Solutions for the sanitation problem
According to the latest unesco statistics around 2 billion people lack proper sanition. But there are a number of simple, clever and cheap technical solutions to help a lage number of people.
Possible solutions can roughly be broken down into the following categories:
- Water saving toilets
- Separation of toilet content (eco san)
- Water free toilets
Depending on the desired objective and the local circumstances it is possible to create sustainable solutions that not only solve the sanitation problem but also creates valuable "by- products" like fluid fertilisers or compost.
Sustainable Waste Water Management
- Nutrients and water in different waste water flows (flush water not included)
Toilet wastewaterc called ?blackwater? is different from the rest of the household water called ?greywater?. Almost all of the nutrients are in the blackwater. Urine is very rich in nutrients but contains little pathogens and pollutants. One way to get a sustainable system is to separate the different flows at the source, by
- collecting urine in one place, faeces in another and greywater somewhere else
- collecting urine separately from the rest of the wastewater
- collecting blackwater separate from the greywater
For farmers, it is important that the end products have a high nutrient content, a low concentration of toxic compounds and a limited hygienic risk.
Urine diversion systems
Urine is separated from the rest of the wastewater
Collects 80-90% of N and 50% of P
Specially designed toilet with a separate collecting bowl 0.5 m3 of urine/ person/year
Urine is stored six months to reduce pathogens
Can be combined with composting of faeces Greywater needs to be treated separately, e.g. in a filter bed.
With dry handling of faeces, usually low costs
Black water systems
Toilet waste is flushed and collected in a storage tank Collects >75% of P, >90% of N, and a large portion of BOD
Vacuum toilet, dry toilets or water closet with an extremely low flush volume connected to gravity sewers
Important to use very small amount of water for flushing or bedding material like bark chips, wood clippings etc. to help hiding from view, educe odour and improves the composting
Treatment, such as liquid composting, is necessary before use to reduce pathogens
Greywater is treated separately, e.g. in a filter bed
Composted faeces and urine as fertilizer
The basis for a sustainable sanitation concept is the decentralised recycling of resources. Systems have been designed that allow for the recycling of nutritients in toilet waste back to arable land without contamination of natural water bodies. Urine diverting eco toilets can be installed without sacrifice of the high hygienic standard at home. Hygienically safe and efficient methods for the application of toilet water to arable land have been developed and are in use in many places around the world.
Pictures from left: Urine separation, mini flush toilets, separation toilet closed and open, Storage tank for dried faeces
Examples of urine diversion toilet systems
- Separate the toilet content at source without any compromises in comfort.
- Example of commercially available separation toilet. Urin is collected in the front separatly from the faeces in the back. This toilet is flushed as usual but with a lot less water and no flushing water is mixed with the urin due to a special meachanism.
- Here is an example of waterless urinals used in the Kastrup airport in Copenhagen / Denmark.
- This is an example of a "standard" bathroom using urine divertion and dry composting of faecal matter in the Tingvall conference centre in Sweden.
- This is how a dual flush urine diverting system could look like schematically. Urine is flushed with 1-2 liters/day and faeces with 2-4 liters. (Source: Jonsson et al. 2000)
- This is the Tingvall conference centre in Sweden from the outside.
