Comparison of tire-sulfur mixotrophic denitrification (T-SMD) and sulfur oxidizing denitrification (SOD) for advanced nitrogen removal of slaughterhouse wastewater

Abstract

Slaughterhouse wastewater (SWW) containing high concentrations of nitrogen and phosphorus could lead to the eutrophication of receiving water environment such as lake, river and reservoir, and even result in ground water contamination. Effluent NH4+-N and COD were effectively removed through the traditional secondary anaerobic-aerobic treatment process, where NO3- and NO2- were produced. This study established two bench-scale upflow packed bed reactors, tire-sulfur mixotrophic denitrification (T-SMD) column and sulfur oxidizing denitrification (SOD) column, to compare the performance for advanced nitrogen removal from synthetic SWW. During the whole study period with a recirculating flow rate of 1 L/d, NO3- removal efficiencies were about 100% and 99.3% for T-SMD and SOD columns, respectively. Effluent TN concentrations were 6.44 and 0.73 mg/L, respectively, which were lower than the newest effluent standard for new enterprises of 20 mg/L in China. T-SMD column showed the lower SO42- productivity due to the existence of mixotrophic denitrification. The pH in both columns remained near-neutral possibly due to the oyster shells addition. The results showed that T-SMD and SOD were the effective technologies for advanced nitrogen removal from SWW.