High Efficiency Biological Phosphorus Removal Technology Based On Biological Absorption

With the increasing management pressure of environmental quality assessment targets,the upgrading of urban sewage treatment plants has become a normal situation,and even more stringent local discharge standards have been introduced in water environment sensitive areas.In order to realize the standard discharge of TP in sewage plant,it is of great significance to study the ultra-high standard phosphorus removal technology.At present,enhanced chemical phosphorus removal and high efficiency precipitation separation at the end of wastewater treatment process are more common methods of TP standard extraction.According to the principles of chemical thermodynamics and kinetics,terminal chemical phosphorus removal is not an optimal solution either in terms of agent utilization efficiency or precipitation rate.According to the theory of biological phosphorus removal,the efficiency of phosphorus removal is affected by the"linkage relationship"of organic matter concentration,yield coefficient and excess sludge discharge,especially in the case of low organic matter concentration,the traditional biological phosphorus removal technology is difficult to achieve the standard discharge.Based on the analysis of the law of anaerobic/aerobic phosphorus release/absorption of phosphorus accumulating bacteria,combined with the technology of side flow phosphorus removal,it is considered that the behavior of discharging phosphorus rich wastewater in anaerobic stage can break the material balance of phosphorus release/absorption of phosphorus accumulating bacteria,and produce phosphorus accumulating bacteria in the state of"phosphorus starvation"in aerobic stage,so as to improve the ability of aerobic active phosphorus absorption of phosphorus accumulating bacteria,can form a balance state of aerobic excess phosphorus absorption with lower phosphorus concentration,and support the ultra-high standard biological phosphorus removal technology based on biological active absorption.Based on this assumption,the author focuses on the aerobic and active phosphorus uptake ability of phosphorus accumulating bacteria in the state of"phosphorus starvation",studies the cultivation of phosphorus rich sludge,anaerobic phosphorus release and aerobic phosphorus uptake characteristics of phosphorus rich sludge,constructs an ultra-high standard biological phosphorus removal technology based on biological active absorption,and further studies the phosphorus removal effect and microbial characteristics of the system.The results are as follows:（1）The experimental sludge was intensively cultured with a sequence batch method with 10.82-17.78mg/L phosphorus concentration.After 21 days of culture,the phosphorus content in the experimental sludge gradually increased from 2.4%to 7.1%.The anaerobic phosphorus release was carried out by adding HAC-COD carbon source to the cultured phosphorus rich sludge.The phosphorus accumulating bacteria in the state of"phosphorus starvation"was formed by discharging part of the phosphorus rich sewage.The aerobic active phosphorus absorption process and phosphorus concentration at the equilibrium point of phosphorus absorption were studied,It was found that the phosphate concentration was lower than the detection limit（<0.01mg/L）even in the minimum"phosphorus starvation"state（side flow ratio of 20%）,which laid a foundation for further study of ultra-high standard biological phosphorus removal technology based on biological active absorption.（2）The paper further studied the carbon source concentration effect on anaerobic phosphorus release process,and found that carbon source is the key to activate the effective phosphorus release potential of phosphorus accumulating bacteria,and COD=300 mg/L is the"boundary"of carbon source concentration.When COD<300 mg/L,the carbon source concentration is the limiting factor of anaerobic phosphorus release.At this time,the maximum phosphorus release amount and effective phosphorus release time are positively related to the carbon source concentration;When COD≥300mg/L,the carbon source concentration is the non limiting factor of anaerobic phosphorus release.The effective phosphorus release time and the maximum phosphorus release concentration basically do not change with the change of carbon source concentration.At this time,the effective phosphorus release time and the maximum phosphorus release concentration are determined by the characteristics of phosphorus rich sludge.The process of anaerobic phosphorus release can be divided into three stages:rapid phosphorus release,slow phosphorus release and stagnant phosphorus release.（3）The effects of carbon source concentration and anaerobic phosphorus release time on the process of aerobic phosphorus uptake were studied.When the carbon source concentration is the limiting factor,the phosphorus absorption capacity of anaerobic phosphorus release sludge is positively related to the carbon source concentration.When the carbon source concentration isn’t the limiting factor,the phosphorus absorption capacity of anaerobic phosphorus release sludge depends on its own characteristics,and the phosphorus absorption capacity of sludge is 25.75mgp/gmlss.The process of aerobic phosphorus absorption can be divided into two stages:rapid phosphorus absorption stage and slow phosphorus absorption stage.The rapid phosphorus absorption stage is the main contribution stage of phosphorus absorption.Most of the phosphorus in the solution is actively absorbed by phosphorus accumulating bacteria at this stage.The slow phosphorus absorption stage reaches the phosphorus absorption equilibrium point to ensure the ultra-low phosphorus concentration of the effluent.In order to fully stimulate the phosphorus absorption capacity of phosphorus accumulating bacteria and consider the consumption of carbon sources,the best conditions for the"anaerobic phosphorus release aerobic phosphorus absorption"of phosphorus accumulating bacteria were:COD300mg/L,phosphorus release time 90min,phosphorus absorption time 240min.（4）The experiment of biological phosphorus removal technology based on biological active absorption was carried out under the condition of"phosphorus starvation"with side flow ratio of 60%.The results showed that,in the stable operation stage,most of the time of effluent TP was lower than the detection limit（<0.01mg/L）,and the average removal rates of effluent TP,COD,NH₃-N and TN were 98.6%,99.0%,91.9%and 79.3%respectively.The test indexes meet the requirements of the first-class A standard of GB18918-2002.Among them,TP index can meet the strict requirements of Taihu Lake Basin,Beijing,Tianjin,Kunming and other local standards,which achieved ultra-high standard biological phosphorus removal based on biological active absorption.（5）After acclimation and cultivation of inoculated sludge,the community structure and species composition of microorganisms changed significantly,and the phosphorus accumulating microorganisms grew rapidly and became the dominant microflora.The main microflora of the five samples were Proteobacteria,Bacteroides,Chioroflex,Actinobacteria and Firmicutes.Proteobacteria was the dominant microflora of phosphorus rich activated sludge.The main microflora of the five samples were Actinobacteria,γ-Proteobacteria,Anaerolineae,α-Proteobacteria,Bacteroidia,Chlorofloxia,δ-Proteobacteria,among which Proteobacteria had a certain abundance in five samples and the highest abundance（47.3%）in phosphorus rich activated sludge,in which is the dominant microflora.At genus level,Pseudomonas is the dominant group of phosphorus rich activated sludge,with the highest abundance（20.7%）.