SHOULD WATER CHLORINATION BE BANNED?
The recorded deaths due to waterborne diseases have demonstrated that water treatment is critical. Thus, methods like water chlorination have been developed to achieve water quality. This procedure has exhibited notable decreases in diarrhoeal diseases, and has shown prolonged disinfecting effects on many microorganisms when used with ammonia. However, there exists protozoa that are resistant to chlorination, and such spores have led to outbreaks that resulted in a decreased economy and an infected population. Moreover, the toxic and corrosive nature of the chlorinating products exposed to employees in the industry raises the question, “Should water chlorination be banned?”
When chlorine is added to water (H2O), hypochlorous acid (HOCl) and/or hypochlorite anions (OCl-) are formed. The combination of these creates free chlorine, the most effective chlorine based disinfectant. Common chlorinating products include chlorine gas (Cl2) and calcium hypochlorite [Ca(OCl)2]. The water treatment process often consists of screening, coagulation, settling, filtering, and disinfection (How is Water Purified?, n.d.); refer to Figure 1. Figure 1: Water …show more content…
The degree of this dissociation is dependent on the initial pH of the treated water. As HOCl is a more effective disinfectant than OCl-, higher concentrations of HOCl are desired. This is because germ surfaces, like OCl-, carry a negative charge, causing them to repel in each other’s presence (What is Chlorination?, n.d., American Chemistry Council, n.d.) Thus, water with a pH below 6.5 is optimal, as the dissociation at this level is minimal, allowing HOCl to dominate. However, when the pH exceeds 8.5, complete dissociation of HOCl will occur, causing OCl- to dominate, resulting in a less effective disinfectant (What is Chlorination?, n.d.). Refer to Figure 5
The recorded deaths due to waterborne diseases have demonstrated that water treatment is critical. Thus, methods like water chlorination have been developed to achieve water quality. This procedure has exhibited notable decreases in diarrhoeal diseases, and has shown prolonged disinfecting effects on many microorganisms when used with ammonia. However, there exists protozoa that are resistant to chlorination, and such spores have led to outbreaks that resulted in a decreased economy and an infected population. Moreover, the toxic and corrosive nature of the chlorinating products exposed to employees in the industry raises the question, “Should water chlorination be banned?”
When chlorine is added to water (H2O), hypochlorous acid (HOCl) and/or hypochlorite anions (OCl-) are formed. The combination of these creates free chlorine, the most effective chlorine based disinfectant. Common chlorinating products include chlorine gas (Cl2) and calcium hypochlorite [Ca(OCl)2]. The water treatment process often consists of screening, coagulation, settling, filtering, and disinfection (How is Water Purified?, n.d.); refer to Figure 1. Figure 1: Water …show more content…
The degree of this dissociation is dependent on the initial pH of the treated water. As HOCl is a more effective disinfectant than OCl-, higher concentrations of HOCl are desired. This is because germ surfaces, like OCl-, carry a negative charge, causing them to repel in each other’s presence (What is Chlorination?, n.d., American Chemistry Council, n.d.) Thus, water with a pH below 6.5 is optimal, as the dissociation at this level is minimal, allowing HOCl to dominate. However, when the pH exceeds 8.5, complete dissociation of HOCl will occur, causing OCl- to dominate, resulting in a less effective disinfectant (What is Chlorination?, n.d.). Refer to Figure 5