ISSN 2321 3361 © 2019 IJESC Research Article Volume 9 Issue No. 6 A Review on Biotechnical Solution for Treatment of Effluents Discharged from Dyeing Industries Aarushi Ruhela1, Sayed Mohammad Faizan2, Sonam Singh3, Bhanu Pratap Singh Kushwaha4, Brajesh Singh Katiyar5 Department of Biochemical Engineering Harcourt Butler Technical University, Kanpur, India Abstract: Diminishing fresh water resources is a global crisis. The consumption of fresh water by anthropogenic activities results in decreasing availability of fresh water. The major cause of water pollution is that water bodies are used as sinks for wastewater generated from domestic and industrial sources. Dyeing industry generate effluent that are rich in colorants and release into the environment which burgeons environmental issues also exacerbating human health. Colour removal from dyeing industry effluent has become a serious challenge due to the presence of synthetic dyes and till now there is no single method scouted which can aggrandize the process of treating coloured waste water. Effluents from dyeing industries contain higher concentrations of suspended solids that can be potentially toxic as they contain recalcitrant pollutant. This present article is a critical review presenting the causes and characteristics of wastewater generated. Also it incorporates different methods used for the decontamination of the effluents and highlighting those which involves biotechnological solution. A comparison between traditional methods and biotechnical solution and how the later one is more efficient is proven. Including a study of different microorganisms and enzymes able to degrade different dyes consummating the task. Keywords: Effluents, Textile Dyes, biotechnical methods, BOD, COD, TDS, TSS. I. INTRODUCTION colours, better light fastness, more resistant to washing and having wider variety of colours. Effluent generated from Textile industries contributes to a great extent in Indian GDP dyeing industries are highly coloured as it contains a variety of affording second largest employment after agriculture[1].It is a synthetic dyes. When the effluent reaches to receiving water multi-billion dollar growing swiftly with the increase in body, the chromospheres of dyes strongly absorb sunlight and number of chromatophilians. Relatively the production of able to obstruct photosynthesis process by the aquatic flora that different types of dyes and pigments has also jumped from 240 results in increasing BOD and COD of water body. Synthetic thousand to 320 thousand metrics tons[2].Dye comprise of far dyes are also responsible for surrounding air pollution due to range of different types based on their solubility, uses and evaporation of effluent as several dyes are potentially toxic. chemical properties. It contains chemical such as sulphuric Removal of colouring material from effluent is a major acid, sodium oxychloride, sodium hydroxide, bleaching problem due to the presence of complex pollutants that resist powder and many more. It has been quantified that10-15%of degradation and tend to persist in environment for long time. the dye is emancipated in the environment during synthesizing these complex pollutants are known as recalcitrant pollutants. and dying process[3]. These discharged effluents contains The chemical structure of dyes contains conjugate double many injurious and destructive components which posses high bonds and aromatic rings but sometime unusual substitution level environmental threat. It involves oily scum, colloidal with halides (Cl and Br), very large molecular size, presence of matter, colour resulting in turbidity, foul smell and unpleasant tertiary and quaternary carbon atom also result in recalcitrant advent distinguished with high COD and BOD values. It can pollutants. also out-turn the physiological and biochemical changes in aquatic life forms [4]. Various Treatment methods for dyeing III. DEFINITION OF TEXTILE DYES: effluents are available but none of them is effective on its own. Different chemical method has shown some success in the A natural or synthetic dye is a material that have an affinity to treatment of dyeing effluent but with some serious drawbacks. substrate to which it is being applied. There are different Diverse chemical and physical decolourization methods sources depending on which dyes can be classified as Natural (Adsorption, precipitation, flocculation, oxidation, electrolysis, (derived from plant source e.g. roots, leaves) and Synthetic filtration, coagulation, use of activated carbon, and membrane (derived from petrochemical e.g. coal) and different pigment extraction)are productive for colour expulsion but utilizes can be formulated by varying concentration of several supplement amount of energy and chemical[5]. Other methods chemicals. such as RO, Nano filtration, MEE are effective but expensive IV. CATEGORY OF DYES: for a treatment on large scale[6]. In such a developing era, need for aesthetic appeal is rising that II. NEED FOR TREATMENT OF EFFLUENT: has evolved new shades of dyes. Therefore, there are numerous type of dyes been used in the