Greywater Recycling

Greywater recycling aims at advancing the use of cost-effective and replicable practices, to ensure water availability and address water scarcity challenges at a local level.

What is greywater recycling?

Greywater recycling is the practice of reusing wastewater generated from residential, commercial and industrial bathroom sinks, bathtub and shower drains, and equipment drains for secondary uses in households, communities, and industries. Greywater recycling is a sustainable approach for water resources management and can be cost-effective in the long term.

Why recycle greywater?

Recycling greywater helps to increase water availability, reduce water demand from municipal water supply and to decrease wastewater load of sewerage systems. Also, recycling and reusing water on-site or nearby reduces the energy needed for water and wastewater transportation and/or for pumping groundwater.

How can greywater be treated?

Depending on the end use of the treated greywater, one has to select a treatment process. Greywater can be treated with physical, chemical or biological processes. Most treatment units reported in the literature are based on physical processes (i.e. sedimentation and disinfection), while the more advanced ones incorporate chemical and biological treatment.

More advanced greywater treatment technology developed is based on membrane bioreactors. Only a few off-the-shelf systems are commercially available and few are tested on full-scale for long time periods