| Utilizing biodegradable polymers material poly(butylenesuccinate), PBS to removal nitrate of water is a new technical, the PBS filling in the biological denitrification reactor can serve both as adhering carrier and carbon source for denitrifying microbe, and have a great efficiency in removal nitrate of water. To optimize the removal nitrate of water used by PBS and understand which highly active aerobic denitrifiers work in the PBS biological denitrification reactor. The experiment studies are following aspects:1. Isolation and identification of aerobic denitrifying bacteria in PBS biological reactor. Using the commercially available PBS built a continuous freshwater PBS biological denitrification reactor and using artificial sewage to build natural biofilm. After the reactor shows a stability of nitrate remove effect, get the biofilm, dilution the biofilm solution and spread plates, then pick a single colony cultured. Seven denitrifying bacteria were isolated, but when we look at the rate of removal of NOx--N, there were three aerobic denitrifying bacteria have a strong nitrogen removal capacity:DN-3,DN-5,DN-6. We do morphological and scanning electron microscopy experiment on them, and using16S rDNA PCR amplification and sequencing technology to the three bacteria. Compared to the Genbank datebase, related phylogenetic tree was built, the identification shows they were Phyllobacterium, Gordonia, Sphingomonas.2. Studying the denitrification characteristics and degradation ability of PBS of the isolated three efficient denitrifying bacteria. We use cone bottles as reaction vessel, which were inoculated with the enrichment broth ofDN-3, DN-5, DN-6, DN-3,5, DN-3,6, DN-5、6, DN-3、5、6in order to carry out static freshwater denitrification experiment. Nitrate, nitrite, total nitrogen (TN) were timing detected. We found that the nitrate removal efficiency of alone strain of bacteria is better than combination of two or combination of three strains of bacteria. DN-3strain has the best nitrate removal efficiency under aerobic condition, initial N03--N148mg/L, pH7.0±0.2,28℃,24hours later, the N03--N removal efficiency of DN-3was up to95.2%and the TN removal efficiency of DN-3was up to82.9%after36hours, no nitrite accumulated. Using cone bottles with PBS granule as reactors which inoculated with DN-3, DN-5and DN-6strains to carry out freshwater static denitrification experiments. TOC was timing detected. The result shows that the TOC value of DN-3was a bit higher than DN-5,DN-6and the contrast, it maybe has a capacity of degradation of PBS.3. Studying the growth curve, change curve of pH, optimal bacteria added and optimal denitrification conditions of DN-3and test its actual using effect. Using cone bottles as reaction vessel which inoculate30%of the enrichment broth of DN-3, at15～40℃, pH5.5～8.0to carry out freshwater static denitrification experiment. The result shows that the DN-3strain was sensitive to temperature but do well in a large range in pH condition. Meanwhile we make sure that the best denitrification condition of DN-3strain was about30℃, pH7.0～7.5. Using commercial PBS to build a set of continuous freshwater biological denitrification reactor under30±2℃,pH7.0±0.3, mixing5%of the enrichment inoculation of DN-3with artificial sewage to build biofilm. The contrast was using pure artificial sewage to build biofilm. Nitrate and nitrite concentration was timing detected. The result shows that using mixed DN-3enrichment broth artificial has a high speed to build biofilm in the first five days compared with pure artificial sewage. The effect of denitrification of two reactors didn’t has much different after built biofilm, the real best nitrate removal rates was99.7%and no nitrite was accumulated. |
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