Richard V. Dumilag, Bea A. Crisostomo, Zae-Zae A. Aguinaldo et al.

Reviews in Fisheries Science & Aquaculture • 2022

Collectively known as eucheumatoids, Eucheuma denticulatum, Kappaphycus alvarezii, K. malesianus, and K. striatus are the main farmed seaweed species in the Philippines. The success of seaweed farming for over five decades in the country is due, in part, to the high diversity of cultivars maintained by the Filipino farmers. Notwithstanding the fact that many eucheumatoid cultivars are presently (and consistently) recognized by the Filipino farmers, there has been no attempt to summarize the current state of the local traditional knowledge about the diversity of this seaweed group, especially with reference to the taxonomy, cultivar designation and distribution. Factors based on present day local knowledge on the eucheumatoid cultivars and what is known on genetic identification in the Philippines were also discussed. A total of 66 cultivars recognized across 58 provinces in the Philippines were documented. Most of these cultivars were morphologically identified as either K. alvarezii or K. striatus, however, the majority were yet to be genetically identified. In part, due to higher demand of kappa-carrageenan extract as compared from the iota type, K. alvarezii and K. striatus were widely cultivated in the Philippines than that of E. denticulatum. Only in the southern Philippines that K. malesianus is currently cultivated. The diverse cultivars identified in this study suggest that the Filipino farmers possess important traditional knowledge that can be useful for future crop selection and breeding.

Timothy Prince Chidike Ezeorba, Emmanuel Sunday Okeke, Mida Habila Mayel et al.

Bioresource Technology Reports • 2024

Achieving renewable clean energy to meet increasing global demand and counter overreliance on depleting unsustainable sources has recently drawn significant research interest. Similarly, to attain the sustainable development goals (SDGs) “zero hunger” agenda, massive agricultural/food productions are embarked on, leading to increased agro-food waste (AFW) generation with enormous handling costs to evade its contribution to environmental pollution. The advent of biorefineries has fostered a healthy balance for tackling challenges from AFW and unsustainable energy – thereby promoting circular bioeconomy (CBE). Integrating several emerging microbial/enzymatic bioconversion processes has facilitated the overall increase in process efficiency. This review, therefore, provides extensive information on the ecological and environmental impacts of AFW, as well as its biorefinery processes for a circular bioeconomy and environmental sustainability. We also critically reviewed advances in integrated bioconversion processes and microbial/enzymatic engineering for AFW valorization. Finally, limitations and prospects for real-life application of these recent approaches were suggested.

Kimitaka Asatani, Haruo Takeda, Hiroko Yamano et al.

Energies • 2020

Scientific research plays an important role in the achievement of a sustainable society. However, grasping the trends in sustainability research is difficult because studies are not devised and conducted in a top-down manner with Sustainable Development Goals (SDGs). To understand the bottom-up research activities, we analyzed over 300,000 publications concerned with sustainability by using citation network analysis and natural language processing. The results suggest that sustainability science’s diverse and dynamic changes have been occurring over the last few years; several new topics, such as nanocellulose and global health, have begun to attract widespread scientific attention. We further examined the relationship between sustainability research subjects and SDGs and found significant correspondence between the two. Moreover, we extracted SDG topics that were discussed following a convergent approach in academic studies, such as “inclusive society” and “early childhood development”, by observing the convergence of terms in the citation network. These results are valuable for government officials, private companies, and academic researchers, empowering them to understand current academic progress along with research attention devoted to SDGs.

Luciano Caseli

Anais da Academia Brasileira de Ciências • 2018

In this review we discuss about the immobilization of enzymes in Langmuir-Blodgett films in order to determine the catalytic properties of these biomacromolecules when adsorbed on solid supports. Usually, the conformation of enzymes depends on the environmental conditions imposed to them, including the chemical composition of the matrix, and the morphology and thickness of the film. In this review, we show an outline of manuscripts that report the immobilization of enzymes as LB films since the 1980's, and also some examples of how the surface properties of the floating monolayer prepared previously to the transfer to the solid support are important to determine the efficiency of the resulting device.

