| The waste water treatment technology with immobilized microorganismis a new technique developed within these years, which can not only be usedto dispose the wastewater with heavy metal, poisonous organic wastewater aswell as the wastewater with phosphorus, but also be applied to removeammonia. Treating wastewater by using immobilized microorganismtechnology is of special advantage and comprehensive benefit, which hasbecome the highlight in wastewater treatment study.Based on the latest research findings on immobilized microorganismtechnology in both domestic and abroad, nitrifying sludge and denitrifyingsludge have been cultivated by using normal activated sludge as inoculatingsludge. After successfully cultivating them, we studied the using ofimmobilized microorganisms technology in treating waste water.In this paper, the enriched or cultivated activated sludge, nitrifying anddenitrifying sludge were immobilized in pellets mixed all together with themethods of freezing-thawing and mixed embedding, in which polyvinylalcohol (PVA) and sodium alginate was two kinds of carrier. Fluid bed as thereactor was performed continuously. Every method has its predominance todifferent kinds of wastewater. The intensity of pellets and the feasibility ofsingle-stage simultaneous nitrifying and denitrifying bio-denitrification onaerobic condition were researched. The effect on single-stagebio-denitrification of pH value, temperature, dissolved oxygen (DO), hydraulicretention time (HRT) and gas flow was studied,and the same with respectiverules.The result shows that single-stage bio-denitrification was realized mainlybecause through the immobilization there has been a micro aerobicenvironment formed in the carriers under which nitrifying and denitrifyingprocess can be achieved easily. The mixture of nitrifying with denitrifyingsludge has smart cooperatives in that the efficiency of bio-denitrification ofthis experiment is superior to that of conventional single-stagebio-denitrification.Through the medium of compare the effect of using the method ofimmobilization with the polyvinyl alcohol by freezing and thawing, themethod of immobilization with sodium alginate, the method of immobilizationwith the polyvinyl alcohol and sodium alginate by freezing and thawing indisposing different kinds of waste water, we got some conclusions as follows:The pellets, which were made by using the method of immobilization with thepolyvinyl alcohol by freezing and thawing four times, had great mechanicalstrength and aeration endurance but had little mass transfer. Using the pelletswhich immobilized activated sludge and nitrifying sludge by this method intreating waster water, we got the optimum pH value, temperature and HRTwere 8 , 25℃, 5h respectively. When the reaction time is 19 day, the removeratio of COD and NH3-N got optimum. The remove ratio of COD is 80.1%and the value of COD is 54.7 mg/L, which of COD is 54.7% and the value ofNH3-N is 12.3mg/L.The pellets, which were made by using the method of immobilizationwith the sodium alginate by immersing in CaCl2 solution, had litter mechanicalstrength and resistance to shock. The pellets will rupture on the occasions ofhigh load and high temperature. Using the pellets which immobilized activatedsludge and nitrifying sludge by this method in treating waster water, we gotthe optimum pH value, temperature and HRT were 8, 25℃, 5h respectively.When the reaction time is 19 day, the remove ratio of COD and NH3-N gotoptimum. The remove ratio of COD is 86.3% and the value of COD is 61.5mg/L, which of COD is 39.5 % and the value of NH3-N is 10.9mg/L.The pellets, which were made by using the method of immobilizationwith the polyvinyl alcohol and sodium alginate mixed active carbon powderby freezing and thawing, had the optimum cytoactive, mechanical strength,mass transfer. The method can solve problem of the inconsonant mechanicalstrength with mass transfer. Using the pellets which immobilized activatedsludge and nitrifying sludge by this method in treating waster water whichcontain ammonia nitrogen, we got the optimum pH value, temperature, DOand HRT were 8 , 30℃, 3mg/L,10h respectively. When the reaction time is 33day, the remove ratio of NH4-N, NO2-N, NO3-N and TIN got optimum, thevalue was 10.1mg/L, 58.2mg/L,0mg/L,68.3mg/L respectively.By using those three methods in treating waste waster for more than 40days, it shows that the method had higher operation stability. The cytoactive ofpellets didn't decrease after running over 40 days, and the pellets didn't swellup or deform. Hence these bioreactors would possess good application future.
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