Effect of post-treatment conditions on the inactivation of helminth eggs (Ascaris suum) after the composting process

Safe and appropriate disposal of human waste is a basic requirement for sanitation and protection of public health. For proper sanitation and nutrient recovery, it is necessary to ensure effective treatment methods to complete pathogen destruction in excreta prior to reuse. Composting toilets convert faeces to a reusable resource such as fertilizer or humus for organic agriculture. A composting toilet for rural Burkina Faso was created by modifying a commercial model available in Japan to improve hygiene and increase food production. The toilet has shown to result in a degraded final product, but its effectiveness for pathogen destruction was unclear due to low temperatures generated from the toilet. This study aimed to sanitize compost withdrawn from the composting toilet for food production by setting post-treatment conditions. The inactivation kinetics of Ascaris suum eggs, selected as an indicator for helminth eggs, was determined during post-treatment at different temperatures (30 degrees C, 40 degrees C, 50 degrees C and 60 degrees C) with varying moisture contents (MC) (50%, 60% and 70%). The treatment of compost in a possible additional post-treatment after the composting process was tried in the laboratory test. Inactivation of A. suum eggs was fast with greater than two log reductions achieved within 2 h for temperature 50 degrees C and 50% MC and greater than three log reductions for temperature 60 degrees C and 50% MC within 3h. Statistical analysis showed the significant impact of temperature and moisture on the inactivation rates of A. suum eggs. The post-treatment can efficiently increase helminth eggs destruction prior to reuse.