Algae bioreactor

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A close up of microalgae - Pavlova sp. CSIRO ScienceImage 7604 Microalgae.jpg
A close up of microalgae – Pavlova sp.

An algae bioreactor is used for cultivating micro or macroalgae. Algae may be cultivated for the purposes of biomass production (as in a seaweed cultivator), wastewater treatment, CO2 fixation, or aquarium/pond filtration in the form of an algae scrubber. [1] Algae bioreactors vary widely in design, falling broadly into two categories: open reactors and enclosed reactors. Open reactors are exposed to the atmosphere while enclosed reactors, also commonly called photobioreactors, are isolated to varying extents from the atmosphere. Specifically, algae bioreactors can be used to produce fuels such as biodiesel and bioethanol, to generate animal feed, or to reduce pollutants such as NOx and CO2 in flue gases of power plants. Fundamentally, this kind of bioreactor is based on the photosynthetic reaction, which is performed by the chlorophyll-containing algae itself using dissolved carbon dioxide and sunlight. The carbon dioxide is dispersed into the reactor fluid to make it accessible to the algae. The bioreactor has to be made out of transparent material.

Contents

Historical background

The first microalgae cultivation was of the unicellular Chlorella vulgaris by Dutch microbiologist Martinus Beijerinck in 1890. Later, during World War II, Germany used open ponds to increase algal cultivation for use as a protein supplement. [2] Some of the first experiments with the aim of cultivating algae were conducted in 1957 by the Carnegie Institution for Science in Washington. In these experiments, monocellular Chlorella were cultivated by adding CO2 and some minerals. The goal of this research was the cultivation of algae to produce a cheap animal feed. [3]

Metabolism of microalgae

Algae are primarily eukaryotic photoautotrophic organisms which perform oxygenic photosynthesis. These types of algae are classified by their light-harvesting pigments which give them their color. [2] The green algae species, also known as Chlorophyta, are often used in bioreactors due to their high growth rate and ability to withstand a variety of environments. Blue-green algae, also known as cyanobacteria, are classified as prokaryotic photoautotrophs due to their lack of a nucleus. Light provides essential energy the cell needs to metabolize CO2, nitrogen, phosphorus and other essential nutrients. The wavelengths and intensities of light are very important factors. [4] Available CO2 is also an important factor for growth and due to the lower concentration in our atmosphere, supplementary CO2 can be added as seen with the bubble column PBR below. Microalgae also possess the ability to take up excess nitrogen and phosphorus under starvation conditions, which are essential for lipid and amino acid synthesis. Higher temperatures and a pH above 7 and below 9 are also common factors. [4] Each of these factors may vary from species to species so it is important to have the correct environmental conditions while designing bioreactors of any sort.

Types of bioreactors

Bioreactors can be divided into two broad categories, open systems and photobioreactors (PBR). The difference between these two reactors are their exposure to the surrounding environment. Open systems are fully exposed to the atmosphere, while PBRs have very limited exposure to the atmosphere.

Commonly used open systems

Raceway pond at the Bromley waste water treatment plant in Christchurch, New Zealand used for algae cultivation. Solray Algae to Biofuels opening 24.jpg
Raceway pond at the Bromley waste water treatment plant in Christchurch, New Zealand used for algae cultivation.

Simple ponds

The simplest system yields a low production and operation cost. Ponds need a rotating mixer to avoid settling of algal biomass. However, these systems are prone to contamination due to the lack of environmental control. [5]

Raceway ponds

A modified version of a simple pond, the raceway pond uses paddle wheels to drive the flow in a certain direction. [6] The pond is continuously collecting biomass while providing carbon dioxide and other nutrients back into the pond. Typically, raceway ponds are very large due to their low water depth. [5]

Other systems

Less common systems include an incline cascade system where flow is gravity-driven to a retention tank, from where it gets pumped back up to start again. This system can yield high biomass densities, but also entails higher operating costs. [7]

Commonly used photobioreactors (PBRs)

Nowadays, 3 basic types of algae photobioreactors have to be differentiated, but the determining factor is the unifying parameter – the available intensity of sunlight energy.

plastic plate photobioreactor for the cultivation of microalgae and other photosynthetic organisms. It has an operational volume of 500 liters. Photobioreactor PBR 500 P IGV Biotech.jpg
plastic plate photobioreactor for the cultivation of microalgae and other photosynthetic organisms. It has an operational volume of 500 liters.

