Waste to Energy and Resource

BACKGROUND
Interest in using “Biomass” and “Solid Wastes” for energy production has been increasing dramatically, as biomass is a renewable resource for energy and environmentally friendly material. Additionally, there are many other solid waste materials which can be utilized to generate energy efficiently and more economically. For example, Sewage sludge, unavoidable product from wastewater treatment, and Municipal Solid Wastes which mostly contain carbon and other organic matters as well as inorganic matters such as heavy metals. The improper disposal of sewage sludge wastes can cause all types of pollution: air, soil, and water. Indiscriminate dumping of sewage sludge wastes can contaminate surface and ground water supplies. These negative environmental impacts are only a result of solid waste disposal; they do not include the substantial environmental degradation resulting from the extraction and processing of materials at the beginning of the product life cycle. Therefore, it has become a matter of urgency to unearth alternative options to solve this problem. Incineration is the main technology in Singapore, which is used for converting those solid waste materials into heat via complete combustion process. The heat produced is used to generate super-heated steam which is subsequently used to drive turbo-generators to produce electricity. However, burning of solid wastes in incinerators leads to the seriously negative environmental and public health effects which caused by the release of toxic gases such as NOx, furans and dioxins. Moreover, there is less and less space for land fill of ashes, arising from the incineration process, in a comparatively small country.

Figure 1 Gasification for conversion biomass and/or solid wastes into clean energy

GASIFICATION, whereby biomass and/or wastes is converted to synthesis gas (a mixture of H2 and CO) and other gases, provides an attractive alternative process to incineration as the reducing (or oxygen-deficient) atmosphere in gasifier does not provide environment required for those toxic gases to be formed, and hence preventing the aforesaid problems of incineration.

IMPORTANCE OF THIS GASIFICATION AND WASTE-TO-ENERGY RESEARCH
As Singapore is an energy import society, energy security is one of the most important issues. By this energy recovery from solid waste materials such as “waste” woody biomass and other solid wastes which need to be disposed in every single day, it would reduce the dependence on imported fuel and raise the level of energy self-sufficiency.
Moreover, the disposal of solid residues such as char and ashes – the unavoidable solid by-products from gasification facilities – is also one of the concerns as ashes may contain concentrations of mineral compounds, heavy metals and also organic compounds (i.e. PAHs) arising from incomplete combustion of solid wastes. As a result, disposal of the ashes is creating grave risks to the environment as well as human health. Majority of ashes is dumped or used in low-valued methods such as using as a land-fill material. However, the cost of landfilling is now dramatically increasing due to the presence of toxic compounds, strict environmental regulations and limited availability of landfill space, especially in land-limited countries likes Singapore. From those points of view, it is important to develop beneficial applications of ashes as well as char to solve the concerns associated with their disposal. This will not only provides a cost-effective and environmental friendly way of recycling the solid residue wastes from gasification, significantly reducing its environmental effects, but also produces the highly-valued products.

SCOPE OF WORK
Figure 2 shows the overview of our GASIFICATION AND WASTE-TO-ENERGY researches which includes three main parts: (i) biomass and solid wastes gasification for syngas and/or electricity generation, focusing on both experimental and numerical simulation works; (ii) evaluation of human health and environmental effects of all emissions from the gasification system, mainly focusing on establishing a standard protocol for rapid screening of gasification ashes on the basis of in vitro and in vivo testing; and (iii) utilization of solid residual wastes generated from gasification process, mainly focusing on the conversion of fly/bottom ashes, char and other residues into high value materials.

Figure 2 Summary of our GASIFICATION AND WASTE-TO-ENERGY researches

Figure 2A Hybrid Energy System Combined Gasifier and Solar Energy (Green Building)

 

PARTNERSHIPS AND COLLABORATION
We have cooperated with industrial partner, i.e. Bioplas Energy (Asia Pacific) Pte Ltd., on developing of gasification systems (medium and industrial scales) for biomass and solid waste. Moreover, we have also cooperated with Sembcorp on developing of high value products from ash wastes arising from gasification and/or incineration facilities. 

OUR ACHIEVEMENTS
We have successfully conducted gasification of biomass and some solid wastes such as sewage sludge, chicken and horse manures and food waste by using downdraft fixed bed gasifier (lab scale) in order to produce syngas (as a fuel for electricity generation). We are now moving forward to the next step by collaborating with industrial partner in developing of gasification systems (including medium and industrial scales). Moreover, we are now also cooperating with another industrial partner in developing of high value products from ash wastes arising from gasification and/or incineration facilities.

MEDIA EXPOSURE

1. Eco-friendly way to dispose of waste(published at Apr 8, 2016, THE STRAITSTIMES):http://www.straitstimes.com/singapore/eco-friendly-way-to-dispose-of-waste

2. Found: Powerful ways of reusing waste(published at Nov 3, 2017, THE STRAITSTIMES):http://www.straitstimes.com/singapore/found-powerful-ways-of-reusing-waste

So far, our works have results in the significant amount of scientific publications and conference papers, as shown bellows:

Publications

T. Maneerung, S. Kawi, C.H. Wang, “Biomass Gasification Bottom Ash as a Source of CaO Catalyst for Biodiesel Production via Transesterification of Palm Oil”, Energy Conversion and Management, 92, 234-243 (2015).

Y.P Cheng, Z. Thow, C.H. Wang, “Biomass Gasification with CO2 in a Fluidized Bed”,  Powder Technology, 296, 87-101 (2016).

Z. Ong, YP Cheng, T. Maneerung, Z. Yao, Y. Dai, Y.W. Tong, C.H. Wang, “Co-gasification of woody biomass and sewage sludge in a fixed-bed downdraft gasifier”, AIChE Journal, 61, 2508-2521 (2015).

