Читать книгу Pollutants and Water Management - Группа авторов - Страница 56

Water is one of the most essential resources for the existence of animal and plant life. The existence of plants, animals, and humans on Earth depends on nature playing an important role in providing water (Sharma et al. 2016). Rivers, lakes, and reservoirs are a major source of water in India. Some 80% of India's population is dependent on 14 major rivers for food and their livelihood. A growing population, accelerating industrialization, intensification of agriculture, and expanding urbanization exert heavy pressure on our vast but limited water resources. Despite so many priceless advantages, it is a poorly managed resource (Nwankwoala and Nwagbogwu 2012) because of its easy availability at a low cost. Both surface and groundwater resources are under stress. The increase in the growth rate of industrialization and urbanization created an unconstructive and adverse impact on water resources. The main reasons of water pollution are: (i) soil weathering; (ii) decomposition of organic materials; and (iii) untreated or not efficiently treated discharge effluent from industries, sewage, and municipal waste. From these mentioned causes, industrial pollution is considered as one of the factors causing the degradation of water quality (Järup 2000). Water discharge from industries and households carries chemicals and biological matter, which leads to an increase in demands on oxygen (DO) present in water, thereby reducing the level of DO due to biological oxygen demand (BOD) and chemical oxygen demand (COD) (Afzal et al. 2018).

In developing countries like India, the major contributors to water pollution are the endpoints of effluents released from industries. Contaminated wastewater released from industrial areas creates negative impacts on human health and also makes the soil quality unsuitable for irrigation purposes and crops. So, it becomes crucially important to access the quality of water before directly discharging it into the environment (Bharti et al. 2013). Based on the industry type, many levels of pollutants are directly or indirectly discharged through public sewer lines into water bodies (Kumar et al. 2018. 2019). According to the State of India's Environment (SoE) 2019 report (www.downtoearth.org.in/news/pollution/grossly‐polluting‐industries‐more‐than‐doubled‐in‐8‐years‐soe‐in‐figures‐64962), there has been a substantial increase in the number of grossly polluting industries (GPIs) between 2011 and 2018. There was a 136% increase in the number of GPIs over the period for the demands of the increasing population in the country.

GPIs are defined as industries that discharge more than 100 000 L of wastewater and/or hazardous chemicals into rivers or water bodies. The different types of GPIs are pulp and paper mills, distilleries, sugar mills, textile units, tanneries, thermal power plants, food, dairy, and beverage industries, chemical units, slaughterhouses, etc. As a result of this, the freshwater that Indian rivers carry is now so severely polluted that rivers threaten the very life they once nurtured. There are 992 GPIs in the river Ganga and its tributaries, i.e. Kali and Ramganga, and, from these, 851 industrial units are found in Uttar Pradesh, 61 in Uttarakhand, 43 in West Bengal, and 40 in Bihar (www.downtoearth.org.in/news/pollution/faith‐to‐filth‐thanks‐to‐kumbh‐prayagraj‐sinks‐in‐solid‐waste‐64579). The major water pollution contributors in Kosi, Ramganga, and Kali river catchments are tanneries, sugar and distilleries, and pulp and paper units. Panigrahi and Pattnaik (2017) in their report mentioned that the Gomati River near Lucknow urban center is mostly polluted by heavy metals. Malik et al. (2014) mentioned that many industries are situated near the bank of the Yamuna River, therefore, it is considered the most polluted river in India. Ahirwar et al. (2015) state the major cause of water pollution in the River Son is due to effluents discharged from thermal power plants and pulp and paper industries. Therefore, it can be said that water body pollution due to industrial discharge affects the food web and hampers public health (Ahirwar et al. 2015). It becomes crucially important to access and control the quality of water bodies by proper treatment of the wastewater at the source itself before directly discharging it to the environment (Bharti et al. 2013).

This chapter examines the major contributing wastewater industries, their present status, and the major pollutants released from different types of industries situated in India. The impact of pollutant discharge from these industries into rivers, drains, and so on, are also discussed in detail. The current status and quality of rivers including the River Ganga and its tributaries, Yamuna, Cauvery, Narmada, and Bandi are also highlighted. The role of different legal authorities and monitoring bodies to control the water pollution caused by industries and their rules, regulations, and drawbacks are explained in the last section of the chapter.