Screening of physicochemical treatment processes for reducing toxicity of hair care products wastewaters

Toxicity of Beauty Salon Effluents Contaminated with Hair Dye on Aquatic Organisms

Cosmetic residues have been found in water resources, especially trace elements of precursors, couplers, and pigments of hair dyes, which are indiscriminately disposed of in the sewage system. These contaminants are persistent, bioactive, and bioaccumulative, and may pose risks to living beings. Thus, the present study assessed the ecotoxicity of two types of effluents generated in beauty salons after the hair dyeing process. The toxicity of effluent derived from capillary washing with water, shampoo, and conditioner (complete effluent-CE) and effluent not associated with these products (dye effluent-DE) was evaluated by tests carried out with the aquatic organisms Artemia salina, Daphnia similis, and Danio rerio. The bioindicators were exposed to pure samples and different dilutions of both effluents. The results showed toxicity in D. similis (CE50 of 3.43% and 0.54% for CE and DE, respectively); A. salina (LC50 8.327% and 3.874% for CE and DE, respectively); and D. rerio (LC50 of 4.25-4.59% and 7.33-8.18% for CE and DE, respectively). Given these results, we can infer that hair dyes, even at low concentrations, have a high toxic potential for aquatic biota, as they induced deleterious effects in all tested bioindicators.

Treatment of cosmetic industry wastewater by flotation with Moringa oleifera Lam. and aluminum sulfate and toxicity assessment of the treated wastewater

The production of personal hygiene and body products generates wastewater with a high load of surfactants, a high chemical oxygen demand (COD), and abundant oils and greases. Aluminum sulfate (AS) and two solutions of natural coagulant from Moringa oleifera Lam. seeds prepared with a 1M NaCl solution and 1.5M NaCl solution were used. Aluminum sulfate, Moringa oleifera Lam. in 1M NaCl, and Moringa oleifera Lam. in 1.5M NaCl solutions reduced turbidity at rates 94.48%, 98.07%, and 97.87%; reduced COD at rates 46.36%, 49.15%, and 42.7%; and reduced oil and grease at rates 98.72%, 78.65%, and 97.41%, respectively. Mutagenicity tests with guppies showed a lower toxicity of Moringa oleifera Lam. extract compared with aluminum sulfate. This work shows that Moringa oleifera Lam. extract has high potential for use as an alternative to aluminum sulfate; therefore, this study will contribute to proposals for the sustainable treatment of effluents from the cosmetic industry.

Effective treatment of emulsified oil wastewater by the coagulation–flotation process

Ship emulsified oil wastewater was used as the research object in this study. The highly efficient coagulant demulsification degreasing mechanism and microbubble flotation technology were combined and the effects of coagulant type and dosage amount on the demulsification of emulsified oil wastewater were evaluated. The influence of the mixed coagulation effect of pH values, temperature, and hydraulic condition parameters were determined and water intake, air intake, and oil content were regulated. The coagulant for the demulsification of emulsified oil wastewater was screened; the dosage was 500 mg L⁻¹, and the removal capacity of the coagulant was in the following order: polyaluminum ferric chloride (PAFC) > polyaluminum chloride (PAC) > polysilicate aluminum ferric sulfate (PSAFS) > alum > Al₂(SO₄)₃ > polyferric sulfate > FeCl₃. Polyacrylamide (PAM) with added water was used to further reduce the oil content. The PAFC, PAC, and PSAFS were selected as coagulation–air flotation dynamic test alternative agents. The investment quantities of PAFC, PSAFS and PAM were 300 mg L⁻¹, 300 mg L⁻¹ and 30 mg L⁻¹, respectively. The stirring time was 5 min, the pH value was 6.5–6.9, the flow rate was 0.25 m³ h⁻¹, the oil content of the emulsified oil wastewater was 3000–5000 mg L⁻¹ and the effluent oil was stable below 15 ppm. The microbubble generation device using air flotation effluent was used in the two air flotation treatments to enhance the device efficiency. The air flotation device adopted the structural design of the upper part of the water inlet and the lower part of the micro-air bubble, which can increase the collision probability of the microbubble and improve the efficiency of oil removal.

Ship emulsified oil wastewater was used as the research object in this study.