| Molasses spent wash was a complicated pollutant, contained a great quantities of dark brown colored recalcitrant organic compounds. As the consequent of conventional biological treatment is not ideal, the immobilized cell technology is a new feasible way to improve the efficiency of biological decolorization. This paper study the feasibility of the use of the immobilized Aspergillus flavus A5P1, which our own isolated, in the decolorization of the molasses spent wash as well as the function of the corresponding bioreacter, as to establish a new approach to improve the efficiency of biological decolorization. The content of this paper includes:(1)determining the concentration of molasses spentwash and the time that Aspergillus flavus A5P1can reach its optimal decolorization;(2) making a choice of several typical organic natural materials and inorganic materials, and using them as immobilized carrier, and then selecting the most suitable ones matching the system of decolorization;(3) selecting loofah as the carrier to immobilize, and optimized its conditions of preparation of immobilized cells and decolorization of molasses spentwash;(4) Establishing reactor with immobilized cell to make the decolorization test of molasses spentwash..The results showed that the decolorization ability of molasses alcohol wastewater by Aspergillus flavus A5P1is reducing as the wastewater’s concentration was increasing, and the best concentration of molasses spentwash is2%. Under this concentration, the maximum decolorization rate and dry cells weight were47.62%and0.65g, respectively. The natural organic material carrier is better for fixing and decoloring as it’s more suitable for cell growth, as compared to the inorganic material, and the large porosity of the carrier can be fixed more bacterial cells than the small porosity one. And loofah was choosed as the best carrier. The optimal decolorization conditions by the immoblilize cells were pH5.0,40℃,150r· min-1, inoculum4.3×104spores· mL-1and2g loofah per60ml, at this condition the immobilized cells weight was0.3385g (cells dry weight), the decolorization rate of wastewater contents of2%molasses spentwash is65.68%, the the adsorption by loofah and the cell were4%and7.1%, respectively.The study also found that the immobilization could promote the growth of the strain. The production rate of H2O2and decolorization rate both were increased. The decolorization rate by the immobilized cells was enhanced about14%compared to the free cells. The result preliminarily showed that immobilization could enhance the growth metabolic activity, and make the decolorization rate and the production of hydrogen peroxide vitality of immobilized cells were both higher than the free cells. Immobilized carrier played a role of promoting the growth of the mold. The immobilized cells could remain the decolorization rate above50%within4cycles.An immobilized cells bioreactor was built for the continuous decolorization of molasses spent wash. The different concentration of nutrition, the simulated wastewater as well as the different concentration of simulated wastewater were investigated. It was found that the bioreactor could operate for10days and it was contaminated with pH decreased significantly due to the rich nutrition of the wastwater. When feeding in the simulated wastewater which configurated with pigment substance extracted from wastewater, the bioreactor operated stably for about25days. And the decolorization rate was kept50%within18days. When improving the simulated wastewater concentration from A475nm=3.5to A475nm=4.0, the decolorization rate was about35%. The preliminary result showed that the immobilized cells has a effect to promoted decolorization of molasses spentwash. |
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