Study on the effect of sulfate in the treatment of high ammonia organic wastewater

To obtain a better understanding of effect of sulfate in the treatment of high strength ammonia organic wastewater, we mainly studied the critical concentration of sulfate sludge could endure, the transformation of main microbial phases and the effluent parameters with the sulfate concentration of influent water increasing in anaerobic-aerobic (A/O) process. The results showed that the activated sludge could endure the sulfate concentration up to utmost 6500 mg/L as removal ratios of CODcr, NH4+ and TN attained 90%, 92% and 85%, respectively. With the increase of the sulfate concentration, SOUR of sludge weakened gradually due to inhibition of sulfate and sulfide, and main microbial phases changed from metazoan to protozoa, eventually to planktons. After innovatively analyzing the metabolic balance (metabolic pathways and intermediate products) of CODcr and NO3- with mathematical method, results indicated that heterotrophic sulfate reduction and autotrophic denitrification-desulfurization gradually strengthened and heterotrophic denitrification weakened. NO3- reduced via autotrophic denitrification-sulfurization increased from 28.76% in phase 1 all the way to 62.69% in phase 4, while NO3- reduced via heterotrophic denitrification decreased from 71.24% in phase 1 all the way to 37.31% in phase 4 simultaneously.