Flat plate PBR

A plate reactor simply consists of inclined or vertically arranged translucent rectangular boxes, which are often divided in two parts to affect an agitation of the reactor fluid. Generally, these boxes are arranged into a system by linking them. Those connections are also used for making the process of filling/emptying, introduction of gas and transport of nutritive substances. The introduction of the flue gas mostly occurs at the bottom of the box to ensure that the carbon dioxide has enough time to interact with algae in the reactor fluid. Typically, these plates are illuminated from both sides and have a high light penetration. Disadvantages of the flat plate design are the limited pressure tolerance and high space requirements. [8]

tubular glass photobioreactor for the cultivation of microalgae and other photosynthetic organisms. It has an operational volume of 4000 liters. Photobioreactor PBR 4000 G IGV Biotech.jpg
tubular glass photobioreactor for the cultivation of microalgae and other photosynthetic organisms. It has an operational volume of 4000 liters.

Tubular PBR

A tubular reactor consists of vertically or horizontally arranged tubes, connected together, in which the algae-suspended fluid circulates. The tubes are generally made out of transparent plastics or borosilicate glass, and the constant circulation is kept up by a pump at the end of the system. The introduction of gas takes place at the end/beginning of the tube system. This way of introducing gas causes the problem of carbon dioxide deficiency and high concentration of oxygen at the end of the unit during the circulation, ultimately making the process inefficient. The growth of microalgae on the walls of the tubes can inhibit the penetration of the light as well. [8]

Bubble column PBR

Vertical bubble columns, a project at the Universidad EAFIT to utilize algae to reduce CO2 emissions. Bubblecolumn.jpg
Vertical bubble columns, a project at the Universidad EAFIT to utilize algae to reduce CO2 emissions.

A bubble column photo reactor consists of vertically arranged cylindrical columns made out of transparent material. The introduction of gas takes place at the bottom of the column and causes a turbulent stream to enable an optimum gas exchange. The bubbling also acts as a natural agitator. Light is typically sourced from outside the column, however recent designs introduce lights inside the column to increase light distribution and penetration. [8]

Industrial usage

The cultivation of algae in a photobioreactor creates a narrow range of industrial application possibilities. There are three common pathways for cultivated biomass. Algae may be used for environmental improvements, biofuel production and food/biofeed. [9] Some power companies [10] already established research facilities with algae photobioreactors to find out how efficient they could be in reducing CO2 emissions, which are contained in flue gas, and how much biomass will be produced. Algae biomass has many uses and can be sold to generate additional income. The saved emission volume can bring an income too, by selling emission credits to other power companies. [11] Recent studies around the world look at the algae usage for treating wastewater as a way to become more sustainable. [12]

The utilization of algae as food is very common in East Asian regions [13] and is making an appearance around the world for uses in feedstock and even pharmaceuticals due to their high value products. [9] Most of the species contain only a fraction of usable proteins and carbohydrates, and a lot of minerals and trace elements. Generally, the consumption of algae should be minimal because of the high iodine content, particularly problematic for those with hyperthyroidism. Likewise, many species of diatomaceous algae produce compounds unsafe for humans. [14] The algae, especially some species which contain over 50 percent oil and a lot of carbohydrates, can be used for producing biodiesel and bioethanol by extracting and refining the fractions. The algae biomass is generated 30 times faster than some agricultural biomass, [15] which is commonly used for producing biodiesel.

Microgeneration

The Bio-Intelligent Quotient (BIQ) House in Hamburg IBA Hamburg BIQ (2).nnw.jpg
The Bio-Intelligent Quotient (BIQ) House in Hamburg

The BIQ House  [ de ] built in 2013 [16] [17] in Germany is a showcase experimental bionic house using glass facade panels for the cultivation of micro algae. [18] Once the panels heat up thermal energy can also be extracted through a heat exchanger in order to supply warm water to the building. [18] The technology is still in an early stage and not yet fit for a wider use.

The Green Power House in Montana, United States used newly-developed Algae Aquaculture Technology within a system that uses sunlight and woody debris waste from a lumber mill for providing nutrients to eight algae ponds of the AACT that cover its floor. [19] Identified challenges of algae façades include durability of microalgae panels, the need for maintenance, and construction and maintenance costs [20]

In 2022, news outlets reported about the development of algae biopanels by a company for sustainable energy generation with unclear viability. [21] [22]

See also

Related Research Articles

<span class="mw-page-title-main">Biofuel</span> Type of biological fuel

Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels such as oil. Biofuel can be produced from plants or from agricultural, domestic or industrial biowaste. Biofuels are mostly used for transportation, but can also be used for heating and electricity. Biofuels are regarded as a renewable energy source. The use of biofuel has been subject to criticism regarding the "food vs fuel" debate, varied assessments of their sustainability, and possible deforestation and biodiversity loss as a result of biofuel production.

