Greywater reuse: water treatment kit for household grey water

A kit designed to treat household waste water for reuse could be one of the ways to tackle water scarcity in rural areas of the Middle East and North Africa, according to a Canadian organisation.

“This is a household-based technology mainly for rural areas to treat grey water that comes from the kitchen sink and bath for re-use,” said Hammou Laamrani, project coordinator at the Regional Water Demand Initiative [WaDImena] of the International Development Research Centre (IDRC), based in Canada.

[...] The kit consists of two large PVC barrels about 1.2m high, each able to contain up to 200 litres of water, pipes and sand. Before reaching the barrels, the waste water goes through a separate filter where things like small bits of food are removed. The barrels are filled with sand; there is an anaerobic digestion of the organic matter when the water goes through the sand filter and becomes cleaner.

“The quality of the treated water is improved chemically and biologically; it [the filter] removes the pathogens, particularly the E. coli that could pose a health risk. It also removes parasite eggs as they cannot go through the filter because the filter is a kind of a bio-membrane that removes all those things,” Laamrani explained.

[...] It has a socio-economic impact, it has a positive impact on the environment and it’s viable in terms of technology used,” Laamrani said.

Waste water treated by sand filter has very little nitrogen and potassium, and in terms of chemical pollution poses no risk for the soil, according to Laamrani. It is not a risk to soil because it does not have mineral components that can increase soil salinity and degradation, and it is not a risk to human beings in terms of exposure to pathogens, he said.

“It reduces the amount of water that goes into cesspits – sanitation in rural areas. So they don’t need to clean the cesspit so often – only once every three months, instead of once a week. This reduces the cost of emptying the cesspits,” he said.

“This water can also be used for productive purposes. It is used for the irrigation of saplings, particularly olive trees like we saw in Jordan… This water can also be reused in the household, like for flushing toilets,” he said.

However, it is not suitable for crops or vegetables consumed without cooking, like cucumbers and tomatoes, he said.

“The cost of the kit is $300-400, and in some cases even less depending on the price of components in any given market. If you take into account the productive use of the treated waste water and the reduced frequency of cesspit evacuation, outlay costs can be recouped in a year in places like Jordan and Lebanon,” the IDRC official said, adding that they also had projects in the occupied Palestinian territories and Yemen.

Maintenance is simple: sand in the barrels needs to be changed every 10-15 years, Laamrani said.

One of the drawbacks with the system initially was the smell: “There was no technology to remove the smell when the water was in the barrels. But it has been overcome with a new system that takes the gas out of the barrels… No longer is there a risk of attracting ants or other insects,” he said

Source: IRIN, 23 Mar 2009

See below IDRC”s Waste to Water video (in two parts) on the greywater reuse in the Middle East – Quicktime and Windowas versions are available here.