T. Maneerung, J. Liew, Y. Dai, S. Kawi, C. Chong, C.H. Wang, “Activated carbon derived from carbon residue from biomass gasification and its application for dye adsorption: kinetics, isotherms and thermodynamic studies”, Bioresource Technology, 200, 350–359 (2016).

Z. Yang, S.K. Koh, W.C. Ng, R.C.J. Lim, H.T.W. Tan, Y.W. Tong, Y. Dai, C. Chong, C.H. Wang, “Potential Application of Gasification to Recycle Food Waste and Rehabilitate Acidic Soil from Secondary Forests on Degraded Land in Southeast Asia”, Journal of Environmental Management, 172, 40-48 (2016).

X. Zhen, L. Rong, W.C. Ng, C. Ong, G. H. Baeg, W. Zhang, S.N. Lee, S.F.Y. Li, Y. Dai, Y.W. Tong, K.G. Neoh, C.H. Wang, “Rapid toxicity screening of gasification ashes”, Waste Management, 50, 93-104 (2016).

S. You, Z. Yang and C.H. Wang, “Toward Understanding Drug Release from Biodegradable Polymer Microspheres of Different Erosion Kinetics Modes”, J. Pharm. Sci., 105, 1934-1946 (2016).

T. Maneerung, S. Kawi, Y. Dai, C.H. Wang, “Sustainable Biodiesel Production via Transesterification of Waste Cooking Oil by using CaO Catalysts Derived from Chicken Manure”, Energy Management and Conversion, 123, 487-497 (2016).

S. You, W. Wang, Y. Dai, Y. W. Tong, C.H. Wang, “Comparison of the co-gasification of sewage sludge and food wastes and cost-benefit analysis of gasification- and incineration-based waste treatment schemes”, Bioresource Technology, 218, 595-605 (2016).

S. You, YW Tong, K.G. Neoh, Y. Dai, C.H. Wang, “On the Association between Outdoor PM2.5 Concentration and the Seasonality of Tuberculosis for Beijing and Hong Kong”, Environmental Pollution, 218, 1170-1179, (2016).

P. Dong, T. Maneerung, W.C. Ng, X. Zhen, Y. Dai, Y.W. Tong, Y.P. Ting, S.N. Koh, C.H. Wang, K.G. Neoh, “Chemically treated carbon black waste and its potential applications”, J. Hazardous Material, 321, 62-72 (2017).

X. Zhen, W.C. Ng, Fendy, Y. W. Tong, Y. Dai, K.G. Neoh, C.H. Wang, “Toxicity assessment of carbon black waste: a by-product from oil refineries”, J. Hazardous Material, 321, 600-610 (2017).

S. You, K.G. Neoh, Y.W. Tong, Y. Dai, C.H. Wang, “Variation of household electricity consumption and potential impact of outdoor PM2.5 concentration: A comparison between Singapore and Shanghai”, Applied Energy, 188, 475-484 (2017).

X. Kan, Z. Yao, J. Zhang, Y.W. Tong, W. Yang, Y. Dai, C.H. Wang “Energy performance of an integrated bio-and-thermal hybrid system for lignocellulosic biomass waste treatment”, Bioresource Technology, 228, 77-88 (2017).

Z. Yao, W. Li, X. Kan, Y. Dai, Y. W.Tong, C.H. Wang, “Anaerobic Digestion and Gasification Hybrid System for Potential Energy Recovery from Yard Waste and Woody Biomass”, Energy, 124, 133-145 (2017).

L. Zhang, K.C. Loh, J. Lee, C.H. Wang, Y. Dai, Y.W. Tong, “Three-stage anaerobic co-digestion of food waste and horse manure”, Scientific Report, 7, 1269 (2017).

S. Ramachandrana, Z. Yao, S. You, T. Massier, U. Stimming, C.H. Wang, “Life Cycle Assessment of a Sewage Sludge and Woody Biomass Co-gasification System”, Energy, 137, 369-376 (2017).

S. You, Z. Yao, Y. Dai, C.H. Wang, “A comparison of PM exposure related to emission hotspots in a hot and humid urban environment: Concentrations, compositions, respiratory deposition, and potential health risks”, Science of the Total Environment, 599-600, 464-473 (2017).

C.H. Wang, D. Zhao, A. Tsutsumi, S. You, “Sustainable energy technologies for energy saving and carbon emission reduction”, Aplied Energy, 194, 223-224 (2017).

C.H. Wang, Y.W. Tong, K.C. Loh, R. Wang, X. Li, “Advanced technologies on sustainable energy and environment: SET2016 virtual special issue”,  Energy, 137, 350-352 (2017).

S. You, Y.S. Ok, S. S. Chen, D.C.W. Tsang, E.E. Kwon, J. Lee, C.H. Wang, “A Critical Review on Sustainable Biochar System through Gasification: Energy and Environmental Applications”, Bioresource Technology, 246, 242-253 (2017).

S.S. Chen, T. Maneerung, D.C.W. Tsang, Y.S. Ok, C.H. Wang, “Valorization of Biomass to Hydroxymethylfurfural, Levulinic Acid, and Fatty Acid Methyl Ester by Heterogeneous Catalysts”, Chem. Eng. J. 328, 246-273 (2017).

Y. Shen, M.T.T. Tan, C. Chong, W. Xiao, C.H. Wang, “An environmental friendly animal waste disposal process with ammonia recovery and energy production: Experimental study and economic analysis”, Waste Management, 68, 636-645 (2017).

X. Li, M. Lin, Y. Dai, C.H. Wang, “Comparison-based optical assessment of hyperboloid and ellipsoid reflectors in a beam-down solar tower system with linear Fresnel heliostats”, Journal of Solar Energy Engineering, 139(6) (2017).

W.C. Ng, S. You, R. Ling, K.Y.H. Gin, Y. Dai, C.H. Wang, “Co-gasification of woody biomass and chicken manure: syngas production, biochar reutilization, and cost-benefit analysis”, Energy, 139, 732-742 (2017).

