Mixture Design Using Low-Cost Adsorbent Materials for Decolourisation of Biomethanated Distillery Spent Wash in Continuous Packed Bed Column

During ethanol fermentation from molasses, a large quantity of coloured wastewater is generated called spent wash. The spent wash mainly consists of melanoidins which contribute to its colour. Melanoidin is recalcitrant compounds which are toxic and inhibitory to the micro-organisms and make the degradation of spent wash a difficult task. Therefore, conventional anaerobic digestion and aerobic treatment are incapable of bringing the spent wash characteristics to the level set by CPCB. The advanced technology of multiple-effect evaporator and reverse osmosis is unaffordable. None of the existing technology promises to provide foolproof solution with return on investment. Therefore, through this study, we are presenting a novel approach for decolourisation of spent wash with some return on investment through crop cultivation. Our methodology involves initial qualitative study using Soil, Sand, DYS, and Bagasse on decolourisation followed by quantitative study through packed bed, sand, DYS and bagasse showed the maximum decolourisation of 73.33%, 66.086%, 62.958% and 59.646%, respectively. Later, column studies with soil, sand and bagasse were carried out. The efficiency of packed bed column depends on the composition of packed modified soil. Therefore, various combinations were tested, and maximum decolourisation of 98% was achieved with 175 mL of soil, 75 mL of sand and 0 mL of bagasse. Nutritional analysis of spent modified soil reveals increased quality.