Treatment of Industrial effluents by Ozonation process for energy recovery and Color removal

Abstract

Most industries produce effluents which are environmental hazards due to presence of color and recal citrant COD. One useful way of remediating these effluents is by using them in production of biofuels through fermentation process. The use of industrial effluents as substrate for producing biofuels is advantageous in that on top of producing energy, the effluent is bioremediated before discharge. However, in many occasions, the production process is limited by its low energy yields and productivity due to presence of toxicants and refractory substances. This necessitates some form of substrate pretreatmen t like; biological, physical - chemical and the advanced oxidation processes (AOPs). Ozonation is one of the AOP process applied in industrial effluent pretreatment. The current study reviews the use of ozonation is used to enhance biofuel fermentation proce ss and remove the colored recalcitrant substances before its discharge. Ozonation was found to increase the biodegradability of recalcitrant and toxicants in substrates for higher bioenergy yields. In pretreatment of solid substrates like the sludge, the process solubilizes the particulate substrate with minimal effects on energy contents of the substrates. Our data on digested distillery effluent indicate that the process can be used to remediate the color before the effluent is discharged. Though the pro cess produced some increase in biodegradability, it was observed that the use of ozone overdose caused reduction in the biodegradability enhancement possibly due to production of toxic intermediates. Ozonation is one of the most selective AOP to unstable b onds. Its application in treatment of colored textile effluent results in almost complete color removal but with low COD elimination. More studies are required on integration of ozonation with other processes with the aim of enhancing both technical and ec onomic cost - effectiveness of bioenergy production and the color removal