Characteristics and Methods of Treating Cosmetic Wastewater Generated by the Cosmetics Industry: A Review of Current Research

Cosmetic wastewater is increasingly recognized not only as a disposal problem but also as a potential source of recoverable water and formulation-derived compounds. This review critically examines the relationship between cosmetic formulation chemistry, wastewater composition, pollutant removal mechanisms, membrane separation, fouling behaviour, and reuse-oriented treatment design. Cosmetic wastewater shows high compositional variability, with reported COD values ranging from approximately 2400 mg O2/L to more than 100,000 mg O2/L, depending on product type, cleaning practices, and raw material losses. Surfactants, emulsifiers, oils, polymeric thickeners, preservatives, fragrances, UV filters, dyes, and microplastics contribute differently to organic load, emulsion stability, toxicity, and treatment resistance. Conventional treatment processes reduce coarse, suspended, emulsified, and biodegradable fractions, but they are limited by low biodegradability, sludge generation, inhibitory compounds, and incomplete removal of persistent micropollutants. Advanced oxidation, adsorption, electrochemical processes, and hybrid systems can improve the transformation, phase transfer, retention, and polishing of recalcitrant compounds, with AOPs typically achieving COD removal of approximately 55–85% and hybrid systems improving overall performance by about 10–25% compared with biological treatment alone. Membrane technologies are evaluated as selective barriers enabling clarification, polishing, water reuse, and resource recovery. MBRs can remove more than 90–95% of COD and BOD5, while NF/RO polishing may reject more than 90–95% of selected recalcitrant organics and microcontaminants. The novelty of this review lies in shifting the discussion from end-of-pipe wastewater treatment toward source-oriented recovery, integrated treatment trains, and mechanism-based selection of technologies before cosmetic wastewater becomes diluted, mixed, and difficult to reuse.