A critical review on textile wastewater treatments: Possible approaches.

Textile industries are responsible for one of the major environmental pollution problems in the world, because they release undesirable dye effluents. Textile wastewater contains dyes mixed with various contaminants at a variety of ranges. Therefore, environmental legislation commonly obligates textile factories to treat these effluents before discharge into the receiving watercourses. The treatment efficiency of any pilot-scale study can be examined by feeding the system either with real textile effluents or with artificial wastewater having characteristics, which match typical textile factory discharges. This paper presents a critical review of the currently available literature regarding typical and real characteristics of the textile effluents, and also constituents including chemicals used for preparing simulated textile wastewater containing dye, as well as the treatments applied for treating the prepared effluents. This review collects the scattered information relating to artificial textile wastewater constituents and organises it to help researchers who are required to prepare synthetic wastewater. These ingredients are also evaluated based on the typical characteristics of textile wastewater, and special constituents to simulate these characteristics are recommended. The processes carried out during textile manufacturing and the chemicals corresponding to each process are also discussed.

https://link.springer.com/content/pdf/10.1007/s13762-018-2130-z.pdf

Textile dye wastewater characteristics and constituents of synthetic effluents : a critical review

The textile production industry is one of the oldest and most technologically complex of all industries. The fundamental strength of this industry flows from its strong production base of a wide range of fibers/yarns from natural fibers like cotton, jute, silk, and wool to synthetic/man-made fibers like polyester, viscose, nylon, and acrylic. With escalating demand for textile products, textile mills and their wastewater have been increasing proportionally, causing a major problem of pollution in the world. Many chemicals used in the textile industry cause environmental and health problems. Among the many chemicals in textile wastewater, dyes are considered important pollutants. Worldwide environmental problems associated with the textile industry are typically those associated with water pollution caused by the discharge of untreated effluent and those because of use of toxic chemicals especially during processing. The effluent is of critical environmental concern since it drastically decreases oxygen concentration due to the presence of hydrosulfides and blocks the passage of light through water body which is detrimental to the water ecosystem. Textile effluent is a cause of significant amount of environmental degradation and human illnesses. About 40 % of globally used colorants contain organically bound chlorine, a known carcinogen. Chemicals evaporate into the air we breathe or are absorbed through our skin; they show up as allergic reactions and may cause harm to children even before birth. Due to this chemical pollution, the normal functioning of cells is disturbed and this, in turn, may cause alteration in the physiology and biochemical mechanisms of animals resulting in impairment of important functions like respiration, osmoregulation, reproduction, and even mortality. Heavy metals, present in textile industry effluent, are not biodegradable; hence, they accumulate in primary organs in the body and over time begin to fester, leading to various symptoms of diseases. Thus, untreated or incompletely treated textile effluent can be harmful to both aquatic and terrestrial life by adversely affecting the natural ecosystem and causing long-term health effects. Environmental hazards and health problems associated with chemicals used in textile industry are discussed in this chapter.

Environmental and Health Effects of Textile Industry Wastewater

Water pollution caused by the discharge of hazardous textile effluents is a serious environmental problem worldwide. In order to assess the pollution level of the textile effluents, various physico-chemical parameters were analyzed in the textile wastewater and agricultural soil irrigated with the wastewater (contaminated soil) using atomic absorption spectrophotometer and gas chromatography-mass spectrometry (GC-MS) analysis that demonstrated the presence of several toxic heavy metals (Ni, Cu, Cr, Pb, Cd, and Zn) and a large number of organic compounds. Further, in order to get a comprehensive idea about the toxicity exerted by the textile effluent, mung bean seed germination test was performed that indicated the reduction in percent seed germination and radicle-plumule growth. The culturable microbial populations were also enumerated and found to be significantly lower in the wastewater and contaminated soil than the ground water irrigated soil, thus indicating the biotic homogenization of indigenous microflora. Therefore, the study was aimed to develop a cost effective and ecofriendly method of textile waste treatment using native soil bacterium, identified as Arthrobacter soli BS5 by 16S rDNA sequencing that showed remarkable ability to degrade a textile dye reactive black 5 with maximum degradation of 98% at 37 °C and pH in the range of 5–9 after 120 h of incubation.

Toxicity evaluation of textile effluents and role of native soil bacterium in biodegradation of a textile dye.

Cytotoxicity and mutagenicity of textile effluents, treated by gamma radiation in combination hydrogen peroxide was investigated. The Allium cepa , heamolytic, brine shrimp bioassays were used for cytotoxicity evaluation, whereas mutagenicity was tested using Ames tests. Textile effluents were irradiated to the gamma radiation absorbed doses of 5 kGy, 10 kGy and 15 kGy in combination with 20 mM hydrogen peroxide. Before treatment, textile effluents showed a significant cytotoxicity and mutagenicity signs and reduced significantly after treatment. A. cepa showed reduction in cytotoxicity 50%, whereas 56–59% in case of heamolytic test and up 93% reduction in cytotoxicity was recorded by brine shrimp assays. The mutagenicity of gamma radiation treated effluents reduced up to 59% and 54% in case of TA98 and TA100, respectively. Results revealed that the gamma radiation in combination with hydrogen peroxide can be implemented for the detoxification of textile effluents.

Cytotoxicity and mutagenicity evaluation of gamma radiation and hydrogen peroxide treated textile effluents using bioassays

Six textile industries have been selected in East region of Solapur city based on field analysis and characterization studies. Textile effluent from these selected industries is collected and characterized for major pollution indicator parameters namely BOD, COD, TDS, sulphide, sulphate, chloride, hardness, alkalinity, calcium and magnesium. The effluent is dark colored with alkaline pH. The values of BOD and COD are found to be higher than Central Pollution Control Board, Government of India and also ratio of BOD : COD lies between 0.2 - 0.35 indicates that effluent contains large proportion of non-biodegradable matter. The concentration of total dissolved solid are observed to be higher than 5000 mg/L. The effluent also contains high concentration of sulphate, sulphide, chloride, calcium and magnesium, which are responsible for higher hardness of waste water. The results showed that, the textile industries under study area emanate effluent containing pollution indicator parameters considerably higher than standards stipulated by Central Pollution Control Board. Based on these characteristics, it is suggested that the effluent is not be suitable for discharge into environment without treatment.

S. A. Paul

Papers

Studies on Characterization of Textile Industrial Waste Water in Solapur City