X. Li , Y. Shen, X. Kan, T. K. Hardiman, Y. Dai, C.H. Wang, “Thermodynamic assessment of a solar/autothermal hybrid gasification CCHP system with an indirectly radiative reactor”, Energy, 142, 201-214 (2017).

S. You, H. Tong, J. Armin-Hoiland, Y. W. Tong, C.H. Wang, “Techno-economic and Greenhouse Gas Savings Assessment of Decentralized Biomass Gasification for Electrifying the Rural Areas of Indonesia”, Applied Energy, 208, 495-510 (2017).

Z. Yao, S. You, T. Ge, C.H. Wang, “Biomass Gasification for Syngas and Biochar Co-production: Energy Application and Economic Evaluation”, Applied Energy, 209, 43-55 (2018).

J.L.X Hong, T. Maneerung, S.N. Koh, S. Kawi,and C.H. Wang, “Conversion of Coal Fly Ash into Zeolite Materials: Synthesis and Characterizations, Process Design, and Its Cost-Benefit Analysis”, I &EC Research, 56(40), 11565-11574 (2017).

X. Kan, D. Zhou, W. Yang, X. Zhai, C.H. Wang, “An investigation on utilization of biogas and syngas produced from biomass waste in premixed spark ignition engine, Applied Energy, 212, 201-222 (2018).

X. Kan, J. Zhang, Y.W. Tong, C.H. Wang, “Overall evaluation of microwave-assisted alkali pretreatment for enhancement of biomethane production from brewers’ spent grain”, Energy Management and Conversion, 158, 315-326 (2018).

G. Zhan, W.C. Ng, S.N. Koh, C.H. Wang, “Template-Free Synthesis of Alkaline Earth Vanadates Nanomaterials from Leaching Solutions of Oil Refinery Waste”, ACS Sustainable Chemistry & Engineering, 6(2), 2292-2301 (2018).

W.C. Yan, Y. Shen, S. You, S.H. Sim, Z.H. Luo, Y.W. Tong, C.H. Wang, “Model-Based Downdraft Biomass Gasifier Operation and Design for Synthetic Gas Production”, J. Cleaner Production, 178, 476-493 (2018).

G. Zhan, W.C. Ng,W.Y. Lin, S N. Koh, C.H. Wang, “Effective Recovery of Vanadium from Oil Refinery Waste into Vanadium-Based Metal–Organic Frameworks”, Environmental Science & Technology, 52(5), 3008-3015 (2018).

J.X. Zhang, X. Kan, Y. Shen, K.C. Loh, Y.J. Dai, C.H. Wang, Y.W. Tong. “A Hybrid Biological and Thermal Waste-To-Energy System with Heat Energy Recovery and Utilization for Solid Organic Waste Treatment.” Energy, 152, 214-222 (2018).

T. Maneerung, X. Li, C. Li , Y. Dai, C.H. Wang, “Integrated downdraft gasification with power generation system and gasification bottom ash reutilization for clean waste-to-energy and resource recovery system”, J. Cleaner Production, 188, 69-79 (2018).

H. Tong, Y. Shen, J. Zhang, C.H. Wang, T.S. Ge, Y.W. Tong, “A comparative life cycle assessment on four waste-to-energy scenarios for food waste generated in eateries”, Applied Energy, 225, 1143-1157.

W. Y. Lin, W.C. Ng, B.S.E. Wong, S. L.M. Teo, G. d/o Sivananthan, G. H. Baeg, Y. S. Ok, C.H. Wang, “Evaluation of sewage sludge incineration ash as a potential land reclamation material”, J. Hazardous Materials, 357, 63-72 (2018)

S. You, Y.J. Lim, Y. Dai, C.H. Wang, “On the temporal modelling of solar photovoltaic soiling: Energy and economic impacts in seven cities”, Applied Energy, 228, 1136-1146 (2018).

Z. Yao, S. You, Y. Dai, C.H. Wang, “Particulate Emission from the Gasification and Pyrolysis of Biomass: Concentration, Size Distributions, Respiratory Deposition-based Control Measure Evaluation”, Environmental Pollution, 242, 1108-1118 (2018).

C.Y. Li, J.Y. Wu, Y. Shen, X. Kan, Y.J. Dai, C.H. Wang, “Evaluation of a combined cooling, heating, and power system based on biomass gasification in different climate zones in the U.S.”, Energy, 144, 326-340, 2018.

A. Uzi, Y. Shen, K. Sibudjing, A. Levy, C.H. Wang, “Permittivity and chemical characterization of woody biomass during pyrolysis and gasification”, Chem. Eng. J. 355, 255-268 (2019).

S. You, S.W. Ho, T. Maneerung, C.H. Wang, “Techno-economic analysis of geopolymer production from the coal fly ash with high iron oxide and calcium oxide contents”, J. Hazardous Materials, 361, 237-244 (2019).

H. Tong, Z. Yao, J. W. Lim, L. Mao, J. Zhang, T. Ge, Y.H. Peng, C.H. Wang, Y.W. Tong. Harvest green energy through energy recovery from waste: A technology review and an assessment of Singapore. Renewable & Sustainable Energy Reviews, 98, 163-178 (2018).

X. Cui, H. Li, Z. Yao, Y. Shen , Z. He, X. Yang, H. Y. Ng, C.H. Wang, “Removal of nitrate and phosphate by chitosan composited beads derived from crude oil refinery waste: sorption and cost-benefit analysis”, Journal of Cleaner Production, 207, 846-856 (2019).

S. You, Y.S. Ok, D. C.W. Tsang, E.E. Kwon, C.H. Wang, “Towards Practical Application of Gasification: A Critical Review from Syngas and Biochar Perspectives”, Critical Reviews in Environmental Science and Technology, 48 (22-24), 1165-1213 (2018).