<span class="mw-page-title-main">Microalgae</span> Microscopic algae

Microalgae or microphytes are microscopic algae invisible to the naked eye. They are phytoplankton typically found in freshwater and marine systems, living in both the water column and sediment. They are unicellular species which exist individually, or in chains or groups. Depending on the species, their sizes can range from a few micrometers (μm) to a few hundred micrometers. Unlike higher plants, microalgae do not have roots, stems, or leaves. They are specially adapted to an environment dominated by viscous forces.

<span class="mw-page-title-main">Algaculture</span> Aquaculture involving the farming of algae

Algaculture is a form of aquaculture involving the farming of species of algae.

<span class="mw-page-title-main">Photobioreactor</span> Bioreactor with a light source to grow photosynthetic microorganisms

A photobioreactor (PBR) refers to any cultivation system designed for growing photoautotrophic organisms using artificial light sources or solar light to facilitate photosynthesis. Photobioreactors are typically used to cultivate microalgae, cyanobacteria, and some mosses. Photobioreactors can be open systems, such as raceway ponds, which rely upon natural sources of light and carbon dioxide. Closed photobioreactors are flexible systems that can be controlled to the physiological requirements of the cultured organism, resulting in optimal growth rates and purity levels. Photobioreactors are typically used for the cultivation of bioactive compounds for biofuels, pharmaceuticals, and other industrial uses.

<span class="mw-page-title-main">Algal nutrient solution</span>

Algal nutrient solutions are made up of a mixture of chemical salts and seawater. Sometimes referred to as "Growth Media", nutrient solutions, provide the materials needed for algae to grow. Nutrient solutions, as opposed to fertilizers, are designed specifically for use in aquatic environments and their composition is much more precise. In a unified system, algal biomass can be collected by utilizing carbon dioxide emanating from power plants and wastewater discharged by both industrial and domestic sources. This approach allows for the concurrent exploitation of the microalgae's capabilities in both carbon dioxide fixation and wastewater treatment. Algae, macroalgae, and microalgae hold promise in addressing critical global challenges. Sustainable development goals can be advanced through algae-based solutions, to promote a healthy global ecosystem.

GreenFuel Technologies Corporation (GFT) was a startup that developed a process of growing algae using emissions from fossil fuels to produce biofuel from algae.

<i>Scenedesmus</i> Genus of green algae

Scenedesmus is a genus of green algae, in the class Chlorophyceae. They are colonial and non-motile. They are one of the most common components of phytoplankton in freshwater habitats worldwide.

Auxenochlorella protothecoides, formerly known as Chlorella protothecoides, is a facultative heterotrophic green alga in the family Chlorellaceae. It is known for its potential application in biofuel production. It was first characterized as a distinct algal species in 1965, and has since been regarded as a separate genus from Chlorella due its need for thiamine for growth. Auxenochlorella species have been found in a wide variety of environments from acidic volcanic soil in Italy to the sap of poplar trees in the forests of Germany. Its use in industrial processes has been studied, as the high lipid content of the alga during heterotrophic growth is promising for biodiesel; its use in wastewater treatment has been investigated, as well.

<i>Choricystis</i> Genus of algae

Choricystis is a genus of green algae in the class Trebouxiophyceae, considered a characteristic picophytoplankton in freshwater ecosystems. Choricystis, especially the type species Choricystis minor, has been proposed as an effective source of fatty acids for biofuels. Choricystis algacultures have been shown to survive on wastewater. In particular, Choricystis has been proposed as a biological water treatment system for industrial waste produced by the processing of dairy goods.

<span class="mw-page-title-main">Algae fuel</span> Use of algae as a source of energy-rich oils

Algae fuel, algal biofuel, or algal oil is an alternative to liquid fossil fuels that uses algae as its source of energy-rich oils. Also, algae fuels are an alternative to commonly known biofuel sources, such as corn and sugarcane. When made from seaweed (macroalgae) it can be known as seaweed fuel or seaweed oil.

