Greywater
Treatment
Greywater is bath- dish- and wash-water. It breaks down much faster than waste water containing toilet waste and it has
only 1/10 the amount of nitrogen. It can become an excellent source of irrigation.
Here we show two alternatives. One is very simple and effective way using a covered irrigation trench, relying on the soil
and its organisms to treat the water.
Irrigation ditches are simple and reliable to operate. They can be constructed with cementboards for both walls and and tops.
(the commercial name is Cetris board). Greywater is simply pumped into the ditches from a dosing chamber.
Once in the ditch and on the ground the organics is slowly decomposing aided by both micro and macro organisms.
The top cover becomes the walkway between the plant-rows.
For inspection or maintenance the top covers are easy to lift off. A distribution plate is placed under the pipe exit to avoid
for the water to errode the area where the water lands. Food residues and fat from the kitchen discharge will build a successive
clogging mat but will also be consumed by earth worms and Sowbugs etc. Hash cleaning chemicals containing chloride and Fluorides
should be avoided at least not flushed down the sinks.
The second proposal is more for permanent construction with more conventional elements but is a design for greywater and
allows for much less maintenance than if toilet waste is mixed in. Sludge can be removed every four years instead of every
year.
Yearly maintenance is usually required by law when a septic tank is installed for sludge and grease removal. A septic tank needs
to be accessible by a sucktion truck.
If good infiltration soil is not available, as can often be the case in the archipelago or on steep building lots,
the greywater can be pretreated as shown below and as the final treatment be used in planterbeds, sometimes terraced,
as part of the landscaping.
The plants receive both irrigation and fertilization by this method.
For more information in english, go to
click here.
Another possible alternative is treatment in a constructed wetland
www.ecowaves.eu.
Based on 45 years experience
Background
Carl Lindström is a civ. egineer from KTH Stockholm and MIT Cambridge MA. He is the co-founder along with
his parents of the first commercial composting toilet Clivus AB, which later became Clivus Multrum AB. There
was an early assumtion that the system would produce solid compost. Over the years a new process has emerged
called Long-Term Composting (see video on the left) where the end-product is liquid and the solids is left
for several decades. Based on decades of observations, a next generation process-tanks have been developed,
taking less space and working with less maintenance and service than the older Clivus tanks. Carl was in
the 1970ies working for the Swedish Environ-mental Protection Board and later served as environmental attché
in Wash. DC. He works now as earlier with the US corporation Clivus Multrum USA Inc. In 2007 Carl founded
CompostEra AB in Sweden with sights set on solving waste problems in the Swedish archipelago, replacing
the older latrine-collection systems. The new tanks are dimensioned to go for 30-50 years without solids-removal.
Long-Term Composting has found great support in countries where ground water is vulnerable to pollution
from toilet-systems that do not stop disease organisms from spreading into the environent.
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