Kaikai Wu, Pianpian Xu, Lei Zhao et al.

npj Materials Sustainability • 2024

Abstract The conversion of carbon dioxide to medium-chain fatty acids (CO 2 -to-MCFAs) through microbial processes represents a valuable technology for sequestering and exploiting CO 2 , generating superior bio-chemicals from the primary contributor to the greenhouse effect. However, a comprehensive overview and generalization of microbial CO 2 -to-MCFAs are presently deficient. Based on this, the present review systematically summarizes the research progress, explicates the process mechanisms, analyses the key challenges and possible solutions, and anticipates forthcoming research perspectives and priorities for the first time. We proposed two original strategies, namely the synchronous strategy and integrated strategy, from current research into microbial CO 2 -to-MCFAs. The synchronous strategy concurrently achieves hydrogen (H 2 ) and CO 2 assimilation, as well as MCFAs production, by employing a reactor that co-cultivates predominant H 2 /CO 2 -utilizing microorganisms and chain elongation microorganisms. The integrated approaches involve CO 2 -to-precursors (i.e., acetate and ethanol) and subsequent precursors-to-MCFAs, achieved through the use of two bioreactors for separately cultivating H 2 /CO 2 -utilizing microorganisms and chain elongation microorganisms. Mechanistic insights reveal that microbial CO 2 -to-MCFAs predominantly encompasses two processes: H 2 and CO 2 assimilation into precursor and subsequent precursors chain elongation into MCFAs, through a Wood-Ljungdahl pathway and a two-round elongation, respectively. The analyses of key challenges and possible solutions for microbial CO 2 -to-MCFAs underscore the imperative to enhance efficiency and economy and to shed light on metabolic mechanisms. Furthermore, in order to improve the strategy application potential of microbial CO 2 -to-MCFAs, future research perspectives and priorities, e.g. exploitation of functional pure bacteria, screening of functional pure bacteria, multi-omics analysis, genetic modification and enhancement, enhancement of bioreactor stability, specific MCFA production, development of coupled purification technology for MCFAs, and economic benefits and ecological environmental risks, are proposed and prospected. This work is expected to offer a thorough understanding of the microbial CO 2 -to-MCFAs, guide and inspire researchers to address critical challenges in-depth and propel the development of CO 2 -to-MCFAs.

Amit, Divakar Dahiya, Uttam Kumar Ghosh et al.

Sustainability • 2021

This article is an overview of a biosystem of food-industry wastewater (WW) treatment using microalgae towards circular bioeconomy through biosynthesis of compounds of added-value. Focusing on circular bioeconomy with concern to environmental pollution, the management of water-resource and energy-crisis could be combined; by upgrading conventional WW treatment and simultaneously producing a renewable and sustainable source of energy algal-lipids for biodiesel production. Phyco-remediation of food WW using microalgae has revealed many advantages that can fulfill new demands for the WW treatment. WWs can be valuable resources of micronutrients and organic content (carbon source) for algal cultivation. In this review, prospective routes for the production of value-added compounds (polysaccharides, amino acids, biofuels, and biopigments) along with the bioremediation of food industry WW have been discussed. Furthermore, limitations and issues of phyco-remediation of WW using microalgae have also been reviewed with perspectives for further research and development.

Saeed Ranjbar, F. Xavier Malcata

Molecules • 2023

Hydrothermal liquefaction (HTL) represents a beacon of scientific innovation, which unlocks nature's alchemical wonders while reshaping the waste-to-energy platform. This transformative technology offers sustainable solutions for converting a variety of waste materials to valuable energy products and chemicals-thus addressing environmental concerns, inefficiencies, and high costs associated with conventional waste-management practices. By operating under high temperature and pressure conditions, HTL efficiently reduces waste volume, mitigates harmful pollutant release, and extracts valuable energy from organic waste materials. This comprehensive review delves into the intricacies of the HTL process and explores its applications. Key process parameters, diverse feedstocks, various reactor designs, and recent advancements in HTL technology are thoroughly discussed. Diverse applications of HTL products are examined, and their economic viability toward integration in the market is assessed. Knowledge gaps and opportunities for further exploration are accordingly identified, with a focus on optimizing and scaling up the HTL process for commercial applications. In conclusion, HTL holds great promise as a sustainable technology for waste management, chemical synthesis, and energy production, thus making a significant contribution to a more sustainable future. Its potential to foster a circular economy and its versatility in producing valuable products underscore its transformative role in shaping a more sustainable world.

