Anoxic/SBR Reaction System On Nitrogen And Phosphorus Removal

In the wastewater treatment system, nitrogen and phosphorus removal are generally in the same reaction. The conventional synchronous biological nitrogen and phosphorus removal process had defect, it can not be separated from nitrogen and phosphorus removal. Because of the nitrifying bacteria, denitrifying bacteria and Poly-phosphate Accumulating Organisms were in activated sludge systems at the same time. The sludge age of nitrifying bacteria and Poly-phosphate Accumulating Organisms were often in contradictory. Meanwhile, the products mutual inhibition and different strains compete with carbon cause interference between nitrogen and phosphorus removal. Therefore, the general nitrogen and phosphorus removal technology for wastewater treatment can make nitrogen met the standards, but phosphorus removal was difficult to met standards. The uptake and release of phosphorus were two interrelated processes in wastewater biological phosphorus removal process. Poly-phosphate Accumulating Organisms release phosphorus completely in anaerobic environment, it had the best uptake phosphorus in aerobic environment. Poly-phosphate Accumulating Organisms can absorb volatile fatty acids and synthesis polyβ-hydroxyl acid stored in the cell body. The more synthesis polyβ-hydroxyl acid in anaerobic conditions, and the more synthesis of ploy phosphorus in aerobic conditions, phosphorus removal was also better.The experiment connected anoxic reactor and SBR reactor by adding acetic acid in anoxic reactor. Study the optimal dosage of acetic acid and find out reaction condition of SBR reactor under the influence of acetic acid. Experiment results as follows:1. Acetic acid dosage had obviously affected phosphorus release in anoxic reaction. When the acetic acid dosage was less than 300 mg/L, TP increased as acetic acid dosage increased. TP increased 11.37% relative to no acetic acid used in wastewater. When the acetic acid dosage was more than 300 mg/L, TP increased with a small range in wastewater.2. Anaerobic time had obviously affected phosphorus release. When the time was less than 6 h, TP increased as anaerobic time increased. And the largest TP in wastewater was 63.29 mg/L. To continue extend the anaerobic time, TP increased with a small range in wastewater. Indicated the anaerobic time was 6 h, Poly-phosphate Accumulating Organisms had been fully completed release phosphorus. 3. The aeration time of SBR section had obviously effected on nitrogen and phosphorus removal. When the aeration time was less than 5 h, TN and TP removal rates increased with increasing aeration time. Continue to extend the aeration time, TN removal rate increased with a small range.4. The aeration rate of SBR had obviously effected on nitrogen and phosphorus removal. But the aeration rate oversized will lead to sludge breakdown and separate muddy water. At the end of, it can be to reduce nitrogen and phosphorus removal rate.5. MLSS of SBR had obviously effected on nitrogen and phosphorus removal. When the MLSS was less than 2 000 mg/L, TN and TP removal rate increased as MLSS increased. When MLSS was more than 2 000 mg/L, continued increase MLSS, TN removal with a small range. Before the reaction time was less than 4 h, TP removal rates were essentially the same, when the reaction time was more than 4 h, TP removal rates increased, but the maximum removal rate was 87.66%.6. Compared with a single SBR process, hypoxia/SBR system had hypoxia system in front of this process. It is can effective control the sludge age, and the phosphate accumulating bacteria and nitrifying bacteria were controlled in different reactor. It improved nitrogen and phosphorus removal rate.7. The experiment connected anoxic reactor and SBR reactor by adding acetic acid in anoxic reactor. Study the optimal dosage of acetic acid and find out reaction condition of SBR reactor under the influence of acetic acid. The results showed that in anoxic zone every 1mg phosphorus needed 6 mg acetic acid dosage its reaction time was 6 h. Aeration in the SBR response system time was 5h, Aeration capacity was 2.0 m3/L, MLSS were 2 000 mg/L and precipitation time was 60 min. The removal rates of TN and TP were 95.62% and 97.83%. Without the anoxic zone TN and TP removal rates were 92.29% and 85.99%. Therefore in the anoxic zone by adding acetic acid can effectively improve the efficiency of TN and TP removal.