BIOGAS PRODUCTION FROM WASTEWATER FROM THE RUBBER PROCESSING INDUSTRY BY SIMULTANEOUS SULFATE-SULFIDE REMOVAL IN SINGLE STAGE DIGESTER

Abstract

This study focuses on developing the capability to produce biogas from wastewater contaminated with high organic and sulfate concentrationวลสารและพลังงาน ะวัสดุอุปกร, through an integrated system of sulfate removal and biogas production within a single unit. The experiments were conducted under anaerobic conditions with Sulfate/Nitrate (S/N) of 0.5, 1.0, 1.5, 2.0 and 2.5. Additionally, the applicability of the system in industry was investigated. This study indicates that operating at an S/N of 2.0 provided the most efficient biogas production, with a biogas generation of 0.36±0.02 L/gCOD_removed. The composition comprised methane and hydrogen sulfide at 70.2±0.2% and 8.0±0.1 ppm, respectively. Moreover, this condition also showed high efficiency in COD, sulfate and sulfide removal. The average COD in influent and effluent was 12,818.25±13.25 and 1,770.42±10.12 mg/L, respectively. The efficiency in COD treatment was 86.19%. In addition, the system was applied in a rubber sheet manufacturing plant. Wastewater that contains nitrogen in form of nitrate-nitrite from the nitrification system was circulated into the biogas production system to control the S/N ratio in influent at 2.0. It was found that the system could produce more methane gas compared to the previous system that did not include sulfate-sulfide removal process. Through energy balance, electrical energy used for wastewater pump and aerator in the nitrification process was 1.5 kWh per day, while it could produce 9.87 m³/day of methane gas.
This implies that it can substitute 11.8 kWh per day of electricity.