Study On Preparation Of A New Type Of Pumice Filler And Its Application In Water Treatment

At present,the biofilm method is one of the mainstream technologies in wastewater treatment,in which,the research and development of the filler has also been widely concerned.In this paper,a new kind of pumice filler was prepared by using waste glass as the raw material through sintering and modification.The structure and adsorption properties of the new type of pumice fillers were investigated.The operation conditions of the filler and the common polyethylene ball packing in the A/O process were compared and analyzed through laboratory reactors.The effect of nitrogen and phosphorus removal during the process of filming and operation,and the composition of microbial community in biofilm were discussed.The effects of different operating parameters on the performance of the packing in the reactor were researched.The study can provide a certain idea and basis for the application of filler in the water pollution control.The main conclusions are as follows:1.New pumice filler consists of 10 wt%of foaming agent,10 wt%of zeolite,77 wt%of waste glass,1wt%of fluxing agent and 2wt%of foam stabilizer.It is made by sintering,foaming,annealing and other processes.The main composition of the filler elements are O,Si,C,Mg,Na,Ca,Al,the surface is generally 4.2m2/g or more,the bulk density is 0.7g/cm3,the porosity is 55%-65%,the water absorption rate is about 50%,filler chemical stability is 99.5%or more.The filler has good adsorption effect on nitrogen and phosphorus,its adsorption is a complex adsorption process,which consists of physical adsorption,chemical adsorption,ion exchange adsorption and so on.It is affected by pH,initial concentration and temperature.2.By studying the operation of pumice filler and polyethylene ball packing in the reactor,the results showed that under the same operating conditions,the packing of the filler was completed in about 15 days,which shorten half of the time compared to the plastic pellets.The filler has better hydrophilicity and larger membrane volume.The removal rate of COD,NH4+-N and TP of effluent is obviously higher than that of plastic pellet,and it is more resistant to impact loading during the operation.The microbial community composition in the biofilm of the two kinds of fillers was analyzed,it was found that the composition of the microbial community in the reactor of pumice filler was more complicated.In the anaerobic reactor,the microbial community composition of the two fillers was similar,the composition of microbial communities in aerobic reactor was quite different.The facultative anaerobic bacteria existed in aerobic reactor,which was beneficial to the improvement of nitrogen and phosphorus removal efficiency.3.Through the orthogonal experiment,the optimal control strategy of stable operation was studied,under the conditions of HRT of 18h,reflux ratio of nitrification solution of 200%,and C/N of 10,the COD,NH4 +-N,TN,TP removal efficiency of the reactor were over 97%,98%,80%,and 50%.The removal efficiency of COD in the reactor was significantly affected by HRT.The removal efficiency of ammonia nitrogen in the reactor was significantly affected by HRT and C/N,The effect of TN removal in the reactor was significantly affected by C/N and HRT,and the reflux ratio of nitrification was also affected.