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

Abstract

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.