Application Analysis Of Modified Bardenpho And Mbbr Combination Process In The Municipal Wastewater Treatment Plant

As the emissions standards of nitrogen and phosphorus in wastewater became more and more strict,many WWTP are facing the task of upgrading.The wastewater treatment plant in Hebei Province,initially used A/O Process,adopted the combination process of Modified Bardenpho and MBBR(Moving Bed Biofilm Reactor)after the upgrade project.The combination process was taken as the research object in this paper.The function and process parameters of different treatment unit of the WWTP combination process were introduced systematically.The actual operation effect of the wastewater treatment plant combination process was evaluated.The microbial population structure of the activated sludge in the pre-aerobic tank was analyzed by microscopic morphological identification,fluorescence in situ hybridization(FISH)and field emission scanning electron microscopy(FE-SEM).The average concentrations of effluent COD? NH4+-N and SS of effluent were 29.0,1.73 and 7.1 mg/L,respectively,which meet the standard A of urban wastewater treatment plant pollutant discharge standards.The effect of seasonal changes on the performance of combination process was not significant.The removal rates of COD,NH4+-N and SS were kept within a relatively stable range.The average concentration of TP effluent was 0.69mg/L,which couldn't meet the standard A of urban wastewater treatment plant pollutant discharge standards.The average removal rate of effluent TP were 84.8%.The results showed that the poor removal efficiency of TP in operation was mainly due to the large amount of phosphorus in the external reflux sludge mixture,which leads to the increase of the TP concentration in the biochemical reaction tank.The processing load of the biochemical reaction tank was increased.A large amount of nitrate enters the anaerobic tank through external reflux,weakening the phosphorus release reaction of phosphorus accumulating organisms(PAOs),thus affecting the effect of biological phosphorus removal.It is proposed to select reasonable process parameters to reduce the effect of external returned sludge on TP concentration.There was no phenomenon of sludge bulking.The settling performance of the activated sludge was still good.The filamentous bacteria population in activated sludge was dominated by Type 0092 and Type 0041.Microthrix parvicella is a secondary dominant filamentous bacteria.Fluorescence in situ hybridization(FISH)was used to analyze the population structure of the activated sludge microbes in the pre-aerobic tank.The percentage of PAOs in the pre-aerobic tank was 4.7%.The PAOs content in the pre-aerobic tank was lower than that reported by the denitrification and phosphorus removal process(7%-24%).Phosphorus absorption is mainly done in the pre-aerobic tank.The lack of PAOs may be the main cause of poor efficiency of biological phosphorus removal in wastewater treatment.Based on the monitoring and analysis of the operation of wastewater treatment plants,the conclusions can provide theoretical basis and guidance for upgrading the other similar wastewater treatment plants.