Water reuse for sustainable microalgae cultivation: current knowledge and future directions

Lu, Zhiying; Loftus, Sarah E.; Sha, Jun; Wang, Wenxuan; Park, Min; Zhang, Xuezhi; Johnson, Zackary I.; Hu, Qiang

doi:10.1016/j.resconrec.2020.104975

Cited by 64 publications

(43 citation statements)

References 164 publications

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“…The type, amount, and mode of action of these organic molecules depend on the microalgae strain, its growth phase, coexisting bacteria, and growth conditions such as temperature and inorganic nutrients (Bacellar Mendes & Vermelho, 2013; Liu et al, 2016). The type and amount of these OMs depend on the microalgae strain, its growth phase, coexisting bacteria, and growth conditions such as temperature and inorganic nutrient availability (Liu et al, 2016; Lu et al, 2020). Biological effects of these compounds are concentration, physiochemical characterization, and species dependent.…”

Section: Cultivation Of Microalgae In Recycled Watermentioning

confidence: 99%

Sustainable production of microalgae biomass for biofuel and chemicals through recycling of water and nutrient within the biorefinery context: A review

Farooq

2021

GCB Bioenergy

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Commercial‐scale production of microalgae biomass for biofuel and biochemicals requires a substantial amount of water and nutrients. Many studies are conducted to explore the potential of various aqueous streams originating from harvesting stage and different energy recovery steps as an alternative for water and nutrient supply. Presence of toxic organic compounds, unassimilated ions, particulate matter, and high alkalinity in post‐harvest water limit its recyclability. Nutrient recovery from biomass via anaerobic digestion (AD) and various hydrothermal processes is being explored. So, there is a need to understand the impact of harvesting methods, nature and impact of organic compounds, buildup of algogenic organic matter (OM), amount of unused nutrients, and salinity on water recycling. Optimum conditions for maximum nutrient recovery from AD and hydrothermal processes are discussed for effective nutrient recycling. This review is an attempt to understand the challenges associated with the recycling of aqueous streams for water and nutrient requirement for sustainable microalgae cultivation. The effectiveness of a recycling stream is defined here as “biomass ratio.” Possible growth inhibiting factors are identified, and their solutions are suggested along with potential directions for future research. Large‐scale sustainable cultivation of microalgae through recycling of different streams depends on better understanding of biological activity of algal OM through detailed characterization and in‐depth understanding of physiochemical properties.

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Section: Cultivation Of Microalgae In Recycled Watermentioning

confidence: 99%

Sustainable production of microalgae biomass for biofuel and chemicals through recycling of water and nutrient within the biorefinery context: A review

Farooq

2021

GCB Bioenergy

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“…Unicellular eukaryotic microalgae are a diverse and ubiquitous group of plants that are a promising biomass source and a biological feedstock [ 1 , 2 ]. However, the use of microalgae as a feedstock is limited because a large amount of water is needed for its cultivation, and this negatively affects economic viability and environmental sustainability [ 3 ]. Wastewater treatment is currently being used to recycle the water that is necessary for microalgae cultivation [ 4 ].…”

Section: Introductionmentioning

confidence: 99%

“…It has been reported that to produce 1 kg of algae biomass, 1564 L of water are required under pond conditions [ 5 ]. Reusing cultivation water can reduce water usage and nutrient requirements as well as the need for algal wastewater treatment [ 3 ]. Consequently, water reuse after algae harvesting is essential for the economic viability of the microalgae industry and for environmental sustainability.…”

Section: Introductionmentioning

confidence: 99%

“…The effects of water reuse on algae growth are different across algae taxa [ 6 ]. The most researched taxa are green algae, diatoms, cyanobacteria, haptophytes, eustigmatophytes, chrysophytes, and xanthophytes [ 3 ]. However, among the genus of Euglena spp.…”

Section: Introductionmentioning

confidence: 99%

“…In addition to accumulated ions, excreted metabolites, such as dissolved organic matter (DOM) from microalgae is considered to be the main cause of negative biomass growth [ 3 , 6 , 10 ]. For Scenedesmus sp.…”

