Publications by authors named "Wai Yan Cheah"

8 Publications

  • Page 1 of 1

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

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

Progress in waste valorization using advanced pyrolysis techniques for hydrogen and gaseous fuel production.

Bioresour Technol 2021 Jan 22;320(Pt A):124299. Epub 2020 Oct 22.

Henan Province Engineering Research Center For Biomass Value-Added Products, School of Forestry, Henan Agricultural University, Zhengzhou 450002, China; Pyrolysis Technology Research Group, Institute of Tropical Aquaculture and Fisheries (AKUATROP), Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia. Electronic address:

Hydrogen and gaseous fuel derived from wastes have opened up promising alternative pathways for the production of renewable and sustainable fuels to substitute classical fossil energy resources that cause global warming and pollution. Existing review articles focus mostly on gasification, reforming and pyrolysis processes, with limited information on particularly gaseous fuel production via pyrolysis of various waste products. This review provides an overview on the recent advanced pyrolysis technology used in hydrogen and gaseous fuel production. The key parameters to maximize the production of specific compounds were discussed. More studies are needed to optimize the process parameters and improve the understanding of reaction mechanisms and co-relationship between these advanced techniques. These advanced techniques provide novel environmentally sustainable and commercially procedures for waste-based production of hydrogen and gaseous fuels.
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http://dx.doi.org/10.1016/j.biortech.2020.124299DOI Listing
January 2021

Enhancing microalga CY-1 biomass and lipid production in palm oil mill effluent (POME) using novel-designed photobioreactor.

Bioengineered 2020 12;11(1):61-69

College of Food Science and Technology, Nanjing Agricultural University, Nanjing, China.

CY-1 was cultivated using palm oil mill effluent (POME) in a novel-designed photobioreactor (NPBR) and glass-made vessel photobioreactor (PBR). The comparison was made on biomass and lipid productions, as well as its pollutants removal efficiencies. NPBR is transparent and is developed in thin flat panels with a high surface area per volume ratio. It is equipped with microbubbling and baffles retention, ensuring effective light and CO utilization. The triangular shape of this reactor at the bottom serves to ease microalgae cell harvesting by sedimentation. Both biomass and lipid yields attained in NPBR were 2.3-2.9 folds higher than cultivated in PBR. The pollutants removal efficiencies achieved were 93.7% of chemical oxygen demand, 98.6% of total nitrogen and 96.0% of total phosphorus. Mathematical model revealed that effective light received and initial mass contributes toward successful microalgae cultivation. Overall, the results revealed the potential of NPBR integration in CY-1 cultivation, with an aim to achieve greater feasibility in microalgal-based biofuel real application and for environmental sustainability.
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http://dx.doi.org/10.1080/21655979.2019.1704536DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6961591PMC
December 2020

Antibacterial activity of quaternized chitosan modified nanofiber membrane.

Int J Biol Macromol 2019 Apr 22;126:569-577. Epub 2018 Dec 22.

Department of Chemical Engineering, Graduate School of Biochemical Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan. Electronic address:

The electrospinning PAN nanofiber membrane (P-CN) was hydrolysed to convert carboxylic groups as reaction sites and covalently graft chitosan molecule. The chitosan derivatives with quaternary ammonium groups exerted greater efficiency against bacteria as compared to pure chitosan. Hence, the chitosan modified membrane (P-CS), can be functionalized with quaternary amine (i.e., glycidyl trimethyl ammonium chloride, GTMAC) to form quaternized chitosan nanofiber membrane (designated as P-HTCC) under various conditions (acidic, neutral, and alkaline). N-quaternized derivatives of chitosan modified membrane (N-HTCC) showed 72% and 60% degree of quaternization (DQ) under acidic and neutral conditions, respectively. Under alkaline condition, additional quaternization of N, O-HTCC via its amino and hydroxyl groups, has improved up to 90% DQ of the chitosan. The antibacterial activity of the quaternized chitosan modified membrane prepared from acetic acid medium is stronger than that prepared from water and alkaline media. Also, antibacterial activity of quaternized chitosan is stronger than chitosan modified membrane against E. coli. The microbiological assessments showed that the water-stable P-HTCC nanofiber membrane under modification in acidic medium exerted antibacterial activity up to 99.95% against E. coli. Therefore, the P-HTCC membrane exhibited high potential to be integrated into microfiltration membrane to effectively disinfect E. coli.
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http://dx.doi.org/10.1016/j.ijbiomac.2018.12.193DOI Listing
April 2019

Eicosapentaenoic acid production from Nannochloropsis oceanica CY2 using deep sea water in outdoor plastic-bag type photobioreactors.

