ChemicalOxygen Demand Reduction of The Spent Wash Condensate by Applying Sugar Cane Bagasse Ash

Abstract

Distillery spent wash is a highly acidic waste generated during ethanol production in sugar industries. It makes a challenging industrial wastewater, due to its high organic content and complexity and it needs to treat before being released into the environment. The spent wash can evaporate, creating a thick slurry and vaporized liquid. The slurry can be used for different applications such as a fertilizer production. This vaporized fraction can be condensed, and this research study focuses on applying a sustainable waste management approach to reduce the COD of spent wash condensate by using ash generated from bagasse combustion. Four experiments were included in the study. First, H2O2-treated and untreated fly ash and bottom ash from the bagasse combusted boiler were mixed with the spent wash condensate and filtered out to determine the most suitable ash type for COD reduction. Then, the chosen ash type was used in various ratios and retention times to determine the optimum operation conditions. Finally, the COD reduction capacity of the boiler ash was determined by treating condensate multiple times. The results indicated that the optimum COD reduction spent wash condensate to treated bagasse fly ash ratio is 1: 50 (W/V), and the optimum retention time is 02 hours. Furthermore, the treated bagasse fly ash can be used twice to treat the condensate of distillery spent wash, and if it wants to be reused more, it should retreat with H2O2. The average COD value of raw spent wash was around 130,000 – 160,000 mg/L range, and it has reduced to approximately 70,000 mg/L in the spent wash condensate. After ash treatments the COD of spent wash condensate can be reduced to approximately 30,000 mg/L. This method can reduce the spent wash COD by about 75%; additional treatment is required to reduce it to an environmentally disposable level.