Pathogen Removal Options: Emphasizing SOLDIS For The Filtrate Of A GSAP Microflush Toilet

The Microflush toilet system, a low-flush off-grid macro-organism enhanced aerobic digester has been prototyped and shown to be an effective toilet solution for rural communities in the tropical developing world. The system rapidly filters solids in the waste stream from liquids - urine and greywater from hand washing. The solids are digested and vermi-composted with e. fetida and other macro-organisms resulting in high mass reduction and pathogen removal. The resulting compost is harvested every 2-3 years. Successful field trials have been conducted on the system. This paper examines options for removing pathogens in the liquid filtrate. SOLDIS including solar thermal, UV and combination processes as well as SOLDIS-enhanced urine-ammonia treatment are examined. Dynamic models for SOLDIS thermal and UV processes have been developed in order to influence and study the effectiveness of alternative designs. Physical, economic and behavioral factors for each option are considered. Successful field trials will result in a virtually closed sustainable on-site sanitation solution with water used for handwashing, the resulting greywater used for micro-flushing, the blackwater processed to remove pathogens and the final solids product used for agriculture or other productive purposes with the entire process being off-grid.