Tubular photobioreactor design for algal culture. J Biotech

Department of Chemical Engineering, University of Almería, E-04071 Almeria, Spain.
Journal of Biotechnology (Impact Factor: 2.87). 01/2002; 92(2):113-31. DOI: 10.1016/S0168-1656(01)00353-4
Source: PubMed


Principles of fluid mechanics, gas-liquid mass transfer, and irradiance controlled algal growth are integrated into a method for designing tubular photobioreactors in which the culture is circulated by an airlift pump. A 0.2 m(3) photobioreactor designed using the proposed approach was proved in continuous outdoor culture of the microalga Phaeodactylum tricornutum. The culture performance was assessed under various conditions of irradiance, dilution rates and liquid velocities through the tubular solar collector. A biomass productivity of 1.90 g l(-1) d(-1) (or 32 g m(-2) d(-1)) could be obtained at a dilution rate of 0.04 h(-1). Photoinhibition was observed during hours of peak irradiance; the photosynthetic activity of the cells recovered a few hours later. Linear liquid velocities of 0.50 and 0.35 m s(-1) in the solar collector gave similar biomass productivities, but the culture collapsed at lower velocities. The effect of dissolved oxygen concentration on productivity was quantified in indoor conditions; dissolved oxygen levels higher or lower than air saturation values reduced productivity. Under outdoor conditions, for given levels of oxygen supersaturation, the productivity decline was greater outdoors than indoors, suggesting that under intense outdoor illumination photooxidation contributed to loss of productivity in comparison with productivity loss due to oxygen inhibition alone. Dissolved oxygen values at the outlet of solar collector tube were up to 400% of air saturation.

    • "Experiments were carried out outdoors in a set of three fence-type tubular photobioreactors and three raceway reactors. The tubular photobioreactors were built as previously described by Acién et al. [19] and Molina et al. [20]. Each tubular photobioreactor had a working volume of 340 L while raceway reactors had a working volume of 800 L. Tubular reactors consisted of a vertical tubular solar receiver (125 m length and 0.05 m diameter) and a bubble column for heat exchange and O 2 degassing (1.92 m high and 0.25 m diameter). "
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    ABSTRACT: In this work, the outdoor pilot-scale production of marine microalga Nannochloropsis gaditana using centrate from the anaerobic digestion of municipal wastewater was evaluated. For this, outdoor semi-continuous cultures were performed in both tubular and raceway reactors mixing seawater with different centrate percentages (15%, 20% and 30%) as culture medium. It was demonstrated that N. gaditana can be produced using centrate as the only nutrient source but at percentages below 30%. At this level inhibition was caused by an excess of ammonium in both photobioreactors, as confirmed by chlorophyll fluorescence and average irradiance data, thus reducing productivity. At 15% and 20% centrate percentages, biomass productivity was equal to that measured when using Algal culture medium, of 0.48 and 0.10 g L− 1 day− 1 for tubular and raceway reactors respectively. During the experiments nitrogen depuration decreased from 85% to 63% in tubular reactors with the increase of centrate percentage in the culture medium and the decrease in biomass productivity, while in raceway reactors an opposite behavior was observed due to ammonia stripping from the cultures. Phosphorus depuration from the culture medium was 85% whatever the system used and the centrate percentage in the culture medium indicating a phosphorus limitation into the cultures. By supplying additional phosphorus, to achieve an N:P ratio of 5, it was possible to enhance productivity and increase nitrogen depuration in both systems. The use of centrate is confirmed as a useful method for reducing microalgae production costs and for increasing process sustainability. Consequently, it is demonstrated that for the production of microalgae biomass, centrate from wastewater treatment plants can be used as the exclusive nutrient source, achieving high productivities and nutrient removal rates if using suitable strains and if the system is operated adequately
    Algal Research 11/2015; 12:17-25. DOI:10.1016/j.algal.2015.08.002 · 5.01 Impact Factor
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    • "However, it is important to note that the tubular photobioreactor utilized a centrifugal pump for culture flow and mixing, which has a significant amount of shear and can cause a drastic decrease in productivity (Torzillo et al. 2003). This is why many cultivation systems utilize aeration for mixing or airlifts to minimize shear stress (Molina et al. 2001; Sánchez Mirón et al. 2000). Raes et al. (2014) compared Tetraselmis sp. in an open raceway pond and the Biocoil helical photobioreactor and showed that this alga in semicontinuous cultivation achieved productivities of 3 and 0.85 g m −2 day −1 , respectively. "

    Journal of Applied Phycology 09/2015; DOI:10.1007/s10811-015-0710-6 · 2.56 Impact Factor
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    • "Photobioreactors (PBRs) are closed systems for microalgae cultivation and there are currently three main design groups available (Carvalho et al., 2011). These designs are tubular (Molina et al., 2001), flat panel (Issarapayup et al., 2009) or fermenter-type (Carvalho et al., 2006). Tubular and flat-panel PBRs are designed for the efficient harvest of sunlight and are therefore based on the principle of high area to volume ratios. "
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    ABSTRACT: Chlamydomonas reinhardtii (CCAP 11/32C) cells were grown in liquid culture under photoautotrophic conditions using a photobioreactor (PBR) based on oscillatory baffled reactor (OBR) technology. A flotation effect was observed when using a porous gas sparger which resulted in accumulation of microalgae at the top of the column. Linear growth was achieved with a different sparger, designed to produce larger, faster rising gas bubbles. Changes in the mixing intensity had no effect on the maximum growth rate of 0.130OD750/day (±0.010) achieved which was 95% higher than that achieved in T-flasks of 0.067OD750/day (±0.011) under comparable conditions. The increase in growth rate achieved in the OBR was probably a result of increased gas transfer, and exponential growth was not achieved probably due to the relatively low light intensity used of 78μmol/m2s (±20). The results demonstrate the feasibility of OBR technology for use as PBRs with the potential for the duel culture and harvest of microalgal biomass through manipulation of the bubble diameter. This could greatly improve bioprocess economics for microalgae culture.
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