Optimization of column distillation in a wastewater treatment plant

In this research, a study about a wastewater treatment plant treating industrial wastes, hazardous and not, is carried out. In the plant, biological, chemical/physical and distillation/evaporation section are present. Experimental analysis and process simulations of the plant are carried out to show the important role of column distillation. In literature, works about modeling by ANOVA and simulations of this kind wastewater treatment plant are not present. Analysis of COD and water content are carried out in laboratory testes while a process simulator is used to simulate the plant. Results show that the feed of column distillation is excessive and diluted, decreasing the efficiency of the process. A new configuration of the plant can be developed and analyzed: only the evaporated of pre-heater are sent to column, while other distillates are sent to biological section. A sensitivity analysis allows to find the optimal operating conditions for distillation section: temperature of feed 353 K, steam flow rate 155 kg/h, feed flow rate 2500 kg/h, reflux ratio 3.6, COD in residue 28 g/l, solvents in residue 5% w/w and water in distillate 6% w/w. Compared to traditional scheme, the analyzed solution allows to save 33 k€/year of fuel producing steam. Results of ANOVA analysis shows that the temperature of feed and reflux ratio are the most significant factors for distillation. Future researches should verify the obtained results in the real plant.