2.4. Growth conditions and microalgae selection
Microalgae selection was done a priori considering their adaptation (cell density evaluation), followed by nitrogen and phosphorus scavenging and lipid content in the dry biomass. They were initially grown at 25 C in 100% wastewater medium at initial pH 7.2 ± 0.2 in 250 ml Erlenmeyers (working volume of 125 mL) for 14 days in 12:12 h (light:dark) period and 3500 lux. Adaptation was evaluated by cell density evaluation in Neubauer counting chamber.Microalgae that appeared to be better adapted were scaled up to 2 L (working volume of 1.3 L) and cultivated in the same conditions described above. Samples were withdrawn periodically and centrifuged in a Sorvall Legend Mach 1.6 R centrifuge (Sorvall, Germany) at 16,000g for 15 min. Cells were washed once and dried at 60 C until constant weight was achieved for the determination of the growth curves and kinetic parameters. Based on the results, selected cultures were finally scaled up to 6 L, and nitrate and phosphorus removal kinetics were studied.Three strains showing high potential were also evaluated in an 11 L BioFlo Fermenter (New Brunswick Sci., working volume of 9 L) with air enriched with 5% CO2, pH 7.2 ± 0.2 and 3500 lux illumination in 12:12 h light:dark period for 14 days at 25 C.