Experiment Study On Waste Water Treatment By The Anaerobic/Aerobic/Anoxic SBR Process

With the social population growth, economic development, urbanization, industrialization trend intensifies the water pollution phenomenon has been more and more serious, which has become an urgent problem to be solved. Eutrophication has threatened the ecological balance of lakes and rivers seriously. A/O/A mode SBR process as a relatively new treatment method has become a research hotspot at home and abroad, because it solved the competition between denitrifying bacteria and PAOs on carbon, which made the nitrogen and phosphorus can simultaneously achieve good results.Sequencing batch reactor is used for this study, and it achieved domestic sewage treatment through the mode of anaerobic-aerobic-anoxic. Artificial water distribution was been as the experimental water. It respectively researched the sludge age, temperature, aeration rate and the shock load of ammonia nitrogen on the treatment effect of the system, when the water quality concentration maintained COD400mg/L, NH4+-N40mg/L, (it changed when study the effect of NH/-N load on the system)PO43--P5mg/L. The experimental results show that:(1) When the water quality concentration maintained COD400mg/L, NH4+-N40mg/L, PO43--P5mg/L, system processing effect is the best, under the conditions that reaction temperature was 25 ℃, sludge age 25d, aeration rate 64L/h. After a period of continuous operation, the COD、NH4+-N、PO43--P、TN and TP removal rate can reached 92.9%.90.8%、98%、82.9% and 97.8%. The system of sewage treatment can reach 《the town sewage treatment plant pollutant discharge standard》GB18918-2002 grade A standard.(2) Ammonia nitrogen impact load had a great influence on the stable operation of the system. Increasing the concentration of NH4+-N has adverse effects on COD and NH4+-N removal, but the export of NO3-N and NO2--N concentrations were increased with the increase of concentration of NH4+-N decreased. Phosphate removal was not be affected.(3) The system was be maintained in the best condition, namely the biological solids retention time was 25d; temperature was 25 and the oxygen was 64L/h; the imported ammonia nitrogen concentration was 40mg/L. In the best condition and stable operation, the reactor on the substrate processing effect was good. pH and ORP were measured by tracking, which returned that the SBR system of A/O/A mode can be controlled through the real-time test of the pH、ORP.(4) It measured the change of various substrates at the anoxic period and returned that the phenomenon of denitrifying phosphorus removal in test. And it studied the effects of conditions on the denitrifying phosphorus removal. The results show that the sludge age too long or too short were both not conducive to the phenomenon of denitrifying phosphorus removal. There is an obvious phenomenon of denitrifying phosphorus removal when the biological solids retention time 20d or 25 d, and the denitrifying phosphorus removal rates accounted for 7.5%、7.93%of the total phosphorus respectively. When temperature is 20℃ or less there is no phenomenon of denitrifying phosphorus removal in the system. When the temperature were 25℃、30℃, there were both certain denitrifying phosphorus removal. It was evident when 25℃, and the denitrifying phosphorus removal rate accounted for 7.58% of the total phosphorus removal. This result showed that denitrifying phosphorus removal has no special requirements on temperature. The general room temperature 25℃-30℃ could be meet. When the aeration rate is 32L/h denitrifying phosphorus removal phenomenon did not happen. While when it increased to 64L/h、48L/h and 80L/h, there were both appeared denitrifying phosphorus removal phenomenon. And the denitrifying phosphorus removal rate accounted for 8.05%、9.9% and 7.1% of the total phosphorus removal respectively. The denitrifying phosphorus removal effect was the best when the aeration rate was 64L/h.(5) Through dynamic analysis, using Monod equation model to describe the degradation of organic matter in aerobic phase reaction, the curve fitting effect was good. It obtained the Kinetic parameters that saturation constant Ks was 166.93 mg/L and the most of the organic matter degradation rate was 0.42d-1.