Konstantinos P. Papadopoulos, Christina Ν. Economou, Athanasia G. Tekerlekopoulou et al.

Applied Sciences • 2020

Algal/cyanobacterial biofilm photobioreactors provide an alternative technology to conventional photosynthetic systems for wastewater treatment based on high biomass production and easy biomass harvesting at low cost. This study introduces a novel cyanobacteria-based biofilm photobioreactor and assesses its performance in post-treatment of brewery wastewater and biomass production. Two different supporting materials (glass/polyurethane) were tested to investigate the effect of surface hydrophobicity on biomass attachment and overall reactor performance. The reactor exhibited high removal efficiency (over 65%) of the wastewater’s pollutants (chemical oxygen demand, nitrate, nitrite, ammonium, orthophosphate, and total Kjeldahl nitrogen), while biomass per reactor surface reached 13.1 and 12.8 g·m−2 corresponding to 406 and 392 mg·L−1 for glass and polyurethane, respectively, after 15 days of cultivation. The hydrophilic glass surface favored initial biomass adhesion, although eventually both materials yielded complete biomass attachment, highlighting that cell-to-cell interactions are the dominant adhesion mechanism in mature biofilms. It was also found that the biofilm accumulated up to 61% of its dry weight in carbohydrates at the end of cultivation, thus making the produced biomass a suitable feedstock for bioethanol production.

Somdipta Bagchi, Manaswini Behera

SN Applied Sciences • 2020

Hosam M. Saleh, Amal I. Hassan

Fire • 2023

Carbon capture and use may provide motivation for the global problem of mitigating global warming from substantial industrial emitters. Captured CO2 may be transformed into a range of products such as methanol as renewable energy sources. Polymers, cement, and heterogeneous catalysts for varying chemical synthesis are examples of commercial goods. Because some of these components may be converted into power, CO2 is a feedstock and excellent energy transporter. By employing collected CO2 from the atmosphere as the primary hydrocarbon source, a carbon-neutral fuel may be created. The fuel is subsequently burned, and CO2 is released into the atmosphere like a byproduct of the combustion process. There is no net carbon dioxide emitted or withdrawn from the environment during this process, hence the name carbon-neutral fuel. In a world with net-zero CO2 emissions, the anthroposphere will have attained its carbon hold-up capacity in response to a particular global average temperature increase, such as 1.5 °C. As a result, each carbon atom removed from the subsurface (lithosphere) must be returned to it, or it will be expelled into the atmosphere. CO2 removal technologies, such as biofuels with carbon sequestration and direct air capture, will be required to lower the high CO2 concentration in the atmosphere if the Paris Agreement’s ambitious climate targets are to be realized. In a carbon-neutral scenario, CO2 consumption with renewable energy is expected to contribute to the displacement of fossil fuels. This article includes a conceptual study and an evaluation of fuel technology that enables a carbon-neutral chemical industry in a net-zero-CO2-emissions environment. These are based on the use of collected CO2 as a feedstock in novel chemical processes, along with “green” hydrogen, or on the use of biomass. It will also shed light on innovative methods of green transformation and getting sustainable, environmentally friendly energy.

Djamel Ghernaout, Noureddine Elboughdiri

OALib • 2020

For treating wastewater, electrochemical engineering has been rediscovered during the last four decades through the world for its inherent advantages comparatively with traditional technologies especially the chemical and biological techniques. However, the expansion of this technology founded on electric current applying has been retarded by several technical-economic factors especially the detection of disinfection by-products (DBPs) formation. This work focuses on the challenges and future tendencies for this highly-efficient technology to reach the full-scale implementations particularly in disinfecting water. Lately, new versions of electrochemical techniques have been suggested such as employing sulfate radical anion ( 4 SO -) and sunlight to generate OH radicals in TiO 2 photocatalysis and photo-Fenton water treatment. These improvements elevated the electrochemical engineering efficiency and acceptation. However, more efforts remain to be accomplished for water reuse vision. Future researches would focus on integrating membranes processes such as nanofiltration and reverse osmosis for a safe removal of DBPs.

Marina Pereira Colella, Maddalena Ripa, Annalisa Cocozza et al.

Journal of Environmental Management • 2021

Donghyun Ryu, Jin Hyoung Kim, Seon Hyeog Kim et al.

