Research On Membrane Biofouling During The Process Of Drinking-water Production

With the acceleration of the process of industrialization, water pollution andwater quality complex have resulted in a drinking water safety hazards. As people’sliving standards rising, the safety of drinking water has caused more concern.Disinfectants prodects will be produced while traditional water treatment processesare used for drinking water production. Disinfection byproducts produced by naturalorganic matter in water with bromide, iodide and other substitution or addition provedto be teratogenic, genetic mutation or carcinogenic.Membrane separation technology has provided the conditions for the researchand application of the new water treatment technology，due to the advantages ofcovers of small area, stable water quality of effluent, control automatically. But themembrane fouling seriously affects the wide application of the technology. Themembrane fouling not only enhances the cost of drinking water production, but alsocauses the membrane permeability decreased with the restrict of water productionvolume. Biofouling in the membrane filtration is very complex in case of the speciesdiversity, adaptation to the environment, and various metabolites of microorganism.In this thesis, membrane biofouling during the production of drinking-water with surface water has been investigated using ultrafiltration and nanofiltration atdifferent filtration time by means of PCR-DGGE. The major pollution species onmembrane surface as a function of different filtration time dynamics have beenexplored And the water flux and changes in water quality conditions are alsoconsidered in view of fouling.The results shows that ultrafiltration and nanofiltration membrane all have a verygood removal efficiency, and nanofiltration membrane showed better retentioncapacity on microorganisms than the ultrafiltration membrane because of its smallpore size.Through analysis of cultured microbial sequencing on the membrane surface, theultrafiltration pre bacteria, Bacillus, Micrococcus, Pseudomonas spp. can be obtainedExtracting the different periods of sewage membrane microbial DNA forPCR-DGGE analysis and sequencing for the specia bands, we found that theultrafiltration membrane of the first advantages of contaminating bacteria in the caseof deformation of Hymenomycetes handle bacteria and Bacillus spp. In nanofiltrationdeformation of the the Hymenomycetes spp bacteria also showed a tendency interface,in addition to the bacteria of the Pseudomonas also showed a tendency to producedominant pollution.Scanning electron microscopy analysis on fouling layer show that long-termcontamination performance of ultrafiltration membranes exits the layer of mesh adhesion structure while the distribution of various microorganisms in the dirt layer.Nanofiltration membrane short-term fouling showed granular macromolecules groups,and long filter adhesion structure.