The Differential Efficiency of Chlorella vulgaris and Oscillatoria sp. to Treat the Municipal Wastewater

Abstract

The utilization of microalgae to treat wastewater becomes an alternative biological wastewater treatment technique worldwide because of its low cost and environmental clean. Chlorella vulgaris and Oscillatoria sp. were cultured in municipal wastewater under controlled laboratory conditions with continuous light illumination and aeration. Physical properties (pH, TDS and Salinity), and nutrient contents (ammonia, nitrite and total phosphorus)were measured in the raw wastewater. Growth rates of the cultured species in terms of optical densities and cell counts, nutrient salts removal efficiencies were measured during the experimental durations after; 24, 48, 72, 96 , 120 and 144hrs. Lipids, proteins and carbohydrates contents were also evaluated after 144hrs. The recorded optical density of Chlorella vulgaris was 0.188±0.01 at 680 nm and 0.17±0.01 at 750 nm after 24hrs then increased to 1.45±0.002 at 680nm and 1.43±0.01 at 750nm at the end of 120hrs, meanwhile the optical density of Oscillatoria sp. was increased from 0.132±0.01 at 680 nm and 0.102±0.01 at 750 nm after 24hrs to 1.054±0.004 at 680 nm and 0.99±0.002 at 750 nm at the end of 120hrs of the experiment. On the other hand, the cell count of Chlorella vulgaris was enriched from 6.8±2.2 cell/ml after 24hrs to 720±120 cell/ml at the end of 120h of the culturing. Overall, efficiencies of nutrients removal were 99.426%, 100% and 82.211% for ammonia, nitrite and total phosphorus respectively at the end of 120hrs of Chlorella vulgaris culturing, while Oscillatoria sp nutrient removal efficiencies recorded 98.125%, 100% and 84.718% for ammonia, Nitrite and total phosphorus respectively. Chlorella vulgaris biomass was estimated 26.66±7.5% lipid 35.1±1.6% protein and 29.34±3.25% carbohydrate, however Oscillatoria sp. biomass was estimated 11.76±0.79% lipids, 32.9±1.92% protein and 27.36±3.78% carbohydrates.

Keywords: municipal Wastewater, Chlorella vulgaris, Oscillatoria sp., nutrient removal, biochemical parameters.