Study On Theory Of Biological Sponge Iron In The Aerobic Phosphorus Removal Process

With the growing of national economy, environmental pollution aggravate dayby day, eutrophication became progressively worse, cause the extreme shortage ofwater resources. This has caused great concern of the National People. Commonlyused water treatment method with chemical method and biological method, but eachhas its advantages and disadvantages. Chemical method can effectively removephosphorus, but the removal efficiency of organic matter is limited. Biologicalmethod can effectively remove organic matter, but in nitrogen and phosphorusremoval process, the different sludge age of nitrifying bacteria and phosphorusaccumulating bacteria and the competition for matrix, greatly reduced the effect ofbiological method. So the way combining the chemical method and biological method,synchronization to removal nitrogen and phosphorus removal has become a hot fieldof water treatment.This article through to a new type of iron rich metal microporous filler, spongeiron combined with traditional activated sludge method, form the biological spongeiron system. Sponge iron filling in this system not only can be used as a carrier formicroorganism growth, biofilm formation, while releasing a certain amount of ironions in the action of microorganisms. Iron ions not only can promote microbialactivity at the same time, but also can realize the chemical phosphorus removal,realize the effective combination of chemical method and biological method. The first,this paper determined the optimal dosage of sponge iron in the system;the second,studied the influence of the concentration of activated sludge, pH and DO act on therelease of iron ions in the biological sponge iron system; the thind, studied the changeof various forms of phosphorus during phosphorus removal process; Finally, thephosphorus removal model of the system were discussed. The results are as follows:(1) In the biological sponge iron system comparison of different sponge irondosing quantity of reactor effluent COD, NH3-N, TN and TP concentration, it isconcluded that the optimal dosage of sponge iron was90g/L. The average COD,NH3-N, TN and TP of effluent were23.2mg/L,2.5mg/L,11.5mg/L and3.6mg/L. Thewater quality of COD, NH3-N and TN met level A of discharge standard of pollutantsfor municipal wastewater treatment plan, respectively.(2) In the environment of the greater activated sludge concentration andDO concentration, and the smaller pH, the more iron ions will be released.(3) Under aerobic conditions, dual role of microbial corrosion and oxygencorrosion causing Fe0stripping, and microbial corrosion is the main corrosion form.Because oxygen corrosion produce OH-, the pH value of the solution will be increased.Under anaerobic conditions, dual role of microbial corrosion and H2evolutioncorrosion causing Fe0stripping, and the pH of the solution will decline, the lower the aerobic conditions, the iron ions eluted mainly in the form of floc or precipitatepresent in the activated sludge, under anaerobic conditions, mainly in the form of ionspresent in the supernatant.(4) From the sponge iron dosage, pH and DO three kinds of influencing factorson the impact of various forms of phosphorus in the sludge, the maximum effects oniron phosphate. From the proportion of various forms of phosphorus, Fe-P proportionis relatively high, Ca-P proportion is the lowest,this have a great relationship with thesponge iron filling. Or-P ratio have been smaller, therefore, in the biological spongeiron system, phosphorus removal is mainly chemical phosphorus removal, the role ofsmall biological phosphorus removal by.(5) By measuring the concentration of phosphorus in different conditions ofbiological phosphorus removal system sponge over time, establish the biologicalsponge iron system aerobic phosphorus removal model: C=a1eKm1ta2eKm2tb3,Thecorrelation coefficient of the model were higher than in McKinney model, therefore,the model can describe more biological phosphorus removal process of sponge ironsystem.