Nannochloropsis oceanica Cultivation in Pilot-Scale Raceway Ponds—From Design to Cultivation

Pedro Cunha,Hugo Pereira,Nuno Fernandes,Joana T Silva,Joana Silva,João Varela,Manuel Simões,João Pereira,Margarida Costa

doi:10.3390/app10051725

Pedro Cunha, Hugo Pereira + Show 7 more

Open Access

https://doi.org/10.3390/app10051725

Copy DOI

Journal: Applied sciences	Publication Date: Mar 3, 2020
Citations: 20	License type: CC BY 4.0

Affiliation: University of Algarve, University of Porto

Abstract

Raceways ponds are the microalgal production systems most commonly used at industrial scale. In this work, two different raceway configurations were tested under the same processing conditions to compare their performance on the production of Nannochloropsis oceanica. Biomass productivity, biochemical composition of the produced biomass, and power requirements to operate those reactors were evaluated. Water depths of 0.20 and 0.13 m, and culture circulation velocities of 0.30 and 0.15 m s−1 were tested. A standard configuration, which had a full channel width paddlewheel, proved to be the most energy efficient, consuming less than half of the energy required by a modified configuration (had a half channel width paddlewheel). The later showed to have slightly higher productivity, not enough to offset the large difference in energetic consumption. Higher flow velocity (0.30 m s−1) led to a 1.7 g m−2 d−1 improvement of biomass productivity of the system, but it increased the energy consumption twice as compared to the 0.15 m s−1 flow velocity. The latter velocity showed to be the most productive in lipids. A water depth of 0.20 m was the most suitable option tested to cultivate microalgae, since it allowed a 54% energy saving. Therefore, a standard raceway pond using a flow velocity of 0.3 m s−1 with a 0.20 m water depth was the most efficient system for microalgal cultivation. Conversely, a flow velocity of 0.15 m s−1 was the most suitable to produce lipids.

Highlights

Microalgae are a diverse group of microorganisms that combine properties of higher plants with those of some prokaryotes [1,2]
849/10, wasthe obtainedfrom of two raceway ponds with different configurations based on three criteria: areal productivity, energy
N. oceanica growth experiments were performed under three different sets of process conditions (Table 2) in order to determine which of the two raceway configurations were the most promising in terms of productivity, product quality, and energy consumption

Summary

Introduction

Microalgae are a diverse group of microorganisms that combine properties of higher plants with those of some prokaryotes [1,2]. Microalgae occur as unicellular or simple colonial organisms, usually displaying rapid growth rates [4] and photosynthetic efficiencies between 9–10%, in general significantly higher than those of terrestrial plants [5,6,7]. They are key members of the biosphere, as they play an important role in the global carbon and nitrogen cycles. By using light energy to produce organic matter, algal photosynthesis contributes to around 50% of the total planetary primary production [8,9].

Objectives

Methods

Conclusion