Homogeneous sonophotolysis of food processing industry wastewater: Study of synergistic effects, mineralization and toxicity removal

The mineralization of industrial wastewater coming from food industry using an emerging homogeneous sonophotolytic oxidation process was evaluated as an alternative to or a rapid pretreatment step for conventional anaerobic digestion with the aim of considerably reducing the total treatment time. At the selected operation conditions ([H2O2] = 11,750 ppm, pH = 8, amplitude = 50%, pulse length (cycles) = 1), 60% of TOC is removed after 60 min and 98% after 180 min when treating an industrial effluent with 2114 ppm of total organic carbon (TOC). This process removed completely the toxicity generated during storing or due to intermediate compounds.An important synergistic effect between sonolysis and photolysis (H2O2/UV) was observed. Thus the sonophotolysis (ultrasound/H2O2/UV) technique significantly increases TOC removal when compared with each individual process.Finally, a preliminary economical analysis confirms that the sono-photolysis with H2O2 and pretreated water is a profitable system when compared with the same process without using ultrasound waves and with no pretreatment.

► Sono-photolysis is an alternative for the mineralization of industrial wastewater.
► 60/98% of TOC is removed after 60/180 min.
► This process removed completely the toxicity.
► Important synergistic effect between sonolysis and photolysis (H2O2/UV).
► A preliminary economical analysis shows the profitability of the process.