Publications by authors named "Kit Wayne Chew"

60 Publications

Application progress of bioactive compounds in microalgae on pharmaceutical and cosmetics.

Chemosphere 2021 Nov 16:132932. Epub 2021 Nov 16.

Institute of Biological Sciences, Faculty of Science, Universiti Malaya, 50603, Kuala Lumpur, Malaysia. Electronic address:

Microalgae is an autotrophic organism with fast growth, short reproduction cycle, and strong environmental adaptability. In recent years, microalgae and the bioactive ingredients extracted from microalgae are regarded as potential substitutes for raw materials in the pharmaceutical and the cosmetics industry. In this review, the characteristics and efficacy of the high-value components of microalgae are discussed in detail, along with the sources and extraction technologies of algae used to obtain high-value ingredients are reviewed. Moreover, it also includes the latest trends in biotherapy based on high-value algae extracts as materials. In addition, the excellent antioxidant properties of microalgae derivatives are regarded as potential substitutes for safe and environmentally friendly cosmetic production. Only by further studying the mechanism of microalgae bioactive compounds and conducting reasonable clinical trials can safe and compliant microalgae-derived drugs or cosmetics be marketed.
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http://dx.doi.org/10.1016/j.chemosphere.2021.132932DOI Listing
November 2021

Valorization of spent brewery yeast biosorbent with sonication-assisted adsorption for dye removal in wastewater treatment.

Environ Res 2021 Nov 13:112385. Epub 2021 Nov 13.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, Semenyih, Selangor, 43500, Malaysia.

The effluent of textile industries containing synthetic dyes contributed to substantial pollution to water bodies. The biosorption process of Congo Red dye was successfully performed by integrating ultrasonication in the adsorption step with spent brewery yeast as a novel and renewable biosorbent. The adsorption process was hindered when ultrasonication was employed together with the biosorbent, indicating that desorption process had occurred. The adsorption process showed that 4 g/L of biosorbent was the optimum dosage for adsorption of 50 mg/L of Congo Red dye, and that the adsorption equilibrium fitted to the Langmuir model, with kinetics best fitted with pseudo-second order model. The maximum capacity of the adsorption was 52.6 mg/g, showing the potential of spent brewery yeast to aid in removing wastewater pollutants. Maximal Congo Red dye recovery (100%) was achieved in the sonication-assisted desorption studies using 0.01M NaOH as the eluting agent. The ultrasonication effects contributed to the efficient recovery of dye and good conversion of spent brewery yeast to biosorbent can be beneficial for treating pollution from textile wastewater.
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http://dx.doi.org/10.1016/j.envres.2021.112385DOI Listing
November 2021

Novel strategy in biohydrogen energy production from COVID - 19 plastic waste: A critical review.

Int J Hydrogen Energy 2021 Nov 9. Epub 2021 Nov 9.

Center of Excellence in Catalysis for Bioenergy and Renewable Chemicals (CBRC), Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.

Usage of plastics in the form of personal protective equipment, medical devices, and common packages has increased alarmingly during these pandemic times. Though they have served as an excellent protection source in minimizing the coronavirus disease (COVID-19) spreading, they have still emerged as major environmental pollutants nowadays. These non-degradable COVID-19 plastic wastes (CPW) were treated through incineration and landfilling process, which may lead to either the release of harmful gases or contaminating the surrounding environment. Further, they can cause numerous health hazards to the human and animal populations. These plastic wastes can be efficiently managed through thermochemical processes like pyrolysis or gasification, which assist in degrading the plastic waste and also effectively convert them into useful energy-yielding products. The pyrolysis process promotes the formation of liquid fuels and chemicals, whereas gasification leads to syngas and hydrogen fuel production. These energy-yielding products can help to compensate for the fossil fuels depletion in the near future. There are many insights explained in terms of the types of reactors and influential factors that can be adopted for the pyrolysis and gasification process, to produce high efficient energy products from the wastes. In addition, advanced technologies including co-gasification and two-stage gasification were also reviewed.
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http://dx.doi.org/10.1016/j.ijhydene.2021.08.236DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8576595PMC
November 2021

Biotechnology and sustainable environmental health management.

Chemosphere 2021 Nov 8:132798. Epub 2021 Nov 8.

Center of Excellence for Green Energy and Environmental Nanomaterials ([email protected]), Nguyen Tat Thanh University, Ho Chi Minh City, Viet Nam.

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http://dx.doi.org/10.1016/j.chemosphere.2021.132798DOI Listing
November 2021

Recent advances biodegradation and biosorption of organic compounds from wastewater: Microalgae-bacteria consortium - A review.

