Biofilm Characterization In Textile Wastewater Treatment By Combined Pre-ozonation And Biolfltration

With the shortage of the water resource, it is the necessary and demanded way to resolvethe problem of water pollution, and it is important to use clear production in printing industryand to improve the recycled water rate also. This study focused on the treatment ofcombination of ozonation and biological aerated filters on acid rose wastewater according tothe characteristics of textile wastewater.The removal efficiency between the integrated ozone-biological aerated filters and theseparated ozone biological aerated filters (BAF) was compared in this study. The resultsshowed that the decoloration efficiency of separated system was slightly better than theintegrated system without ozone dosage. However, with the increase of the ozone dosage, thedecoloration efficiency of the integrated process was rising faster than the separated one. Thepollutants removal rate of the integrated process also was better than the separated one about5%and8%. The optimum ozone dosage of the integrated ozone-biological aerated filter wasbetween40–60mg/L. Besides the better treatment result, the integrated process saved thecapical cost of the biological contact oxidation ponds and had the characteristics of simplerflow and easier management compare to the separated process.According to the excellent effect of treatment and engineering feasibility, futhur study onthe microorganism in BAF was carried out, which could be the theory and technical guidanceof engineering application of the integrated process. The study of microorganism also canoptimize the integrated flow process and enlarge the application field of the combination ofozonation and biochemical treatment.The biofilms activity in Biological Aerated Filters was quantitatively determined by2,3,5-triphenyl tetrazolium chloride (TTC)-dehydrogenase assay and some major factorsinfluencing the determination were studied in this paper. It was showed that the optimumparameters were the following: ceramic balls of15g, TTC concentration of0.4%, Tris-HClbuffers and pH value of8.0. The incubation time and temperature were4h and40℃respectively. The formazan reduction product could be efficiently extracted by methylbenzene,which could reduce the disturbance of dye color. This study demonstrated that theTTC-dehydrogenase assay could be successfully applied to the determination of biofilms activity in BAF.The differences of the microorganism in different flow processes were also compared.The results showed that the biomass and the biofilm activity in the bottom of separatedsystem were higher than that in the integrated system. The biofilm activity and the biomassdecreased with the increasing of the BAF height and the dye concentration obviously.However, the microorganism characteristics including the biofilm activity and biomass in theintegrated system wasmuch lower in the bottom part than the separated process, presentedinverted “V” shape and increase lightly with the increase of dye concentration and ozonedosage. The results showed that the integrated ozone-BAF process could be applied in largerrange concentration of dye wastewater than the separated one. This study also found that thebiofilm activity and the biomass can be influenced by the temperature and increased with thetemperature in a certain range. The biofilm activity was influenced by the temperature moreapparently the the biomass in integrated process.The SEM photos showed that the original ceramic balls were smoother than those in theBAF which had a lot of microorganism and pollutants on the surface. Through the dominantmicrobes’ identification, the dominant microbes in the integrated ozone-BAF were tiny coligenera, bacillus subtilis, aerosis bacillus and proteus genera. There were two kinds of fungiamong the dominant microbes, facultative anaerobe and aerobic heterotrophy which played animportant role in textile wastewater treatment. The facultative anaerobe mainly convertedMacromolecular organics to by degradation small molecular organics and improved the thebiodegradability. And the aerobic heterotrophy removed the pollutants in wastewater throughaerobic reaction.