Section: Introductionmentioning

confidence: 99%

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Water reuse and growth inhibition mechanisms for cultivation of microalga Euglena gracilis

et al. 2021

Biotechnol Biofuels

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Background Microalgae can contribute to more than 40% of global primary biomass production and are suitable candidates for various biotechnology applications such as food, feed products, drugs, fuels, and wastewater treatment. However, the primary limitation for large-scale algae production is the fact that algae requires large amounts of fresh water for cultivation. To address this issue, scientists around the world are working on ways to reuse the water to grow microalgae so that it can be grown in successive cycles without the need for fresh water. Results In this study, we present the results when we cultivate microalgae with cultivation water that is purified and reused. Specifically, we purify the cultivation water using an ultrafiltration membrane (UFM) treatment and investigate how this treatment affects: the biomass and biochemical components of the microalgae; characteristics of microalgae growth inhibitors; the mechanism whereby potential growth inhibitors are secreted (followed using metabolomics analysis); the effect of activated carbon (AC) treatment and advanced oxidation processes (AOPs) on the removal of growth inhibitors of Euglena gracilis. Firstly, the results show that E. gracilis can be only cultivated through two growth cycles with water that has been filtered and reused, and the growth of E. gracilis is significantly inhibited when the water is used a third time. Secondly, as the number of reused water cycles increases, the Cl− concentration gradually increases in the cultivation water. When the Cl− concentration accumulates to a level of fivefold higher than that of the control, growth of E. gracilis is inhibited as the osmolality tolerance range is exceeded. Interestingly, the osmolality of the reused water can be reduced by replacing NH4Cl with urea as the source of nitrogen in the cultivation water. Thirdly, E. gracilis secretes humic acid (HA)—which is produced by the metabolic pathways for valine, leucine, and isoleucine biosynthesis and by linoleic acid metabolism—into the cultivation water. Because HA contains large fluorescent functional groups, specifically extended π(pi)-systems containing C=C and C=O groups and aromatic rings, we were able to observe a positive correlation between HA concentration and the rate of inhibition of E. gracilis growth using fluorescence spectroscopy. Moreover, photosynthetic efficiency is adversely interfered by HA, thereby reductions in the synthetic efficiency of paramylon and lipid in E. gracilis. In this way, we are able to confirm that HA is the main growth inhibitor of E. gracilis. Finally, we verify that all the HA is removed or converted into nutrients efficiently by AC or UV/H2O2/O3 treatments, respectively. As a result of these treatments, growth of E. gracilis is restored (AC treatment) and the amount of biomass is promoted (UV/H2O2/O3 treatment). Conclusions These studies have important practical and theoretical significance for the cyclic cultivation of E. gracilis and for saving water resources. Our work may also provide a useful reference for other microalgae cultivation.

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Space‐Efficient 3D Microalgae Farming with Optimized Resource Utilization for Regenerative Food

Liu,

Yu,

Liu

et al. 2024

Advanced Materials

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Photosynthetic microalgae produce valuable metabolites and are a source of sustainable food that supports life without compromising arable land. However, the light self‐shading, excessive water supply, and insufficient space utilization in microalgae farming have limited its potential in the inland areas most in need of regenerative food solutions. Herein, we develop a 3D polysaccharide‐based hydrogel scaffold for vertically farming microalgae without needing liquid media. This liquid‐free strategy is compatible with diverse microalgal species and enables the design of living microalgal frameworks with customizable architectures that enhance light and water utilization. This approach significantly increases microalgae yield per unit water consumption, with an 8.8‐fold increase compared to traditional methods. Furthermore, the dehydrated hydrogels demonstrate a reduced size and weight (∼70% reduction), but readily recover their vitality upon rehydration. Importantly, valuable natural products can be produced in our system including proteins, carbohydrates, lipids, and carotenoids. This study streamlines microalgae regenerative farming for low‐carbon biomanufacturing by minimizing light self‐shading, relieving water supply, and reducing physical footprints, and democratizing access to efficient aquatic food production.This article is protected by copyright. All rights reserved

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Water reuse for sustainable microalgae cultivation: current knowledge and future directions

Cited by 64 publications

References 164 publications

Sustainable production of microalgae biomass for biofuel and chemicals through recycling of water and nutrient within the biorefinery context: A review

Sustainable production of microalgae biomass for biofuel and chemicals through recycling of water and nutrient within the biorefinery context: A review

Water reuse and growth inhibition mechanisms for cultivation of microalga Euglena gracilis

Space‐Efficient 3D Microalgae Farming with Optimized Resource Utilization for Regenerative Food

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