Bioresour Technol 2018 Apr 30;253:1-7. Epub 2017 Dec 30.

Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.

In this study, Nannochloropsis oceanica CY2 was grown in deep-sea water (DSW)-based medium in 5-L plastic bag-type photobioreactors (PBRs) for the autotrophic production of Eicosapentaenoic acid (EPA, 20:5n-3). EPA production of N. oceanica CY2 was stimulated when it was grown in 100% DSW amended with 1.5 g L NaNO, achieving a EPA content of 3.1% and a biomass concentration of 3.3 g L. An outdoor-simulated microalgae cultivation system was also conducted to validate the feasibility of outdoor cultivation of the CY2 strain in plastic bag-type PBRs. Using an inoculum size of 0.6 g/L, the biomass concentration in the PBR culture was 3.5 g L, while the EPA content and productivity reached a maximal level of 4.12% and 7.49 mg L d, respectively. When the PBRs were operated on semi-batch mode, the EPA productivity could further increase to 9.9 mg L d with a stable EPA content of 4.1%.
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http://dx.doi.org/10.1016/j.biortech.2017.12.102DOI Listing
April 2018

Biorefineries of carbon dioxide: From carbon capture and storage (CCS) to bioenergies production.

Bioresour Technol 2016 Sep 7;215:346-356. Epub 2016 Apr 7.

Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia; Manufacturing and Industrial Processes Division, Faculty of Engineering, Centre for Food and Bioproduct Processing, University of Nottingham Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia.

Greenhouse gas emissions have several adverse environmental effects, like pollution and climate change. Currently applied carbon capture and storage (CCS) methods are not cost effective and have not been proven safe for long term sequestration. Another attractive approach is CO2 valorization, whereby CO2 can be captured in the form of biomass via photosynthesis and is subsequently converted into various form of bioenergy. This article summarizes the current carbon sequestration and utilization technologies, while emphasizing the value of bioconversion of CO2. In particular, CO2 sequestration by terrestrial plants, microalgae and other microorganisms are discussed. Prospects and challenges for CO2 conversion are addressed. The aim of this review is to provide comprehensive knowledge and updated information on the current advances in biological CO2 sequestration and valorization, which are essential if this approach is to achieve environmental sustainability and economic feasibility.
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http://dx.doi.org/10.1016/j.biortech.2016.04.019DOI Listing
September 2016

Biosequestration of atmospheric CO2 and flue gas-containing CO2 by microalgae.

Bioresour Technol 2015 May 20;184:190-201. Epub 2014 Nov 20.

Nanotechnology & Catalysis Research Centre (NANOCAT), University of Malaya, 50603 Kuala Lumpur, Malaysia; Laboratory of Advanced Catalysis and Environmental Technology, School of Science, Malaysia. Electronic address:

The unceasing rise of greenhouse gas emission has led to global warming and climate change. Global concern on this phenomenon has put forward the microalgal-based CO2 sequestration aiming to sequester carbon back to the biosphere, ultimately reducing greenhouse effects. Microalgae have recently gained enormous attention worldwide, to be the valuable feedstock for renewable energy production, due to their high growth rates, high lipid productivities and the ability to sequester carbon. The photosynthetic process of microalgae uses atmospheric CO2 and CO2 from flue gases, to synthesize nutrients for their growth. In this review article, we will primarily discuss the efficiency of CO2 biosequestration by microalgae species, factors influencing microalgal biomass productions, microalgal cultivation systems, the potential and limitations of using flue gas for microalgal cultivation as well as the bio-refinery approach of microalgal biomass.
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http://dx.doi.org/10.1016/j.biortech.2014.11.026DOI Listing
May 2015
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