On the relation between EPS phosphorus-adsorbing tendency and the bio-phosphorus removal

This paper takes it as its goal to introduce its study results on the relation between EPS phosphorus-adsorbing trend and the bio-phosphorus removal.For this purpose,we have first of all to make clear the role the extra-cellular polymeric substances(EPS) are playing in the biological phosphorus removing process.And that is why we have conducted a simulated research of the urban sewage,trying to monitor the phosphorus removal effect of the anaerobic/aerobic(A/O) alternating SBR biological phosphorus removing system under the different sludge retention periods(SRP).In doing so,we have collected sufficient qualified activated sludge samples,observed and counted all the necessary phosphorus content in the unit mass sample,the EPS adsorbed phosphorus content and the phosphorus-accumulating bacteria(PAO) adsorbed phosphorus content.The results of our study show that,when the SRP is shorter than 48 days,the A/O-SBR biological phosphorus removing system is expected to achieve good removal effect.However,when the effluent total phosphorus concentrations are kept continuously less than 0.5 mg/L,it is expected to reach the optimal standard of the urban sewage treatment and ideal emission.In such a situation,the EPS adsorbed phosphorus content can store a certain amount of phosphorus,no more than 10 mgP/gVSS per gram of the activated sludge EPS adsorbed phosphorus content.And,if there is no change taking place with the EPS adsorbed phosphorus content,there will be 38 mgP/gVSS with per gram of activated sludge of cells of phosphorus content until the sludge retention time changes.However,when the SRT goes on till 12 to 48 days,the EPS adsorbed phosphorus content would be going up to 10 mgP/gVSS,which may lead to intra-cellular phosphorus content change,too.During this period,the intra-cellular phosphorus content would change to 20-38 mgP/gVSS.In addition,the intra-cellular phosphorus content would always remain greater than the EPS adsorbed content,thus keeping the phosphate mainly inside the cells themselves in the A/O-SBR phosphorus removal system.Besides,the EPS adsorbed phosphorus content can not always remain at the level of 10 mgP/gVSS in single cycle,rather,it can change in wavelike form and then goes up even as high as to 20 mgP/gVSS.Luckily enough,such fluctuations can help to adjust the extra-cellular phosphorus concentration and promote PAO to resist the high phosphate load.Nevertheless,at the end of the reaction,the EPS adsorbed phosphorus content can also return to its starting level,therefore,in biological phosphorus removal process EPS mainly plays a buffer role,acting as the transfer media in the process of synthesizing the intra-cellular poly-phosphorus.