Research On Nitrogen Removal And Phosphorus Recovery By The Processes Of Activated Sludge Recycle-Hybrid Submerged Membrane Bioreactor

The nitrogen and phosphorus in wastewater without effective treatment causes water eutrophication, then it brings huge economic losses. Membrane Bioreactor is gradually used in wastewater treatment for its good performance and excellent effluent, however it exists in the low efficiency of phosphorus removal. This paper proposes a new kind of HMBR, by adding bio-filler to improved nitrogen removal, meanwhile through the processes of activated sludge recycle and anaerobic release phosphorus, it can improve the process phosphorus performance and phosphorus recycling.In the laboratory, the optimal HRT is 4h and optimal DO value ranges from 0.8 to 1.5mg/L, for the aim of the removal of TN. Through the static test, the optimal time of anaerobic release phosphorus is 2.0 h and the optimal dosing quantity of acetic acid sodium to solution is 356mg/L of COD concentration. Because of the recycle of activated sludge, the removal efficiency of TP by ASR-HSMBR significantly higher than HSMBR process. In the effluent, TP concentration is about lmg/L, and the removal efficiency is above 80%, it can solve the disadvantages of MBR. Using artificial phosphorus wastewater, the study focuses on the influence of the pH value, material ratio, initial phosphorus concentration and calcium ion concentration to phosphorus recycling. In the conclusion:the optimal pH is 8.5～9.0 between 9.0; Mg:N:P ratio is 2:2:1; Meanwhile the study find that the higher the concentration of initial phosphorus, the more conducive to recovery. The high concentration of calcium ion goes against the generatation of struvite.In the pilot test, the average removal efficiencies of COD and NH4+-N are 95.3% and 90.1%,respectively. At the beginning, the average of TN removal is only 20%. the efficiency of denitrification increase through the increase of bio-filler, during later stage the TN concentrations in effluent is about 10mg/L, TN removal efficiencies up to 80%.And the TP removal efficiency is about 80% in the initial, but it drop to 65%.The optimal time of anaerobic release phosphorus is 3.0 h, and the optimal cycle is 3d.After the recycle of activated sludge processes, the removal efficiency is up to 90.2%.Meanwhile it does not affect the organic and nitrogen removal, on the contrary, the removing efficiency of TN increases in HSMBR. After anaerobic phosphorus release, using chemical precipitation method to phosphorus recovery, in the supernatant the phosphate concentration is 1.29 mg/L, the average removal efficiency is 89.79%.