Study on Bactrial Cellulose Production Using Methanol Wastewater
|Keywords||bacterial cellulose Gluconacetobacter xylinus methanol wastewater fermentation|
Bacterial cellulose (BC) is a kind of ultra pure cellulose which synthesized by microorganisms. It has more excellent unique characteristics than vegetable cellulose and a wide application in food, papermaking, medicine industries etc, which is a material with great business prospect. However, compared with vegetable cellulose mass producing, research of BC is undergoing developing with problem to low yield and high cost. In order to lower the high costs of BC production, especially the costs of carbon sources, the new low-cost carbon sources were developed. Methanol wastewater in chemical engineering, pesticide, medicine and other industry processes contains methanol, water and less other organics. In this study, BC nanofibers with unique properties were synthesized by Gluconacetobacter xylinus that consumed organics in methanol wastewater, which not only effectively reduced the cost of raw materials, but also made the wastewater treated recycling.After naturalizing in the medium which methanol concentration increased gradually, Gluconacetobacter xylinus could grow and produce BC with high tolerance for methanol, which found that the bacteria can live when methanol concentration less than 4.5%, and produce cellulose when methanol concentration less than 2.7%. Then the feasibility study on production of BC using methanol simulated wastewater culture adding methanol mentioned above was carried on. After that, comparation of the yield of BC and removal rate of methanol using methanol wastewater culture, showed that the yield of BC in rotated culture whose prescripton was with pH 6.8, yeast 10.0g, calcium carbonate 20.0g, methanol wastewater 1000mL with condition of 30℃180r·min-1 for 10 days, was to the maximum of 0.21 g·L-1, which reached to 70% of that in glucose medium. Analysis on wastewater quality before and after cultured, removal rate of methanol reduced to 65%, and removal rate of COD, BOD5, TOC reached over 10%, which was better than other fermentation methods. The product produced by Gluconacetobacter xylinus in methanol wastewater media was identified by FTIR analysis, the result showed that the structure was including -OH,-CH2,-CH, C-O, C-C, etc. Through observation of TEM and SEM, investigated by water binding capacity and TG, they showed the typical cellulose structure fabricated into layer-by-layer network and favourate water binding capacity. Investigated by XRD and NMR, characteristic peaks which were similar with that produced in glucose medium, contained main crystal of CelluloseⅠ, and crystal of BC produced in methanol wastewater medium contained not only CelluloseⅠbut also CelluloseП, which caused the crystallinity lower than that in glucose medium.