The Effect Of Different Waterintake VFAs On The Proportion And Diversity Of The Phosphorus In The Convent Ional/Inverted A~2/O System

In the past decades,water environment pollution in China has intensified,water pollution and eutrophication have become the restrict factor to the economic and social development, and the effective sewage treatment is the basic way to solve this problem.In the conventional process of biological nitrogen and phosphorus removal,sludge recirculation in the anaerobic,anoxic andaerobic period.The sludge is consist of nitrifying bacteria,denitrifying bacteria,phosphorus bacteria and other organisms, different bacteria has various best growth environment,so there is a contradiction between nitrogen and phosphorus removal.After worked a lot about conventional and inversion A2/O process of anaerobic andanoxic environment,according to the analysis of experimental phenomena and biological removal of nitrogen and phosphorus in the rule, first proposed the inverted A2/O process. Inverted A2/O process positioned anoxic zone at the first of the whole process, And abort of nitrification liquid reflux in the conventional A2/O process,correspondingly increase sludge reflux ratio at the same time.Through a large number of researcheson the productive experiment,itproved that the inverted A2/O process can Significantly enhanced the ability of removing nitrogen and phosphorus.Volatile fatty acid produced by fermentation, its the main intermediate product of anaerobic digestion process, the formation of methane process is inseparable from the VFA formation, but the accumulation of VFA in anaerobic reactor can reflect the methane bacteria of the inactive state or reactor operating conditions deteriorate,higher VFA(such as acetic acid)concentration of methane bacteria have inhibitory effect.So in the reactor operation, effluent VFA is used as the important control index. This thesis aims to explore the different removal of phosphorus between the conventional A2/O process and inverted A2/O process with the molecular biology technologies on the basis of the macro research, reveals the microscopic theory of phosphorus removal process between the two technologies under different influent VFAs ratio conditions,to provide the theoretical guidance for nitrogen and phosphorus removal process of urban wastewater treatment.Research shows that:1.while the VFAs/CODCr is 30%, conventional system of phosphate removal rate, phosphorus accumulating bacteria proportion, enzyme cutting type, coverage, species richness were 78.88% and 20.36%, 6, 87.5% and 1.29; inverted system corresponding index were 74.44%, 7.93%, 7, 85.4% and 1.55.The diversity index of 30% condition of inverted system is better than that in the conventional process,we can analyse it from the angle of molecular biology that the proportion of phosphorus accumulating bacteria and diversity are all affecting the phosphorus removal process. Under the 30% VFAs/CODCr condition,the diversity affects smaller than the proportion of phosphorus accumulating bacteria. Therefore, the phosphorus removal effect of the inverted system is worse than the conventional system. 2.while the VFAs/CODCr is 60%, conventional system of phosphate removal rate, phosphorus accumulating bacteria proportion, enzyme cutting type, coverage, species richness were 97.62% and 36.34%, 4, 97.9% and 0.77; inverted system corresponding index were 98.04%, 10.09%, 4, 97.9% and 0.77.We can see it from the perspective of molecular biology, the phosphorus removal effect of phosphorus accumulating bacteria activity also affect the process, the two systems has the same effects of diversity on phosphorus removal efficiency.The effects of bacteria activity is higher than the proportion of phosphorus accumulating bacteria.Therefore, the phosphorus removal effect of the inverted condition is better than the conventional.3.while the VFAs/CODCr is 100%, conventional system of phosphate removal rate, phosphorus accumulating bacteria proportion, enzyme cutting type, coverage, species richness were 95.73% and 19.32%, 4, 100% and 0.77; inverted system corresponding index were 98.44%, 15.65%, 6, 97.9% and 1.55.We can analyse it from the angle of molecular biology that the proportion of phosphorus accumulating bacteria and diversity are all affecting the phosphorus removal process. Under thiscondition,the diversity effect is bigger thanthe proportion of phosphorus accumulating bacteria.Therefore, the phosphorus removal effect of the inverted system is better than the conventional system.