<i>Nannochloropsis</i> Genus of algae

Nannochloropsis is a genus of algae comprising six known species. The genus in the current taxonomic classification was first termed by Hibberd (1981). The species have mostly been known from the marine environment but also occur in fresh and brackish water. All of the species are small, nonmotile spheres which do not express any distinct morphological features that can be distinguished by either light or electron microscopy. The characterisation is mostly done by rbcL gene and 18S rRNA sequence analysis.

Algae fuel in the United States, as with other countries, is under study as a source of biofuel.

Wageningen UR has constructed AlgaePARC at the Wageningen Campus. The goal of AlgaePARC is to fill the gap between fundamental research on algae and full-scale algae production facilities. This will be done by setting up flexible pilot scale facilities to perform applied research and obtain direct practical experience. It is a joined initiative of BioProcess Engineering and Food & Biobased Research of the Wageningen University.

<i>Nannochloropsis</i> and biofuels

Nannochloropsis is a genus of alga within the heterokont line of eukaryotes, that is being investigated for biofuel production. One marine Nannochloropsis species has been shown to be suitable for algal biofuel production due to its ease of growth and high oil content, mainly unsaturated fatty acids and a significant percentage of palmitic acid. It also contains enough unsaturated fatty acid linolenic acid and polyunsaturated acid for a quality biodiesel.

<span class="mw-page-title-main">Culture of microalgae in hatcheries</span>

Microalgae or microscopic algae grow in either marine or freshwater systems. They are primary producers in the oceans that convert water and carbon dioxide to biomass and oxygen in the presence of sunlight.

Carbon-neutral fuel is fuel which produces no net-greenhouse gas emissions or carbon footprint. In practice, this usually means fuels that are made using carbon dioxide (CO2) as a feedstock. Proposed carbon-neutral fuels can broadly be grouped into synthetic fuels, which are made by chemically hydrogenating carbon dioxide, and biofuels, which are produced using natural CO2-consuming processes like photosynthesis.

<i>Chlorella vulgaris</i> Species of green alga

Chlorella vulgaris is a species of green microalga in the division Chlorophyta. It is mainly used as a dietary supplement or protein-rich food additive in Japan.

