Evaluation of Microbial Health Risks Associated with the Reuse of Source-separated Human Urine

Introduction Human excreta contain plant nutrients and have traditionally been used for crop fertilisation in many countries. In Japan the recycling of urine and faeces was introduced in the 12 Century and in China human and animal excreta have been composted for thousands of years. Urine is the fraction that contains the major part of the nutrients in domestic wastewater, approximately 80% of the nitrogen, 55% of the phosphorous and 60% of the potassium (Swedish EPA, 1995). At the same time it constitutes less than 1% of the total wastewater volume. Thus it is possible to collect a relatively concentrated fertiliser by separating urine from the wastewater. Faeces contribute a smaller amount of nutrients and involves greater health risks if reused due to the possible presence of enteric pathogens. Human urine does not generally contain pathogens that can be transmitted through the environment.