Detox Fashion: Waste Water Treatment Edited by Subramanian Senthilkannan Muthu

Contents

Sustainable Waste Water Treatment Technologies
P. Senthil Kumar and A. Saravanan

Abstract: Nowadays, the environmental problems associated with residual colour in industrial effluents have posed a serious threat to many environmental scientists. The effluents from the industries have liberated wide variety of pollutants which can directly introduce into the natural water sources. The industrial sector usually consumes enormous amount of water for manufacturing the sportswear, fashion and luxury brands of clothes. In that, several hazardous chemicals were added for colouring and designing purposes which contains many organic and inorganic substances, ammonia, infectious microorganisms, detergents, heavy metals, pesticides and household cleaning aids. These water pollutants are toxic to fish and other aquatic lives and it is also harmful to humans. So, there is a need for removal of toxic pollutants from the industrial effluents. The methods for controlling the water pollution can be majorly classified into three steps: (i) Primary (screening, sedimentation, homogenization, neutralization, mechanical flocculation, chemical coagulation) (ii) Secondary (aerobic and anaerobic treatment, aerated lagoons, activated sludge process, trickling filtration, oxidation ditch and pond) and (iii) Tertiary (membrane technologies, adsorption, oxidation technique, coagulation and flocculation, electrochemical processes, ion exchange method, crystallization, Evaporation). This chapter describes a critical review of the current literature available on various wastewater decolourization techniques being applied to remove the hazardous chemicals from industrial wastewater.

Keywords: Industrial effluent _ Hazardous chemicals _ Pollution _ Treatment _ Colour removal

1 Introduction
Water, air and nourishment are among a portion of the fundamental components in life. Subsequently, natural contaminations and the shrinkage of valuable items have influenced the lives of numerous (Mehta et al. 2015; Bhatnagar et al. 2011). The world comprises of a noteworthy bit (around 71%) of water however freshwater adds to just a minor portion of 2.5%. Be that as it may, more than 60 billion m3 a time of freshwater is expected to adapt to the yearly worldwide populace development of 80 million individuals. Persistent populace development, expanding way of life, environmental change, industrialization, farming and urbanization are setting off the reduction in water asset around the world (Wu et al. 2013). The expulsion of suspended matter from water is one of the real objectives of water treatment. Lately there has been impressive enthusiasm for the improvement of utilization of regular coagulants which can be created from plants. Water, food and energy securities are emerging as increasingly important and vital issues for India and the world. Most of the river basins in India and elsewhere are closing or closed and experiencing moderate to severe water shortages, brought on by the simultaneous effects of agricultural growth, industrialization and urbanization (Ihsanullah et al. 2016). Current and future fresh water demand could be met by enhancing water use efficiency and demand management.

Thus, wastewater/low quality water is emerging as potential source for demand management after essential treatment. An estimated 38,354 million litres per day (MLD) sewage is generated in major cities of India, but the sewage treatment capacity is only of 11,786 MLD. Similarly, only 60% of industrial wastewater, mostly large scale industries, is treated. Performance of state owned sewage treatment plants, for treating municipal waste water, and common effluent treatment plants, for treating effluent from small scale industries, is also not complying with prescribed standards.

According to World Mapper Project (2007), 990 billion m3 of water utilized for domestic and industrial purpose worldwide each year and then this freshwater is transformed into wastewater. This wastewater mostly comprises of hazardous chemical which are persistent in nature. They can gradually accumulate in the food chain, in turn, can cause long-term, irreversible damage to people like cancer, delayed nervous damage, malformation in urban children, mutagenic changes, neurological disorders etc. (Qu et al. 2013). And they also have serious impact upon environment such as eutrophication or oxygen depletion in lakes and rivers. Therefore, many Environmental laws were enacted and their enforcement also made
stricter.

The textile manufacturing utilizes an assortment of chemicals, contingent upon the way of the crude material and final result. Some of these chemicals are diverse compounds, cleansers, colours, acids, soft drinks what’s more, salts. Material finishing sector utilizes a lot of water, basically as a result of colouring and cleaning/washing operations. Clearly the wastewater gushing created from these units contains extensive measures of dangerous toxins (Paul et al. 2012). On the off chance that these waste waters are released into nature they will cause genuine and unsafe effect not just on underground and surface water bodies and land in the encompassing region additionally will adversely affect the sea-going biological framework. Due to utilization of colours and chemicals, effluents are dull in shading, which builds the turbidity of water body.

The qualities of industrial effluents fluctuate and they basically rely upon the kind of material made furthermore, the chemicals utilized. The industrial wastewater gushing contains high measures of operators harming nature and human well being and also it includes suspended and broke down solids, natural oxygen request (BOD), compound oxygen request (COD), chemicals, contain follow metals like Cr, As, Cu and Zn (Qu et al. 2013; Rao et al. 2006).

At whatever point great quality water is rare, water of marginal quality should be considered for use in farming. In spite of the fact that there is no widespread meaning of ‘marginal quality’ water, for all functional purposes it can be characterized as water that has certain attributes which can possibly bring about issues when it is utilized for an expected reason. For instance, brackish water is marginal quality water for farming use due to its high broke up salt substance, and metropolitan wastewater is negligible quality water as a result of the related well being perils. From the perspective of water system, utilization of “negligible” quality water requires more perplexing administration practices and more stringent observing techniques than when great quality water is utilized. Development of urban populations and expanded scope of domestic water supply and sewerage offer ascent to more prominent amounts of metropolitan wastewater. With the current emphasis on ecological health and water contamination issues, there is an expanding attention to the need to discard these waste waters securely and gainfully.