Nanomaterials • 2018

Photosynthesis converts solar energy to electricity in a highly efficient manner. Since only water is needed as fuel for energy conversion, this highly efficient energy conversion process has been rigorously investigated. In particular, photosynthetic apparatus, such as photosystem II (PSII), photosystem I (PSI), or thylakoids, have been isolated from various plants to construct bio-hybrid anodes. Although PSII or PSI decorated anodes have shown potentials, there still remain challenges, such as poor stability of PSII-based systems or need for electron donors other than water molecules of PSI-based systems. Thylakoid membranes are relatively stable after isolation and they contain all the necessary photosynthetic apparatus including the PSII and PSI. To increase electrical connections between thylakoids and anodes, nanomaterials such as carbon nanotubes, nanowires, nanoparticles, or graphene have been employed. However, since they rely on the secondary electrical connections between thylakoids and anodes; it is desired to achieve larger direct contacts between them. Here, we aimed to develop micro-pillar (MP) array anodes to maximize direct contact with thylakoids. The thylakoid morphology was analyzed and the MP array was designed to maximize direct contact with thylakoids. The performance of MP anodes and a photosynthetic fuel cell based on MP electrodes was demonstrated and analyzed.

R Amina, Devika Rajan, M Varsha et al.

International Journal of Pharmaceutical Sciences Review and Research • 2023

Systems for targeted administration and controlled release of medicinal drugs using nanoparticles are known as nanoparticle drug delivery systems. A modern drug delivery system should lower dosage and frequency while minimising negative effects. The nanoparticles can be built into smart systems, encasing medicinal and imaging chemicals as well as bearing stealth property, by manipulating their size, surface properties, and material composition. These devices can also give controlled release therapy and drug delivery to particular tissues.

Amany Ibrahim, Esmail M. El‐Fakharany, Marwa M. Abu‐Serie et al.

Biology • 2022

Methyl orange (MO) is categorized among the recalcitrant and refractory xenobiotics, representing a significant burden in the ecosystem. To clean-up the surrounding environment, advances in microbial degradation have been made. The main objective of this study was to investigate the extent to which an autochthonous consortium immobilized in alginate beads can promote an efficient biodegradation of MO. By employing response surface methodology (RSM), a parametric model explained the interaction of immobilized consortium ( Raoultella planticola , Ochrobactrum thiophenivorans , Bacillus flexus and Staphylococcus xylosus ) to assimilate 200 mg/L of MO in the presence of 40 g/L of NaCl within 120 h. Physicochemical analysis, including UV-Vis spectroscopy and FTIR, and monitoring of the degrading enzymes (azoreductase, DCIP reductase, NADH reductase, laccase, LiP, MnP, nitrate reductase and tyrosinase) were used to evaluate MO degradation. In addition, the toxicity of MO-degradation products was investigated by means of phytotoxicity and cytotoxicity. Chlorella vulgaris retained its photosynthetic performance (>78%), as shown by the contents of chlorophyll-a, chlorophyll-b and carotenoids. The viability of normal lung and kidney cell lines was recorded to be 90.63% and 99.23%, respectively, upon exposure to MO-metabolic outcomes. These results reflect the non-toxicity of treated samples, implying their utilization in ferti-irrigation applications and industrial cooling systems. Moreover, the immobilized consortium was employed in the bioremediation of MO from artificially contaminated agricultural and industrial effluents, in augmented and non-augmented systems. Bacterial consortium remediated MO by 155 and 128.5 mg/L in augmented systems of agricultural and industrial effluents, respectively, within 144 h, revealing its mutual synergistic interaction with both indigenous microbiotas despite differences in their chemical, physical and microbial contents. These promising results encourage the application of immobilized consortium in bioaugmentation studies using different resources.

Ashiqur Rahman, Shanglei Pan, Cymone Houston et al.

