**2.1 Classification of ECs**

ECs are classified into organic, inorganic micro-pollutants like pesticides, personal care products (PCPs), pharmaceuticals, synthetic organic dyes, polycyclic aromatic hydrocarbons (PAHs), heavy metals ions, plasticizers, per-fluorinated compounds, flame retardants, surfactants, etc. (**Figure 1**) generated by human activities such as domestic, health care units, agricultural and industrial pathways [10]. These compounds are a source of concern due to their physical and chemical properties because they are widely distributed in the environment which is harmful to humans and wildlife. These pollutants are difficult to detect and have varied activities and miscellaneous sources of production. Their presence in small concentrations causes chronic toxicity, endocrine disruption, and the expansion of pathogen resistance [11].

**Figure 1.** *Classification of emerging contaminants.*

### *2.1.1 Pesticides*

Pesticides, a class of organic contaminants, based on their physical and chemical properties are categorized as fungicides, herbicides, bactericides, and insecticides which are used in the agricultural sector to control dangerous insects, weeds, and microorganisms, etc. Based on their application sites, pesticides are frequently detected in groundwater causing toxicity and may bio-accumulate in humans and plants, or sediments depending on solubility, reactivity, and characteristics of soil and environment. Among the pesticide contaminants, dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane are commonly used pesticides (about 67%) as compared to other compounds such as phorate, chlorpyriphos, Atrazine, methyl parathione, Bentazone, Diazinon, Cyanazine, Simazine, phosphamidone, Terbuthylazine, Alachlor and Dimethoate [12].

### *2.1.2 Pharmaceutical industry*

Pharmaceuticals are major emerging organic contaminants occurring in small amounts in water resources worldwide [13]. Pharmaceuticals are extensively used on daily basis in human healthcare as well as veterinary medicine such as nutrition, investigative aids, therapy and preventive medicine. Many pharmaceutical products such as drugs (both prescribed and non-prescribed), hormones and antibiotics are extensively detected in the aquatic environment, surface and groundwater and have adverse effects on humans, poultry, livestock and fish farming, etc. Generally, livestock is given medications to reduce diseases and infections. Researchers have examined more than 3000 chemicals used in therapeutic products but only small proportion (ng L−1 doses) has been studied in the field, which possibly will lead to negative effects on human and wildlife. To enhance animal farming, organic fertilizer such as manure and purines as medicines are used which indirectly affect the atmosphere and can reach living organisms through food stuff. Commonly reported pharmaceuticals in wastewater are antibiotics, diclofenac, antacids, clofibric acid, steroids, antidepressants, ciprofloxacin, propranolol, beta blockers, analgesics, salicylic acid, fluoxetine, antipyretics, anti-inflammatory drugs, nitroglycerin, tranquilizers, lipid-lowering drugs and stimulants [14].

Natural or synthetic hormones are also essential ecological contaminants, because of their estrogenic and androgenic impacts on wildlife. Organic and inorganic hormones consist of 17α-estradiol, 17β-estradiol, estrone, equiline, equilenin, estriol, mestranol and norethindrone which can enter atmosphere through farming, and are not completely eliminated from wastewater and harm aquatic life and humans.

### *2.1.3 Personal care products (PCPs)*

Personal care products (PCPs) are household chemicals commonly used for health, odor, beauty, or cleaning. These chemicals are used in personal care products like ornamental cosmetics, soaps, hair and skin care products, lotions, fragrances and sunscreens. PCPs are used in large quantities throughout the world due to which the release of these pollutants in the environment is increasing day by day [15]. Mostly these substances are bioactive and bioaccumulative and harm the environment and humans [16]. The most probable emerging contaminants in PCPs are antiseptics, perfumes pollutants like galaxolide, pest repellants, preservatives diethyl phthalate ultraviolet (UV) filters and Triclosan (TCS) and triclocarban as disinfectant

### *Technologies for Removal of Emerging Contaminants from Wastewater DOI: http://dx.doi.org/10.5772/intechopen.104466*

pollutant. Parabens are antimicrobial preservatives used in cosmetic items, pharmaceuticals, and some food stuffs such as benzyl, butyl, ethyl, isobutyl, isopropyl, methyl, and propyl hydroxybenzoates. Polycyclic musks are used in numerous products such as clean-up products, shampoos, hair care and washing products and cosmetic products. Their use on the outside of human skin increases its discharge in environment without any metabolic changes. Among all these products, cosmetics are frequently used, thus its occurrence in air at low quantity may be a source of damage to human beings, wildlife and environment.

### *2.1.4 Surfactants*

Surfactants are synthetic organic compounds used all over the world in making of household products such as emulsifiers, detergents, paints, and pesticides, in addition to personal care products and are harmful to aquatic species [17]. They are classified as cationic, anionic and zwitterionic surfactants. Frequently used surfactants such as fatty alcohol ethoxylates, linear alkyl benzene sulfonates, lignin sulfonates, and alkyl phenol ethoxylates are produced on a large scale. Furthermore, octylphenol and nonyl-phenol ethoxylates, are highly toxic even at low concentrations and must be substituted in all their uses.

### *2.1.5 Food additives*

Numerous artificial sweeteners such as acesulfame, saccharin and sucralose which are extensively used in foodstuff, pharmaceuticals and hygiene products find their way to domestic wastewater via human excretion. These moderately metabolized sweeteners which pollute the environment are usually hard to remove. Though, latest calculated ratio for predicted environmental concentration (PEC) and predicted no effect concentration (PNEC) of compound sucralose for marine system is below 1 indicating limited threat to aquatic system (plants, algae and fish) [18].