Bioresour Technol 2021 Oct 19;344(Pt A):126159. Epub 2021 Oct 19.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

The litter of persistent organic pollutants (POPs) into the water streams and soil bodies via industrial effluents led to several adverse effects on the environment, health, and ecosystem. For the past decades, scientists have been paying efforts in the innovation and development of POPs removal from wastewater treatment. However, the conventional methods used for the removal of POPs from wastewater are costly and could lead to secondary pollution including soil and water bodies pollution. In recent, the utilization of green mechanisms such as biosorption, bioaccumulation and biodegradation has drawn attention and prelude the potential of green technology globally. Microalgae-bacteria consortia have emerged to be one of the latent wastewater treatment systems. The synergistic interactions between microalgae and bacteria could proficiently enhance the existing biological wastewater treatment system. This paper will critically review the comparison of conventional and recent advanced wastewater treatment systems and the mechanisms of the microalgae-bacteria symbiosis system.
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http://dx.doi.org/10.1016/j.biortech.2021.126159DOI Listing
October 2021

Cultivation of Chlorella vulgaris on dairy waste using vision imaging for biomass growth monitoring.

Bioresour Technol 2021 Dec 8;341:125892. Epub 2021 Sep 8.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

Continuous automation of conventional industrial operations with smart technology have drawn significant attention. Firstly, the study investigates on optimizing the proportion of industrial biscuit processing waste powder, (B) substituted into BG-11 as a source of cultivation medium for the growth of C. vulgaris. Various percentages of industrial biscuit processing waste powder, (B) were substituted in the inorganic medium to analyse the algal growth and biochemical composition. The use of 40B combination was found to yield highest biomass concentration (4.11 g/L), lipid (260.44 mg/g), protein (263.93 mg/g), and carbohydrate (418.99 mg/g) content compared with all the other culture ratio combination. Secondly, the exploitation of colour acquisition was performed onto C. vulgaris growth phases, and a novel photo-to-biomass concentration estimation was conducted via image processing for three different colour model pixels. Based on linear regression analysis the red, green, blue (RGB) colour model can interpret its colour variance precisely.
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http://dx.doi.org/10.1016/j.biortech.2021.125892DOI Listing
December 2021

How does the Internet of Things (IoT) help in microalgae biorefinery?

Biotechnol Adv 2021 Aug 25:107819. Epub 2021 Aug 25.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

Microalgae biorefinery is a platform for the conversion of microalgal biomass into a variety of value-added products, such as biofuels, bio-based chemicals, biomaterials, and bioactive substances. Commercialization and industrialization of microalgae biorefinery heavily rely on the capability and efficiency of large-scale cultivation of microalgae. Thus, there is an urgent need for novel technologies that can be used to monitor, automatically control, and precisely predict microalgae production. In light of this, innovative applications of the Internet of things (IoT) technologies in microalgae biorefinery have attracted tremendous research efforts. IoT has potential applications in a microalgae biorefinery for the automatic control of microalgae cultivation, monitoring and manipulation of microalgal cultivation parameters, optimization of microalgae productivity, identification of toxic algae species, screening of target microalgae species, classification of microalgae species, and viability detection of microalgal cells. In this critical review, cutting-edge IoT technologies that could be adopted to microalgae biorefinery in the upstream and downstream processing are described comprehensively. The current advances of the integration of IoT with microalgae biorefinery are presented. What this review discussed includes automation, sensors, lab-on-chip, and machine learning, which are the main constituent elements and advanced technologies of IoT. Specifically, future research directions are discussed with special emphasis on the development of sensors, the application of microfluidic technology, robotized microalgae, high-throughput platforms, deep learning, and other innovative techniques. This review could contribute greatly to the novelty and relevance in the field of IoT-based microalgae biorefinery to develop smarter, safer, cleaner, greener, and economically efficient techniques for exhaustive energy recovery during the biorefinery process.
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http://dx.doi.org/10.1016/j.biotechadv.2021.107819DOI Listing
August 2021

Microalgal-based biochar in wastewater remediation: Its synthesis, characterization and applications.

Environ Res 2021 Aug 25;204(Pt A):111966. Epub 2021 Aug 25.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

Microalgae are drawing attentions among researchers for their biorefinery use or value-added products. The high production rate of biomasses produced are attractive for conversion into volatile biochar. Torrefaction, pyrolysis and hydrothermal carbonization are the recommended thermochemical conversion techniques that could produce microalgal-based biochar with desirable physiochemical properties such as high surface area and pore volume, abundant surface functional groups, as well as functionality such as high adsorption capacity. The characterizations of the biochar significantly influence the mechanisms in adsorption of pollutants from wastewaters. Specific adsorption of the organic and inorganic pollutants from the effluent are reviewed to examine the adsorption capacity and efficiency of biochar derived from different microalgae species. Last but not least, future remarks over the challenges and improvements are discussed accordingly. Overall, this review would discuss the synthesis, characterization and application of the microalgal-based biochar in wastewater.
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http://dx.doi.org/10.1016/j.envres.2021.111966DOI Listing
August 2021

Algae as potential feedstock for various bioenergy production.

