Study On A~2SBR Denitrifying Phosphorus Removal System

As the problem of eutrophication grows more gravely and the standard ofwastewater effluent is more strictly, the wastewater treatmeant process developedgradually from the period of pure COD removal to the period of simultaneousCOD, nitrogen and phosphorus removal. How to remove nutrient pollutioneconomically and effectively had become one of the hot topics in the field ofwastewater treatment. The conventional technology of nitrogen and phosphorusremoval based on traditional theory is consisted of two absolute processes. It ishard for both of them to get perfect result. The technology of denitrifyingphosphorus removal is remarkable in wastewater treatment field recently.Anaerobic/anoxic sequencing batch reactor fundamentally based on thetechnology of denitrifying phosphorus removal. Removal efficiency andinfluencing factors of the system was studied, and the dynamics models ofdenitrifying phosphorus removal inA2SBR process were established.The effects of two start-up methods on the removal effective of the systemwere checked. The systems reacted as anaerobic/discharging/anoxic/dischargingand anaerobic/anoxic/discharging. The system got enrichment of denitrifyingphosphorus removal bacterium rapidly with the first method, but the stability ofit was not as good as the system with the second method. Stably reacted systemremoved nutrient pollution efficiently. Nitrogen and phosphorus removalefficiencywas95.32% and 91.78% , respectively.The influencing factors including carbon source, electron acceptor,temperature, SRT affecting the removal efficiency of the system were studied.When the influent was in excessively high level of COD, remaining organicmatters inhibited removal phosphorus reaction in anoxic phase; in low level ofCOD, phosphorus releasing reaction was completed, the content of nitrate wassurplus and the effluent grew worse. When glucose was used as the carbonsource, the reaction of denitrifying and phosphorus removal was able to completeeffectively, but the content and the speed of phosphorus releasing were lower.When the concentration of nitrate was low in anoxic phase, phosphorus releasedagain in the system; when the concentration of nitrate was high, the remaining nitrate would inhibit the reaction of phosphorus releasing in the next cycle.Although compared with oxygen or nitrate, the speed of phosphorus removalwaslower when nitrite was electron acceptor, it didn't have obvious inhibition. Theremoval efficiency of COD, nitrate and phosphorus grew slow as the system inlow temperature. The solids retention time of denitrifying phosphorus removalsystem was longer than that of conventional biological phosphorus removalsystem, and it of 34 days was maintained for the system. So controlling all theseinfluencing factors appropriately is the key point of optimizing the SBRdenitrifying phosphorus removal process.This research established the optimum operating parameters and kineticequations of the system by inspecting the results and influencing factors ofdenitrifying phosphorus removal process. It provided the theoretical basis for theoptimization ofA2SBR process parameters, and further improved the denitrifyingphosphorus removal technologysystem.