Decolorization Of Sugarcane Molasses Yeast Wastewater By Electrocoagulation And Biotreatment

Molasses yeast wastewater is a kind of recalcitrant organic wastewater.It has thefeatures of high chemical oxidation demand, dark brown color, high sulfateconcentration and low biodegradability. The decolorization of wastewater is one ofthe most difficult problem in the wastewater treatment. Most studies on thedecolorization of yeast wastewater is focused on the conditions of existing physicaland chemical methods. This research found that the lead acetate can remove thepigments through the charge neutrality. Combining of Aspergillus niger and innerelectrolysis treatments showed efficient decolorization of molasses wastewater. Themolecular changes and types of pigments which were treated through different waysare explored.Lead acetate could be used as pigments flocculation after single factor and theresponse surface design experiments.The optimized condition for lead acetateflocculating are25℃of temperature,10.0of pH,10mg/L of polypropylene amideconcentration,25g/L of lead acetate concenration. The decolorization rate couldreach to93.57%under the optimal condition.The decolorization of molasses yeast wastewater by Aspergillus nigerATCC2124were studied. On the sixth day during Aspergillus niger fermentationcourse, decolorization reached to the highest rate of58.0%. The mechanism ofdecolorization through Aspergillus niger includes two aspects, one is adsorption andthe other is the enzymes which showed catalytic oxidation on pigments. Theadsorption amounted to56.8%of decolorization effect while the enzymes catalysistake up43.2%. The biggest enzyme activity of lignin peroxidase, manganeseperoxidase and laccase were0.327U/ml,22.2U/L,26.8U/L, respectively. Blue shift ofpigment spectrum occurred after treatment of Aspergillus niger ATCC2124.Molecular polarity of pigments turned to be changed through the thin layer chromatographic analysis. Also, a strip of pigment disappeared while another new onewas formed.Combined decoloring by Aspergillus niger ATCC2124and inner electrolysis wasresearched. It was found that Aspergillus niger followed by inner electrolysis showedthe highest decolorization of93.2%-96.0%. The study also found that the innerelectrolytic treatment and Aspergillus niger removed different pigments in MWW. IEcould improve the biomass and enzyme acticity when post-treated with Aspergillusniger. Inner electrolysis could removal the new strip of pigment which formed duringAspergillus niger fermentation. Decolorization at different waves showed thatpigments at610nm were easily to be removed than at475nm by Aspergillus niger.While inner electrolysis showed the similar removal on both of the two wavespigments.