Chemosphere 2022 Jan 19;287(Pt 1):131944. Epub 2021 Aug 19.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

Depletion of non-renewable feedstock and severe wastewater pollution due to human activities have created negative impact to living organisms. The potential solution is to implement wastewater treatment and bioelectricity production through algae-based microbial fuel cell. The algae biomass produced from microbial fuel cell could be further processed to generate biofuels through their unique compositions. The consumption of nutrients in wastewater through algae cultivation and biomass produced to be utilized for energy supply have showed the potential of algae to solve the issues faced nowadays. This review introduces the background of algae and mitigation of wastewater using algae as well as the bioenergy status in Malaysia. The mechanisms of nutrient assimilation such as nitrogen, phosphorus, carbon, and heavy metals are included, followed by the application of algae in microbial fuel cell's chambers. Lastly, the status of algae for bioenergy production are covered.
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http://dx.doi.org/10.1016/j.chemosphere.2021.131944DOI Listing
January 2022

Microalgal-Bacterial Consortia as Future Prospect in Wastewater Bioremediation, Environmental Management and Bioenergy Production.

Indian J Microbiol 2021 Sep 22;61(3):262-269. Epub 2021 Feb 22.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan Malaysia.

In the recent years, microalgae have captured researchers' attention as the alternative feedstock for various bioenergy production such as biodiesel, biohydrogen, and bioethanol. Cultivating microalgae in wastewaters to simultaneously bioremediate the nutrient-rich wastewater and maintain a high biomass yield is a more economical and environmentally friendly approach. The incorporation of algal-bacterial interaction reveals the mutual relationship of microorganisms where algae are primary producers of organic compounds from CO, and heterotrophic bacteria are secondary consumers decomposing the organic compounds produced from algae. This review would provide an insight on the challenges and future development of algal-bacterial consortium and its contribution in promoting a sustainable route to greener industry. It is believed that microalgal-bacterial consortia will be implemented in the near-future for sub-sequential treatment of wastewater bioremediation, bioenergy production and CO fixation, promoting sustainability and making extraordinary advancement in life sciences sectors.
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http://dx.doi.org/10.1007/s12088-021-00924-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8263830PMC
September 2021

Self-healing epoxy coating synthesis by embedment of metal 2-methyl imidazole and acetylacetonate complexes with microcapsules.

Chemosphere 2021 Dec 8;285:131492. Epub 2021 Jul 8.

Department of Chemical and Environmental Engineering, Faculty Science and Engineering, University of Nottingham, Malaysia, 43500, Semenyih, Selangor, Darul Ehsan, Malaysia. Electronic address:

The restoration of mechanical properties is desired for creating the self-healing coatings with no corrosion capabilities. The encapsulation of epoxy resins is limited by various factors in urea and melamine formaldehyde microcapsules. An improved method was developed, where epoxy resin was encapsulated by individual wrapping of poly(melamine-formaldehyde) and poly(urea-formaldehyde) shell around emulsified epoxy droplets via oil-in-water emulsion polymerization method. The synthesized materials were characterized analytically. The curing of the epoxy was achieved by adding the [Ni/Co(2-MI)].2NO as a latent hardener and iron acetylacetonate [Fe(acac)] as a latent accelerator. Isothermal and non-isothermal differential scanning calorimetric analysis revealed lower curing temperature (T = 116 °C) and lower activation energies (Ea ≈ 69-75 kJ/mol). The addition of microcapsules and complexes did not adversely alter the flexural strength and flexural modulus of the epoxy coatings. The adhesion strength of neat coating decreased from 6310.8 ± 31 to 4720.9 ± 60 kPa and percent healing increased from 50.83 to 67.45% in the presence of acetylacetonate complex at 10 wt% of microcapsules.
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http://dx.doi.org/10.1016/j.chemosphere.2021.131492DOI Listing
December 2021

Perspective of Spirulina culture with wastewater into a sustainable circular bioeconomy.

Environ Pollut 2021 Sep 2;284:117492. Epub 2021 Jun 2.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, Semenyih, 43500, Selangor Darul Ehsan, Malaysia. Electronic address:

Spirulina biomass accounts for 30% of the total algae biomass production globally. In conventional process of Spirulina biomass production, cultivation using chemical-based culture medium contributes 35% of the total production cost. Moreover, the environmental impact of cultivation stage is the highest among all the production stages which resulted from the extensive usage of chemicals and nutrients. Thus, various types of culture medium such as chemical-based, modified, and alternative culture medium with highlights on wastewater medium is reviewed on the recent advances of culture media for Spirulina cultivation. Further study is needed in modifying or exploring alternative culture media utilising waste, wastewater, or by-products from industrial processes to ensure the sustainability of environment and nutrients source for cultivation in the long term. Moreover, the current development of utilising wastewater medium only support the growth of Spirulina however it cannot eliminate the negative impacts of wastewater. In fact, the recent developments in coupling with wastewater treatment technology can eradicate the negative impacts of wastewater while supporting the growth of Spirulina. The application of Spirulina cultivation in wastewater able to resolve the global environmental pollution issues, produce value added product and even generate green electricity. This would benefit the society, business, and environment in achieving a sustainable circular bioeconomy.
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http://dx.doi.org/10.1016/j.envpol.2021.117492DOI Listing
September 2021

The conundrum of waste cooking oil: Transforming hazard into energy.

