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Urine separation
- Over-fertilization of the sea is reduced.
- Nutritives are returned to the farmlands.
- Use of artificial fertilizers is reduced.
- Water consumption is reduced.
- Recycling is complete.
Worth knowing! From a traditional water closet sewage, we can retrieve ca 98% of the nitrogen, 68% of the phosphorous and 85% of the potassium in the urine. The nutritives are in the perfect composition to be taken up by plants.
Spreading the urine on farmlands also reduces the need for artificial fertilizers. Production of artificial fertilizers is energy-consuming, and can also give rise to high levels of cadmium in the soil, that gets absorbed by the crops.
Worth knowing! It takes 500 litres of oil to produce the same amount of nutritive substances that 10 households produce (contained in urine och fæces) during 1 year!!!
Urine separating toilets also contribute to reduced water consumption. In coastal districts, access to drinking water of good quality can be a problem due to the intrusion of salt water. Salt water intrusion often occurs when there is an excessive extraction of water in an area.
Urine separation in the Municipality of Tanum
Tanum has developed a Water and sewage policy that was adopted by the municipal council on 2002-01-28.
The policy is for politicians and civil servants when engaged in:
- physical planning
- public water supply and sewage systems
- decision-making and supervision of private sewage systems.
Under the policy, one of the most important questions in local planning is that of how the water supply and sewage system will operate in the planned area. Often it requires a separate investigation as part of the planning work.
With all new local planning within the municipality, there will be the requirement for urine separation in new buildings, and also with extensive alteration of existing buildings. Under the policy, for sewage systems outside the planning area there will still be a requirement for urine separation, and for the remainder to go to a separate or common sewage system. An alternative is a completely dry solution for both urine and faeces. Another alternative can be one of urine separation, with the remainder being connected to the municipal sewage treatment plant, via what is known as a Fåraby contract with the Technical Dept. Such contracts are restricted.
How does it work?
Urine separating toilets differ from standard toilets in that they have a bowl in the front for urine, with the faeces going to the rear. The forward bowl varies in size and style according to the model. In the majority, the forward bowl is flushed to a storage tank using just a small quantity of water. The faeces are either flushed to a sewage treatment system or are composted with no contact with water at all.
Examples of toilet solutions
Single flush separation toilet
The urine and faeces are separated in the toilet. The urine is flushed out with about 2 dl water to a storage tank. The faeces are treated without any water, falling down into a ventilated container below the floor. The container can be installed in the cellar, or under houses on sleeper walls, with external access.
When the container is full it is replaced with an empty one. The full container is then fitted with a tight-fitting lid and will stand for the next six months, which should include the summer months, in order get sufficient reduction of bacteria and viruses. After six months the fæces can then be put into the garden compost for further composting, and can then be used for soil improvement in the garden.
Double flushing separation toilet
The urine and faeces are separated in the toilet. The urine is flushed away with about 2 dl water to a storage tank. The faeces are flushed away, as in a normal toilet, for further treatment in a sludge well and subsequent purification in an infiltration or sand filter trench.
Since this method involves the release of faeces water into the soil it can only be accepted in low populated areas. In more populated areas (recreational planning areas and such) the release of faeces water often carries the risk of pollution of drinking water catchments and ground water.
Composting toilets with urine separation
There are a number of smaller composting toilets having urine separation in which the liquids and solids are collected in a container in the bottom of the toilet. This type of toilet does not require underfloor space, but due to the limited capacity it should not be chosen if there is risk of periodic high usage.
Ventilation
The urine storage tank for single-flush toilets is ventilated via the fan for the solids container. The tank is completely sealed to avoid nitrogen leakage. For toilets having a double-flush, a vent pipe is installed into the urine piping, between the toilet and the tank, and drawn up above the ridge of the roof. The tank is sealed as for the single-flush.
Problems that can be solved
The most common problem with urine separating toilets is stoppage in the trap of the urine piping. Most stoppages are due to hair and paper fibres, and can be cleared using a clearing wire. Crystals can also cause a stoppage, and can effectively be cleared using caustic soda (NaOH). Prior to this, however, the use of 70-80º water should be tried. Furthermore, citric acid can replace caustic soda.
In general, stoppage elsewhere can be avoided if there is at least a 1% fall in the piping, and a diameter greater than 50 mm.
Storing and sanitation of the urine
A urine mixture is basic and has pH value of about 9. The higher the pH value and temperature, the quicker is the sanitation process. After a six-month storage at 20º, the urine can be used as a fertilizer on all crops, including raw, as long as there is at least a month between spreading and harvesting, and that the urine has been harrowed in. If the urine tank is underground, the storage temperature is about 4-5ºC, and the bacteria killing process is less effective. Caution should therefore be exercised when spreading urine from ´cold storage´.
Spreading the urine
In the Municipality of Tanum there are six farmers who collect urine for spreading on farmlands. To ensure that tank-emptying is kept to once a year, the tank should have a volume of at least 2 m³.
Emptying the tank and spreading the urine on one´s own land is permitted by the Environment Department only after application and on condition the following requirements are met:
- The site has land suitable, i.e. suitable soil, type of soil and vegetation e.g. agricultural land, flowers, lawns, bushes etc. For spreading on vegetable gardens the urine should be harrowed in.
- Concentrated urine should be diluted 1 part urine to 8 parts water when spreading on vegetation, and spreading during rain and late evening reduces evaporation.
- The diluted urine should be spread during the period of vegetation (May - September)
- Spreading should not take place when there is risk of nuisance to human health.
- Spreading should not take place closer than 100 m from a source of water supply, or 50 m from a watercourse.
- Only environmentally approved materials should be used for cleaning toilets, otherwise there is risk of the urine containing poisonous substances.
