CECs can result from commercial, domestic, agricultural, and industrial origins, like any pollutant. They can be detected in remote and unlikely areas due to their persistence and long‐distance mobility. Some of these substances can disturb the endocrine system, interfering with the hormonal action of animals and humans; they are referred to as EDCs and can cause reproductive effects, hormonal dysfunction, fertility problems, and diseases such as cancer, etc. (Nawaz and Sengupta, 2019; EPA, 2020).
EDCs include steroids, alkylphenols, polyaromatics, organic oxygen compounds, pesticides, and others (Salimi et al., 2017). They can be synthetic or natural. Examples of synthetic compounds are alkylphenols, phthalates, polychlorinated biphenyls, bisphenol A (BPA), and pharmaceutical agents such as estrogen 17α‐ethinylestradiol (Salimi et al., 2017). Among natural EDCs are the estrogens estrone, estriol, and 17β‐estradiol. Estrogens are hormones responsible for several female endocrine functions, and some of them can be used in the production of contraceptives and hormone replacement medicine (Hamid and Eskicioglu, 2012).
Few studies in the literature discuss the biodegradation, metabolization, and effects of CECs (Salimi et al., 2017). However, the advance of modern technologies, such as high‐performance liquid chromatography, allow the detection of substances in lower concentrations (on the order of ng/L) in different environmental matrices. Thus, studies have been carried out to investigate and improve the removal of these compounds from both domestic and industrial wastewaters. Biological treatment (activated sludge and biofilm‐based processes) and AOPs (ozonation, TiO2 photocatalysis, Fenton process, and photo‐Fenton process) have been extensively investigated for this purpose.
Conclusion
The primary contaminants found in industrial wastewater have been shown to commonly originate from human activities. Industrial wastes are becoming more recalcitrant, complex, and abundant due to the increasing development of society, and the list of pollutants. This chapter addressed the effects of toxic heavy metals, oil and grease, biocides, dyes, recalcitrant and organic compounds, and contaminants of emerging concern.
Regarding toxic heavy metals, it is important to differentiate between heavy metals and toxic metals. The classification of many elements and compounds is largely based on their density. However, not every heavy element is toxic. With that in mind, copper, lead, chromium, cadmium, zinc, and arsenic are the most important. Bioaccumulation, vomiting, diarrhea, and inflammation are the usual symptoms of toxic heavy metal poisoning. Furthermore, such pollutants negatively impact humans and other species, hindering their reproductivity and metabolism, which unbalances the food chain as a whole.
Chemically speaking, dyes were developed to resist degradation since they have hydrophilic and chromophoric groups that provide color and strong persistence in aqueous phases. The primary consumer of dyes is the textile industry, which generates millions of dollars annually worldwide. Other sectors are also important in this context, such as the paper, tannery, food, pharmaceutical, and cosmetic industries. It must be noted that natural‐based dyes are not the focus of this discussion since they are much more biodegradable than synthetic dyes and are less frequently used.
Oil and grease have always been one of the primary human contaminants in wastewaters. However, society is and will continue to be strongly dependent on petroleum and its derivatives. Thus, oil and grease from this industry will continue to