Blackwater (waste)

Blackwater is a relatively recent term used to describe water containing fecal matter and urine. It is also known as brown water, foul water, or sewage. It is distinct from greywater or sullage, the residues of washing processes.

In practice

Water coming from other domestic equipment than toilets (eg bath, shower, sinks, washing machines, ... is called greywater and is usually kept separate from blackwater (which comes from toilets) to reduce the amount of water that gets heavily polluted.

Separation of blackwater and greywater nowadays happens with all ecological buildings. Especially in autonomous buildings, the separation is always present. It is also commonly used on recreational vehicles where separate tanks collect blackwater and graywater wastes.

Processing

Blackwater contains pathogens which need to decompose before they can be released safely into the environment. It is difficult to process blackwater if it contains a large quantity of excess water, or if it must be processed quickly, because of the high concentrations of organic material. However, if blackwater does not contain excess water, then it is easily processed through composting. The heat produced by naturally occurring thermophilic microorganisms, will heat the compost to over 60 degrees C, and destroy all harmful pathogens. The compost is eventually reduced to safe fertilizer after about 1 year. [ [http://www.weblife.org/humanure/ weblife.org: Humanure Handbook: Contents ] ]

Elimination

Blackwater can be avoided by making use of composting toilets and vermicomposting toilets. In certain autonomous buildings as earthships, this is almost always present and allows to heavily reduce the water requirements of the building (which, with earthships, it generates itself). Besides saving water, composting toilets allow the user to reuse the nutrients found herein (eg for growing crops/trees).

ee also

* Composting toilet
* Humanure
* Nightsoil

References