Y. Shen, C. He, X. Chen, A.A. Lapkin, W. Xiao, C.H. Wang, “Nitrogen removal and energy recovery from sewage sludge by combined hydrothermal pretreatment and CO2 gasification”, ACS Sustainable Chemistry & Engineering, 6 (12), 16629-16636 (2018).

Y. Shen, X. Li, Z. Yao, X. Cui, C.H. Wang, “CO2 gasification of woody biomass: Experimental study from a lab-scale reactor to a small-scale autothermal gasifier”, Energy, 170, 497-506 (2019).

X Kan, X. Chen, Y. Shen, A.A. Lapkin, M. Kraft, C.H. Wang, “Box-Behnken design based CO2 co-gasification of horticultural waste and sewage sludge with addition of ash from waste as catalyst”, Applied Energy, 242, 1549-1561 (2019).

L. Li, Z. Yao, S.You, C.H. Wang, C. Chong, X. Wang, “Optimal design of negative emission hybrid renewable energy systems with biochar production”, Applied Energy, 243, 233-249 (2019).

X. Li, X. Kan, X. Sun, Y. Zhao, T. Ge, Y. Dai, C.H. Wang, “Performance analysis of a biomass gasification-based CCHP system integrated with variable-effect LiBr-H2O absorption cooling and desiccant dehumidification”, Energy 176, 961-979 (2019).

H Li, H. Tian, T.H. Chang, J. Zhang, S.N. Koh, X. Wang, C.H. Wang, P.Y. Chen, “Environmentally-responsible synthesis of V2O5 nanosheets from gasification wastes for flexible supercapacitors”, ACS Sustainable Chemistry & Engineering, 7, 12474−12484 (2019).

Q. Hu, Y. Shen, J.W. Chew, T. Ge, C.H. Wang, “Chemical looping gasification of biomass with Fe2O3/CaO as the oxygen carrier for hydrogen-enriched syngas production”, Chem. Eng. Journal, 379, 122346 (2019).

X. Li, A. Lin, C.H. Young, Y. Dai, C.H. Wang, “ Energetic and economic evaluation of hybrid solar energy systems in aresidential net-zero energy building”, Applied Energy, 254, 113709 (2019).

G. Zhan, Z. Yao, W.C. Ng, H. Li, M X. Lim, Y. Zhi, S.N. Koh, C.H. Wang, “Economic production of monoclinic bismuth vanadate from wastevanadium ions: Process design and cost-benefit analysis”, Journal of Cleaner Production, 240, 118188 (2019).

C.Y. Li , Y. Shen , J.Y. Wu, Y.J. Dai , C.H. Wang, “Experimental and modeling investigation of an integrated biomass gasifier–engine–generator system for power generation and waste heat recovery”, Energy Conversion and Management, 199, 112023 (2019).

Tian, J. Li, M. Yan, Y.W. Tong, C.H. Wang, X. Wang, “Organic waste to biohydrogen: A critical review from technological development and environmental impact analysis perspective”, Applied Energy, 256, 113961 (2019).

J. Zhang, Q. Hu, Y. Qu, Y. Dai, Y. He. C.H. Wang, Y. Tong, “Integrating food waste sorting system with anaerobic digestion andgasification for hydrogen and methane co-production’, Applied Energy, 257, 113988 (2020).

W. Y. Lin, A.K. Prabhakar, B. C. Mohan, C.H. Wang, “A factorial experimental analysis of using wood fly ash as an alkaline activator along with coal fly ash for production of geopolymer-cementitious hybrids”, Science of the Total Environment 718, 135289 (2020).

X. Li, Y. Shen, L. Wei, C. He, A.A. Lapkin, W. Lipinski, Y. Dai, C.H. Wang, “Hydrogen production of solar-driven steam gasification of sewage sludge in an indirectly irradiative fluidized-bed reactor”, Applied Energy, 261, 114229 (2020).

Q. Hu, Y. Dai, C.H. Wang, “Steam co-gasification of horticultural waste and sewage sludge: Product distribution, synergistic analysis and optimization”, Bioresource Technology 301, 122780 (2020).

X. Li, C.H. Wang, “2017 PV Danckwerts Memorial Lecture Special Issue Editorial: Advances in Emerging Technologies of Chemical Engineering towards Sustainable Energy and Environment: Solar and Biomass”, Chem. Eng. Sci., 215, 115384 (2020).

Q. Hu, X. Liu, J. Lu, C.H. Wang, “Operations scheduling of waste-to-energy plants under uncertainty”, Journal of Cleaner Production 253, 119953 (2020).

X. Kan, L. Wei, X. Li, H. Li, D. Zhou, W. Yang, C.H. Wang, “Effects of the Three Dual-fuel Strategies on Performance and Emissions of a Biodiesel Engine”, Applied Energy, 262, 114542 (2020).

L. Wei, X. Li, W. Yang, Y. Dai, C.H.Wang “Optimization of operation strategies of a syngas-fueled engine in a distributed gasifier-generator system driven by horticulture waste”, Energy Conversion and Management, 208, 15 112580 (2020).

L. Zhang, F. Li, A. Kuroki, K.C. Loh, C.H. Wang, Y. Dai, Y.W. Tong, “Algal biochar enhanced mesophilic and thermophilic anaerobic co-digestion of algal biomass and food waste: Semi-continuous operation and microbial community analysis”, Bioresource Technology. 302, 122892 (2020).

F. Li, X. He, C.A. Shoemaker, C.H. Wang, “Experimental and numerical study of biomass catalytic pyrolysis using Ni2P-loaded zeolite: Product distribution, characterization and overall benefit”, Energy conversion and management 208, 112581 (2020).

D. Yao, C.H. Wang, “Pyrolysis and in-line catalytic decomposition of polypropylene to carbon nanomaterials and hydrogen over Fe- and Ni-based catalysts”, Applied Energy, 265, 114819 (2020).