Water • 2021

Produced water (PW) is the largest waste stream generated by the oil and gas industry. Traditional treatment of PW burdens the industry with significant expenses and environmental issues. Alternatively, microalgal-based bioremediation of PW is often viewed as an ecologically safe and sustainable platform for treating PW. Moreover, the nutrients in PW could support algal growth. However, significant dilution of PW is often required in algal-based systems due to the presence of complex chemical contaminants. In light of these facts, the current work has investigated the potential of cultivating Galdieria sulphuraria and Chlorella vulgaris in PW using multiple dilutions; 0% PW, 5% PW, 10% PW, 20% PW, 50% PW and 100% PW. While both algal strains can grow in PW, the current results indicated that G. sulphuraria has a higher potential of growth in up to 50% PW (total dissolved solids of up to 55 g L−1) with a growth rate of 0.72 ± 0.05 g L−1 d−1 and can achieve a final biomass density of 4.28 ± 0.16 g L−1 in seven days without the need for additional micronutrients. Additionally, the algae showed the potential of removing 99.6 ± 0.2% nitrogen and 74.2 ± 8.5% phosphorus from the PW.

Rebecca M. Brown, Amin Mirkouei, David W. Reed et al.

Renewable and Sustainable Energy Reviews • 2022

Mária Čížková, Dana Mezricky, Marián Rucki et al.

Molecules • 2019

Red mud is a by-product of alumina production containing lanthanides. Growth of green microalgae on red mud and the intracellular accumulation of lanthanides was tested. The best growing species was Desmodesmus quadricauda (2.71 cell number doublings/day), which accumulated lanthanides to the highest level (27.3 mg/kg/day), if compared with Chlamydomonas reinhardtii and Parachlorella kessleri (2.50, 2.37 cell number doublings and 24.5, 12.5 mg/kg per day, respectively). With increasing concentrations of red mud, the growth rate decreased (2.71, 2.62, 2.43 cell number doublings/day) due to increased shadowing of cells by undissolved red mud particles. The accumulated lanthanide content, however, increased in the most efficient alga Desmodesmus quadricauda within 2 days from zero in red-mud free culture to 12.4, 39.0, 54.5 mg/kg of dry mass at red mud concentrations of 0.03, 0.05 and 0.1%, respectively. Red mud alleviated the metal starvation caused by cultivation in incomplete nutrient medium without added microelements. Moreover, the proportion of lanthanides in algae grown in red mud were about 250, 138, 117% higher than in culture grown in complete nutrient medium at red mud concentrations of 0.03, 0.05, 0.1%. Thus, green algae are prospective vehicles for bio-mining or bio-leaching of lanthanides from red mud.

Shoko Kusama, Seiji Kojima, Ken Kimura et al.

Nature Communications • 2022

Biophotovoltaics (BPV) generates electricity from reducing equivalent(s) produced by photosynthetic organisms by exploiting a phenomenon called extracellular electron transfer (EET), where reducing equivalent(s) is transferred to external electron acceptors. Although cyanobacteria have been extensively studied for BPV because of their high photosynthetic activity and ease of handling, their low EET activity poses a limitation. Here, we show an order-of-magnitude enhancement in photocurrent generation of the cyanobacterium Synechocystis sp. PCC 6803 by deprivation of the outer membrane, where electrons are suggested to stem from pathway(s) downstream of photosystem I. A marked enhancement of EET activity itself is verified by rapid reduction of exogenous electron acceptor, ferricyanide. The extracellular organic substances, including reducing equivalent(s), produced by this cyanobacterium serve as respiratory substrates for other heterotrophic bacteria. These findings demonstrate that the outer membrane is a barrier that limits EET. Therefore, depriving this membrane is an effective approach to exploit the cyanobacterial reducing equivalent(s).

Amin Mojiri, Maedeh Baharlooeian, Mohammad Ali Zahed

International Journal of Environmental Research and Public Health • 2021

Antibiotics are frequently applied to treat bacterial infections in humans and animals. However, most consumed antibiotics are excreted into wastewater as metabolites or in their original form. Therefore, removal of antibiotics from aquatic environments is of high research interest. In this study, we investigated the removal of sulfamethoxazole (SMX) and ofloxacin (OFX) with Chaetoceros muelleri , a marine diatom. The optimization process was conducted using response surface methodology (RSM) with two independent parameters, i.e., the initial concentration of antibiotics and contact time. The optimum removal of SMX and OFX were 39.8% (0.19 mg L -1 ) and 42.5% (0.21 mg L -1 ) at the initial concentration (0.5 mg L -1 ) and contact time (6.3 days). Apart from that, the toxicity effect of antibiotics on the diatom was monitored in different SMX and OFX concentrations (0 to 50 mg L -1 ). The protein (mg L -1 ) and carotenoid (μg L -1 ) content increased when the antibiotic concentration increased up to 20 mg L -1 , while cell viability was not significantly affected up to 20 mg L -1 of antibiotic concentration. Protein content, carotenoid, and cell viability decreased during high antibiotic concentrations (more than 20 to 30 mg L -1 ). This study revealed that the use of Chaetoceros muelleri is an appealing solution to remove certain antibiotics from wastewater.