References

  1. ↑ Zhu, Yunhua; Schmidt, Andrew; Valdez, Peter; Snowden-Swan, Lesley; Edmundson, Scott (2022-03-21). "Hydrothermal Liquefaction and Upgrading of Wastewater-Grown Microalgae: 2021 State of Technology". OSTI. doi: 10.2172/1855835 . OSTI   1855835. S2CID   247648577 .
  2. 1 2 Hu, Qiang; Richmond, Amos (4 June 2013). Handbook of microalgal culture. Wiley. ISBN   978-0-470-67389-8. OCLC   827267000.
  3. ↑ "Achmed Khammas - Das Buch der Synergie - Teil C - Die Geschichte der Solarenergie". www.buch-der-synergie.de. Retrieved 2022-05-03.
  4. 1 2 Su, Yanyan (March 2021). "Revisiting carbon, nitrogen, and phosphorus metabolisms in microalgae for wastewater treatment". Science of the Total Environment . 762: 144590. Bibcode:2021ScTEn.762n4590S. doi:10.1016/j.scitotenv.2020.144590. ISSN   0048-9697. PMID   33360454. S2CID   229696313.
  5. 1 2 Costa, Jorge Alberto Vieira; Freitas, Bárbara Catarina Bastos; Santos, Thaisa Duarte; Mitchell, Bryan Gregory; Morais, Michele Greque (2019), "Open pond systems for microalgal culture", Biofuels from Algae, Elsevier, pp. 199–223, doi:10.1016/b978-0-444-64192-2.00009-3, ISBN   978-0-444-64192-2, S2CID   146179919 , retrieved 2022-05-03
  6. ↑ Huesemann, M.; Williams, P.; Edmundson, Scott J.; Chen, P.; Kruk, R.; Cullinan, V.; Crowe, B.; Lundquist, T. (2017-09-01). "The laboratory environmental algae pond simulator (LEAPS) photobioreactor: Validation using outdoor pond cultures of Chlorella sorokiniana and Nannochloropsis salina". Algal Research. 26: 39–46. doi: 10.1016/j.algal.2017.06.017 . ISSN   2211-9264. OSTI   1581797.
  7. ↑ Richmond, Amos; Hu, Qiang, eds. (2013-05-07). Handbook of Microalgal Culture. doi:10.1002/9781118567166. ISBN   9781118567166.
  8. 1 2 3 Yen, Hong-Wei; Hu, I-Chen; Chen, Chun-Yen; Nagarajan, Dillirani; Chang, Jo-Shu (2019), "Design of photobioreactors for algal cultivation", Biofuels from Algae, Elsevier, pp. 225–256, doi:10.1016/b978-0-444-64192-2.00010-x, ISBN   978-0-444-64192-2, S2CID   239352174 , retrieved 2022-05-03
  9. 1 2 Guedes, A. Catarina; Amaro, Helena M.; Sousa-Pinto, Isabel; Malcata, F. Xavier (2019), "Algal spent biomass—A pool of applications", Biofuels from Algae, Elsevier, pp. 397–433, doi:10.1016/b978-0-444-64192-2.00016-0, ISBN   9780444641922, S2CID   134091203 , retrieved 2022-05-04
  10. ↑ Patel, Sonal (May 1, 2016). "A Breakthrough Carbon-Capturing Algae Project". Powermag. Texas, USA: powermag.com. Retrieved 16 November 2018.
  11. ↑ Umweltbundesamt Archived 2009-07-21 at the Wayback Machine
  12. ↑ Kumar, Vinod; Jaiswal, Krishna Kumar; Verma, Monu; Vlaskin, Mikhail S.; Nanda, Manisha; Chauhan, Pankaj Kumar; Singh, Ajay; Kim, Hyunook (June 2021). "Algae-based sustainable approach for simultaneous removal of micropollutants, and bacteria from urban wastewater and its real-time reuse for aquaculture". Science of the Total Environment. 774: 145556. Bibcode:2021ScTEn.774n5556K. doi:10.1016/j.scitotenv.2021.145556. ISSN   0048-9697. S2CID   234062541 – via Science Direct.
  13. ↑ "Algae, The Food That Could Save Humanity". Le Monde . France: worldcruch.com. July 9, 2016. Retrieved 16 November 2018.
  14. ↑ "Toxic diatoms". NOAA Northeast Fisheries Science Center. NOAA. September 1, 2014. Retrieved 16 November 2018. the family Pseudo-nitzschia; under certain conditions these diatoms can produce toxins harmful to humans
  15. ↑ Ullah, Kifayat; Ahmad, Mushtaq; Sofia; Sharma, Vinod Kumar; Lu, Pengmei; Harvey, Adam; Zafar, Muhammad; Sultana, Shazia; Anyanwu, C.N. (2014). "Algal biomass as a global source of transport fuels: Overview and development perspectives". Progress in Natural Science: Materials International. 24 (4): 329–339. doi: 10.1016/j.pnsc.2014.06.008 .
  16. ↑ Talaei, Maryam; Mahdavinejad, Mohammadjavad; Azari, Rahman (1 March 2020). "Thermal and energy performance of algae bioreactive façades: A review". Journal of Building Engineering. 28: 101011. doi:10.1016/j.jobe.2019.101011. ISSN   2352-7102. S2CID   210245691.
  17. ↑ Wilkinson, Sara; Stoller, Paul; Ralph, Peter; Hamdorf, Brenton; Catana, Laila Navarro; Kuzava, Gabriela Santana (1 January 2017). "Exploring the Feasibility of Algae Building Technology in NSW". Procedia Engineering. 180: 1121–1130. doi: 10.1016/j.proeng.2017.04.272 . ISSN   1877-7058.
  18. 1 2 Nazareth, Aaron (2018). "Bionic architecture". Research Project. Unitec Institute of Technology: 1–69.
  19. ↑ Proksch, Gundula (2012). "Growing Sustainability - Integrating Algae Cultivation into the Built Environment". Edinburgh Architecture Research EAR. 33.
  20. ↑ Talaei, Maryam; Mahdavinejad, Mohammadjavad; Azari, Rahman; Haghighi, Hadi Motevali; Atashdast, Ali (1 August 2022). "Thermal and energy performance of a user-responsive microalgae bioreactive façade for climate adaptability". Sustainable Energy Technologies and Assessments. 52: 101894. doi:10.1016/j.seta.2021.101894. ISSN   2213-1388. S2CID   246353563.
  21. ↑ "Algae biopanel windows make power, oxygen and biomass, and suck up CO2". New Atlas. 11 July 2022. Retrieved 21 August 2022.
  22. ↑ Paleja, Ameya (13 July 2022). "Algae-filled panels could generate oxygen and electricity while absorbing CO2". interestingengineering.com. Retrieved 21 August 2022.

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