Abstract:
Yeast having the ability to decolorize molasses pigment were isolated from pickled fruit, pickled vegetable, spoilaged h i t and soil in Thailand. Among them, one isolated strain showed the highest decolorization activity in synthetic medium. The decolorization yield of this strain was up to 68.91% in synthetic medium which contained 2.0% glucose and 0.1% sodiumnitrate, pH 6.0 at 3 within 8 days under shaking condition. The color intensity, COD and BOD were reduced above 68.91%, 90.54% and 81.30%, respectively.The decolorization yield, COD and BOD removal efficiencies of isolated strain in raw molasses wastewater with and without supplemented nutrient were 74.86%, 99.98%, 75.62% and l3.l3%, 77.8 1%,51.48%, respectively. On the other hand, the decolorization yield, COD and BOD removal efficiencies of isolated strain in wastewater from anaerobic pond with and without supplemented nutrient were 42.32%, 88.37%, 53.73% and 17.13%, 77.75%, 43.92%, respectively.The molecular weight pattems of various types of molasses wastewater were studied by using the Gel Filtration Chromatography. The molecularweight fraction in both raw molasses wastewater and wastewater from anaerobic pond showed the same pattern. After cultivation with yeast strain, the larger molecular weight fraction were decreased in both types of wastewater. The supplemented nutrients could increase the ability of the strain to decrease the larger molecular weight fraction in both types of wastewater.In the continuous and fed-batch system, the strain also showed the interested results. In the continuous system, the strain showed the constant decolorization yield of 50% during four times operation with 10% raw wastewater feeding. In fed-batch system, the isolated strain gave the decolorization yield as 51.31%, 16.33% and 13.09% at first, second 'and third batch respectively.The isolated yeast was identical with Citeromyces matritensis by comparing with Citeromyces matritensis ATCC 14086.