J Hazard Mater 2021 09 16;417:126129. Epub 2021 May 16.

School of Energy and Chemical Engineering, Xiamen University Malaysia, Jalan Sunsuria, Bandar Sunsuria, 43900 Sepang, Selangor, Malaysia; College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China. Electronic address:

Waste cooking oil (WCO) is considered as one of the hazardous wastes because improper disposal of WCO can cause significant environmental problems such as blockages of drains and sewers as well as water or soil pollution. In this review, the physical and chemical properties of WCO are evaluated along with its regulations and policies in different countries to promote WCO refined biofuels. Blended WCO can be an auxiliary fuel for municipal solid waste incinerators while the heat produced is able to form superheated steam and subsequently generate electricity via combined heat and power system. Also, WCO contains high ratio of hydrogen atoms compared to carbon and oxygen atoms, making it able to be catalytically cracked, synthesizing hydrogen gas. WCO-based biodiesel has been traditionally produced by transesterification in order to substitute petroleum-based diesel which has non-degradability as well as non-renewable features. Hence, the potentials of hazardous WCO as a green alternative energy source for electricity generation, hydrogen gas as well as biofuels production (e.g. biodiesel, biogas, biojet fuel) are critically discussed due to its attractive psychochemical properties as well as its economic feasibility. Challenges of the WCO utilization as a source of energy are also reported while highlighting its future prospects.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126129DOI Listing
September 2021

Resource recovery from industrial effluents through the cultivation of microalgae: A review.

Bioresour Technol 2021 Oct 26;337:125461. Epub 2021 Jun 26.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

Industrial effluents such as pharmaceutical residues, pesticides, dyes, and metal processes holds abundant value-added products (VAPs), where its recovery has become essential. The purpose of such recovery is for sustainable treatment, which is an approach that considers the economic, social, and environmental aspects. Microalgae with its potential in the recovery process from effluents, can reduce energy usage of waste management strategies and regenerate nutrients such as carbon, phosphorus, and nitrogen. Microalgae cultures offer the use of inorganic materials by microalgae for their growth and the help of bacteria to produce biomass, thus, resulting in the absence of secondary emissions due to its ability to eliminate volatile organic compounds. Moreover, recovered bioactive compounds are transformed into bioethanol, bio-fertilizers, biopolymer, health supplements and animal feed. Therefore, it is significant to focus on an economical and efficient utilization of microalgae in recovering nutrients that can be further used in various commercial applications.
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http://dx.doi.org/10.1016/j.biortech.2021.125461DOI Listing
October 2021

Discovery of α-Glucosidase Inhibitors from Marine Microorganisms: Optimization of Culture Conditions and Medium Composition.

Mol Biotechnol 2021 Nov 29;63(11):1004-1015. Epub 2021 Jun 29.

Institute of Biotechnology, Vietnam, Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay District, 100000, Hanoi, Vietnam.

Various studies showed that the suppression of α-glucosidase activity can impede the glucose absorption in our body, and therefore, it can be used to treat type 2 diabetes. Hence, the compounds with anti-α-glucosidase have gained considerable attention because of their potential application in diabetes treatment. In previous literature studies, these anti-α-glucosidase compounds were extracted from plants and fungus. Less studies are being conducted to identify the anti-α-glucosidase compounds in the microbial community. In this study, 23 marine bacterial strains were screened for their potential to suppress the α-glucosidase activity. The highest inhibitory activity was exhibited by isolated L06 which was identified as Oceanimonas smirnovii EBL6. The cultivation conditions, such as temperature and pH, were optimized to increase the production of α-glucosidase inhibitors by Oceanimonas smirnovii EBL6 strain. The result findings showed that the highest yield of α-glucosidase inhibitors can be obtained at the culture time of 120 h, fermentation temperature of 30 °C, and pH 4.6. Under these conditions, the inhibitory activity of α-glucosidase can reach 81%. The IC of n-butanol extract was 13.89 μg/ml, while standard acarbose was 31.16 μg/ml. Overall, these findings suggest that Oceanimonas smirnovii produces α-glucosidase inhibitors and could been applied in the biochemical and medicinal fields in the future.
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http://dx.doi.org/10.1007/s12033-021-00362-3DOI Listing
November 2021

Computational Lock and Key and Dynamic Trajectory Analysis of Natural Biophors Against COVID-19 Spike Protein to Identify Effective Lead Molecules.

