2. Techniques for water treatment

Water treatment is defined as the removal of the above contaminants using some specific process. In most of the water treatment processes, conventional adsorption process with activated carbon is adopted and the adsorption capacity is substantially decreased in presence of high concentration of organic matters in water where the active sites are mostly occupied by these materials. In recent times, there are various technologies have been employed for the removal of water contaminants such as filtration (ceramic, bio sand, membrane, and activated carbon based filtration), heat and UV radiation, chemical treatment (coagulation-flocculation,

chemical disinfection), and desalination (reverse osmosis, distillation). The various techniques in water treatment can categorized into following six classes [19]:

• Adsorption

compounds (VOCs), pesticides, phenolic compounds, phthalates, and nitrogen-containing compounds, are often detected in polluted water [11]. Many of these compounds have been found to be carcinogenic, even in very low concentrations. WHO Guidelines for drinking water quality, levels are set for 28 organic constituents (i.e., microcystin-LR, chlorinated alkanes, chlorinated benzenes and miscellaneous), 33 pesticides, and 9 disinfectant by-products, due to their health effects on humans [12]. It is noteworthy to mention that, occurrence of pharmaceutical and personal care products and perfluoroalkyl acids in aquatic environment has been recognized as

Inorganic contaminants include metals, salts and other compounds that do not contain carbon. Many of them are naturally occurring and should be considered as an integral part of those waters, e.g., calcium carbonate and bicarbonate in hard water. The metal ions such as Hg(II), Pb(II), Cr(III), Cr(VI), Ni(II), Co(II), Cu(II), Cd(II), Ag(I), As(V) and As(III) are toxic from eco toxicological point of view. Besides, the pollution by the radioactive elements is of major

Pathogens such as bacteria, viruses and parasites may be present in very low concentration in drinking water; but cause many infectious diseases and are considered as one of the major risk factors with drinking water safety [14]. The pathogenic microorganisms enter in to water body through sewage discharge as a major source or through the wastewater from industries like slaughterhouses. Water-borne pathogens have been the causes of many disease outbreaks such as diarrhea, cholera, gastro-intestinal illness [15]. The recurrence of water-borne pathogens is due to a number of reasons like heavy water contamination, population explosion, change in potable water treatment methods, globalization of commerce and travel. It has been made possible to detect pathogen based water contamination to a large extent owing to the improved methods for detection and source tracking [16, 17]. The most serious health risk is related with ingestion of water which is contaminated with fecal matter and the discharge of wastewater into various ambient water bodies is what contributes to the multiplication of

Water treatment is defined as the removal of the above contaminants using some specific process. In most of the water treatment processes, conventional adsorption process with activated carbon is adopted and the adsorption capacity is substantially decreased in presence of high concentration of organic matters in water where the active sites are mostly occupied by these materials. In recent times, there are various technologies have been employed for the removal of water contaminants such as filtration (ceramic, bio sand, membrane, and activated carbon based filtration), heat and UV radiation, chemical treatment (coagulation-flocculation,

numbers of such pathogens (bacteria, viruses, protozoa and helminthes) [18].

emerging issue in environmental chemistry [13].

64 Emerging Pollutants - Some Strategies for the Quality Preservation of Our Environment

concern looking into their long-term hazardous impacts.

2. Techniques for water treatment

1.2.2. Inorganic contaminants

1.2.3. Pathogens


There are specific advantages and disadvantages for a particular process. The nanotech based processes are promising option in current water treatment processes because of their target specificity, ease of separation, high adsorption per unit area, as well as less maintenance.