Gustavo P. M. K. Ciniciato, Fong-Lee Ng, Siew‐Moi Phang et al.

Scientific Reports • 2016

Microbial fuel cells operating with autotrophic microorganisms are known as biophotovoltaic devices. It represents a great opportunity for environmentally-friendly power generation using the energy of the sunlight. The efficiency of electricity generation in this novel system is however low. This is partially reflected by the poor understanding of the bioelectrochemical mechanisms behind the electron transfer from these microorganisms to the electrode surface. In this work, we propose a combination of electrochemical and fluorescence techniques, giving emphasis to the pulse amplitude modulation fluorescence. The combination of these two techniques allow us to obtain information that can assist in understanding the electrical response obtained from the generation of electricity through the intrinsic properties related to the photosynthetic efficiency that can be obtained from the fluorescence emitted. These were achieved quantitatively by means of observed changes in four photosynthetic parameters with the bioanode generating electricity. These are the maximum quantum yield (Fv/Fm), alpha (α), light saturation coefficient (Ek) and maximum rate of electron transfer (rETRm). The relationship between the increases in the current density collected by the bioanode to the decrease of the rETRm values in the photosynthetic pathway for the two microorganisms was also discussed.

Spyridon Achinas, Johan Horjus, Vasileios Achinas et al.

Sustainability • 2019

Biofuels production is expected to be an intrinsic confluence to the renewable energy sector in the coming years under the European regulations for renewable energy. Key standpoints of the biofuels promotions are the reduction of national carbon emissions and rural deployment. Despite jubilant outlook of biofuels for sustainable development, research efforts still tend to link the biofuel industry and regional growth. The aim of this study is to explore and review the biofuels industry through a socio-political, techno-economic, legal and environmental (PESTLE) analysis approach, and discuss the interrelation between technological facets and sustainable deployment.

Maira Anam, Helena I. Gomes, Geoffrey Rivers et al.

Sustainable Energy & Fuels • 2021

An illustrative diagram of a biophotovoltaic system highlights its main components and several steps of electron transport.

Deepak Rawat, Udita Sharma, Pankaj Poria et al.

ISME Communications • 2022

Phototrophic communities of autotrophic microalgae and heterotrophic bacteria perform complex tasks of nutrient acquisition and tackling environmental stress but remain underexplored as a basis for the bioremediation of emerging pollutants. In industrial monoculture designs, poor iron uptake by microalgae limits their productivity and biotechnological efficacy. Iron supplementation is expensive and ineffective because iron remains insoluble in an aqueous medium and is biologically unavailable. However, microalgae develop complex interkingdom associations with siderophore-producing bacteria that help solubilize iron and increase its bioavailability. Using dye degradation as a model, we combined environmental isolations and synthetic ecology as a workflow to design a simplified microbial community based on iron and carbon exchange. We established a mutualism between the previously non-associated alga Chlorella sorokiniana and siderophore-producing bacterium Ralstonia pickettii . Siderophore-mediated increase in iron bioavailability alleviated Fe stress for algae and increased the reductive iron uptake mechanism and bioremediation potential. In exchange, C. sorokiniana produced galactose, glucose, and mannose as major extracellular monosaccharides, supporting bacterial growth. We propose that extracellular iron reduction by ferrireductase is crucial for azoreductase-mediated dye degradation in microalgae. These results demonstrate that iron bioavailability, often overlooked in cultivation, governs microalgal growth, enzymatic processes, and bioremediation potential. Our results suggest that phototrophic communities with an active association for iron and carbon exchange have the potential to overcome challenges associated with micronutrient availability, while scaling up bioremediation designs.

Mohd Atiqueuzzaman Khan, Huu Hao Ngo, Wenshan Guo et al.

Bioresource Technology • 2019

Chenba Zhu, Ruo‐Lan Zhang, Longyan Cheng et al.

