Photosynthetic performance of two Nannochloropsis spp. under different filtered light spectra

Abstract

Microalgae growth in closed photobioreactors is greatly inhibited by elevated temperatures caused mainly by the infra-red portion of light. Current passive evaporative cooling systems for temperature control in outdoor photobioreactors are neither economical nor sustainable. Here we built a novel flat plate photobioreactor with its illumination surface customized with insulated glazing units (IGP). The IGP design enabled transmission of more than 50% of visible light while blocking 90% of ultraviolet and infrared radiations. The growth and productivity of Nannochloropsis sp. (MUR 267) in the IGP was compared against conventional flat plate photobioreactors subjected to the full spectrum (HLP) and also externally modified spectrum (CLP) of halogen lights. High temperature (up to 42 o C) resulted in no growth in the HLP. Biomass productivities of Nannochloropsis sp. grown in the CLP was significantly higher than the IGP due to higher light transmission and lower temperature profiles recorded in the CLP. Lipid content of Nannochloropsis was highest in the CLP (60.23%) while protein was highest in the IGP (42.43%). All photosynthesis parameters were negatively affected in the HLP. The IGP's ability to remove infrared (heat) makes this newly developed photobioreactor a promising and sustainable cultivation system for mass algal production especially for high value products.

Effect of Selected Light Spectra on the Growth of <i>Chlorella spp</i>. (Chlorophyta)

“…The higher density of the alga obtained under the white light (Figure 3) is due to its positive impact on photosynthesis (Sorokin, 1958;Vadiveloo et al, 2016). The lower cell density under the blue spectra would be due to reduced irradiance from the blue filter.The cell density of the Chlorella spp.…”

“…Photovoltaic devices (PVDs) are used to convert solar energy to electrical energy and a maximum efficiency of 20 % has been reported from commercially available PVDs (Moheimani and Parlevliet, 2013;Vadiveloo et. al., 2016).…”

“…The spectral distribution of light (e.g. blue, red, yellow or pink) including quality and quantity control microalgae growth, productivity and photosynthetic efficiency (Tredici and Zittelli, 1998;Vadiveloo et. al., 2016;Zhu et.…”

Algal Cultivation for Treating Wastewater in African Developing Countries: A Review

“…Recent studies have cited algal turf scrubber (ATS) system as an upcoming alternative for the cultivation of algae specially adapted for the treatment of wastewater effluents. [ 51 ] According to Sandefur et al., [ 52 ] ATS system consists of operation in which water that is rich in nutrients is allowed to flow over mixed‐assemblage of filamentous algal species attached to the physical support, mimicking the natural habitat of the algae (Figure 2). These algae can be harvested with ease, as this system is easy to operate and less expensive to construct.…”

“…Light is the most limiting factor for the cultivation of microalgae due to its phototropic lifestyle. [ 52 ] However, only light ranging from 400 to 700 nm, which accounts for 47% of the total solar spectrum is utilized by microalgae for photosynthesis. [ 65 ] This photosynthetically active radiation directly depends on seasonality, geographical location, and latitude.…”