Use of heterogeneous activated carbon supported copper catalyst for catalytic wet oxidation of biomethanated spent wash: Reaction kinetics, catalyst stability, catalyst deactivation kinetics and biochemical methane potential

Abstract

In the present study, the potential of activated carbon (AC) supported copper catalyst was investigated during catalytic wet oxidation (CWO) of pretreated high strength biomethanated spent wash (BMSW) stream which is originated from alcohol distillery. Prior to wet oxidation (WO) treatment, the BMSW was centrifuged to remove suspended solids. During CWO treatment at 220 °C temperature, the chemical oxygen demand and color removals of 72% and 97%, respectively, were observed from the centrifuged BMSW (catalyst dose = 3.4 g L−1, reaction time = 3 h). The analysis of treated liquid samples confirmed the formation of acetic acid in large concentrations which is one of the major precursors of methane during post anaerobic treatment. The kinetic expressions for WO and CWO processes were also developed using initial rate method. However, the recovered and regenerated catalyst could only be reused twice in CWO runs. The biochemical methane potential (BMP) test results showed significant production of biogas from the treated BMSW. Based on the findings, it can be inferred that the CWO of BMSW can be a potential treatment method before its disposal in the environment.