Research On The Advanced Treatment To Remove Phosphorus With Bentonite And Diatomite Being Modified And Compounded

Phosphorus is an essential element in water for biological growth,but high phosphorus content can cause eutrophication.So it is vital to control the phosphorus content in water.It is a promising technology that utilizes the special structure of clay minerals to achieve in water phosphorus adsorption.It is in an exploratory stage that being applied in practical engineering,especially for advanced treatment,although it has a variety of advantages,like excellent performance of phosphorus removal,being simple to operate,low operational cost,plus the rich resources of the clay minerals.The further research needs to be continued to provide technical support for this method.This paper mainly focuses on the modified method of bentonite and diatomite,their influential factors.Their microstructures of modified and non-modified were researched through technology measures,like SEM,XRD.The optimum operation of mechanic stirring clarifier with the compound of bentonite and diatomite is explored which is used to treat the effluent form secondary sedimentation tank in the multistage A/O process.It can provide a reference for the treatment of low phosphorus concentration in wastewater or advanced treatment on the effluent form secondary sedimentation tank.The main conclusions in this paper are as follows:1.The efficiency of phosphorus removal that is only bout 8% is not ideal when the dosage of bentonite is 500mg/L.The removal effect of phosphorus is way better after the modification with 5% of hydrochloric acid and heating at 400? for 2h.A huge amount of static beaker tests show that the efficiency of phosphorus removal is about 50% when the dosage of modified bentonite is 500mg/L,the pH value is 6 to 7,the optimal temperature is about 25?,the mixed reaction time is 15 min and the settling time is 30 min.2.The efficiency of phosphorus removal that is only bout 6% is not ideal when the dosage of diatomite is 700mg/L.The removal effect of phosphorus is way better after the modification with 10%of hydrochloric acid and heating at 400? for 2h.A huge amount of static beaker tests show that the efficiency of phosphorus removal is about 48%when the dosage of modified diatomite is 700mg/L,the pH value is 6 to 7,the optimal temperature is about 25?,the mixed reaction time is 15 min and the settling time is 30 min.3.According to appropriate proportions,bentonite and diatomite is blended and modified.The results show that the efficiency of phosphorus removal is about 76% when the best conditions are acquired that the dosage of the compound is 500mg/L and the mass ratio of bentonite and diatomite is 60%:40%.The mechanic stirring clarifier with the compound of bentonite and diatomite is used to treat the effluent form secondary sedimentation tank in the multistage A/O process.The results show that the dosage is 500mg/L,the best optional agitation speed is 25r/min,the best hydraulic retention time is 2h.In the circumstances,the removal efficiency for total phosphorus reaches to 82%.The total phosphorus concentration is less than 0.5mg/L,up to the emission standard of A.4.Based on a huge amount of references and market researches,the technical economy analysis of advanced treatment on the effluent form secondary sedimentation tank with the compound of bentonite and diatomite is made.The conclusion suggests that it is feasible,both theoretically and economically.