Optimization of a plant for treatment of industrial waste solutions: Experimental and process analysis

The present paper deals with the optimization of an industrial plant that treats waste solutions coming from different manufacturing processes. In particular, an extensive experimental work was carried out to understand whether some streams could be diverted from the distillation column in order to recover solvents, suitable as secondary fuel. Experimental tests, including four full factorial designs, optimized the consumption of reagents in the Fenton process: the specific consumptions were 0.65 g L−1 of H2O2 and 0.42 g L−1 of FeSO4·7H2O, when treating the evaporated fractions from multiple-effect evaporator, concentrator and dryer, diverted from the distillation column. The application of the Fenton process increased the abatement of the chemical oxygen demand (COD) and the oxygen uptake rate (OUR). The optimization of the feed entering the distillation column led to a water content lower than 5%vol in the distilled fraction: hence, such solvents could be used as additional fuel in a dual-fuel boiler. The economic analysis showed that it could be possible to save around 420,000 € y−1.