Reinvent of a New Public Toilet Wastewater Treatment System Using Forward Osmosis as the Key Unit: A Resources Close-Loop Model in Urban LID

摘要

To solve the sanitation problems and achieve the resource recovery goal, a new toilet system using FO (forward osmosis) as the key unit was developed. The FO membrane module was used for enrichment of source separated urine collected by vacuum toilets. After enrichment, the volume of the urine was greatly reduced and could be conveniently used as a fertilizer. Lab experiments were carried out to decide the optimal operation conditions of the FO system, and 2 M NaCl was used as the draw solution with cross flow velocity of 55 cm/s. In this condition, an average water flux about 2.5 LHM, rejection rate over 80%, and concentration times of 2.5 were achieved. A pilot scale toilet system with 6 stools was built to testify the operation result. The result showed that the system produced high quality fertilizer without addition of water and other substances and the quality of the reclaimed water basically satisfied the demands for toilet flush.