The boost of the greenhouse gases (GHGs, largely carbon dioxide – CO2) emissions owing to anthropogenic activity is one of the biggest global threats. Bio-CO2 emission reduction has received more and ...more attention as an environmentally sustainable approach. Microalgae are very popular in this regard because of excellent speed of growth, low costs of production, and resistance to extreme environments. Besides, most microalgae can undergo photosynthesis, where the CO2 and solar energy can be converted into sugar, and subsequently become biomass, providing a renewable and promising biofuel strategy with a few outstanding benefits. This review focuses on presenting CO2 sequestration by microalgae towards wastewater treatment and biodiesel production. First, the CO2 fixation mechanism by microalgae viz., sequestration and assimilation of CO2 in green microalgae as well as cyanobacteria were introduced. Besides, factors affecting CO2 sequestration in microalgae, containing microalgae species and cultivation conditions, such as light condition, photobioreactor, configuration, pH, CO2 concentration, temperature, and medium composition, were then comprehensively discussed. Special attention was given to the production of biodiesel as third-generation biofuel from various wastewater (CO2 biofixation), including processing steps of biodiesel production by microalgae, biodiesel production from wastewater, and improved methods. Furthermore, current life cycle assessment (LCA) and techno-economic analysis (TEA) used in biodiesel production were discussed. Finally, the research challenges and specific prospects were considered. Taken together, this review provides useful and updated information to facilitate the development of microalgal “green chemistry” and “environmental sustainability”.
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•Both wastewater repair and carbon dioxide fixation are achieved with microalgae.•The information on CO2 fixation mechanism inside the algal cells is limited.•Wastewater as a nourishment source for microalgae growth can yield biodiesel.•Nutrient starvation is the most typical method to enhance lipid production.•Integration of LCA and TEA enables systematic analysis and provides more info.
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•The mechanism for removing nutrients via microalgae-bacteria consortia is discussed.•Light is an important operational parameter for efficiently removing nutrients.•Bio-flocculation ...using bacteria is a superior method for microalgal harvest.•Recent bioenergy production via microalgae-bacteria consortia is elaborated.
Conventional wastewater treatment using activated sludge cannot efficiently eliminate nitrogen and phosphorus, thus engendering the risk of water eutrophication and ecosystem disruption. Fortunately, a new wastewater treatment process applying microalgae-bacteria consortia has attracted considerable interests due to its excellent performance of nutrients removal. Moreover, some bacteria facilitate the harvest of microalgal biomass through bio-flocculation. Additionally, while stimulating the functional bacteria, the improved biomass and enriched components also brighten bioenergy production from the perspective of practical applications. Thus, this review first summarizes the current development of nutrients removal and mutualistic interaction using microalgae-bacteria consortia. Then, advancements in bio-flocculation are completely described and the corresponding mechanisms are thoroughly revealed. Eventually, the recent advances of bioenergy production (i.e., biodiesel, biohydrogen, bioethanol, and bioelectricity) using microalgae-bacteria consortia are comprehensively discussed. Together, this review will provide the ongoing challenges and future developmental directions for better converting nitrogen and phosphorus wastewater into bioenergy using microalgae-bacteria consortia.
Wastewater treatment remains a critical issue globally till date despite various technological advancements and breakthroughs. Heavy metal in wastewater poses a great threat to human health if ...untreated properly, which makes its removal of utmost importance. Among various wastewater treatment techniques, adsorption is the most common technique to remove heavy metal in wastewater due to its flexible design, operation, and cost-effectiveness. Activated carbon being the most conventional adsorbent to remove heavy metal ion in wastewater owing to its microporous structure and ease of surface functionalization. However, the activated carbon separation from wastewater solution has been difficult and its high cost have prohibited its wide usage. Recently, the emergence of different novel materials has also showed their competitiveness in heavy metal ion removal. These promising novel materials exhibit several excellent attributes, for example large surface area, great mechanical strength, and high chemical inertness. This paper presents a brief review on the use, theory and future perspectives of conventional, as well as novel materials towards heavy metal adsorption in wastewater treatment application.
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•Adsorption is most common technique for heavy metal removal in wastewater treatment.•Activated carbon is the conventional adsorbent material.•Novel materials with high specific area are beneficial in heavy metal removal.•Usage of conventional and novel materials towards heavy metal removal are discussed.
Antibiotic resistance genes (ARGs) have been recognized as emerging pollutants that are widely distributed and accumulated in most of aquatic environment. Although many ARGs-removal technologies are ...employed, a corresponding discussion of merits and limitations of known technologies is still currently lacking. More importantly, the removal mechanisms of ARGs remain unclear, hindering their ecological feasibility. Thus, further in-depth studies are highly required. In this review, the occurrence and risk of ARGs in aquatic environment are introduced, and the main routes and potential impacts of ARGs dissemination are enumerated. In addition, several novel ARGs detection methods are critically reviewed. Notably, to ensure greater applicability of these technologies, systematic information on how recent technologies impact the ARGs removal and control are comprehensively compared and summarized. Finally, future research directions to alleviate the risk of ARGs in aquatic environment are briefly introduced. Taken together, this review provides useful information to facilitate the development of innovative and feasible ARGs removal technologies and increase their economic viability and ecological sustainability.