C.H. Wang, Y.S. Ok, S. You, X. Wang, “The research and development of waste-to-hydrogen technologies and systems”, Applied Energy, 268, 115015 (2020).

Y. Shen, S. Song, B.W.Y. Thian, S. L. Fong, A.W.L. Ee, S. Arora, S. Ghosh, S.F.Y. Li, H.T.W. Tan, Y. Dai, C.H. Wang, “Impacts of biochar concentration on the growth performance of a leafy vegetable in a tropical city and its global warming potential”, J. Cleaner Production, 264, 121678 (2020).

Q. Hu, C.H. Wang, “Insight into the Fe2O3/CaO-based chemical looping process for biomass conversion”, Bioresource Technology 310, 123384 (2020).

S. Song, S. Arora, A. K. C. Laserna, Y. Shen, B. W. Y. Thian, J. C. Cheong, Jonathan K. N. Tan, Z. Chiam, Siew Lee Fong, Subhadip Ghosh, Yong Sik Ok, S. F. Y. Li, H. T. W. Tan, Yanjun Dai, C.H. Wang, “Biochar for urban agriculture: Impacts on soil chemical characteristics and on Brassica rapa growth, nutrient content and metabolism over multiple growth cycles”, Science of The Total Environment, 727, 138742 (2020).

L. Li, X. Li, C. Chong, C.H. Wang, X. Wang, “A decision support framework for the design and operation of sustainable urban farming systems“, J. Cleaner Production, 268, 121928 (2020).

Q. Sun, X. Fu, R. Xi, C.H. Wang, N. Yan, “Mesoporous Silica-Encaged Ultrafine Bimetallic Nanocatalysts for CO2 Hydrogenation to Formates”, ChemCatChem, 11, 5093–5097 (2019).

Z. Yao, X. He, Q. Hu, W. Cheng, H. Yang, C.H. Wang, “A hybrid peripheral fragmentation and shrinking-core model for fixed-bed biomass gasification”, Chem. Eng. Journal, 400, 124940 (2020).

A.K. Prabhakar, B.C. Mohan, T.S. Tay, S.S.C. Lee, S.L.M. Teo, C.H. Wang, “Incinerated Sewage Sludge Bottom Ash- Chemical processing, Leaching patterns and Toxicity testing”, Journal of Hazardous Material, 402, 123350 (2021).

F. Li, M. J. Hülsey, N. Yan, Y. Dai, C.H. Wang, “Co-transesterification of waste cooking oil, algal oil and dimethyl carbonate over sustainable nanoparticle catalysts”, Chem. Eng. J., 405, 127036 (2021).

X. Li, J. Chen, W. Lipinsky, Y. Dai, C.H. Wang “A 28 kWe multi-source high-flux solar simulator: Design, characterization, and modeling”, Solar Energy, 211, 569-583 (2020).

J. Chen, X. Li, Y. Dai, C.H. Wang, “Energetic, economic, and environmental assessment of a Stirling engine based gasification CCHP system”, Applied Energy, 281, 116067 (2021).

D. Yao, H. Li, Y. Dai, C.H. Wang, “Impact of temperature on the activity of Fe-Ni catalysts for pyrolysis and decomposition processing of plastic waste”, Chem. Eng. J., 408, 127268 (2021).

Q. Hu, J. Jung, D. Chen, K. Leong, S. Song, F. Li, B. Mohan, Z. Yao, A. K. Prabhakar, X. H. Lin, E. Y. Lim, L. Zhang, G. Souradeep , Y.S. Ok, H.W. Kua, S. F. Y. Li, H. T. W. Tan, Y. Dai, Y. W. Tong, Y. Peng, S. Joseph, C.H. Wang “Biochar Industry to Circular Economy”, Science of the Total Environment, 757, 143820 (2021).

X.Y. Sun, J.L. Chen, Y. Zhao, X. Li, T.S. Ge, C.H. Wang, Y.J. Dai, “Experimental investigation on a dehumidification unit with heat recovery using desiccant coated heat exchanger in waste to energy system”, Applied Thermal Engineering, 185, 116342 (2021).

L. Wei, P. Jiang, W. Yang, X. Liu, Y. Dai, C. A. Shoemaker, C.H. Wang, “Input parameter tuning of 3D biodiesel engine simulation using parallel surrogate optimization algorithm, Computers and Chemical Engineering, 145, 107180 (2021).

O. Yaqubi, M. H. Tai, D. Mitra, C. Gerente, K. G. Neoh, C.H. Wang, Y. Andres, “Adsorptive Removal of Tetracycline and Amoxicillin from Aqueous Solution by Leached Carbon Black Waste and Chitosan-carbon Composite Beads”, Journal of Environmental Chemical Eng., 9(1) 104988 (2021).

D. Mitra, B. C. Mohan, M. H. Tai, C. Zhou, M. H. B. Hashim, K. Y.H. Gin, C.H. Wang, K. G. Neoh, “Emerging Pharmaceutical and Organic Contaminants Removal using Carbonaceous Waste from Oil Refineries”, Chemosphere, 271, 129542 (2021).

Q. Sun, B.W. J. Chen, N. Wang, Q. He, A. Chang, C.M. Yang, H. Asakura, T. Tanaka, M. J. Hglsey, C.H. Wang, J. Yu, N. Yan, “Zeolite‐Encaged Pd–Mn Nanocatalysts for CO2 Hydrogenation and Formic Acid Dehydrogenation”, Angewandte Chemie, 59, 2–11 (2020).

X.Y. Sun, J.L. Chen, Y. Zhao, X. Li, T.S. Ge, C.H. Wang, Y.J. Dai, “Experimental investigation on a dehumidification unit with heat recovery using desiccant coated heat exchanger in waste to energy system”, Applied Thermal Engineering, 185, 116342 (2021).

