IMPACT OF SALINITY ON COD TREATMENT EFFICIENCY IN THE SOY SAUCE WASTEWATER TREATMENT BY UASB MODEL IN VITRO

Abstract

That untreated wastewater containing a large number of organic compounds is discharged directly into the running water would lead to several negative effects on the environment. Besides the environmental problems, wastewater containing both high organic compounds and high salinity concentration would cause more difficulties to set up the treatment procedure. In this study, we applied the UASB (Upflow Anaerobic Sludge Blanket) model in the COD (Chemical Oxygen Demand) treatment of high salinity wastewater such as soy sauce production wastewater. Anaerobic activated sludge was taken from the anaerobic tank of the wastewater treatment system of Mekong company (Duc Hoa district, Long An province). After that, the sludge was mixed and put into the UASB column, input volume was 40% of the total column volume. The microbial community in the sludge is the source of bio-remediation factors of the UASB column. Finally, the model was performed in the laboratory and investigated the COD treatment effect on different salinity concentration synthetic wastewater (NaCl concentrations are 0.59%, 0.89%, 1.18%, respectively), the capacity of the model is 10 liters per day. During 180 days of the experiment, the chemical indicators such as pH, COD, N-NH4, P-PO4 were analyzed, and the amount of biogas produced in the model was tracked. As a result, the maximum COD treatment efficiency of the model was 77.2% at the wastewater sample containing 0.89% NaCl, the average biogas capacity gained 8.5 liters per day, and the microbial density at this stage reached 1.5 × 108 CFU/mL. The UASB column could be able to withstand a high rate and changed loading flow, the result of this study provides the evidence that UASB model could be applied to organic wastewater treatment processing in a high salt concentration.