Production Rules And Application Of Extracellular Polymeric Substances

Bioflocculants produced by microorganisms are expected to be useful because they are safe for the environment and human. But there are problems such as expenses compared with synthetic flocculants. To cut down the medium cost and raise productivity of the bioflocculant, some kinds of organic industrial wastewater were tried to serve as mediums.The strain GX4-1(identified as Pseudomonas sp.), producing bioflocculating substances, was isolated from activated sludge by using Kaolin clay solution. GX4-1 can grow on wastewater of producing chitosane to produce bioflocculant. Fermentation was carried out on a rotary shaker(150 rpm) at 30℃ for 24hr with 50mL of the medium in 250mL flasks. The production of the flocculant was associated with cell growth. The maximum flocculant formation was observed at the end of logarithmic growth phase and the early stationary phase. After 70 hr the flocculating activity of culture broth decreased slowly. Whether the culture medium was sterilized or not made little difference on bioflocculant production. Both the culture broth and cells had flocculating activity throughout the process of fermentation. The cell-removed supernatant with high flocculating activity more than 90% was obtained by mild centrifugal separation (8000 rpm).Another fermentation style (fed-batch culturing) for bioflocculant was tried. The fermentation process with Aand E medium has got succeeded.At the same time,a lot of facters ware studied,such as pH,time.Bioflocculant By Pseudomonas sp.GX4-1 and polyaluminim chloride are complexed. The chelated flocculant is applied to domestic sewage and wastewater of producing chitosane ,the result showed that the treated result is barter than any one of its components and reduses dosage of bioflocculant and polyaluminim chloride.When flocculation tests were carried out using in various solid wastewater such as soil suspension, kaolin suspension, spinning wastewater, flocculating activity was markedly increased in the presence of Ca2+ compared with that of the control where distilled water was used instead of cation solutions. The synergistic effects of Ca2+ were most effective at basic pH ranges. Comparison with other inorganic and organic flocculants, Bioflocculant By Pseudomonas sp. also showed higher flocculating efficiency on many different wastewater.