Greywater (also spelled graywater, grey water, gray water) or sullage is all wastewater generated in households or office buildings from streams without fecal contamination. By definition greywater is generally waste water from showers, baths, basins, and washing machines. Greywater treatment is easier than municipal wastewater treatment, generating a large interest in its reuse and recycling. Typical applications for greywater recycling and re-use are toilet flushing, irrigation and other non-potable uses.
Reusing wastewater is a crucial part of the sustainable management of water resources. Greywater can be an important alternative water source, especially in arid and touristic areas, where the biggest water demand is usual in the dry period. The potential ecological benefits of greywater recycling include:
However, greywater can be contaminated with different kinds of soluble and insoluble substances and must be treated properly. Contaminants in greywater include traces of dirt, food, grease, hair, and certain household cleaning products. Typically, media filtration and ultrafiltration based treatment technologies are used. Ultra-filtration to prevent particles, bacteria and viruses of passing through. Ultimately, greywater can be disinfected with ultraviolet and/or chlorination, to ensure residual disinfection at point-of-use. It is very stable process and compact design and High effluent quality and low sludge production.