Phycoremediation of greywater using chlorella vulgaris

The increase in anthropogenic activities across the globe is rising the water scarcity problem at an alarming rate. The non-compliance of discharge standards in most of the conventional centralized treatment systems calls the need for source separation and state-of-the-art treatment practices. 60%-75% of domestic wastewater is contributed by greywater, and the reuse of greywater emerging from the bathing, kitchen, and washing sources is a recommended paradigm shift to counter the above-mentioned water crises. From the past few decades, bacterial degradation of greywater is on moot due to the meager of nutrients and organic matter in comparison to domestic wastewater. In the present work, the biological degradation of greywater using the algae Chlorella vulgaris is carried out. Greywater samples were collected from three different places of the metropolitan city Chennai and analyzed for basic quality parameters. All the samples were inoculated with C. vulgaris in a controlled environment of 680 nm for a duration of 12 h per day and 12 h in no light. Growth analysis, total nitrogen (TN) removal, total phosphorous (TP) removal, and total organic carbon (TOC) removal were monitored for the inoculated batch samples. In all the samples, the algal growth reached the stationary phase after 6-7 days of inoculation. From the observed initial values ranging between 12.93 and 17.8, 7.42 and 13.42, and 31.6 and 73.85 mg/L, respectively, for TN, TP, and TOC, complete removal of TP is observed in all the samples. TN removal in the samples varied from 80.1% to 88.8%, and an average removal of 60% TOC is observed. Even though the results of the study are on par with other treatment technologies, efforts should be made to increase the productivity of algal biomass.