Treating Urban Wastewater: Nutrient Removal by Using Immobilized Green Algae in Batch Cultures

Essential roles of microalgae during the tertiary treatment of municipal wastewater have been proven. In order to avoid wash out of the biomass and also modify the quality of the treated wastewater; some techniques such as cell immobilization have been developed. To do so, in this study four samples from two species of microalgae (Chlorella vulgaris and Chlamydomonas sp.) were determined and confirmed by taxonomic identification. The samples were immobilized in calcium alginate beads. Within 10 days the amounts of nitrate (No3(-)-N) and orthophosphate (Po4(3-)-P) were measured to calculate the removal efficacy for each individual sample. Based on the standard methods, the amount of nitrate and orthophosphate were determined every 3 days within 10 days. The results indicate that immobilized microalgae are able to remove the nutrients and reduce the amount of nitrate and orthophosphate, significantly. Furthermore, the C. vulgaris (YG02) was the best species in this experience with 72% and 99% of reduction in the amount of nitrate and orthophosphate, respectively.