Enhanced Nitrogen And Phosphorus Removal Technology Based On The Reducing Emission Of The Excess Sludge

The text investigated the enhanced nitrogen and phosphorus removal effect based onthe reduction of excess sludge by using combined process of “Anaerobic and anoxiapool+Aerobic pool+membrane bioreactor”, and the hybrid city sewage as researchobject. It studied the effect on A2O-MBR combined process by the various parametersof seasonal variation, the reflux ratio, A/O volume ratio, aeration, and analyzed thedifferences of remove effect between combination of technology and traditionaltechniques and sludge reduction.When the range of reaction pool temperature was9-25℃, the pH is6.5-8.0,anaerobic pool within the DO range of0.1-0.4mg L-1, aerobic pool within the DOrange of1.5-6.6mg L-1, the average removal rates of COD、BOD5in the systemwere96.8%,93.7%, respectively, the average removal rate of TN, NH3-N, TP were76.6%,93%,96.5%, respectively. All were better than “indicators of urban sewagetreatment plant pollutant discharge standard”(GB18918-2002) the level of Astandard.With seasonal changing, COD, TN, NH3-N treatment decreased significantly,but did not affect TP treatment effect, influence degree was TN> NH3-N> COD>TP; with the inner circulating reflux ratio increased, the average removal rate of TNincreased gradually, and the emergence of TP first increased and then decreased, andhad little effect on COD, NH3-N; It was considered that the system’s optimal refluxratio is2; under the three kinds of operating conditions of the volume ratio of0.58,0.68,0.78, when the effective volume ratio was0.78, the average COD removal ratewas the highest, with A/O effective volume ratio increasing, the removal rate of TN、TP also increased. When DO increased from1-2mg/L to5-6mg/L, the averageremoval rate of TN、TP had the same trend, increasing at first and then decreasing,when the DO was located in the2-3mg/L range, the average removal rate was thehighest. The removal effect of A2O-MBR combined process and the traditional A2Oprocess were compared and analyzed, the removal effect A2O-MBR combinedprocess was good and stable. A2O-MBR combination process had a significantadvantage, the removal rate of TP was greater than85%, TP removal rate oftraditional A20technology mainly concentrated in the interval of <80%and95%-100%, and removing effect was not stable.The average concentration of the anaerobic tank, anoxic, aerobic tank were11.08g L-1,7.1g L-1,5.8g L-1, respectively. When the system was running well,the sludge flocs zoogloea had structure compact, clear outline; the average sludgeyield was about0.24kg/kg COD, much lower than conventional sludge yield of0.60kg/kg COD, when the sludge age SRT=60d, removal and phosphorus removal effectwas stable, too large and too little amount of mud will affect the phosphorus removalsystem. In this test the water, sodium hypochlorite, sulfuric acid, citric acid cleaningof membrane, membrane flux can be recovered to the original98.2%.The combined process of A2O-MBR with sludge reduction, can also achieve theeffect of enhanced nitrogen and phosphorus removal. The residence time ofmembrane interception prolongs the nitrifying bacteria in membrane tank, namely thelonger sludge age, it can avoid the loss of nitrifying bacteria, improve the nitrification;retention function of membrane can gather a large number of PAOs, it improves theproportion of phosphorus accumulating bacteria in the activated sludge system, andavoid the negative effects of long SRT.