TREATMENT OF WASTEWATER COUPLED WITH THE SEQUESTRATION OF CARBON DIOXIDE BY TWIN LAYER CULTIVATION OF MICROALGAE

Abstract

Microalgae provides an eco-friendly solution for wastewater treatment, CO2 fixation and lipid and pigments production. High-nutrient wastewater such as solid waste leachate, anaerobic digestate and poultry wastewater has high turbidity, dark color and high concentration of nutrients. Therefore, it cannot be treated using microalgal systems and need to be diluted prior to treatment. This study assessed the potential of Tetradesmus obliquus for treatment of high-nutrient wastewater using twin layer cultivation system. For this purpose, high nutrient wastewater was diluted by wetland treated municipal wastewater prior to microalgal treatment. Results showed that microalgae cultivated in poultry wastewater gave the highest biomass productivity and CO2 fixation of 5.13 and 9.25 g/m2 /d respectively. Similarly, the maximum nutrient removal rate was achieved from poultry wastewater, which as 31.6, 39.3 and 3.5 mg/d for NH4 + -N, TKN and PO4 -3 -P respectively. In contrast, the highest lipid content of 30% was observed in microalgae cultivated in municipal wastewater. However, lipid productivity was maximum in biomass grown in poultry wastewater, which was 1.48 g/m2

/d. Chlorophyll a, b and carotenoid content of microalgae grown in poultry wastewater were 36.6%, 47.3% and 47.4% higher than municipal wastewater. Thus, successful microalgal treatment of high-nutrient wastewater can be performed through its prior dilution. Keywords: Microalgal Biomass; Lipids; Pigments; Poultry Wastewater; Solid Waste Leachate; Anaerobic Digest