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•The dissemination of ARGs in aquatic environment is introduced.•The latest ARGs detection technologies are proposed and compared.•ARGs removal technologies towards aquatic environment are compared and discussed.
To better make nanomedicine entering the clinic, developing new rationally designed nanotherapeutics with a deeper understanding of tumor biology is required. The tumor microenvironment is similar to ...the inflammatory response in a healing wound, the milieu of which promotes tumor cell invasion and metastasis. Successful targeting of the microenvironmental components with effective nanotherapeutics to modulate the tumor microvessels or restore the homeostatic mechanisms in the tumor stroma will offer new hope for cancer treatment. We here highlight the progress in constructing nanotherapeutics to target or modulate the tumor microenvironment. We discuss the factors necessary for nanomedicines to become a new paradigm in cancer therapy, including the selection of drugs and therapeutic targets, controllable synthesis, and tempo‐spatial drug release.
Pharmaceutical and Personal Care Products (PPCPs) removal coupling with bioenergy production by microalgae has attracted growing attention. However, the biological interactions between PPCPs and ...microalgae are unclear during microalgal biosorption and biodegradation of PPCPs. In this study, an optimal ciprofloxacin (CIP) and sulfadiazine (SDZ) removal efficiency were achieved 100% and 54.53% with carbohydrate productivity of >1000 mg L−1 d−1 by Chlamydomonas sp. Tai-03, respectively. The elimination routes indicated that CIP removal was mainly achieved by biodegradation (65.05%) whereas SDZ was mainly removed by photolysis (35.60%). The visualization evidence of microscopic imaging Raman spectrometer supported the favorable biosorption of CIP due to its positive charge (+10.20 mV). Meanwhile, the tendency for gradual reduction of CIP in extracellular polymeric substances (EPS) indicated that suspended microalgal cell facilitated CIP uptake and biodegradation. Furthermore, photolysis and biodegradation pathways were thoroughly analyzed to demonstrate that intermediates were less toxic and had no adverse effect on the subsequent ethanol conversion. This study provides valuable information for the development of a novel microalgal PPCPs removal. These findings reveal the possible biological mechanisms of biosorption and biodegradation of PPCPs in microalgae, which could further enhance the feasibility of microalgal applications for simultaneous PPCPs remediation and alternative energy production.
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•65.05% CIP and 17.05% SDZ were biodegraded by Tai-03, which was higher than sludge.•The visual evidence by MI-RS represented the favorable biosorption of CIP.•Positive charge facilitated CIP uptake and biodegradation.•12 CIP and 9 SDZ intermediates were identified in photolysis and biodegradation.•The toxicity of intermediates was preliminarily estimated by ECOSAR analysis.
Microalgae have become imperative for biological wastewater treatment. Its capability in biological purification of wastewaters from different origins while utilizing wastewater as the substrate for ...growth has manifest great potentials as a sustainable and economical wastewater treatment method. The wastewater grown microalgae have also been remarked in research to be a significant source of value-added bioproducts and biomaterial. This paper highlights the multifaceted roles of microalgae in wastewater treatment from the extent of microalgal bioremediation function to environmental amelioration with the involvement of microalgal biomass productivity and carbon dioxide fixation. Besides, the uptake mechanism of microalgae in wastewater treatment was discussed in detail with illustrations for a comprehensive understanding of the removal process of undesirable substances. The performance of different microalgae species in the uptake of various substances was studied and summarized in this review. The correlation of microalgal treatment efficacy with various algal strain types and the bioreactors harnessed for cultivation systems was also discussed. Studies on the alternatives to conventional wastewater treatment processes and the integration of microalgae with accordant wastewater treatment methods are presented. Current research on the biological and technical approaches for the modification of algae-based wastewater system and the maximization of biomass production is also reviewed and discussed. The last portion of the review is dedicated to the assertion of challenges and future perspectives on the development of microalgae-based wastewater treatment technology. This review serves as a useful and informative reference for readers regarding the multifaceted roles of microalgae in the application of wastewater biotreatment with detailed discussion on the uptake mechanism.
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•Multifaceted roles of microalgae in wastewater biotreatment was critically reviewed.•Uptake mechanism of microalgae in the removal of undesirable substances was studied.•Robust algae growth achieved via rectification with bioprocessing technology.•Limitation and future work on algal technology in wastewater treatment are presented.
