The Wastewater Nutrient Removal Efficiences of Chlorella sorokiniana and Scenedesmus obtusiusculus

Abstract

Urine treatment and nutrient removal was studied on a pilot scale in the DESAH building for a period of 3 months. The essence of the study was to evaluate the practical nutrient removal efficiencies of Chlorella sorokiniana and Scenedesmus obtusiusculus . The microalgae were grown on 3 different media― namely; mixture (mixed treated and untreated urine), untreated urine and control, and their nutrient removal efficiencies were investigated. Urine that has passed through the OLAND RBC system served as treated urine, and Bold’s basal medium served as the control. The OLAND RBC system was able to remove 95.7% of total chemical oxygen demand (COD), 27.1% total nitrogen, 99.7% ammonium, 88.6% total phosphorus and 89.3% ortho-phosphate from the influent urine. Low nutrient removal performance at a very high N: P molar ratios were observed in microalgae in the untreated urine. However, the nutrient removal capacities of microalgae were very high at reduced N: P molar ratios in the mixed medium. Chlorella sorokiniana was able to remove 63.2% TN and 55.8% TP at a low N: P molar ratio of 8.5:1, while Scenedesmus obtusiusculus removed 45.9% TN and 76.3% TP at an N: P molar ratio of 6.9:1. The results indicate that nutrient removal by microalgae is most efficient in mixed OLAND RBC treated and untreated urine culture. Therefore, the integration of the OLAND RBC system when designing microalgae induced wastewater treatment technologies for sanitation purposes is advocated.