Biotechnology for Biofuels • 2018

This study proved the feasibility of BICCAPS recycling culture with the first practical example. More importantly, the produced algal biomass can be harvested without any flocculant supplement. Thus, this process can reduce both culturing and harvesting costs in algal biomass production.

Hei Tsun Tse, Shuai Luo, Jian Li et al.

Bioprocess and Biosystems Engineering • 2016

Lisa Bauer, Karolína Ranglová, Jiří Masojídek et al.

Applied Sciences • 2021

The interest in microalgae products has been increasing, and therefore the cultivation industry is growing steadily. To reduce the environmental impact and production costs arising from nutrients, research needs to find alternatives to the currently used artificial nutrients. Microalgae cultivation in anaerobic effluents (more specifically, digestate) represents a promising strategy for increasing sustainability and obtaining valuable products. However, digestate must be processed prior to its use as nutrient source. Depending on its composition, different methods are suitable for removing solids (e.g., centrifugation) and adjusting nutrient concentrations and ratios (e.g., dilution, ammonia stripping). Moreover, the resulting cultivation medium must be light-permeable. Various studies show that growth rates comparable to those in artificial media can be achieved when proper digestate treatment is used. The necessary steps for obtaining a suitable cultivation medium also depend on the microalgae species to be cultivated. Concerning the application of the biomass, legal aspects and impurities originating from digestate must be considered. Furthermore, microalgae species and their application fields are essential criteria when selecting downstream processing methods (harvest, disintegration, dehydration, product purification). Microalgae grown on digestate can be used to produce various products (e.g., bioenergy, animal feed, bioplastics, and biofertilizers). This review gives insight into the origin and composition of digestate, processing options to meet requirements for microalgae cultivation and challenges regarding downstream processing and products.

Tobias Wenzel, Daniel Härtter, Paolo Bombelli et al.

Nature Communications • 2018

Some photosynthetically active bacteria transfer electrons across their membranes, generating electrical photocurrents in biofilms. Devices harvesting solar energy by this mechanism are currently limited by the charge transfer to the electrode. Here, we report the enhancement of bioelectrochemical photocurrent harvesting using electrodes with porosities on the nanometre and micrometre length scale. For the cyanobacteria Nostoc punctiforme and Synechocystis sp. PCC6803 on structured indium-tin-oxide electrodes, an increase in current generation by two orders of magnitude is observed compared to a non-porous electrode. In addition, the photo response is substantially faster compared to non-porous anodes. Electrodes with large enough mesopores for the cells to inhabit show only a small advantage over purely nanoporous electrode morphologies, suggesting the prevalence of a redox shuttle mechanism in the electron transfer from the bacteria to the electrode over a direct conduction mechanism. Our results highlight the importance of electrode nanoporosity in the design of electrochemical bio-interfaces.

Yong Kang, Lingling Xu, Jinrui Dong et al.

Nature Communications • 2024

Chronic diabetic wounds are at lifelong risk of developing diabetic foot ulcers owing to severe hypoxia, excessive reactive oxygen species (ROS), a complex inflammatory microenvironment, and the potential for bacterial infection. Here we develop a programmed treatment strategy employing live Haematococcus (HEA). By modulating light intensity, HEA can be programmed to perform a variety of functions, such as antibacterial activity, oxygen supply, ROS scavenging, and immune regulation, suggesting its potential for use in programmed therapy. Under high light intensity (658 nm, 0.5 W/cm 2 ), green HEA (GHEA) with efficient photothermal conversion mediate wound surface disinfection. By decreasing the light intensity (658 nm, 0.1 W/cm 2 ), the photosynthetic system of GHEA can continuously produce oxygen, effectively resolving the problems of hypoxia and promoting vascular regeneration. Continuous light irradiation induces astaxanthin (AST) accumulation in HEA cells, resulting in a gradual transformation from a green to red hue (RHEA). RHEA effectively scavenges excess ROS, enhances the expression of intracellular antioxidant enzymes, and directs polarization to M2 macrophages by secreting AST vesicles via exosomes. The living HEA hydrogel can sterilize and enhance cell proliferation and migration and promote neoangiogenesis, which could improve infected diabetic wound healing in female mice.

Kiran Kumar V., Man mohan K., K. Gunaseelan et al.

