Efficient treatment of high-salinity aquaculture effluents through synergistic membrane distillation and VUV/UVC photolysis

Effluents from mariculture facilities typically marked contain high salinity and organic loadings, including anti-parasitic chemicals such as formaldehyde. The direct discharge of such effluents poses serious environmental risks, thus requiring the development of sustainable methods for their treatment. Within this context, a novel approach based on the synergistic integration of thermally driven membrane distillation (MD) and vacuum-ultraviolet/ultraviolet-C (VUV/UVC) photolysis is proposed for the treatment of highly polluted saline water without the need of intensive pretreatments or chemical additives. In this specific work, the performances of the proposed integrated treatment process were explored for inland mariculture effluent. The MD system was able to reclaim 90 % of the effluent as distilled water. Concurrently, salts in the MD concentrate were recovered. The subsequent polishing of the MD permeate solution via VUV/UVC photolysis allowed the abatement of the volatiles present in the MD permeate, bringing the concentrations of formaldehyde and total organic carbon (TOC) below the detection limits (0.5 mg L−1 for both techniques) within 20 min of treatment. The novel integrated system improves the purity of the recycled water and serves as an example of sustainable mariculture effluent management, advancing towards zero-liquid discharge within this field.