Cultivation of Ascochloris sp. ADW007-enriched microalga in raw dairy wastewater for enhanced biomass and lipid productivity

A potential microalgal strain was isolated from dairy industrial effluent contaminated water and genetically identified as a close relative of Ascochloris sp. The current study demonstrates growth, biomass and lipid productivity of Ascochloris sp. ADW007 and simultaneous bioremediation of raw dairy waste water (RDW). Indoor microalgal cultivation studies were conducted in controlled conditions of light and temperature, while outdoor pilot-scale experiments were performed in errant conditions using semi-cylindrical barrel shaped open troughs. The rate of biomass productivity of ADW007 was improved with RDW as growth nutrient in indoor bench-scale (0.102 ± 0.003 g/L/d) and outdoor pilot-scale cultivations (0.207 ± 0.003 g/L/d) when compared with the algal growth in synthetic BG 11 medium (0.086 ± 0.004 g/L/d) and TAP medium (0.099 ± 0.003 g/L/d), respectively. Similarly, in outdoor conditions, the lipid content reached maximum to 34.98 ± 0.21% with volumetric and areal lipid productivities of 0.072 ± 0.001 g/L/d and 9.63 ± 0.08 g/m2/d, respectively. With this, the estimated annual algal oil production is nearly 20,495 ± 1953 gallons/acre/yr, if cultivated throughout the year. C18:0/C18:1 were the predominant fatty acids in lipid which indicates a great potential of ADW007 for biodiesel production and simultaneous bioremediation processes using RDW. Post-harvesting process includes hollow fiber filtration followed by activated carbon treatment and resulted in 95.1, 79.7 and 98.1% reduction in chemical oxygen demand, nitrate and total phosphate, respectively.