H2, (=0.33 bar) and an optimal revolution (R-s = 200 rpm) of a shaker. (C) 2017 Elsevier B.V. All rights reserved.