Mol Biotechnol 2021 Oct 22;63(10):898-908. Epub 2021 Jun 22.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia.

New pandemic infection of coronaviridae family virus spread to more than 210 countries with total infection of 1,136,851 and 62,955 (4.6%) deaths until 5th April 2020. Which stopped the regular cycle of humankind but the nature is consistently running. There is no micro molecule remedy found yet to restore the regular life of people. Hence, we decided to work on natural biophores against the COVID proteins. As a first step, major phytoconstituents of antiviral herbs like Leucas aspera, Morinda citrifolia, Azadirachta indica, Curcuma longa, Piper nigrum, Ocimum tenuiflorum, and Corallium rubrum collected and performed the lock and key analysis with major spike protein of COVID-19 to find the best fitting lead biophore using computational drug design platform. The results of protocol run showed, phytoconstituents of Morinda citrifolia and Leucas aspera were found lower binding energy range of - 55.18 to - 25.34 kcal/mol, respectively and compared with Hydroxychloroquine (HCQ) (- 24.29 kcal/mol) and Remdesivir (- 25.38 kcal/mol). The results conclude that, core skeletons chromen, anthracene 9, 11 dione and long-chain alkyl acids/ester-containing biophores showen high stable antagonistic affinity with S-protein. Which leads the breakdown of spike protein and ACE2 receptor complex formation and host mechanism of corono virus. In addition, the dynamic trajectory analysis confirmed the complete denaturation of spike protein by the molecule 4-(24-hydroxy-1-oxo-5-n-propyltetracosanyl)-phenol from Leucas aspera and stability of spike-ligand complex. These biophores will aid the researcher to fabricate new promising analogue and being recommended to assess its COVID-19 treatment.
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http://dx.doi.org/10.1007/s12033-021-00358-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8219180PMC
October 2021

Micro (nano) plastic pollution: The ecological influence on soil-plant system and human health.

Sci Total Environ 2021 Sep 17;788:147815. Epub 2021 May 17.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

Global plastic pollution has been a serious problem since many years and micro (nano) plastics (MNPs) have gained attention from researchers around the world. This is because MNPs able to exhibit toxicology and interact with potentially toxic elements (PTEs) in the environment, causing soil toxicity. The influences of MNPs on the soil systems and plant crops have been overlooked despite that MNPs can accumulate in the plant root system and generate detrimental impacts to the terrestrial environments. The consumption of these MNPs-contaminated plants or fruits by humans and animals will eventually lead to health deterioration. The identification and measurement of MNPs in various soil samples is challenging, making the understanding of the fate, environmental and ecological of MNPs in terrestrial ecosystem is limited. Prior to sample assessment, it is necessary to isolate the plastic particles from the environment samples, concentrate the plastic particles for analysis purpose to meet detection limit for analytical instrument. The isolation and pre-concentrated steps are challenging and may cause sample loss. Herein, this article reviews MNPs, including their fate in the environment and toxic effects exhibited towards soil microorganisms, plants and humans along with the interaction of MNPs with PTEs. In addition, various analysis methods of MNPs and management of MNPs as well as the crucial challenges and future research studies in combating MNPs in soil system are also discussed.
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http://dx.doi.org/10.1016/j.scitotenv.2021.147815DOI Listing
September 2021

Disposal methods, health effects and emission regulations for sulfur hexafluoride and its by-products.

J Hazard Mater 2021 09 14;417:126107. Epub 2021 May 14.

School of Energy and Chemical Engineering, Xiamen University Malaysia, Jalan Sunsuria, Bandar Sunsuria, 43900 Sepang, Selangor Darul Ehsan, Malaysia; College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China. Electronic address:

Sulfur hexafluoride (SF) is the most potent greenhouse gas contributed by the power and semiconductor industries. The global emissions of gas in the past 10 years have increased tremendously due to lack of disposal routes. This was brought to 190 nations' attention in the Kyoto Protocol for the need of emission control measures to reduce its impacts of climate change and global warming. Various novel techniques have surfaced to tackle this issue, such as non-thermal plasma (NTP) which includes radio frequency plasma, microwave plasma, dielectric barrier discharge, and electron beam. The main by-products resulting from the decomposition of SF by these techniques are sulfur oxyfluorides, sulfur dioxide, hydrofluoric acid, and fluorine gas. This environmental and health effects as well as global emission of SF gas are considered a threat to humans and the climate, where modern disposal methods of contaminated SF gas and its by-products should replace the conventional approaches. Relevant government policies on the safety and disposal concern of SF gas are reviewed and challenges and further research directions for the disposal of SF gas are highlighted in this review article.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126107DOI Listing
September 2021

Plastic waste associated with the COVID-19 pandemic: Crisis or opportunity?