industries. Generally dyes used in Dyeing of textile is a chemical process. It includes a number of industries can be broadly categorised as- toxic chemicals to make the process efficient. Today Synthetic Sulphur dyes-These are insoluble and made soluble dyes are used instead of Natural dyes due to their superior by the help of caustic soda and sodium sulphide. Dyeing is performance as compared to natural dyes as it imparts brighter IJESC, June 2019 22999 http://ijesc.org/ done at high temperature with large quantities of salt so that disperse in water. These were originally developed for the colour penetrates into the fibre. dyeing of cellulose acetate-azoic dyes-dyes characterised by Direct dyes-they colour cellulose fibre directly the presence of azo group as a chromospheres. These are found without the use of mordents. They Have Poor fastness to in many of synthetic dyes. washing. Acid dyes-These are used on wool, other animal and Disperse dyes-They are water insoluble. These are manufactured fibres. They are widely used on nylon when high finely ground and are available as a paste or powders that get wash fastness is required. Table 1. Types of Dye Type of Dye Instance Structure Acid dye Acid violet 30 Azodye Bismarck brown R Basic dye Basic yellow 28 Disperse dye Dispersed red 220 Reactive dye Reactive red I Vat dye Vat blue 4 Mordant dye Mordant Brown 33 Naphthol dye Naphthol yellow S Gel dye BCG(Bromocresol green) Pigments Pigment blue 15 Sulfur dye Indophenol Natural dye Cochineal IJESC, June 2019 23000 http://ijesc.org/ V. CHARACTERISTICS OF WASTE-WATER Elango (Et al) compared the physio chemical parameters of DISCHARGED FROM DYEING INDUSTRIES: textile dyeing effluent with standard BIS limits. The results of In order to improve environmental condition, it is important to the analysis are presented in TABLE (2).[7] analyse all the features of textile dyeing effluents. Gomathi Table 2. Characteristic of waste water discharged from textile dyeing industries. Parameters Observed Values BIS Limits Colour Colour,Hazel 5200 25 pH at 300 C 8.66 5.5-9 Total Hardness 970 500 BOD,mg/l 970 100 COD,mg/l 3080 250 TDS,mg/l 242220 2100 TSS,mg/l 7116 100 Turbidity,NTU 81.5 10 Chlorides, as Cl-, mg/l 42487 600 Sulphides, as S2-, mg/l 0.46 2 Silica, as SiO2, mg/l 1087 250 Calcium, as Ca, mg/l 172.3 200 Iron, as Fe, mg/l 0.16 3 Oil and grease, mg/l 18 10 VI. ENVIRONMENT AND HEALTH ISSUES: 90% in solution is the reverse osmosis which is a type of filtration method. Some years ago, few experiments were The toxic effluent generated from dyeing industries if exposed carried out for the treatment in industry in which the discharge to environment, might cause ruination of earth’s natural beauty rate required was up to 93% after operation[9].Extraction of by polluting land, water and surrounding air that result in vat dyes using reverse osmosis technique was studied by heavy diseases to human, animals and shorten their life. It also Kashefi and Bahrami[10]. Effect of various parameter like feed affects biotic and aquatic life forms. The intrusion of dyes concentration, pH, temperature, etc is carried out on the effect parameters like DO, BOD etc. BOD, COD and DO are experiment and then a survey is done. The experiment makes co-related. The adverse effect is seen on aquatic organisms as use of 30mg/L dye solution where it was found out that pH 4 they suffocate and die when higher COD in effluent induces and temperature 25°C were the most favourable conditions for the BOD as a result it consumes more dissolved oxygen. The the technique. The maximum rate of discharge was obtained at toxicity of water also gets increased due to changing the value 94% after completing through the membranes in the of water pH for example water with pH value of about 10 are experiment[10]. exceptional and may be a sign of pollution by strong bases such as NaOH and Ca(OH)2 [8] .On the other hand, Chemical Technique- evaporation of effluent cause emission of toxic chemicals in Chemical technique consists of techniques like chlorination, surrounding that destroy the stratospheric ozone layer result in neutralization, ozonation etc. Chemical techniques employ the raising global warning. application of chemical reactions to improve the water quality. The most widely used chemical techniques is VII. TRADITIONAL TECHNIQUES: chlorination. Bacteria are eliminated using a strong oxidising agent generally chlorine (Cl ). Industrial wastewater There are many by which treatment of dyeing industries treatment uses one of the most prominent chemical method effluents can be carried out. These methods can be broadly that is neutralization. In concept, ₂neutralization is the process classified as follows: of maintaining the pH level at neutral by the addition of acid Physical Technique and base. One of the other method used for wastewater Chemical Technique treatment is ozonation, it is very efficient in deterioration of Biological Technique colour that are reactive in nature, also reduces COD and other poisonous contaminants of the wastewater generated from Physical Technique- dyeing industries efficiently [11-15].