| Biofilter is an important biofilm process for wastewater treatment, its critical technology being media attached with microbe and its core issue performance of biofilter. In addition to a concentrated study of a new microbe-catalyzed media which can not only stimulate microbial growth but also promote biomass attachment, this dissertation carries out a full-scale experiment of performance of anoxic variable rate biofilter with this microbe-catalyzed media in municipal wastewater treatment. The conclusion is as follows:(1) Through orthogonal sintering experiments of media and contrasting experiments for biomass attachment, the optimal component proportion of the microbe-catalyzed media and the optimal sintering process are obtained by the studies on the productive exploitation. Compared with ceramic granule and blast furnace slag, microbe-catalyzed media has a coarser surface, a bigger available pore volume, a quicker and better biofilm growth, and is ideal for wastewater treatment.(2) Based on analysis of the indexes evaluating physical properties of microbe attached media used for biofilm process, it is pointed out that the surface micro-pore distribution is the main physical index to describe the physical properties of porous media surface, and the index system composed of available pore volume and corresponding expected value of pore diameter and coarse degree of the media surface is given at the same time. This is a new approach to evaluating porous media.(3) For the first time surface coarse degree of porous media is defined quantitatively through fractal theory and fractional dimension. As a result, means of studying surface coarse degree of porous media is advanced from qualitative description to quantitative computation, and from apparent summary to deep micro-analysis. The fractional dimension value is calculated of micro-catalyzed media, ceramic granule and blast furnace slag as 2.70~2.78, 2.75 and 2.53 respectively in the study.Expected value of pore diameter as put forward in this dissertation is a new parameter based on statistics theory, which, unlike the concepts of median pore diameter and mean diameter, can effectively characterize the diameter distribution features without the inconveniences of the pore diameter curve.(4) Variable rate structure of biofilter is created for the first time, which greatly lessens the bio-filter's need for washing and relieve clogging of biofilter. Results of full-scale device experiments show that: if sludge is discharged once time every 2~4weeks, washing duration of media layer would be 2-4 months.(5) It takes about 50d for full-scale anoxic variable rate biofilter with microbe-catalyzed media to finish start-up at 22~28C. When influent flow varies between 485~737m3/d and HRT of biofilter between 7.7~5.0h (HRT of media layer between 3.9~2.6h), effluent COD is below 120 mg/L, SS is below 30 mg/L, and some of effluent BODs is slightly above 30 mg/L (the probability is about 40%) at normal temperature of 17~27C. Influent P is removed to some degree, while effluent NHa-N increases a little. During the operation the pH is kept around 7.0. HRT, depth of media layer and water temperature have great influence on the biofilter performance. The dynamic model of the organic substances degradation in media layer is induced asfollows: S = (S1 - Sn) / n(1 + K2iXiti) + Sn, and according to experiment data involvedK.2 and Sn were given.(6) Microbes in media layer mostly exist as biofilm, and there is high correlation between the attached biomass and the relevant TTC dehydrogenase activity. The degradation of organic matter mainly accords with anaerobic approach, and the different species of microbes maintain a balanced metabolism. Sulfate reduction bacteria do not suppress methane production bacteria.The study shows great value of application as it provides support for the utilization of anoxic variable rate biofilter with microbe-catalyzed media in municipal wastewater treatment.
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