Research On The Advanced Treatment To Remove Phosphorus In Municipal Sewage By Multistage A/O Process And Modified Diatomite

Using modified diatomite for municipal sewage advanced treatment is a new technology,possess high removal efficiency,low running cost,small project investment,and other features.But it is still in the stage of exploration both theoretically and practically,and the study is fewer in the advanced treatment,thereby the application of the technology is yet to be supported by further study on technique principle and optimization of process parameters.The effect of the conventional iron and aluminum to remove phosphrous is only the coagulation,and produce a lot of difficult processing of chemical sludge;however,using the modified diatomite to remove phosphrous is the common-effect of neutralization,flocculation,physical adsorption and precipitation reaction,after the desorption and regeneration,the diatomite sludge is possible to achieve resource recycling.Based on the above-mentioned facts,in this paper the modified method of diatomite and its influential factors were researched,aeration rate and C/N ratios were considered to investigate the effect on property of phosphorus removal in the multistage A/O process,study of the optimum operation conditions to treatment the effluent of the multistage A/O process by mechanical clarifier was carried out to find a approach to improve the phosphorus removal efficiency,in order to provide a reference for advanced treatment of tail water or treating low concentration phosphorus in sewage.The main contents are as follows:First,when the dosage was 500mg/L,the phosphorus removal efficiency of diatomite was only about 6%,the treatment efficiency was not ideal;the phosphorus removal performance was the best when the mixture ratio of PAC?ferric chloride and diatomite was 25:5:70;the treatment rate of the modified product by surface structure method was increased by 28%than which by compound method.The static beaker test showed that when modified diatomite was used to remove phosphorus from sewage,the optimal dosage was 500 mg/L,the best pH value was 6 to 7,the optimum temperature was about 25?,the best mixed reaction time was 15min,and the best settling time was 30min,in this case,the removal efficiency of modified diatomite for phosphorus was about 76%.Second,organic compound and total phosphorus removal had little difference under different aeration rates in multistage A/O process,but ammonia nitrogen removal efficiency was improved,and biological phosphorus removal efficiency was decreased as the aeration rate was increased.The COD and ammonia nitrogen removal rates were both ideal under different C/N ratios,but the C/N ratio had a tremendous bearing on total nitrogen and total phosphorus,the removal efficiency of which were improved as the C/N ratio was increased,the C/N ratio increased from 3 to 8,correspondingly,total phosphorus removal rate increased from 30%to 72%.Third,using the mechanical stirring clarifier to advanced treatment of the tail water,the results showed that the optimal dosage was 500 mg/L,the best influent flow was 30 L/h,and the optimum mechanical stirring speed was 12r/min,in this case,the average removal efficiencies for total phosphorus,COD and ammonia nitrogen were 79.06%,49.11%and 37.29%respectively,the total phosphrous in the effluent was less than 0.5mg/L,reached the emission standard of A,COD and ammonia nitrogen had been further removal.Moreover,analysis of the different mechanism of action of modified diatomite suspension when it was used to remove pollutants,this method was feasible in the technology.