Decolorization of spentwash: a comparative analysis of physical, chemical and biological approaches

Agro-industrial and solid waste disposal is a serious issue of concern especially in developing countries. Waste disposal from industrial production should be in tune with environmental management practices. Waste produced by Molasses based distilleries; called spentwash poses various kind of problems when disposed to water bodies. It is due to presence of different organic and inorganic substances in the waste in which melanoidin compound is mainly responsible for its dark brown color. Although the process of biomethanation reduces the BOD and COD of spentwash, the colour of effluent remains a big threat to water bodies when it comes to disposal. After the process of biomethanation, spentwash is called as PMDSW (Post Methanated Distillery Spentwash). So far, different approaches have been applied to reduce the opacity/colour and other physical and chemical properties of spentwash to make it more applicable in agriculture and feasible for disposal. In this background, the present study present a comparative analysis of physical, chemical and biological approaches used in decolourization of spentwash. The study used bagasse and chemically modified bagasse (CMB) as physical method, hydrogen peroxide as chemical and Phenerochete chrysosporium (PC) as a biological method to find comparative decolourization efficiency. The study compared efficiency of physical, chemical and biological method at 0% (control) dilution, 60% and 80% dilution in alternate days. The result showed that the dilution played a significant role in colour removal in all treatments. The study also found that hydrogen peroxide (T4) to be the maximum efficient method among all treatments as compared to control. However, the study also revealed that T6 (Phenerochete Chrysososporium) is a eco-friendly alternative of colour removal which is less efficient than chemical method(H₂O₂). The study enhances the understanding of different decolourization approaches and suggest biological approach as most suitable method for color removal.