J Hazard Mater 2021 09 13;417:126108. Epub 2021 May 13.

School of Energy and Chemical Engineering, Xiamen University Malaysia, Jalan Sunsuria, Bandar Sunsuria, 43900 Sepang, Selangor, Malaysia; College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China. Electronic address:

Coronavirus Diseases 2019 (COVID-19) pandemic has a huge impact on the plastic waste management in many countries due to the sudden surge of medical waste which has led to a global waste management crisis. Improper management of plastic waste may lead to various negative impacts on the environment, animals, and human health. However, adopting proper waste management and the right technologies, looking in a different perception of the current crisis would be an opportunity. About 40% of the plastic waste ended up in landfill, 25% incinerated, 16% recycled and the remaining 19% are leaked into the environment. The increase of plastic wastes and demand of plastic markets serve as a good economic indicator for investor and government initiative to invest in technologies that converts plastic waste into value-added product such as fuel and construction materials. This will close the loop of the life cycle of plastic waste by achieving a sustainable circular economy. This review paper will provide insight of the state of plastic waste before and during the COVID-19 pandemic. The treatment pathway of plastic waste such as sterilisation technology, incineration, and alternative technologies available in converting plastic waste into value-added product were reviewed.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126108DOI Listing
September 2021

Advancement of green technologies: A comprehensive review on the potential application of microalgae biomass.

Chemosphere 2021 Oct 15;281:130886. Epub 2021 May 15.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, Semenyih, 43500, Selangor Darul Ehsan, Malaysia. Electronic address:

Microalgae have drawn significant interest worldwide, owing to their enormous application potential in the green energy, biopharmaceutical, and nutraceutical industries. Many studies have proved and stated the potential of microalgae in the area of biofuel which is economically effective and environmentally friendly. Besides the commercial value, the potential of microalgae in environmental protection has also been investigated. Microalgae-based process is one of the most effective way to treat heavy metal pollution, compared to conventional methods, it does not release any toxic waste or harmful gases, and the aquatic organism will not receive any harmful effects. The potential dual role of microalge in phytoremedation and energy production has made it widely explored for its capability. The interest of microalgae in various application has motivated a new focus in green technologies. Considering the rapid population growth with the continuous increase on the global demand and the application of biomass in diverse field, significant upgrades have been performed to accommodate green technological advancement. In the past decade, noteworthy advancement has been made on the technology involving the diverse application of microalgae biomass. This review aims to explore on the application of microalgae and the development of green technology in various application for microalgae biomass. There is great prospects for researchers in this field to delve into other potential utilization of microalgae biomass not only for bioremediation process but also to generate revenues from microalgae by incorporating clean and green technology for long-term sustainability and environmental benefits.
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http://dx.doi.org/10.1016/j.chemosphere.2021.130886DOI Listing
October 2021

A comprehensive review on the techniques for coconut oil extraction and its application.

Bioprocess Biosyst Eng 2021 Sep 19;44(9):1807-1818. Epub 2021 May 19.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia.

Virgin coconut oil is a useful substance in our daily life. It contains a high percentage of lauric acid which has many health benefits. The current industry has developed several methods to extract the oil out from the coconut fruit. This review paper aims to highlight several common extraction processes used in modern industries that includes cold extraction, hot extraction, low-pressure extraction, chilling, freezing and thawing method, fermentation, centrifugation, enzymatic extraction and supercritical fluid carbon dioxide. Different extraction methods will produce coconut oil with different yields and purities of lauric acid, thus having different uses and applications. Challenges that are faced by the industries in extracting the coconut oil using different methods of extraction are important to be explored so that advancement in the oil extraction technology can be done for efficient downstream processing. This study is vital as it provides insights that could enhance the production of coconut oil.
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http://dx.doi.org/10.1007/s00449-021-02577-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8132276PMC
September 2021

Pyrolysis: An effective technique for degradation of COVID-19 medical wastes.

Chemosphere 2021 Jul 23;275:130092. Epub 2021 Feb 23.

