The fate of Entamoeba histolytica during sewage treatment using anaerobic digesters.

ABSTRACT A resource which has as yet made only a minor contribution to energy supplies is methane gas produced from waste materials, but in Europe this potentially could provide up to 20% of the total energy requirement. As the existing energy sources are already declining, interest in the anaerobic digestion of organic material to produce energy has aroused a great deal of interest. The use of this process for sewage sludge treatment is also gathering apace after 100 years of application and development. Two main problems which are created from increased industrial activity include increasing energy and environmental problems, as well as the onset of disease epidemics. Within any normal “healthy” human population there will always be a certain number of individuals suffering from or acting as carriers of diseases due to pathogenic organisms. These pathogens, present in the intestinal tract, are voided in faeces and are commonly found in sewage sludges. The protozoan pathogen Entamoeba histolytica is a common micro-organism present in polluted waters, particularly in warm climates. The sewage produced from communities may be treated in a number of ways, including anaerobic digestion to produce a stable sludge and by-products such as fertiliser for farms and methane gas for energy. The fate of E. histolytica has been investigated during the anaerobic digestion of activated and primary sludges. Anaerobic digesters appeared to eliminate E. histolytica within hours of their addition. A number of techniques were also investigated to determine the presence of viable Entamoeba cell numbers.