Study On The Treatment Of Domestic Sewage By SBR Micro-Expansion Activated Sludge Process

Activated sludge method is one of the most commonly used methods in sewage treatment plants at home and abroad.However,this method has two drawbacks.One is that the sludge is liable to deteriorate and swell;the other is that the cost of the treatment process is slightly higher.The micro-expansion activated sludge method is a new method for sewage treatment.The theory of sludge micro-expansion was first proposed by Professor Peng Yongzhen,that is,by reducing the dissolved oxygen concentration of the activated sludge wastewater treatment system,the activated sludge can produce filamentous bacteria sludge.Swelling,controlling the degree of swelling will not cause sludge loss.The filamentous bacteria have the advantages of larger specific surface area and lower oxygen saturation constant than the fungal micelles to improve the quality of effluent water and save energy.Since it was proposed,it has been recognized and paid attention by many researchers,and has gradually become a research hotspot.However,due to the short time proposed for this theory,it is difficult to study.At present,there is no comprehensive and systematic report on the start and maintenance of sludge micro-expansion and the realization of the micro-expansion activated sludge method under low temperature conditions.In this paper,the SBR process?sequential batch activated sludge method?was used to study the start-up and maintenance conditions of the micro-expanded activated sludge method.The main operating parameters were operating mode,dissolved oxygen DO value?DO <0.5mg / L?,and sewage The sludge load Ns,temperature,etc.,and the system's nitrogen and phosphorus removal efficiency can be optimized as much as possible while successfully starting the sludge micro-expansion state,providing more theoretical support for the practical application of the sludge micro-expansion theory.In addition,microswelling methods such as dyeing and sulfur accumulation experimentsThe identification of the dominant bacteria in the sludge is of great significance to the further improvement of the sludge micro-expansion energy-saving theory.The research results show that:?1?In the whole aerobic mode,under normal temperature conditions,Ns and domesticated sludge remain unchanged at 0.4 kg COD /?kg MLSS · d?,and DO cannot be successfully started when DO is 0.5 mg / L In the swelling activated sludge method,the SVI is maintained at about 100,and when the DO is 0.3 mg / L,the Ns remains unchanged.The sludge will swell malignantly.Under the same conditions,the A / O mode is used.When the DO is 0.3 mg / L,the sludge deteriorates and swells for about 15 days,and the SVI slowly recovers to about 186,and the sludge micro-swelling state can be successfully started.?2?In the full aerobic mode With the synergistic effect of DO 0.3mg / L and Ns 0.3 kg COD /?kg MLSS · d?,after a short period of malignant expansion,the micro-expanded activated sludge method can be successfully started and maintained for 30 days;In the mode,low DO and low Ns can be used to achieve a micro-expansion state,but the effect of Ns changes is smaller than that in the full aerobic mode.?3?After the micro-expanded activated sludge process was successfully started,the removal effect of NH₄⁺-H and COD in both modes was good,but the removal of TN and PO43--P was better in A / O mode.By increasing the post-anaerobic section,it will become A / O / A mode,and prolong the aeration period of the aerobic section,which can greatly improve the removal rate of TN and PO43--P.Under the synergistic conditions of DO of 0.3mg / L and Ns of 0.3 kg COD /?kg MLSS · d?,the removal rates of TN and PO43--P were increased to about 90%,respectively.?4?In A / O operation mode,sludge expansion is not caused by low temperature or high temperature alone.Under low temperature conditions,the cooling rate affects the sludge expansion rate.The larger the cooling rate,the higher the expansion rate.At 7o C,the removal rates of COD,NH₄⁺-H,and TN all decrease significantly,and the removal rate of PO43--P increases.The duration of qi and the duration of hypoxia can increase the N removal rate.Under different low temperature conditions,when DO is 0.3mg / L,different Ns are required to cooperate with it to successfully start the micro-expanded activated sludge method.At extremely low temperature of 7 degrees,DO needs to increase by 0.5mg / L.And synergistic effect with 0.03 kg /?kg · d?Ns can successfully start the micro-expanded activated sludge method.