Center of Excellence in Catalysis for Bioenergy and Renewable Chemicals (CBRC), Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand; Center of Excellence on Petrochemical and Materials Technology (PETROMAT), Chulalongkorn University, Pathumwan, Bangkok, 10330, Thailand. Electronic address:

COVID-19 has led to the enormous rise of medical wastes throughout the world, and these have mainly been generated from hospitals, clinics, and other healthcare establishments. This creates an additional challenge in medical waste management, particularly in developing countries. Improper managing of medical waste may have serious public health issues and a significant impact on the environment. There are currently three disinfection technologies, namely incineration, chemical and physical processes, that are available to treat COVID-19 medical waste (CMW). This study focuses on thermochemical process, particularly pyrolysis process to treat the medical waste. Pyrolysis is a process that utilizes the thermal instability of organic components in medical waste to convert them into valuable products. Besides, the technique is environmentally friendly, more efficient and cost-effective, requires less landfill capacity, and causes lower pollution. The current pandemic situation generates a large amount of plastic medical wastes, which mainly consists of polyethylene, polypropylene, polystyrene, polyethylene terephthalate, and nylon. These plastic wastes can be converted into valuable energy products like oil, gas and char through pyrolysis process. This review provides detailed information about CMW handling, treatment, valuable product generation, and proper discharge into the open environment.
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http://dx.doi.org/10.1016/j.chemosphere.2021.130092DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7901847PMC
July 2021

Green bioprocessing of protein from Chlorella vulgaris microalgae towards circular bioeconomy.

Bioresour Technol 2021 Aug 21;333:125197. Epub 2021 Apr 21.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, Semenyih 43500, Selangor Darul Ehsan, Malaysia. Electronic address:

The work aimed to study the potential in producing a system with high microalgal protein recovery and separation by utilizing a one-step or integrated downstream process. This in turn enables green biorefinery of protein, contributing to circular bioeconomy whereby less energy, labor, and cost are required for the process. By utilizing electric three phase partitioning flotation system, high protein recovery yield, R of 99.42 ± 0.52% and high separation efficiency, E of 52.72 ± 0.40% system was developed. Scaling up also showed high protein recovery yield with R value of 89.13 ± 1.56%. Total processing duration (extraction, separation, and purification) was also significantly reduced to 10 min. This system showed remarkable potential in reducing processing time, alternatively cost of production, benefiting microalgal downstream processing. Concisely, through this system, microalgal bioprocessing will no longer be complex allowing a wide array of potentials for further studies in this field.
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http://dx.doi.org/10.1016/j.biortech.2021.125197DOI Listing
August 2021

Liquid triphasic systems as sustainable downstream processing of Chlorella sp. biorefinery for potential biofuels and feed production.

Bioresour Technol 2021 Aug 31;333:125075. Epub 2021 Mar 31.

Department of Chemical and Materials Engineering, College of Engineering, Tunghai University, Taichung 407, Taiwan; Research Centre for Smart Sustainable Circular Economy, Tunghai University, Taichung 407, Taiwan; Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan. Electronic address:

Microalgae are potential sustainable renewable sources of energy but are highly underutilized due to the expensive and time-consuming downstream processing. This study aims at curbing these obstacles by extracting multiple components with a single processing unit. In this work, an ultrasound-assisted liquid triphasic flotation system was incorporated to extract proteins, lipids, and carbohydrates by phase separation. The parameters involved were optimized and the final recovery efficiency of proteins, lipids, and carbohydrates was determined. A control run involving conventional three-phase partitioning and a 15-fold scale-up system with the recycling of phase components were also performed. Gas Chromatograph and Fourier Transform Infrared spectroscopy were used to examine the potential of extracted products as a source of biofuel. This biorefinery approach is crucial in commercializing microalgae for biodiesel and bioethanol generation with a side product of purified proteins as feed.
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http://dx.doi.org/10.1016/j.biortech.2021.125075DOI Listing
August 2021

Can algae contribute to the war with Covid-19?

Bioengineered 2021 12;12(1):1226-1237

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Semenyih, Selangor Darul Ehsan, Malaysia.

The world at large is facing a new threat with the emergence of the Coronavirus Disease 2019 (COVID-19) pandemic. Though imperceptible by the naked eye, the medical, sociological and economical implications caused by this newly discovered virus have been and will continue to be a great impediment to our lives. This health threat has already caused over two million deaths worldwide in the span of a year and its mortality rate is projected to continue rising. In this review, the potential of algae in combating the spread of COVID-19 is investigated since algal compounds have been tested against viruses and algal anti-inflammatory compounds have the potential to treat the severe symptoms of COVID-19. The possible utilization of algae in producing value-added products such as serological test kits, vaccines, and supplements that would either mitigate or hinder the continued health risks caused by the virus is prominent. Many of the characteristics in algae can provide insights on the development of microalgae to fight against SARS-CoV-2 or other viruses and contribute in manufacturing various green and high-value products.
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http://dx.doi.org/10.1080/21655979.2021.1910432DOI Listing
December 2021

Waste biorefinery towards a sustainable circular bioeconomy: a solution to global issues.

Biotechnol Biofuels 2021 Apr 7;14(1):87. Epub 2021 Apr 7.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia.