F. Li, X. He, A. Srishti, S. Song, H.T.W. Tan, D.J. Sweeney, S. Ghosh, C.H. Wang, “Water hyacinth for energy and environmental applications: A review”, Bioresource Technology, 327, 124809 (2021).

Y. Shuai, H. Zhang, B.G. Lougou, B. Jiang, A. Mustafa, C.H. Wang, F. Wang, J. Zhao, “Solar-driven thermal chemical redox cycles of ZrO2 supported NiFe2O4 for CO2 reduction into chemical energy, Energy, 223, 120073 (2021).

S. Arora, J. Jung, M. Liu, X. Li, A. Goel, J. Chen, S. Song, C. Anderson, D. Chen, K. Leong, S. H. Lim, S. L. Fong, S. Ghosh, A. Lin, H.W. Kua, H.T.W. Tan, Y. Dai, C.H. Wang, “Gasification biochar from horticultural waste: An exemplar of the circular economy in Singapore”, Science of the Total Environment 781, 146573 (2021).

L. Zhang, Y. Cui, T. Zhang, Q. Hu, Y. W. Tong, Y. He, Y. Dai, C.H. Wang, Y. Peng, “Food waste treating by biochar-assisted high-solid anaerobic digestion coupled with steam gasification: Enhanced bioenergy generation and porous biochar production”, Bioresource Technology, 331, 125051 (2021).

M. Liu, F. Li, H. Liu, C.H. Wang, “Synergistic effect on co-gasification of chicken manure and petroleum coke: an investigation of sustainable waste management”, Chem. Eng. Journal, 128008 (2020).

J.T.E. Lee, Y.S. Ok, S. Song, P.D. Dissanayake, H. Tian, Z.K. Tio, Ruofan Cui, E.Y. Lim, M.C. Jong, S.H. Hoy, T. Q.H. Lum, T.H. Tsui, C.S. Yoon, Yanjun Dai, C.H. Wang, H.T.W. Tan, Y.W. Tong, “Biochar utilisation in the anaerobic digestion of food waste for the creation of a circular economy via biogas upgrading and digestate treatment”, Bioresource Technology 333, 125190 (2021).

A. Lin, Y.K. Tan, C.H. Wang, H.W. Kua, H. Taylor, “Utilization of waste materials in a novel mortar-polymer laminar composite to be applied in construction 3D-printing”, Composite Structures 253:11, 112764 01 (2020).

L. Zhang, K.C. Loh, S. Sarvanantharajah, Y. Shen, Y.W. Tong, C.H. Wang, Y. Dai, “Recovery of nitrogen and phosphorus nutrition from anaerobic digestate by natural superabsorbent fiber-based adsorbent and reusing as an environmentally friendly slow-release fertilizer for horticultural plants”, Waste and Biomass Valorization 11(10), 5223-5237 (2020).

C.Y. Li, J.Y. Wu, Y.J. Dai, C.H. Wang, “Multi-criteria optimization of a biomass gasification-based combined cooling, heating, and power system integrated with an organic Rankine cycle in different climate zones in China”, Energy Conversion and Management, 243, 114364 (2021).

X. Li, J. Chen, X. Sun, Y. Zhao, C. Chong, Y. Dai, C.H. Wang, “Multi-criteria decision making of biomass gasification-based cogeneration systems with heat storage and solid dehumidification of desiccant coated heat exchangers”, Energy 233, 121122 (2021).

J. Liu, A.Goel, H. Kua, C.H. Wang, Y. Peng, “Evaluating the Urban Metabolism Sustainability of Municipal Solid Waste Management System: An Extended Exergy Accounting and Indexing Perspective”, Applied Energy, 300, 117254 (2021).

Q. Hu, X. He, Z. Yao, Y. Dai, C.H. Wang, “Gaseous production kinetics and solid structure analysis during isothermal conversion of biomass pellet under different atmospheres”, Journal of Energy Institute, 98, 53-62 (2021).

J. Zhang, X. Cao, Z. Yao, Q. Lin, B. Yan, X. Cui, Z., He, X. Yang, C.H. Wang, G. Chen, “Phytoremediation of Cd-contaminated farmland soil via various Sedum alfredii oilseed rape cropping systems: Efficiency comparison and cost-benefit analysis”, Journal of Hazardous Material, 419, 126489 (2021).

J. Liu, A. Goel, H. W. Kua, C.H. Wang, Y.H. Peng, “Evaluating the Urban Metabolism Sustainability of Municipal Solid Waste Management System: An Extended Exergy Accounting and Indexing Perspective”, Applied Energy, 300, 117254 (2021).

X. He, Q. Hu, H. Yang, C.A. Shoemaker, C.H. Wang, “Dynamic Modeling with Experimental Calibration for the Syngas Production from Biomass Fixed-bed Gasification”, AIChE Journal, e17366. https://doi.org/10.1002/aic.17366 (2021).

M. H. Tai, B. C. Mohan, Z. Yao, C.H. Wang, “Superhydrophobic leached carbon Black/Poly(vinyl) alcohol aerogel for selective removal of oils and organic compounds from water”, Chemosphere, 286, 131520 (2021).

X. He, C.H. Wang, C. A.  Shoemaker, “Multi-objective Optimization of an Integrated Biomass Waste Fixed-bed Gasification System for Power and Biochar Co-production”, Computer and Chemical Engineering, 154, 107457 (2021).

L. Wang, L. Chen, C.S. Poon, C.H. Wang, Y.S. Ok, V. Mechtcherine, D.C.W. Tsang, “Roles of Biochar and CO2Curing in Sustainable Magnesia Cement-Based Composites”, ACS Sustainable Chemistry & Engineering, 9, 25, 8603-8610 (2021).

H. Li, S. Huang, Z. Yao, Q. Wang, C.H. Wang, “Flow battery electrolyte from carbon black incineration fly ash: A feasibility study of an environment friendly disposal process”, Waste Management, 133, 28-36 (2021).

