The Experimental Study Of Removing Nitrogen And Phosphorus Of 7-tank MSBR Technique

7-tank Modified Sequencing Batch Reactor( MSBR) is a new waste water treatment technique with the ability of removing phosphorus and nitrogen . Its denitrifying function is arranged on the end of the technique flow , where the carbon source is insufficient for denitrifying bacteria to denitrify resulting in the low removal rate of nitrogen of 7-tank MSBR system. There are two ways to solve this problem now, one is to supply part of original waste water to denitrifying phase at the cost of deceasing the removal rate of phosphorus; the other is to add the additional carbon source in denitrifying phase directly, which will need more carbon source . However,based on the theory of denitrifying dephosphatation , the way of utilizing the process of denitrifying dephosphatation to solve the post-denitrifying problem has been put forword in this paper. After comparing and analyzing the influence factors and environment of denitrifying dephosphatation technique , it was found that the technique environment of 7-tank MSBR was also suitable for the growth of denitrifying phosphorus removal bacteria , therefore, the theory of denitrifying dephosphatation was applied into MSBR technique, and the function of denitrifying dephosphatation in 7-tank MSBR was studied.First of all ,the experiment system of 7–tank MSBR was established ,then the mechanism and effect of removing nitrogen and phosphorus of 7-tank MSBR was studied. from the result of this experiment, it was shown that the removal rate of CODcr, NH₄⁺-N,TP of 7-tank MSBR with addition of external carbon source could reach 90.3%,78.6%,81.5% separately, comparing with 6-tank MSBR technique which part of original waste water was suppled to denitrifying phase, the rate of removing phosphorus of 7-tank MSBR was improved by 11%, and the rate of removing NH₄⁺-N was improved by 5.3%. Therefore , it was obvious that the effect of removing phosphorus and NH₄⁺-N of 7-tank MSBR was better than 6 tank MSBR's .Sequentely , the way of modifying the flow was applied to realize the process of denitrifying dephosphatation in 7-tank MSBR technique; the effect of removing phosphorus and nitrogen were also studied and discussed in this experiment . From the result, it was shown that , in the modified 7 tank MSBR without addition of external carbon source, the removal rate of CODcr could reached 87% , the removal rate of TP could reached 75.4%, and the removal rate of NH₄⁺-N was 66%. Comparing with 6 tank without separating the original waste water to denitrifying phase, it is almost same for their removal rate of phosphorus , however ,the rate of removing NH4+-N of 7-tank MSBR technique was higher at 6.1% than that of 6-tank MSBR technique.The result of experiment indicated that it was feasible to utilize the theory of denitrifying dephosphatation for solving partly the problem of insufficient carbon source in post- denitrifying of 7-tank MSBR technique .