| A two-SBR is a novel Simultaneous phosphorus and nitrogen removal system which combined an anaerobic/anoxic sequencing batch reactor (A2-SBR) and a nitrification SBR (O-SBR) together. With the metabolizing characters of denitrifying phosphorus removing bacteria (DPB) and nitrobacteria, the reactor was operated by the different ratios of initial COD, nitrogen and phosphorus (COD/N/P). The indexes of removing efficiencies of COD, nitrogen and phosphorus were conducted during the progress. The pH in the system was maintained at between 7 and 8 by use of the pH meter. And the temperature of range for the system was about 20-25℃. The MLSS was controlled between 1800-2100mg/L. During the whole studying the exchange volume ratio of the two SBR was stabilized 65%, the following conclusions were shown:(1) After the end of the anaerobic/ aerobic step of the start-up process, it was estimated that about 40.8% of PAO playing the role on denitrifying phosphorus removal. After anaerobic/anoxic/aerobic step, the 100% PAO in the reactor had the ability just as DPB.(2) There were three ranges for the DPB release the phosphorus, linearity part, approximate linearity part and horizontal part. The linearity part was the key phase that the DPB release of intercellular poly-P accompanied by taking up the soluble carbon scource. The linearity part was changed with the different influence COD. when COD concentration was 250mg/L, 300mg/L or 350mg/L, the linearity part was changed from 20～30min to 50～60min, respectively. Sometime it could extended to the whole anaerobic phase about 100min.(3) Based on changing of the ratio of COD/N/P, the DPB in the anaerobic phase had the basic ability about 8～9mgP/gMLSS for release of phosphorus. The value was far lower than the release of phosphorus by the PAO stored the carbon source in the form of PHB. The decreased of the influence phosphorus concentration, there was the decreasing of net release of phosphorus in the anaerobic phase and the MLSS also decreased. But for a short-term of low phosphorus concentration in wastewater, it had no impact on the denitrifying phosphorus removal in the anoxic phase.(4) When the DPB take up the acetate as the carbon source, the system had the performance of releasing phosphorus about 0.09-0.11mgP/mgCOD. And the ratio of the phosphate uptake and release was 1.2～1.6mgP/mgP, the maximum value was 1.85mgP/mgP. The denitrifying phosphorus removal capability of DPB in the anoxic phase was lower than the PAO's in the aerobic phase.(5) Comparing the influence COD300mg/L and 350mg/L to 250mg/L, the system achieved a stabilized performance for the ammonia nitrogen removal rate about 75%. There is no clear relationship between ammonia nitrogen removal rate and the ratio of COD and nitrogen. But when the influence of COD kept at a constant value, higher ratio of COD and nitrogen could acquire good removal efficiency and consequent lower nitrate and nitrite concentration in the effluents, nearly to 100%..(6) The reactor could achieve the stabilized performance for the phosphorus removal with deferent operated conditions.When the initial COD concentration was 250mg/L, the ratio of COD and nitrogen was between 3.5 and 5, and the ratio of COD and phosphorus was between 20.8 and 100, the condition of ratio COD and nitrogen was 3.5 took the higher phosphorus removal efficiency ,from 95.7% to 99.1%;When the initial COD concentration was 300mg/L, the ratio of COD and nitrogen was between 3.5 and 6 and the ratio of COD and phosphorus was between 21.4 and 100, the condition of ratio COD and nitrogen was 4.5 took the higher phosphorus removal efficiency ,from 97.4% to 98.9%;When the initial COD concentration was 350mg/L, the ratio of COD and nitrogen was between 3.5 and 6.5, and the ratio of COD and phosphorus was between 38.9 and 100, the condition of ratio COD and nitrogen was 4.4 took the higher phosphorus removal efficiency ,from 94.3% to 96.7%;The novel two-SBR system had the higher performance for phosphorus removal, the average removal efficiency was much more than 90%.
|
PDF Full Text Request