Disinfection By-Product Formation and Mitigation Strategies in Point-of-Use Chlorination with Sodium Dichloroisocyanurate in Tanzania

Abstract

Abstract. Almost a billion persons lack access to improved drinking water, and diarrheal diseases cause an estimated 1.87 million deaths per year. Sodium dichloroisocyanurate (NaDCC) tablets are widely recommended for household water treatment to reduce diarrhea. Because NaDCC is directly added to untreated water sources, concerns have been raised about the potential health impact of disinfection by-products. This study investigated trihalomethane (THM) production in water from six sources used for drinking (0.6-888.5 nephelometric turbidity units) near Arusha, Tanzania. No sample collected at 1, 8, and 24 hours after NaDCC addition exceeded the World Health Organization guideline values for either individual or total THMs. Ceramic filtration, sand filtration, cloth filtration, and settling and decanting were not effective mitigation strategies to reduce THM formation. Chlorine residual and THM formation were not significantly different in NaDCC and sodium hypochlorite treatment. Household chlorination of turbid and non-turbid waters did not create THM concentrations that exceeded health risk guidelines.

Trihalomethanes formation in point of use surface water disinfection with chlorine or chlorine dioxide tablets

“…On the other hand, much less is known about the effect of point‐of‐use disinfection on chemical water quality, for instance regarding the formation of undesirable disinfection by‐products (DBPs) (Lantagne et al . ; Smith et al . ).…”

“…THMs formation in point of use surface water disinfection is less well investigated (Lantagne et al . ; Smith et al . ).…”

“…On the other hand, much less is known about the effect of point-of-use disinfection on chemical water quality, for instance regarding the formation of undesirable disinfection by-products (DBPs) (Lantagne et al 2010;Smith et al 2010). Several chlorinated DBPs such as trihalomethanes (THMs) are formed when dissolved organic matter and other precursors in water react with chlorine (Serodes et al 2003).…”

Renewable energy powered membrane technology: Fluoride removal in a rural community in northern Tanzania

“…TOC is used to quantify natural organic matter (NOM) which has been emphasized as the precursor to disinfection by-products including trihalomethanes (THMs) [38]. United States Environmental Protection Agency (USEPA) indicates that water with TOC above 2 mg/L requires treatment to avoid THMs formation [39] and in consequence this is a target value for this case study as chlorination is often performed in an uncontrolled manner in Tanzania [40]. In the European guideline for drinking water, TOC is related to the indicator parameters, and it should not show abnormal change.…”

Utilisation of Water Purification “Tablets” at Household Level in Namibia and Tanzania

“…The tablets are active over wide ranges of pH, turbidity, hardness, and pathogenic challenge. The chemical is resistant to sunlight damages, offers single use packaging and its low weight packaging approach make it easy for distribution [24]. Clasen and Edmondson [25] reported that the use of household water treatment methods such as aqua tabs reduces the burden of Diarrhea in the community.…”