F. Li, D. J. Sweeney, Y. Dai, C.H. Wang, “Effect of novel Ni2P-loaded catalysts on algal pyrolysis bio-oil’, Renewable and Sustainable Energy Reviews, 151, 111575 (2021).

F. Li, K. Zhao, T.S.A. Ng, Y. Dai, C.H. Wang, “Sustainable production of bio-oil and carbonaceous materials from biowaste co-pyrolysis”, Chem. Eng. J., 427, 131821 (2021).

D. Mitra, M.H. Tai, E.B. Abdullah, C.H. Wang, K.G. Neoh, “Facile fabrication of porous waste-derived carbon-polyethylene terephthalate composite sorbent for separation of free and emulsified oil from water”, Separation and Purification Technology, 279, 119664 (2021).

A. Mozhi, A. K. Prabhakar, B. C. Mohan, V. Sunil, J. H. Teoh, C.H. Wang, “Toxicity effects of size fractions of incinerated sewage sludge bottom ash on human cell lines”, Environmental International, 158, 106881 (2022).

X. Li, J. Chen, Q. Hu, P. Chu, Y. Dai, C.H. Wang, “Solar-driven gasification in an indirectly-irradiated thermochemical reactor with a clapboard-type internally-circulating fluidized bed”, Energy Conversion and Management, 248, 114795 (2021).

Q. Liu, W. Zhong, A. Yu , C.H. Wang, “Modelling the co-firing of coal and biomass in a 10 kWth oxy-fuel fluidized bed”, Powder Technology, 395, 43-59 (2022).

X. Li, L. Wei, C.W. Lim, J. Chen, P. Chu, W. Lipinski, N. Yan, Y. Dai, C.H. Wang, “Experimental and numerical study on thermal performance of an indirectly irradiated solar reactor with a clapboard-type internally circulating fluidized bed, “Applied Energy”, 305, 117976 (2022).

S. Song, J.W. Lim, J.T.E. Lee, J.C. Cheong, S.H. Hoy, Q.Hu, J. K.N. Tan, Z. Chiama, S. Aroraa, T. Q.H. Lum, E.Y. Lim, C.H. Wang, H.T.W. Tan, Y. W. Tong, “Food-waste anaerobic digestate as a fertilizer: The agronomic properties of untreated digestate and biochar-filtered digestate residue”, Waste Management, 136, 143-152 (2021).

M. Liu, Z. Shen , S. Zhou, J. Xua, Q. Liang, C.H. Wang, H. Liu, “Gas-solid reaction induced particle collision and aggregation”, Combustion and Flame, 237, 111885 (2022).

L. Zhang, D. Yao, T.H. Tsui , K.C. Loh, C.H. Wang, Y. Dai, Y.W. Tong, “Plastic-containing food waste conversion to biomethane, syngas, and biochar via anaerobic digestion and gasification: Focusing on reactor performance, microbial community analysis, and energy balance assessment”, Journal of Environmental Management, 306, 114471 (2022).

X. He, Q. Hu, J. Chen, W.Q. Leong, Y. Dai, C.H. Wang, “Energy and environmental risk assessments of poultry manure sustainable solution: an industrial case study in Singapore”, Journal of Cleaner Production, 339, 130787 (2022).

A.K. Prabhakar, P. Krishnan, S.S.C. Lee, C.S. Lim, A. Dixit, B.C. Mohan, J.H. Teoh, S.D. Pang, D.C.W. Tsang, S. LM. Teo, C.H. Wang, “Sewage sludge ash-based mortar as construction material: Mechanical studies, macrofouling, and marine toxicity”, Science of the Total Environment, 824, 153768 (2022).

H. W. Kua, X. He, H. Tian, A. Goel, T. Xu, W. Liu, D. Yao, S. Ramachandran, X. Liu, Y.W. Tong , Y. Dai, Y. Peng, C.H. Wang, “Life cycle climate change mitigation through next-generation urban waste recovery systems in high-density Asian cities: A Singapore Case Study”, Resources, Conservation & Recycling, 181, 106265 (2022).

J. Pottas, L. Li, M. Habib, C.H. Wang, J. Coventry, W. Lipiński, “Optical alignment and radiative flux characterization of a multi-source high-flux solar simulator”, Solar Energy, 236, 434-444 (2022).

P. Chu, Q. Hu, J. Chen, C. Y.A. Loh, A. Lin, X. Li, D. Chen, K. Leong, Y. Dai, C.H. Wang, “Performance analysis of a pilot-scale municipal solid waste gasification and dehumidification system for the production of energy and resource”, Energy Conversion and Management, 258, 115505 (2022).

Z. Yao, A.K. Prabhakar, B.C. Mohan, C.H. Wang, “An Innovative Accelerated Carbonation Process for Treatment of Incineration Bottom Ash and Biogas Upgrading”, Waste Management, 144, 203-209 (2022).

L. Zhang, F. Li, T.H. Tsui, K. Yoh, J. Sun, K.C. Loh, C.H. Wang, Y. Dai, Y. W. Tong, “Microbial succession analysis reveals the significance of restoring functional microorganisms during rescue of failed anaerobic digesters by bioaugmentation of nano-biochar-amended digestate”, Bioresource Technology, 352, 127102 (2022).

V. Wells, A. Riaz, Q. Sun, X. Li, N. Yan, C.H. Wang, W. Lipinsk, “Mesoporous silica-encaged ultrafine ceria–nickel hydroxide nanocatalysts for solar thermochemical dry methane reforming”, Applied Physics Letters, 120, 143905 (2022).

M.H. Tai, B.C. Mohan, C.H. Wang, “Freeze-casting multicomponent aerogel membrane with controllable asymmetric multilayer configuration for high flux gravity-driven separation of oil-water emulsion”, Separation and Purification Technology, 293, 121087 (2022).

