Greywater Management in Low and Middle-Income Countries - SSWM

structure), disinfectants, bleach, and other problematic products must be substituted
by environmentally friendly products. Oil and grease from kitchen must be retained
by adequate processes.
Appropriate greywater treatment systems range from very simple and low-cost
greywater treatment. Primary treatment is required to lower the risk of clogging of
secondary treatment steps. Septic tank systems and simple sedimentation tanks
regular maintenance and greater attention by the household, as they are frequently
by-passed or removed, thus jeopardising subsequent treatment or management
main cause for system failure.
greywater is used. If discharged into streams, greywater should be submitted to
primary and secondary treatment, with removal of organic compounds, suspended
solids, pathogenic organisms, and nutrients to acceptable levels. Most countries
a combination of primary and secondary treatment (e.g. a septic tank followed by a
water bills and increasing food security. The in-house reuse of greywater generally
requires a disinfection stage and special in-house installations, thus making the
system more complex and vulnerable. In-house reuse of greywater in low and
middle-income countries is therefore not recommended.
Greywater reuse is especially recommended in areas facing water stress such as
the Middle East and Sub-Saharan Africa. In regions with an abundance of freshwater
such as in South-East Asia, other options may be more appropriate such as for
based management systems will only be successful if based on an effective demand
and socio-cultural acceptance.
Direct reuse of untreated greywater in irrigation is not recommended. Irrigated
greywater should undergo primary treatment as irrigated soil acts as a natural
secondary treatment step. Secondary treatment is advisable in cases where large
quantities of surfactants are used. Irrigation techniques must be carefully chosen
to avoid direct human and crop contact with the hygienically unsafe greywater.
Subsurface irrigation techniques are most appropriate, while sprinkler irrigation
should be avoided. The mulch trench distribution system is a promising low-cost
alternative to conventional piped-based subsurface irrigation techniques, however,
long-term experience with this system is still missing.
Conclusions
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