Microbial Community Succession In Saline Mustard Wastewater Treatmrnt System

High salinity in mustard wastewater affects osmotic pressure of cells, damages the metabolic activity of the enzyme, and increasing the density of water. Those will lead to the difficulty of biological treatments, and there’s no efficiency process to deal with. A new bio-cage technology has been developed and stared up in Yuquan mustard wastewater treatment station. Traditional biological method(Optical Microscopy) and modern molecular biology techniques(PCR-DGGE, Mi Seq) were totally applied during the start-up phase and load increasing stages of the reactor to detect the microbial communities.Monitoring water quality in the start phase, new bio-cage technology had a higher organic removal rate than traditional dial process. The successful start-up of bio-cage2 indicated its effective ability for COD and nitrogen removal. Microscopic examination revealed the fact that there was always a filamentous bulking in the front of the bio-disk, while bio-cage acted more adaptable to the circumstance with a dense biofilm. Meanwhile, DGGE profile analysised by Quantity One reflected the intelligent screening filter of the seeding sludge by the reactor during the phase, the highest similarity between the samples and the seeding sludge was only 57.7%, while the similarity between the bottom and the seeding sludge was higher than the front in each reactor. Richness and Shannon index showed the same trend. Clustering samples by Complete Linkage algorithm, results showed that reactors screened species intelligently.Enhancing the influent load to 4.5kg COD/(m3 filter·d), new bio-cage reactor still had the ability to remove COD and denitrify. There may exist some organic that can not be biodegradable, which could be the breakthrough point to improve its capability. Microscopic examinations discovered some kinds of protozoon and meazoan adhere to biological variation. When the load were in low or middle period, similarity of biofilm samples along the reactor with seeding sludge wew increasing, while high loading level may lead to adequate nutrients to feed the microorganism that were not dominant in seeding sludge, so that microbial richness and H index were higher in the end of the reactor. Water treatment efficiency of a process was negatively correlated with the similarity of the front and end samples. The influence of the reactor type is much more important than the microbial structure for the community. Uploading these sequences to Gen Bank to get the reception number,Comparing the sequences with NCBI gene bank, highly homologous species could be found for all these sequences. Uncultured Firmicutes bacterium and other 12 species have been found in seeding sludge and reactor all the time, Uncultured Firmicutes bacterium and other 5 species eliminated as the load lifting, while Uncultured Thiothrix sp. and other 7 species took the dominate role gradually in the process. The nitrification bacteria are Nitrospira sp. and Beta-proteobacterium,while denitrification bacteria are Uncultured Flavobacterium sp. and Azoarcus sp..Mi Seq had been used to study the microbial community of biofilms in high loading level. The order of species’ richness is: seeding sludge< the front biofilm< the middle biofilm and the end biofilm. Beta diversity discovery showed that five samples had been divided into three parts: seeding sludge, the middle biofilm and the end biofilm, and the front biofilm. Venn diagram obtain 100 core OUT, while 39 OTU died out after seeding. Meanwhile, 5 and 3 new OTU had been discovered in the middle biofilm and the end biofilm, respectively. 30 results had been obtained in the Phylum level, the largest proportion in samples were Actinobacteria、Bacteroidetes、Chloroflexi、Firmicutes、Planctomycetes、Proteobacteria. 250 results have been discovered in the category level, the dominant species in seeding sludge were Denitromonas、Flavobacteriaceae and Bizionia. The dominant species in the front biofilm were Arcobacter、Azonexus and Thauera. The dominant species in the middle biofilm were Anaerolineaceae 、Anaerolineaceae and Comamonadaceae. The dominant species in the end biofilm were Anaerolineaceae、Nitrosomonas and Thauera. Nitrification and denitrification rates in seeding slugde were 0.69% and 19.26%. Nitrification along the reactor were 0.70%、6.88% and 11.52%. Denitrification along the reactor were 18.14%、12.22% and 15.90%.