In Sweden, in several neighbourhood, urine separation toilets are common since the nineties. Urine separated can be used as fertilizer.
Description of the Process
As Håkan Jönsson (Hakan.Jonsson@lt.slu.se) form the Department of Agricultural Engineering of Uppsala wrote in his school paper (Urine separation - Swedish experiences), in Sweden during the 1990s, urine separation has been thoroughly investigated in several research projects. In these measurements between 50% and 85% of the urine has been source separated, depending on the motivation and dedication of the inhabitants. Those inhabitants were equipped with toilets with separated channels for urines and feces. The initial problems connected with the system, mainly stoppages in the toilet u-bend, have now largely been overcome and now the system functions without any large problems. The urine is sanitised by enclosed storage and recommendations have been developed. The storage period recommended depends on which crops that are to be fertilised, storage conditions, and type of system. Urine can be a very useful fertilizer since is the urban waste fraction containing the largest amounts of nutrients. It contains approximately 70% of the nitrogen and 50% of the phosphorous and potassium in all household waste and wastewater fractions. The fertilising effect of urine to cereals has for nitrogen been found to be close to that of chemical fertiliser (∼90%) and for phosphorous to be equal to that of chemical fertiliser. The measured ammonia emissions after fertilisation to cereal crops have been 5% ±5%. If the system is correctly designed, the ammonia emissions from collection, transport and storage are insignificant (
In Sweden' toilets before urine was not collected separatly from feces. When they are mixed, like in standard toilets worldwide, is not efficient anymore to separate them again.
Factors that contributed to the success of the project
The environmental effects of urine separation have been investigated in several studies. They have all concluded that compared to a conventional sewage system, urine separation will recycle much more plant nutrients, especially nitrogen, and will have lower water emissions of nutrients. Generally, urine separation has also been found to save energy. Urine separation has in all studies been found preferable to the conventional system from an environmental point of view.
Role of different stakeholders in the system during the realization and maintenance of the project
Urine separation received much interest from researchers in Sweden during the 1990s. There were three important research groups. The largest group was centred in the Uppsala-Stockholm region and consisted of researchers from SLU (Swedish University of Agricultural Sciences), SMI (Swedish Institute for Infectious Disease Control), JTI (Swedish Institute for Agricultural and Environmental Engineering), and KTH (Royal Institute of Technology). In addition to these groups, some individual researchers in other places have been active. To finance this research, the housing and agricultural sectors have made the largest contributions. The water and wastewater sector has also made a large contribution, while the contributions by other sectors of society, for example the environmental sector, have been small. The most important financing bodies have been: BFR (Swedish Council for Building Research), SLF (Swedish Farmers Foundation for Agricultural Research), VAFORSK (Swedish Municipalities Sewage Research Program), Swedish Board of Agriculture, Stockholm Water Inc., National Cooperation of HSB, and Stockholmshem Inc.