Various NGO (including Medecins Sans Frontieres MSF) guidelines suggest that human excreta in emergency settings (for example, cholera and Ebola treatment centres) may be disinfected by the application of concentrated chlorine solutions of around 0.5 per cent. However, chlorine-based disinfectants are thought to lose their bactericidal and virucidal properties rapidly when in contact with high levels of organic matter and chlorine application may result in the production of toxic chlororganic compounds. Physiochemical disinfection using hydrated lime has been suggested as a more effective alternative to excreta disinfection.
Research undertaken at the University of Brighton (funded by USAID) assessed the disinfection efficacy of 0.5 per cent chlorine solutions (HTH, NaDCC and household bleach) and hydrated lime suspensions (of 10, 20 and 30 per cent) against viruses and bacteria within excreta matrices. The results demonstrated that lime suspensions were more effective disinfectants than chlorine solutions (0.5 per cent), especially when excreta matrices contained high concentration of solids and organic matter. However, a chlorine solution of 0.5 per cent was used for this study and MSF protocols currently advise the use of two per cent solutions. Therefore, it is extremely important and timely to assess whether this higher chlorine concentration significantly increases disinfection efficacy.
Medecins Sans Frontieres has funded this applied research into the disinfection of human excreta in emergency settings using highly concentrated chlorine solutions (ARDHEES).
Putting disinfection processes into practice in Haiti.
The project commenced in 2017 and will end in 2018.
The aim of this research is to develop human excreta disinfection protocols that can be followed by MSF WASH response staff in emergency settings so as to minimise the risks of ongoing disease transmission and to improve safe working conditions for operators.
This project is ongoing; output, findings and impact will be updated in due course.
The project will provide an opportunity to further existing research in a highly productive way and the work is very likely to elucidate important findings of considerable practical relevance to MSF within a relatively short project period. The project will greatly enhance understanding of excreta disinfection processes in emergency settings. This information will be extremely important to achieving improved sanitation for patients and operators in such settings and wherever human excreta poses an immediate health hazard to dense human populations.
Research will be undertaken at the University of Brighton, but the findings will be applied abroad in emergency settings.
Diogo Trajano Gomes Da Silva
This project is ongoing. Output, findings and impact will be updated in due course.