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Industrial Wastewater Contaminants and Their Hazardous Impacts
Camila Pesci Pereira1, JoĂŁo Pedro Neves Goldenstein2, and JoĂŁo Paulo Bassin1,2
1 Chemical Engineering Program, COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
2 Civil Engineering Program, COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
Introduction
Industrial and technological development and population growth have provided countless advances in society and improved quality of life. However, the increase in production and consumption capacity also negatively impacts the planet due to emission of harmful gases and the increasing production and consequent disposal of solid wastes and wastewaters from domestic and industrial sources. The volume and concentration of contaminants present in waste streams depend on several factors such as population density, level of technological development in the country or region, climate, seasonality, etc.
Contamination of water and soil by industrial waste is a global concern. For most industries, providing access to clean, affordable water is one of the biggest challenges. In addition, industrial wastewater contains several polluting compounds (Hashemi et al., 2018; Barak et al., 2020). Thus, there is a need to establish the management of and industrial wastewaters based on strict environmental protocols, with the objective of eliminating these contaminants from the environment as much as possible. As a result, through the use of recent technologies, research has been carried out to provide intelligent solutions not only from an environmental point of view but also from an economic standpoint. Therefore, several technologies based on physical, chemical, and biological methods are investigated (Hashemi et al., 2018).
This chapter describes some of the contaminants present in industrial wastewaters, their environmental impacts, and their risks to human health. In addition, the efforts made to evaluate and define the best ways to control their dissemination in the environment are presented, as well as the treatment processes used and studied for eliminating contaminants.
Toxic Heavy Metals
Heavy metals are a classic group of metallic elements that cannot be overlooked as industrial wastewater contaminants due to their toxicity. According to the World Health Organization (WHO), some of these pollutants (e.g. arsenic, lead, mercury, and cadmium) are included in the top 10 issues of primary concern (air pollution, arsenic, asbestos, benzene, cadmium, dioxin and dioxinâlike substances, inadequate or excess fluoride, lead, mercury, and highly hazardous pesticides) because they are widely spread worldwide, they are highly hazardous, and negatively affect human health and natural ecosystems (WHO, 2020). Moreover, such substances are significantly dense and persistent and have shown toxicity even at part per billion (ppb) levels (Yadav et al., 2019). Compared to other contaminants, heavy metals can be neither degraded nor destroyed and can easily accumulate along the food chain. This phenomenon, known as bioaccumulation, increases the concern about suitable methods to treat industrial wastewaters.
Heavy metals are natural constituents of the Earth's crust, and heavy metal contamination in the environment results from natural and anthropogenic sources. Human activities are the leading causes of pollution. First, these metals are found in the form of chemical compounds or elemental state in rocks as ore deposits, which are explored through mining techniques. Environmental contamination by these compounds is not only a result of the business of mining â the largest contributor to heavy metal pollution â but may also be caused by improperly treated industrial wastewaters that reach natural ecosystems. The most common heavy metals found in industrial wastewaters are lead, cadmium, mercury, arsenic, copper, zinc, nickel, and chromium, which come from the paint, mining, metal manufacturing (electroplating, smelting, finishing, etc.), and textile industries (Akpor et al., 2014). From natural sources, the main contributions come from volcanic activity, soil erosion, and runâoff. These hazardous waters deteriorate aquatic systems and terrestrial environments and retard biota growth (i.e., seed germination, chlorophyll production, and enzyme activity), with reported cases of carcinogenic, teratogenic, mutagenic, and neurotoxic effects.
There are multiple criteria to define an element as a heavy metal; however, one of the most frequently adopted classifications is based on the eleme...