| Simultaneous fixed-film nitrification, denitrification and enhanced phosphorus uptake were investigated in a lab-scale HITNP (Harbin Initiative Technology of Nitrogen and Phosphorus removal) configuration. This innovative nutrient removal process was a combined activated sludge and fixed-film process, worked with supernatant recycle regime. Hybrid activated sludge-biofilm reactor was applied in the experiment unit to solve the problem of overgrowing of slow growing nitrifiers by faster heterotrophs. High anaerobic sludge concentration originated from supernatant recycle and total anaerobic/aerobic sludge recycle of HITNP other than part sludge recycle of traditional A2/O configuration contributed to high phosphorus removal efficiency. The purpose of the experiment was to examine phosphorus and nitrogen removal capacity of urban sewage by the HITNP system. Results of long term operation of HITNP working with low TKN/COD ratio domestic wastewater show effective phosphorus and nitrogen removal efficiency because it maximizes the utilization of organic substrate for phosphorus and nitrogen removal by simultaneous anoxic phosphorus uptake and denitrification. The removal efficiency and effluent concentration of TP, NH+4-N, TN and COD are 91.1%, 88.7%, 58.1%, 88.6% and 0.27 mg/L, 1.74 mg/L, 17.30 mg/L and 24.38 mg/L in average, respectively. |
