A Review of Greywater Characteristics and Treatment Methods

Greywater (GW) is defined as wastewater from kitchen, bath and laundry excluding streams from toilets. GW can be classified as either low-load GW (excluding kitchen and laundry) or high-load GW (including kitchen and/or laundry). In recent years many studies have been carried out on GW treatment.

This review provides information on the GW characteristics, existing guidelines for wastewater reuse and the present state of art in GW treatment as well as their advantages and limitations.

This article revealed that GW quality is highly variable and dependent on the source of production. Physical processes have been shown to achieve only a limited treatment of the GW, therefore the use of these methods alone is recommended in the low strength GW. The chemical treatments were reported to provide good removal of the suspended solids, pathogens and surfactants in the low strength grey water but could not efficiently remove the BOD. Biological processes achieved good general treatment of GW, but the nutrient imbalance of GW limits the performance of these systems.

However, the combination of aerobic biological process with physical pretreatment and disinfection is recommended in the high strength GW as the most economical solution.