Nitrogen and phosphorus removal processes under different aeration strengths in the principal-type tank of alternate multiple tanks system and process control

ABSTRACTThe alternate multiple tanks (AMT) system was a new highly compact sewage treatment with cost-effective balance and automated management. Dissolved oxygen (DO) and oxidation-reduction potential (ORP) as monitoring indicators are closely linked to contaminants and controlling strategy. Thus, this paper was to investigate the N and P removal mechanisms and the real-time control under different aeration strengths through the principal-type tank. Results showed that N and P removal could reach an optimal balance when the air–water ratio (Rs) was 30 with 540L-air/h and 18L-water/h. Under such a condition, the TP, TN, ammonia and nitrate remained 0.4 mg/L (88.4% of removal efficiency), 5.0 mg/L (84.7%), 0.5 mg/L (98.4%) and 4.0 mg/L, respectively, during the discharge. However, restrained aeration reduced the P release and uptake efficiencies and retarded the ammonia oxidation and nitrification, and excessive aeration broke the balance of P release and uptake, prevented denitrification, and had no more ...