Capsule abstract: Multifaceted roles of microalgae in the applications of wastewater treatment via biological remediation were presented.
•C. sorokiniana had a great ability to biotransformation SMX.•SMX was biodegraded through CYP450 monooxygenase system with microalgae.•A novel biotransformation pathway of SMX by C. sorokiniana was ...firstly proposed.•MD approaches helped to explain the reactive sites of SMX biodegradation.•DFT calculation can well elucidate the biotransformation product of SMX.
Recently, the biotransformation of sulfamethoxazole (SMX) by microalgae has attracted increasing interest. In particular, cytochrome P450 (CYP450) has been suggested to be the main enzymatic contributor to this biodegradation. However, the molecular evidence of CYP450 enzymes being involved in SMX biodegradation remains relatively unclear, hindering its applicability. Herein, the biodegradation of SMX by Chlorella sorokiniana (C. sorokiniana) was investigated, and comprehensively elucidated the reaction mechanism underlying CYP450-mediated SMX metabolism. C. sorokiniana was able to efficiently remove over 80% of SMX mainly through biodegradation, in which CYP450 enzymes responded substantially to metabolize SMX in cells. Additionally, screening of transformation products (TPs) revealed that N4-hydroxylation-SMX (TP270) was the main TP in the SMX biodegradation pathway of microalgae. Molecular dynamics (MD) simulation suggested that the aniline of SMX was the most prone to undergo metabolism, while density functional theory (DFT) indicated that SMX was metabolized by CYP450 enzymes through H-abstraction-OH-rebound reaction. Collectively, this work reveals key details of the hydroxylamine group of SMX, elucidates the SMX biodegradation pathway involving CYP450 in microalgae in detail, and accelerates the development of using microalgae-mediated CYP450 to eliminate antibiotics.
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Microalgal Torrefaction for Solid Biofuel Production Ho, Shih-Hsin; Zhang, Congyu; Tao, Fei ...
Trends in biotechnology (Regular ed.),
September 2020, 2020-09-00, 20200901, Letnik:
38, Številka:
9
Journal Article
Recenzirano
Microalgae are recognized as promising feedstocks for biofuel production and have been intensively studied. However, a systematic investigation of the relationship between cellular components and ...fuel properties in microalgae is currently absent. This review introduces recent advances in microalgal torrefaction and critically evaluates the properties of torrefied products from the viewpoint of molecular conversion. We also critically review how to regulate biosynthesis to better modulate microalgal metabolism and how cellular components impact fuel properties. Process optimization to improve solid fuel properties using different torrefaction technologies are furthermore comprehensively compared and summarized. This review provides new insights into developing innovative microalgal solid biofuels and increasing their commercial viability.
The proportions of microalgal components affect solid biofuel properties.Synthetic biology is a promising approach to regulate microalgal components.Torrefied microalgae have excellent fuel properties with superior storage and transportation characteristics.Several torrefaction technologies for microalgal solid biofuel upgrading are currently being evaluated.
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•Carbon capture via microalgae is a promising alternative for CO2 mitigation.•Carbon assimilation is the most important rate-limiting step in photosynthesis.•Strategies to enhance ...microalgal carbon capture are reviewed.•Enhancing the CO2-biofixing efficiency needs sufficient ATP.•NMs could enhance CO2 capture and light conversion through microalgal growth.
Anthropogenic carbon dioxide (CO2) emissions are one of the most serious global risks humanity is facing in the 21st century. Biodegradation of CO2 has obtained increasing attention as an environment-friendly technology. Microalgae are receiving worldwide attention in this regard due to their rapid growth rate, strong adaptability to extreme environments, and low production cost. Additionally, microalgae are very important CO2 fixers in the ecological environment, fixing carbon as biomass through photosynthesis. Although many review studies have focused on carbon capture, utilization and storage (CCUS) using microalgae, the comprehensive review on summarizing the updated strategies to further enhance carbon capture using microalgae is still lacking. Therefore, this review initially introduces the various carbon capture strategies, especially the biological route. The efficiency of CO2 capture using microalgae can vary according to the state of microalgal species, physiology, and environmental conditions, such as CO2 concentrations, pH, light intensity, and dissolved oxygen. Then, photosynthesis and related carbon-fixation mechanisms in microalgae are systematically discussed. More critically, the recent developments in trends and strategies to further enhance microalgal CO2 fixation (such as mutagenesis, genetic engineering, and intervention through nanomaterials) are comprehensively discussed and summarized. Among them, nanomaterials could considerably enhance the rates of relative electron transport in photosynthetic system II as well as reactive oxygen species levels in microalgae, thus improving the general photosynthesis towards carotenoids. Furthermore, current challenges are highlighted, and future perspectives are provided. The study could help guide academia and industry in redirecting their efforts to increase the performance of microalgal CO2 fixation.
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