Rcycling Caramel From The Molasses Yeast Wastewater And Anaerobic Treatment For The Wastewater

Yeast is a single cell micro-organisms, which is currently the only micro-organisms in the world that has annual production of more than one million tons. And the yeast is widely used in food, wine, medicine, cosmetic, animal feed and so on. In the molasses yeast industry, a large number of complex molasses yeast wastewater, which has high concentration of organic substances and sulfate, can be discharged. After common biochemical treatment process, the COD and color of molasses yeast wastewater fail to reach the discharge standards.Based on the comprehensive analysis of the pollution feature and characteristics of organic pollutants in molasses yeast wastewater, the recycling caramel technology was built; Meanwhile, The processes and processes parameters of anaerobic biological treatment for the molasses yeast wastewater were discussed. The reduction rates of the anaerobic process of the yeast wastewater before and after recycling caramel were compared. So it is worthy of realistic significance of new comprehensive control of molasses yeast wastewater. The main results are as below:(1) The pollution feature and characteristics of organic pollutants were investigated through the conventional water quality test and GC-MS analysis technology. A large number of phenols, ketones and esters in molasses yeast wastewater lead to high degree of chromaticity. The macromolecular refractory substance, that benzene compounds, long chain hydrocarbons and heterocyclic compounds in molasses yeast wastewater can be the direct cause of poor biodegradability.(2) The ultrafiltration membrane separation process was adopted for recycling caramel: adjusting pH—ultrafiltration treatment—evaporating and concentrating—vacuum drying. The caramel, recycled in the process that operating in 5kDa ultrafiltration membrane separation and concentrating with one volume distilled water, has the best physical and chemical indexes. About 30 g caramel can be recycled from 2L molasses yeast wastewater, the recovery of caramel is about 15g/L. The sample was detected 79200 EBC in color ratio, 2.94 in red index and 4.96 in yellow index, it had salt stability and acid stability.The physical and chemical indexes of caramel are basically complied with national standard(GB8117-2001).(3) The device of anaerobic treatment for molasses yeast wastewater treatment was provided, and determined the optimum conditions. Ⅰstage Upflow Anaerobic Sludge Bed(UASB)—ozone treatment —Ⅱ stage UASB anaerobic treatment process was finally adopted in yeast wastewater treatment. The total emission reduction of yeast wastewater after caramel recycling can reach 88% and removal rate of color was 82.9% under this combining technology recycling caramel and anaerobic treatment, it provided a good foundation for the follow-up aerobic treatment and advanced treatment.