Enhanced Biogas Production from Sugarcane Vinasse using Electro-Fenton as Pre-treatment Method

Abstract

High concentration of organic matter in the sugarcane vinasse is potential as a biogas feedstock, but its a very high organic matter (expressed by chemical oxygen demand (COD), >100,000 mg/L) disturbs the biological activity during anaerobic digestion (AD). The maximum COD concentration in vinasse that is recommended as an initial condition of biogas feedstock is 75,000 mg/L. Furthermore, complex characteristics of vinasse make it necessary to be pre-treated before it is converted to biogas. Therefore, an advanced oxidation process (AOP) such as electro-Fenton (EF) is applied as a pre-treatment method in the AD of vinasse. The goal of this study was to investigate the effect of pre-treatment of vinasse using the EF method on biogas production. The process of EF was conducted with a variation of voltage (4, 6, 8 V) under the batch system and constant operating conditions such as treatment time, initial pH, the ratio of [H2O2] to [COD], and distance between electrodes. Moreover, the process of AD was run using anaerobic digesters having a volume of 2 L under the batch system at room temperature. The AD was conducted for 40 days. The results showed that the best EF could decrease the COD as much as 81.14% at 4 V with constant operation conditions (treatment time of 60 min, initial pH of 4.34, a ratio of [H2O2] to [COD] of 0.6 and distance electrodes of 3 cm). Furthermore, the pre-treatment of EF increased biogas volume successfully (6.02 L). The applicability of the first-order, second-order, and Behnajady-Modirshahla-Ghanbery (BMG) was investigated to evaluate the removal of the COD value. This primary concern is that the electro-Fenton treatment is favorable to decrease the organic matter of sugarcane vinasse.