D. Yao, H. Li, B. C. Mohan, A. K. Prabhakar, Y. Dai, C.H. Wang, “Conversion of waste plastic packings to carbon nanomaterials: investigation into catalyst material, waste type, and product applications”, ACS Sustainable Chemistry & Engineering, 10, 3, 1125–1136 (2022).

Q. Hu, Y.S. Ok, C.H. Wang, “Sustainable and Highly Efficient Recycling of Plastic Waste into Syngas via a Chemical Looping Scheme”, Environmental Science and Technology, 56, 12, 8953–8963 (2022).

B. Wang, A. Rahbari, M. Hangi, X. Li, C.H. Wang, W. Lipiński, Topological and hydrodynamic analyses of solar thermochemical reactors for aerodynamic-aided window protection, Engineering Applications of Computational Fluid Mechanics 16 (1), 1195-1210 (2022).

J.T.E. Lee, E.Y. Lim, L. Zhang, T.H. Tsui, H. Tian, M. Yan, S. Lim, M.A. Majid, M.C. Jong, J. Zhang, C.H. Wang, Y. S. Ok, Y.W. Tong, “Methanosarcina thermophila bioaugmentation and its synergy with biochar growth support particles versus polypropylene microplastics in thermophilic food waste anaerobic digestion”, Bioresource Technology, 360, 127531 (2022).

J.T.E. Lee, N. Dutta, L. Zhang, T.T.H. Tsui, S. Lim, Z. K. Tio, E.Y. Lim, J. Sun, J. Zhang, C.H. Wang, Y.S. Ok, B.K. Ahring, Y.W. Tong, “Bioaugmentation of Methanosarcina thermophila grown on biochar particles during semi-continuous thermophilic food waste anaerobic digestion under two different bioaugmentation regimes”, Bioresource Technology, 360, 127590 (2022).

B. Wang, X. Li, Y. Dai, C.H. Wang, “Thermodynamic analysis of an epitrochoidal rotary reactor for solar hydrogen production via a water-splitting thermochemical cycle using nonstoichiometric ceria”, Energy Conversion and Management, 268, 115968 (2022).

Z. Yao, T. Zhao, W. Su, S. You, C.H. Wang, “Towards understanding respiratory particle transport and deposition in the human respiratory system: Effects of physiological conditions and particle properties”, Journal of Hazardous Materials, 439, 129669 (2022).

Q. Liu, W. Zhong, A. Yu, C.H. Wang, “Co-firing of coal and biomass under pressurized oxy-fuel combustion mode in a 10 kWth fluidized bed: Nitrogen and sulfur pollutants”, Chem. Eng. Journal, 450, 138401 (2022).

X. He, C.C.Y Ling, Z. Sun, X. Xu, F. Y. Li, X. Wang, H.T.W. Tan, Mohamed Lokman Mohd Yusof, Subhadip Ghosh, Chi-Hwa Wang, “Sustainable management of water hyacinth via gasification: Economic, environmental, and toxicity assessments”, Journal of Cleaner Production, 372, 133725b (2022).

X. He, Y. Wang, M. H. Tai, A. Lin, S. Owyong, X. Li, K. Leong, M. L.M. Yusof, S. Ghosh, C.H. Wang, “Integrated applications of water hyacinth biochar: A circular economy case study”, Journal of Cleaner Production 378, 134621 (2022).

Y. Wang, G. Lin, X. Li, M. H. Tai, S. Song, H. T. Wah Tan, K. Leong, E. Y. B. Yip, G. Y. C. Lee, Y. Dai, C.H. Wang, “Meeting the heavy-metal safety requirements for food crops by using biochar: An investigation using sunflower as a representative plant under different atmospheric CO2 concentrations”, Science of the Total Environment, 867, 161452 (2023)

B. Wang, X. Li, X. Zhu, Y. Wang, T. Tian, Y. Dai, C.H. Wang, “An epitrochoidal rotary reactor for solar-driven hydrogen production based on the redox cycling of ceria: Thermodynamic analysis and geometry optimization”, Energy, 270, 126833 (2023).

K. Yuanting, Tang, Y.M. Toh, C.H. Wang, Z. Li, “Upcycling of waste plastics to carbon nanomaterials”, in Circularity of Plastics, Sustainability, Emerging Materials and Valorization of Waste Plastics, Elsevier pp71-100 (2023).

A.K. Prabhakar, B.C. Mohan , M.H. Tai, Z. Yao, W. Su, S.L.M. Teo, C.H. Wang, “Green, non-toxic and efficient adsorbent from hazardous ash waste for the recovery of valuable metals and heavy metal removal from waste streams”, Chemosphere 329, 138524 (2023).

J. Liu, H. W. Kua, C.H. Wang, Y.W. Tong, J. Zhang, Y. Peng, “Extended exergy accounting theory to design waste-to-energy management system under uncertainty”, Energy, 278, 127924 (2023).

J. Liu, H.W. Kua, C.H. Wang, Y.W. Tong, J. Zhang, Y. Peng, “Improving urban ecosystem holistic sustainability of municipal solid waste-to-energy strategy using extended exergy accounting analysis”, Science of the Total Environment, 904, 166730 (2023).

J. Wu. Y. Chen, Y. Xu, S. Chen, H. Lv, Z. Gan, X. Zhu, R. Wang, C.H. Wang, T. Ge, “Facile synthesis of structured adsorbent with enhanced hydrophobicity and low energy consumption for CO2 capture from the air”, Matter, Matter 7, 1–17, (2024).

D. Xu, B. Wang, X. Li, Y. W. Cheng, W. Fu, Y. Dai, C.H. Wang, “Solar-driven biomass chemical looping gasification using Fe3O4 for syngas and high-purity hydrogen production”, Chem. Eng. J. 479, 147901 (2024).