Startup of a UASB Reactor Using Kitchen Effluent

Abstract

This study was designed to evaluate the treatability performance of a single-stage upflow anaerobic sludge blanket (UASB) reactor at neutral pH and constant mesophilic temperature, and to investigate the biogas yield of a single-stage UASBR using kitchen effluent. For this purpose 70% of UASB reactor was seeded with anaerobic digester and activated sludge of the nearby wastewater treatment plant. The acclimatization process continued for about 18 days in the laboratory. The seed sludge provided 36.50 g of volatile suspended solids (VSS). The loading rate was increased stepwise in order to avoid organic loading shocks. Hydraulic retention time (HRT) was also studied. Mixing was done twice a day for about 15 to 20 min. It was observed that the treatment of high-ranged kitchen effluent is technically feasible provided the pH of the system is kept near to neutral. This can be achieved by adding NaHCO₃ to the feed solution. The volumetric loading rate of 1.5 kg-COD/m³.day and an HRT of 18 h are the conservative figures that warrant a removal efficiency of more than 78% and thus kitchen effluent quality can be brought within the limits of Pak-NEQS. The UASB reactor seems to be a viable option not only in terms of pollution reduction, but it also helps in the conversation of wastes into energy (biogas). The amount of biogas yield from the UASB reactor, using kitchen effluent is 0.32m³/kg-COD_rem at optimum operating conditions, with 61% methane contents. Since Pakistan is facing a shortage of energy, encouraging such technologies can help to tackle the problem of energy crises