A critical review on the treatment of dye-containing wastewater: Ecotoxicological and health concerns of textile dyes and possible remediation approaches for environmental safety

Natural dyes have been used from ancient times for multiple purposes, most importantly in the field of textile dying. The increasing demand and excessive costs of natural dye extraction engendered the discovery of synthetic dyes from petrochemical compounds. Nowadays, they are dominating the textile market, with nearly 8 × 105 tons produced per year due to their wide range of color pigments and consistent coloration. Textile industries consume huge amounts of water in the dyeing processes, making it hard to treat the enormous quantities of this hazardous wastewater. Thus, they have harmful impacts when discharged in non-treated or partially treated forms in the environment (air, soil, plants and water), causing several human diseases. In the present work we focused on synthetic dyes. We started by studying their classification which depended on the nature of the manufactured fiber (cellulose, protein and synthetic fiber dyes). Then, we mentioned the characteristics of synthetic dyes, however, we focused more on their negative impacts on the ecosystem (soil, plants, water and air) and on humans. Lastly, we discussed the applied physical, chemical and biological strategies solely or in combination for textile dye wastewater treatments. Additionally, we described the newly established nanotechnology which achieves complete discharge decontamination.

https://www.mdpi.com/2076-3417/11/14/6255/pdf

Diversity of Synthetic Dyes from Textile Industries, Discharge Impacts and Treatment Methods

A review on biosurfactants: properties, applications and current developments.

The synthetic dyes and chemicals used in industries produce a tremendous amount of contaminated water. Most of the poisonous dyes generated from different textileindustries are released directly to the environment. As a consequence, the discharge of wastewater from a large number of textile industries without prior treatment leads to significant negative impacts on human health. The utilization of efficient and inexpensive nano-adsorbent may reduce the adverse impacts of dyes in the environment due to their unique properties. To alleviate these issues, attention has been paid to develop efficient adsorbents for the removal of undesirable species from wastewater. Efficient and selective removal of dyes is gaining importance to reduce the environmental problems. Comparison of degradation efficiencyfor different catalysts could be a holistic approach that should be taken under consideration owing to search a suitable adsorbent. An in-depth evaluation of extensive variety of advanced adsorbents reported in literature for dye degradation has been furnished. In addition to underscoring the physico-chemical properties of different adsorbents, this review also endorses the mechanisms and efficiencies within the adsorption process. The challenges of dye degradation process are focused to reduce the adverse impacts of dyes in the environment. The critical assessment of next generation adsorbents would presumably be promoted the clean and affordable water purification process in practice.

Step towards the sustainable toxic dyes removal and recycling from aqueous solution- A comprehensive review

Isolation of lipase-secreting bacteria by deploying used frying oil as selective substrate - science tackles a potential health hazard

Rapid industrialization has provided comforts to mankind but has also impacted the environment harmfully. There has been severe increase in the pollution due to several industries, in particular due to dye industry, which generate huge quantities of wastewater containing hazardous chemicals. Although tremendous developments have taken place for the treatment and management of such wastewater through chemical or biological processes, there is an emerging shift in the approach, with focus shifting on resource recovery from such wastewater and also their management in sustainable manner. This review article aims to present and discuss the most advanced and state-of-art technical and scientific developments about the treatment of dye industry wastewater, which include advanced oxidation process, membrane filtration technique, microbial technologies, bio-electrochemical degradation, photocatalytic degradation, etc. Among these technologies, microbial degradation seems highly promising for resource recovery and sustainability and has been discussed in detail as a promising approach. This paper also covers the challenges and future perspectives in this field.

https://www.tandfonline.com/doi/pdf/10.1080/21655979.2020.1863034

A critical review on advances in the practices and perspectives for the treatment of dye industry wastewater.

Increased population and industrialization generate a large number of organic pollutants that create problems on the planet earth. The level of freshwater is reducing which has pushed the society to reuse/recycle wastewater. Eco-friendly and economically sound treatment of industrial wastewater has attracted global attention and hence is a thrust area of research. Organic compounds rich wastewater can be used to generate bioenergy and value-added products from the resource recovery point of view. Wastewater treatment(s) can be used to trap energy from industrial effluents in form of biofuel, bioenergy and biogas. Recovered products can be used in various ways such as recovered nutrients for (bio)fertilizer production and algal biomass for bioplastic production. Microbial electrochemical technology is a promising approach for resource recovery. This review article aims to present and discuss trends and scientific developments about recovery of value-added products from dye industry effluent. It also provides state-of-art technical information about technologies for remediation of pollutants from dye industry effluent with emphasis on nanotechnological approaches and microbial electrochemical technologies (METs). It narrates literature on classification and properties of dyes, effects of dye pollutants on environment and human health and factors affecting degradation of dyes. Generation of bioenergy and recovery of valuables from dye industrial wastewater along with challenges and perspectives of this research area have been covered.

Trends in dye industry effluent treatment and recovery of value added products

Actinomycete strains from cottonseed soap-stock (a dark gelatinous waste from oil refinery) were obtained. Cultures were analyzed for the enzyme lipase, protease and cellulase production using plate assay(s). Best lipolytic isolates were further quantitatively analyzed for lipase production, using substrate p-nitrophenyl palmitate (p-NPP). Cultures were characterized by morphological and molecular studies. The potent lipase producing strain of actinomycete was optimized for pH, temperature, inoculum size, carbon and nitrogen sources. Further, the lipolytic strain of actinomycete was grown on synthetic media and growth factors were optimized by RSM (Response Surface Methodology) for maximum production of lipase. Total 49 cultures were obtained from enriched soap-stock samples; among them 7 isolates were strains of actinomycete. Potent actinomycete strains were identified as Nocardiopsis alba, Streptomyces leeuwenhoekii, Streptomyces caelestis, Streptomyces werraensis and Streptomyces sclerotialus. Based on quantitative lipase production study, Nocardiopsis alba was selected as the best lipase producer. Optimized results of process parameter studies for lipase production by Nocardiopsis alba were: 5mL inoculum size, temperature 40 ∘ C, shaking at 130 rpm, pH 8.0 and cottonseed oil as the best carbon source. Cottonseed oil, K2HPO4 and cellulose were noted as main factors as optimized by Central Composite Design (CCD), where the culture showed highest (65.78 U/mL/min) lipase production. Findings of the research would offer potential environmental benefits along with socio-economic benefits if implemented suitably.

Toral Shindhal

Papers

A critical review on advances in the practices and perspectives for the treatment of dye industry wastewater.

Trends in dye industry effluent treatment and recovery of value added products

Process parameter studies by central composite design of response surface methodology for lipase activity of newly obtained Actinomycete

Lipolytic Nocardiopsis for reduction of pollution load in textile industry effluent and SWISS model for structural study of lipase.