Pretreatment of cosmetic wastewater by dissolved ozone flotation (DOF)

Dissolved ozone flotation (DOF) treatment method was applied to oxidize soluble substances, i.e., emerging micropollutants that are not completely removed by dissolved air flotation (DAF) in cosmetic wastewater treatment. With the DOF method, solid particles float on the top of the treated solution, and soluble substances are oxidized by ozone. Twelve aluminium-based coagulants were used in the experiments: Al 6010, Al 3010, Al 3030, Al 3035, Al 1019, Al 2019, PAX XL19, PAX16, Flokor 1.3, Flokor 1S, Flokor 1.2a, and Megafloc. Of all the coagulants, the two with the highest efficiency were selected: Al 3010 and Al 6010. The results obtained by both treatment methods, DOF and DAF, show similar chemical oxygen demand (COD) removal 79.1% and 78.8%, respectively, and total suspended solids (TSS) removal 95.2% and 94.4%, respectively, for Brenntag 6010. For Brenntag 3010 removal rate of 81.3% and 81.0% COD was observed, and the same 96.3% TSS removal for both DAF and DOF methods. However, extended removal of micropollutants was observed in the DOF method. The headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) analysis was used to identify the compounds in wastewater and to evaluate the effectiveness of both methods that were used. The HS-SPME-GC-MS results confirmed that the DOF process with using coagulant Al 3010 had better removal efficiency compared with DAF. The removal rate of micropollutants including endocrine disruptors for DOF was 96.3% compared with 93.8% when using DAF treatment.