Enhancement of CO2 biofixation and lipid production by Chlorella vulgaris using coloured polypropylene film

Chlorella vulgaris was cultivated with light at different wavelengths (λmax) and irradiation intensities (I) by applying a coloured tape (CT) as a simple, inexpensive light filter. C. vulgaris was cultivated in a standard medium using blue (CTB), green (CTG), red (CTR), yellow (CTY) and white (CTW) CT to filter the light, as well the unfiltered light (U). The influence of λmax and I on specific growth rate (μ), nutrient removal efficiency (% RE of total nitrogen, TN, and phosphorus, TP), CO2 fixation rate (RC) and lipid productivity (Plipid) were evaluated. The highest biomass concentration Xmax of 2.26 g L−1 was measured for CTW with corresponding μ, TN and TP RE, RC and Plipid values of 0.95 d−1, 92% and 100%, 0.67 g L−1 d−1 and 83.6 mg L−1 d−1, respectively. The normalised μ and Plipid for U were significantly lower than in CTW of 33–50% and 75%, respectively. The corresponding non-normalised parameter values for CTB were significantly lower at 0.45 d−1, 0.18 g L−1, 15% and 37%, 0.03 g L−1 d−1 and 1.2 mg L−1 d−1. Results suggest a significant impact of I and λmax, with up to a 50% increase in growth and nutrient RE from optimising these parameters.