Domestic wastewater excluding toilet streams is called greywater. When it is collected only from wash basin and
bathroom, it is named as “light greywater” because of embodying a small fraction of contaminants. Light
greywater makes up of more than 50% of the domestic wastewater with a great reusability potential when
properly treated. Henceforth, greywater treatment can be a part of preservation of fresh water resources.
Nowadays, advanced treatment methods requiring high investment and operating costs are used for greywater
treatment. However, bioremediation of greywater can be an economic alternative as a result of low energy
requirement of microalgal remediation systems. Moreover, microalgae can be harvested to refine its oil for
further processes. In this study, treatment of light greywater with Chlorella variabilis is investigated. Wash basin
and bathroom light greywater samples were collected and treated separately. After the initial chemical and
microbiological analyses, the suspended solids were removed via centrifugation. Then, microalgae cultivated in
raw greywater and 30% diluted (with tap water) samples. After 19 days of cultivation, Chlorella variabilis was
removed from the media by another centrifuge. Final analyses were done, and removal efficiencies of COD,
BOD5, TP and TN were calculated in addition to total coliform, Escherichia coli, Enterococcus, total bacteria, and
Pseudomonas aeruginosa analyses. The results show up to 92.3% COD, 91.9% BOD5, 85.6% TN and>97% TP
remediation. Additionally, microbiological analysis results show this water can be reused for toilet flushing.