SRT对A2/O-MBBR工艺中聚磷菌特性的影响

采用强化生物除磷系统(A~2/O-MBBR)联合工艺,在不同污泥龄(SRT)(20 d、15 d、10 d、6 d、3 d)的条件下,考察A~2/O系统各区聚磷菌生化代谢特性的变化。结果表明,A~2/O-MBBR联合工艺采用双泥系统,分相培养了硝化菌和聚磷菌,该系统的微环境有利于自养型硝化菌的生长和积累,硝化反应已不是A~2/O-MBBR联合工艺运行的限制因素,SRT缩短对系统中总氮(TN)、化学需氧量(COD)去除效果影响不大,可溶性正磷酸盐(SOP)去除率随SRT缩短而逐步上升,SRT为3 d时去除率最大为94%。聚-β-羟基丁酸(PHB)是聚磷菌(PAOs)去除污染物所需碳源和能量的中转站,在胞内聚合物与能量转化过程中起重要作用,不同SRT下胞内聚合物的代谢含量与释磷、吸磷含量有密切关系,代谢量越多,释磷、吸磷量越多。SRT为6 d时,厌氧段聚磷菌具有最佳的释磷性能,形成了具有显著释磷作用的菌种。缺氧区胞内聚合物代谢规律与好氧区相似,对于反硝化聚磷菌来说,在SRT为10 d时对PHB的利用率最高,代谢活性最好;而对于传统聚磷菌来说,在SRT为6 d时其代谢性能最佳,且聚磷菌占全菌比例最大。短泥龄条件有利于提高胞内聚合物的单位污泥质量分数、驯化出积累PHB质量分数较高的微生物种群,其中SRT为6 d时各胞内聚合物含量最高,A~2/O-MBBR联合工艺的处理效果最佳。

On the effect of sludge age on the behaviors of phosphorus accumulating organisms in processing A2/O-MBBR

The paper is oriented to a study of the effects of sludge age on the behaviors or performance of the phosphorus accumulating organisms in processing A2/O-MBBR by using a combined reactor in the stable phosphorus removal system,in which various phosphate accumulating organisms (PAOs) can be measured and tested for their biochemical metabolic features under five different sludge retention time (SRT) lengths,such as 20 d,15 d,10 d,6 d,3 d,respectively.The results have shown that it is possible to cultivate the nitrobacteria and PAOs in A2/O-MBBR combined reactor in the two sludge systems,respectively,which tends to be conducive to the growth and accumulation of the autotrophic nitrifying bacteria with nitrification instead of being a constraining factor,for the decrease of SRT proves to have little effect on the removal of the total nitrogen and chemical oxygen demand.Rather,it can help to promote the removal efficiency of the soluble orthophosphate (SOP) by its peak rate of 94％ at SRT =3 d.However,since polyhydroxybutyrate (PHB) is a kind of intracellular carbon and energy storage compounds of microbes,they may have an important function in transforming the intracellular energy and compounds of SRT.On the other hand,since the metabolic products resulted from the intracellular polymeric substance are closely-related to the sorption/desorption of phosphorus,it would be possible to release and absorb more phosphorus due to the intracellular metabolism of more polymers on the condition when the sludge retention time can be extended to 6d.Thus,PAOs of anaerobic proves to be the best or most powerful phosphorus releaser,and the strain can have a great function in the phase of phosphorus release and the metabolic regularity of the intracellular polymer structure in the anoxic zone tends to be much similar in the aerobic zone.Therefore,if the sludge retention time can be made extended,the intracellular PHB content can also be increased and then enhance its phosphorus absorption power by stimulating the phosphorus accumulating organisms.To denitrify the phosphate-accumulating organisms (DNPAOs),the metabolic activities would come to produce its best effects on the 10d with the PHB utilization rate turning to its highest rate.However,the greatest microbial population of PAOs would come and behave best when the SRT has been cultured by 6 d whereas lack of enough long SRT would conduce to increase the mass fraction of intracellular polymer per unit sludge and acclimate more microbial population containing higher mass fraction of PHB,especially when the SRT comes on the 6d,when the intracellular polymers can increase their releasing rate to maximum and the process of A2/O-MBBR has the best treatment effect.