Assessment of Recommendation for the Containment and Disinfection of Human Excreta in Cholera Treatment Centers

Abstract

Containment, safe handling and disinfection of human excreta in cholera treatment centers (CTC) are key to preventing the onward spread of the disease. This study compared the efficacy of three chlorine-based approaches at concentrations of 0.5%, 1%, and 2% and one hydrated lime-based (Ca(OH)2 at 30% w:v) approach. Experiments followed existing Médecins Sans Frontières (MSF) cholera guidelines. Three simulated human excreta matrices consisting of either raw municipal wastewater (4.5 liters), or raw municipal wastewater plus 1%, or 20% faecal sludge (w:v), were treated in 14 liter Oxfam® buckets containing 125 mL of chlorine solution or hydrated lime suspension. Bacterial indicators (faecal coliforms (FC) and intestinal enterococci (IE)) and viral indicator (somatic coliphages (SOMPH)) were used to determine treatment efficacy following contact times of 10, 30 and 60min. Results showed that efficacy improved as chlorine concentrations increased. No statistical differences were observed with respect to the various contact times. Overall median log removal for 0.5% chlorine were: FC (1.66), IE (1.41); SOMPH (1.28); for 1% chlorine: FC (1.98), IE (1.82); SOMPH (1.79); and for 2% chlorine: FC (2.88), IE (2.60), SOMPH (2.38). Hydrated lime (30%) provided the greatest overall log removal for bacterial indicators (FC (3.93) and IE (3.50), but not for the viral indicator, SOMPH (1.67)). These findings suggest that the use of 30% hydrated lime suspensions or 2% chlorine solutions may offer a simple public health protection measure for the containment, safe handling, and disinfection of human excreta during humanitarian emergencies.

Keywords

• sanitation
• wastewater
• faecal sludge
• excreta
• pathogens
• disinfection
• chlorine
• hydrated lime
• WASH