Global issues such as environmental problems and food security are currently of concern to all of us. Circular bioeconomy is a promising approach towards resolving these global issues. The production of bioenergy and biomaterials can sustain the energy-environment nexus as well as substitute the devoid of petroleum as the production feedstock, thereby contributing to a cleaner and low carbon environment. In addition, assimilation of waste into bioprocesses for the production of useful products and metabolites lead towards a sustainable circular bioeconomy. This review aims to highlight the waste biorefinery as a sustainable bio-based circular economy, and, therefore, promoting a greener environment. Several case studies on the bioprocesses utilising waste for biopolymers and bio-lipids production as well as bioprocesses incorporated with wastewater treatment are well discussed. The strategy of waste biorefinery integrated with circular bioeconomy in the perspectives of unravelling the global issues can help to tackle carbon management and greenhouse gas emissions. A waste biorefinery-circular bioeconomy strategy represents a low carbon economy by reducing greenhouse gases footprint, and holds great prospects for a sustainable and greener world.
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http://dx.doi.org/10.1186/s13068-021-01939-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8028083PMC
April 2021

Abatement of hazardous materials and biomass waste via pyrolysis and co-pyrolysis for environmental sustainability and circular economy.

Environ Pollut 2021 Jun 1;278:116836. Epub 2021 Mar 1.

School of Energy and Chemical Engineering, Xiamen University Malaysia, Jalan Sunsuria, Bandar Sunsuria, 43900, Sepang, Selangor, Malaysia; College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, Fujian, China.

The remarkable journey of progression of mankind has created various impacts in the form of polluted environment, amassed heavy metals and depleting resources. This alarming situation demands sustainable energy resources and approaches to deal with these environmental hazards and power deficit. Pyrolysis and co-pyrolysis address both energy and environmental issues caused by civilization and industrialization. The processes use hazardous waste materials including waste tires, plastic and medical waste, and biomass waste such as livestock waste and agricultural waste as feedstock to produce gas, char and pyrolysis oil for energy production. Usage of hazardous materials as pyrolysis and co-pyrolysis feedstock reduces disposal of harmful substances into environment, reducing occurrence of soil and water pollution, and substituting the non-renewable feedstock, fossil fuels. As compared to combustion, pyrolysis and co-pyrolysis have less emission of air pollutants and act as alternative options to landfill disposal and incineration for hazardous materials and biomass waste. Hence, stabilizing heavy metals and solving the energy and waste management problems. This review discusses the pyrolysis and co-pyrolysis of biomass and harmful wastes to strive towards circular economy and eco-friendly, cleaner energy with minimum waste disposal, reducing negative impact on the planet and creating future possibilities.
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http://dx.doi.org/10.1016/j.envpol.2021.116836DOI Listing
June 2021

Algae biopolymer towards sustainable circular economy.

Bioresour Technol 2021 Apr 12;325:124702. Epub 2021 Jan 12.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

The accumulation of conventional petroleum-based polymers has increased exponentially over the years. Therefore, algae-based biopolymer has gained interest among researchers as one of the alternative approaches in achieving a sustainable circular economy around the world. The benefits of microalgae biopolymer over other feedstock is its autotrophic complex to reduce the greenhouse gases emission, rapid growing ability with flexibility in diverse environments and its ability to compost that gives greenhouse gas credits. In contrast, this review provides a comprehensive understanding of algae-based biopolymer in the evaluation of microalgae strains, bioplastic characterization and bioplastic blending technologies. The future prospects and challenges on the algae circular bioeconomy which includes the challenges faced in circular economy, issues regard to the scale-up and operating cost of microalgae cultivation and the life cycle assessment on algal-based biopolymer were highlighted. The aim of this review is to provide insights of algae-based biopolymer towards a sustainable circular bioeconomy.
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http://dx.doi.org/10.1016/j.biortech.2021.124702DOI Listing
April 2021

Reuniting the Biogeochemistry of Algae for a Low-Carbon Circular Bioeconomy.

Trends Plant Sci 2021 07 15;26(7):729-740. Epub 2021 Jan 15.

Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia. Electronic address:

Given their advantages of high photosynthetic efficiency and non-competition with land-based crops, algae, that are carbon-hungry and sunlight-driven microbial factories, are a promising solution to resolve energy crisis, food security, and pollution problems. The ability to recycle nutrient and CO fixation from waste sources makes algae a valuable feedstock for biofuels, food and feeds, biochemicals, and biomaterials. Innovative technologies such as the bicarbonate-based integrated carbon capture and algae production system (BICCAPS), integrated algal bioenergy carbon capture and storage (BECCS), as well as ocean macroalgal afforestation (OMA), can be used to realize a low-carbon algal bioeconomy. We review how algae can be applied in the framework of integrated low-carbon circular bioeconomy models, focusing on sustainable biofuels, low-carbon feedstocks, carbon capture, and advances in algal biotechnology.
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http://dx.doi.org/10.1016/j.tplants.2020.12.010DOI Listing
July 2021
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