Degradation of Aniline and Antimony in Printing and Dyeing Wastewater by Micro-Oxygenated Hydrolytic Acidification and Their Removal Effects on Chemical Oxygen Demand and Ammonia Nitrogen.

The degradation characteristics of aniline and antimony in printing and dyeing wastewater during the micro-oxygenated hydrolytic acidification process and its effect on COD and ammonia nitrogen removal were investigated in this experiment. Firstly, the effects of control factors such as pH, dissolved oxygen (DO), and sludge concentration on COD and ammonia nitrogen removal in the hydrolysis acidification section were optimized. It was recommended that the pH value should be maintained at 6.5; low DO (0–0.5 mg/L) could assist in the conversion of nitrogen for subsequent treatment; the optimum treatment temperature was 25 °C; finally, it was recommended that the sludge concentration should be controlled at 4 mg/L during the operation. Secondly, the effects of aniline and antimony on COD and nitrogen removal were investigated. It was found that when the concentration of aniline was increased from 0.4 mg/L to 5.4 mg/L, the COD concentration in the effluent increased by 96.5%, which indicated that aniline was toxic to anaerobic sludge and obviously inhibited the degradation of COD. When the concentration of antimony was increased from 0.05 mg/L to 2.05 mg/L, the COD removal rate was only 2.9%, which was much lower than that of the water samples with no antimony added. The anaerobic sludge concentration decreased from 5.58 g/L to 3.44 g/L, which indicated that aniline and antimony had a strong inhibitory effect on the activity of anaerobic bacteria and inversely affected COD removal. [ABSTRACT FROM AUTHOR]