PAC-enhanced BAF For Removal Of Nitrogen And Phosphorus

This project is a tail water stabilization project of a wastewater treatment plant.The purpose is to carry out deep nitrogen and phosphorus removal treatment on the tail water of Grade B standard,so that COD,NH3-N,SS and other specifial indicators can be stabilized to level A standard of "Discharge standard of pollutants for municipal wastewater treatment plant"(GB18918-2002),and TN ≤ 8mg/L,TP ≤0.5mg/L.This study is based on the existing biological aeration filter nitrogen and phosphorus removal technology designed to a new water treatment process.It’s better treatment performance,more impact load,operation and maintenance costs lower,more environmentally friendly.In this paper,two kinds of pre-denitrification biological aerated filter were used to construct two groups of different filter material combinations:Expanded Polystyrene-Zeolite biological aeration filter(Z-E BAF)and Zeolite-Expanded Polystyrene biological aeration filter(E-Z BAF).Analyzing the start-up characteristic of the two kinds of combinations,and researching the running efficiency of different influencing factors.Then,the two groups were run under the optimum operating conditions respectively.In result,excellent filter material combination to provide theoretical guidance for practical engineering.Research indicates:Compared with Z-E BAF,E-Z BAF start-up faster,better biofilm activity,better thickness.Until the first 14 d of Z-E BAF continuous operation,the water quality has been relatively stable,the eye observation found that the filler attached to a layer of light yellow and transparent floc.Observed with a microscope,the biofilm thickness of filler is about 45μm and rich in microbial species in aerobic pool,which rotifer,paramecium and filamentous bacteria more,the start-up process has been basically completed.When the E-Z BAF continuous operation to the first 10 d,the water quality has been relatively stable,the observation found that the filler attached to a layer of light yellow and transparent floc.Observed with a microscope,the biofilm thickness of filler is about 60μm and rich in microbial species in aerobic pool,mainly cocci,bacilli and filamentous bacteria.there are a large number of rotifers,amoeba,paramecium,hypoxia.On the filter are mainly cocci and bacilli in Anoxia pond,which indicates that the biofilm growth of the E-Z BAF reactor is in good condition and the start-up process has been basically completed.The effects of three factors,such as hydraulic load,gas-water ratio and reflux ratio,were studied.The water temperature was between 22.0℃ and 30.0℃,the p H was 7.5~9.0,the anoxia pond oxygen content was 0~0.5mg/L,the oxygen pool oxygen content was 2~4mg/L,the optimum conditions for the removal of COD,NH3-N,TN and other pollutants were determined by orthogonal test.The best working conditions are as follows: Z-E BAF the best operating hydraulic load is 0.53m/h,the ratio of gas to water is 3: 1,the reflux ratio is 1.5:1;E-Z BAF the best operating hydraulic load is 0.795m/h,the ratio of gas to water is 3 : 1,the reflux ratio is 1.5: 1.In this study,PAC as a chemical phosphorus removal pharmacy,the dosage of 100mg/L,Z-E BAF and E-Z BAF after treatment of COD,NH3-N,SS and other indicators can be stable to achieve level A standard of "Discharge standard of pollutants for municipal wastewater treatment plant"(GB18918-2002)",and TN≤8mg / L,TP≤0.5 mg / L.Compared with Z-E BAF,E-Z BAF has better effect on the removal of COD,NH3-N,SS,TN,TP and other pollutants,and has stronger impact resistance.