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.
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).
See also
References
