2023-10-26 バース大学
◆染料を含む工業廃水の多くは未処理のまま水路に放出され、これが人間、動物、植物の健康に幅広い脅威をもたらしています。染料を取り除くための方法はいくつか存在しますが、染料が一度廃水システムに到達すると、処理プロセスは非常にエネルギーを消費するため、全世界的な規制が必要です。染料は水中で可視光の透過度を減少させ、水中植物の光合成を妨げ、食物連鎖に影響を及ぼします。染料は魚にも影響を及ぼし、鰓や脳に沈着し、毒性効果を引き起こすことがあります。また、染料は土壌の微生物コミュニティのバランスを崩し、人間にアレルギー、喘息、皮膚炎、中枢神経系の障害、臓器の機能障害、癌リスク増加などの影響を及ぼすこともあります。
◆染料を取り除くための効果的な方法は不足しており、染料の使用を持続可能にするためにインフラ、投資、規制の努力が必要です。
＜関連情報＞
- https://www.bath.ac.uk/announcements/do-or-dye-synthetic-colours-in-wastewater-pose-a-threat-to-food-chains-worldwide/
- https://www.nature.com/articles/s43017-023-00489-8
染料を含む廃水の環境影響と修復 Environmental impacts and remediation of dye-containing wastewater
Jiuyang Lin,Wenyuan Ye,Ming Xie,Dong Han Seo,Jianquan Luo,Yinhua Wan & Bart Van der Bruggen
Nature Reviews Earth & Environment Published:26 October 2023
DOI:https://doi.org/10.1038/s43017-023-00489-8
Abstract
Synthetic dyes are used in various industries including textile processing, food production and the pharmaceutical sector. Yet, approximately 80% of the dye-containing wastewaters produced are often released untreated into waterways or used directly for irrigation, causing detrimental impacts on human health and ecosystems. In this Review, we discuss the environmental impact of dye-containing wastewater and explore the chemical, biological and physical mitigation strategies used to treat and decontaminate dye-containing wastewaters. Untreated synthetic dyes cause coloration of receiving water bodies, hindering the degree of visible light reaching the photic ozone, and have carcinogenic, mutagenic and teratogenic properties that have toxic impacts on plants, animals and humans. Chemical treatment methods such as coagulation are the most widely adopted treatment methods; however, they require careful sludge management to be effective. Biological degradation, involving the implementation of enzymes, microorganisms and plants, is an environmentally friendly and energy-efficient approach for dye degradation, but it requires lengthy reaction times and the use of selective bio-organisms for target dyes. Advanced membrane-based physical separation can achieve effective removal of dyes and inorganic salts from highly saline dye-containing wastewater, while also enabling their recovery and reuse. Strengthened regulatory requirements and development of non-toxic dyes are required in conjunction with these remediation treatments to effectively mitigate dye-related pollution.
Key points
- Untreated synthetic dyes released into aquatic environments reduce the light available for photosynthesis by primary producers, with consequential impacts for the whole food chain. In addition, dyes are also directly harmful to plants, animals and humans, with human health implications including increasing allergy and cancer risk.
- Chemical coagulation and electro-coagulation are widely adopted methods of dye removal. However, coagulant efficacy and sludge management are crucial for efficient removal of dyes.
- Advanced oxidation processes, which encompass chemically mediated advanced oxidation processes, photocatalysis and electrocatalysis, have been proven effective at dye degradation. To ensure these methods are sustainable and safe, it is crucial to minimize chemical and energy consumption and monitor and manage the toxic by-products that can be generated during the process.
- Biological degradation is an eco-friendly and energy-efficient method for dye removal through the utilization of enzymes, microorganisms (bacteria, fungi, yeast and algae) and plants, but these methods require a long reaction time, owing to slow kinetics during dye degradation.
- Emerging membrane-based physical separation techniques, including tight ultrafiltration, loose nanofiltration and electro-driven nanofiltration, show a great potential in fractionation of dyes and salts from highly saline dye-containing wastewater. These methods also enable efficient recovery of dyes and salts to promote a circular economy in the textile sector.
- To achieve sustainable and safe synthetic dye use, these advanced remediation technologies must be implemented in combination with proper regulation of dye-containing wastewater discharge in collaboration between governing bodies and industry stakeholders.
