Urine separation - Swedish experiences
|Rapportnr||EcoEng Newsletter 1|
|Type||Rapport, alleen pdf|
'Urine is the urban waste fraction containing the largest amounts of nutrients. It contains approximately 70% of the nitrogen and 50% of the phosphorus and potassium in all household waste and wastewater fractions. During the 1990-ies, urine separation has been thoroughly investigated in several research projects in Sweden. In these measurement between 50% and 85% of the urine has been source separated, depending on the motivation and dedication of the inhabitants.
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.
The fertilising effect of urine to cereals has for nitrogen been found to be close to that for chemical fertiliser ( ~90%) and for phosphorus to be equal to that for chemical fertiliser. The measured ammonia emissions after fertilisation to cereal crops has been 5% +/-5%. If the system is correctly designed, the ammonia emissions from collection, transport and storage are insignificant (<1%).
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 form an environmental point of view.
Urine separation is now well documented and can be recommended for implementation under most conditions.'
Bron: Jonsson (2001) in EcoEng newsletter.