Sustainable Energy Technologies and Assessments • 2021

Péter Bakonyi, Jakub Peter, Stanisław Koter et al.

Journal of CO2 Utilization • 2019

Hana Nur Fitriana, Soo‐Youn Lee, Sun-A Choi et al.

Applied Sciences • 2021

The green microalga Haematococcus pluvialis accumulates astaxanthin, a potent antioxidant pigment, as a defense mechanism against environmental stresses. In this study, we investigated the technical feasibility of a stress-based method for inducing astaxanthin biosynthesis in H. pluvialis using electric stimulation in a two-chamber bioelectrochemical system. When a cathodic (reduction) current of 3 mA (voltage: 2 V) was applied to H. pluvialis cells for two days, considerable lysis and breakage of algal cells were observed, possibly owing to the formation of excess reactive oxygen species at the cathode. Conversely, in the absence of cell breakage, the application of anodic (oxidation) current effectively stimulated astaxanthin biosynthesis at a voltage range of 2–6 V, whereas the same could not be induced in the untreated control. At an optimal voltage of 4 V (anodic current: 30 mA), the astaxanthin content in the cells electro-treated for 2 h was 36.9% higher than that in untreated cells. Our findings suggest that electric treatment can be used to improve astaxanthin production in H. pluvialis culture if bioelectrochemical parameters, such as electric strength and duration, are regulated properly.

Peter Bateson, Jack E. H. Fleet, Anthony S. Riseley et al.

Biology • 2018

Photobioelectrochemical systems are an emerging possibility for renewable energy. By exploiting photosynthesis, they transform the energy of light into electricity. This study evaluates a simple, scalable bioelectrochemical system built from recycled plastic bottles, equipped with an anode made from recycled aluminum, and operated with the green alga Chlorella sorokiniana . We tested whether such a system, referred to as a bio-bottle-voltaic (BBV) device, could operate outdoors for a prolonged time period of 35 days. Electrochemical characterisation was conducted by measuring the drop in potential between the anode and the cathode, and this value was used to calculate the rate of charge accumulation. The BBV systems were initially able to deliver ~500 mC·bottle −1 ·day −1 , which increased throughout the experimental run to a maximum of ~2000 mC·bottle −1 ·day −1 . The electrical output was consistently and significantly higher than that of the abiotic BBV system operated without algal cells (~100 mC·bottle −1 ·day −1 ). The analysis of the rate of algal biomass accumulation supported the hypothesis that harvesting a proportion of electrons from the algal cells does not significantly perturb the rate of algal growth. Our finding demonstrates that bioelectrochemical systems can be built using recycled components. Prototypes of these systems have been displayed in public events; they could serve as educational toolkits in schools and could also offer a solution for powering low-energy devices off-grid.

Yanshan Wang, Dao‐Bo Li, Feng Zhang et al.

Frontiers of Environmental Science & Engineering • 2018

Asha Singh, Rozi Sharma, Deepak Pant et al.

The Science of The Total Environment • 2021

Nan Li, Xubin Zhang, Meng‐Meng Zhao et al.

Journal of Cleaner Production • 2020

Peng Zhou, Guoshuai Liu, Han Wang et al.

Process Biochemistry • 2021

Jian Sun, Wenjing Xu, Bihai Cai et al.

Chemosphere • 2019

Hareb Al Jabri, Probir Das, Shoyeb Khan et al.

Water • 2020

The treatment of different types of wastewater by physicochemical or biological (non-microalgal) methods could often be either inefficient or energy-intensive. Microalgae are ubiquitous microscopic organisms, which thrive in water bodies that contain the necessary nutrients. Wastewaters are typically contaminated with nitrogen, phosphorus, and other trace elements, which microalgae require for their cell growth. In addition, most of the microalgae are photosynthetic in nature, and these organisms do not require an organic source for their proliferation, although some strains could utilize organics both in the presence and absence of light. Therefore, microalgal bioremediation could be integrated with existing treatment methods or adopted as the single biological method for efficiently treating wastewater. This review paper summarized the mechanisms of pollutants removal by microalgae, microalgal bioremediation potential of different types of wastewaters, the potential application of wastewater-grown microalgal biomass, existing challenges, and the future direction of microalgal application in wastewater treatment.