Tannery Wastewater Treatment Using an Upflow Anaerobic Fixed Biofilm Reactor (UAFBR)

Abstract

An upflow anaerobic fixed biofilm reactor (UAFBR), which retains a high concentration of accumulated biomass in the form of biofilm supported by a carrier, has been developed to treat tannery wastewater. The effects of major process variables such as hydraulic retention time (HRT), organic loading rate (OLR), temperature on chemical oxygen demand (COD) removal, and methane yield performances of the reactor were evaluated. The technology ensures the retention of the active methanogenic biomass within the reactor, independent of the HRT, with minimum particle washout. This aids the conversion of COD and results in a reduction in effluent suspended solids (SS). COD removal (60-75%) and methane yield (0.36 m³ CH₄/kg COD_rem) remained stable across a range of organic loading rates and under conditions of temperature shock. The COD removal and methane yield is higher than the values reported previously. The biofilm colonisation on two types of microcarriers was compared. Porous polyurethane foam material was found to be more suitable than Raschig rings as a microcarrier in the UAFBR reactor. Both SEM and TEM techniques were used to study the morphology of the biofilm, the location of bacteria in the biofilm, and species diversity and community structure.