Environmental Sustainability of Reactive Dye Containing Textile Wastewater Treatment Through Ozonation and Peroxide-Assisted Ozonation

The main motivation and rationale of this study was to interpret the wastewater treatability results in terms of their implications for environmental sustainability as such an evaluation did not take place so far. Ozonation and combined peroxide (peroxydisulfate/percarbonate)/ozone treatments were applied to simulated reactive dyebath effluent bearing Reactive Red 21 -commercially known as Remazol Brilliant Red BB (RR21; 100 mg/L reactive dye; 25 mg/L TOC)- 50 g/L NaCl and 15 g/L Na₂CO₃ under previously optimized reaction conditions (1.5 mM peroxide, 72 mg/min ozone feed rate) at its natural, alkaline pH (= 11.0–11.5). The treatment systems were examined based on color (peak visual absorbance value of RR21) and total organic carbon (TOC) removal rates. The life cycle assessment (LCA) methodology was adopted to determine the environmental impacts of the proposed chemical oxidation systems with a functional unit of 1 m³ treated effluent to choose the most sustainable treatment alternative. The GaBi software was used for modeling and the CML 2001 method to evaluate the environmental impact categories: Abiotic depletion-elements (ADP-elements), abiotic depletion-fossil (ADP-Fossil), acidification (AP), eutrophication (EP), freshwater aquatic ecotoxicity (FAETP), global warming (GWP), human toxicity (HTP), marine aquatic ecotoxicity (MAETP), ozone depletion (ODP), photochemical ozone creation (POCP) and terrestrial ecotoxicity (TETP) potentials. The results designated that ozonation in the absence of peroxides required an electricity input of 1.390 kWh/m³ as the alternative with the least unwanted environmental impacts. Furthermore, it was possible to lower the environmental impacts by using renewable energy sources instead of grid electricity.