Kok Siew Ng

Brunel University London · Department of Chemical Engineering

This study proposes a novel integrated material recovery and waste-to-hydrogen concept in view of enhancing resource efficiency and minimising environmental impact. A comprehensive techno-economic evaluation is conducted on an integrated system consisting of material recovery facility (MRF) and gasification of rejected materials for hydrogen produc...

Over the coming years, the world is projected to witness an upsurge in “drop-in” aviation biofuel production as part of the renewable energy and bioeconomy developments. This paper presents a comprehensive review of the current status of biojet fuel development and uptake in global commercial aviation industry, including state-of-the-art certified...

This report summarises the 4-year fellowship project (2018-2021) funded by UKRI/NERC, led by Dr Kok Siew Ng at the Department of Engineering Science, University of Oxford. The report and other publications can be found via https://eng.ox.ac.uk/synergors/publications/. Please cite this report as: Ng, K.S., Hatton, L., Martinez-Hernandez, E. (2021)...

Significant loss of valuable resources and increasing burdens on landfills are often associated with a lack of proper planning in waste management and resource recovery strategy. A sustainable waste management model is thus urgently needed to improve resource efficiency and divert more waste from landfills. This paper proposes a comprehensive syste...

This publication is an extension of “Malaysia versus Waste” authored by Dr Kok Siew Ng and Dr Eleni Iacovidou, featured in The Chemical Engineer (IChemE) in July 2020 (https://www.thechemicalengineer.com/features/malaysia-versuswaste/) to cover a wider aspect of municipal solid waste management in Malaysia. This work is mostly based on literature s...

This publication is an extension of “Malaysia versus Waste” authored by Dr Kok Siew Ng and Dr Eleni Iacovidou, featured in The Chemical Engineer (IChemE) in July 2020 (https://www.thechemicalengineer.com/features/malaysia-versuswaste/) to cover a wider aspect of municipal solid waste management in Malaysia. This work is mostly based on literature s...

In the UK, half a million tonnes of spent coffee ground (SCG) waste are generated annually. Current SCG management practices of landfill and energy-from-waste (EfW) facilities either underutilise its valuable constituents or have negative environmental impacts. This study investigates the prospects of SCG-based biorefineries by assessing the impact...

Although two-stage gasifier design offers a number of advantages i.e., producing high-quality gas (high H2 content, low CO2 and other impurities) and tolerating high degree of heterogeneity of feedstock, its economic feasibility is yet to be evaluated. In this study, a techno-economic assessment is fully conducted to assess the economic feasibility...

Process economics is one of the crucial aspects for evaluation of process designs. It is often the main criterion in justifying the feasibility of a new design or modification of a plant. Many biomass based technologies are not yet widely employed. This is primarily attributed to the high capital investment and operating costs associated with these...

Life cycle assessment (LCA) is an ISO14040-44 methodology essential to embed design and decision making of product, process and service systems. This is a fundamental learning resource on LCA.

Resources embedded in the waste streams are not properly recovered and most of them are ended up in landfills or only recovered as energy via energy-from-waste (EfW) facilities. Innovative resource recovery from waste strategies are urgently needed to maximise resource efficiency, divert waste from landfills and reduce reliance on EfW. This study p...

Renewable energy has emerged as an economically realistic alternative for supplying global energy needs to drive human production activities and modern comfort. It is also a viable strategy to achieve the reduction of greenhouse gas emissions and decarbonize other supply chains, while addressing some of the UN's sustainable development goals. Howev...

Households are highly resource intensive in terms of energy consumption and waste generation, and resource utilisation and management in households has wider implications at the national level. This paper applies systems thinking approach at the household level for the first time. The approach takes into consideration energy supply and demand, wast...

Carbon emissions from the aviation industry are a significant concern and the adoption of sustainable aviation fuel has the potential of mitigating the environmental impacts. Hydrothermal liquefaction (HTL) has great potential to produce sustainable aviation fuel employing organic waste feedstock but requires further development to reduces costs an...

MALAYSIA is on track to miss its 2020 targets to divert 40% of waste from landfill and increase recycling rates to 22%. According to the most recent stats available, almost 90% of waste was reportedly disposed to sanitary landfills, while only 10.5% was recycled. These targets were set out as far back as August 2005 in Malaysia’s National Strategic...

The utilization of bio-oil could be an attractive option in the future, attributed to its high bulk energy density and ease of transportation. However, the primary challenge in promoting the commercialization of technologies using bio-oil is high capital investment and operating costs. The key to resolve this challenge is to maximize the value of p...

Highly efficient macroalgae based chemical factories and environmental protection have been comprehensively studied for the first time to displace fossil resources to mitigate climate change impact. Wild macroalgae can be used to treat wastewaters, marine environment, soil and sludge by (bio)phytoremediation during growth phase and biosorption afte...

The UK is facing tremendous challenges in tackling food waste diversion from landfill. Whilst much effort has been made to prevent food waste, there is still a lack of attention and strategic approach in dealing with resource recovery and valorisation of food waste. This paper presents a systematic framework for sustainable organic waste management...

Garden waste collected by, or on behalf of, local authorities (LAs) in the UK is normally managed in composting facilities, as required by environmental permitting. At composting facilities, garden waste undergoes biodegradation, a process in which aerobic microorganisms break down and digest the organic matter, producing carbon dioxide, nitrates,...

Unlocking the potential and value of lignocellulosic residues is an important step in making biorefineries economically and environmentally promising. This calls for a holistic and systematic approach in designing sustainable industrial systems. In this work, biorefinery systems via biochemical route (acetone–butanol–ethanol or ABE system) and ther...

This report is the outcome of a Resource Recovery from Waste mini-project led by University of Leeds. The project aimed to explore higher value applications of fibre recovered through a steam rotating autoclave, which is a form of a Mechanical Heat Treatment (MHT) process. It processes mixed municipal solid waste or materials with similar character...

This chapter provides an overview of value-added production using extremophiles as well as the advantages and challenges for process development in a biorefinery concept. The chapter then shows a modeling framework that includes metabolic flux modeling, growth kinetics, and bioreactor models as well as process simulation. The model results are the...

Biorefineries are processing facilities that convert biomass into value-added products such as biofuels, biochemicals, bioenergy/biopower, and other biomaterials. Various types of biorefineries have been presented in the literature. Most of them are mainly defined based on the individual feedstock, such as corn-based biorefinery, wood-based biorefi...

The production of electricity from microbes was first demonstrated in the early 1900s when scientific enquiries were made about the nature of the electrical effects associated with the decomposition of organic compounds due to the influence of microorganisms. This discovery inspired further investigations into the use of electrochemical devices to...

Sustainability assessment of resource recovery from waste is an important prerequisite for informed and sound decision-making. Life Cycle Sustainability Assessment (LCSA) has been developed to support this process, yet its use is still constrained by the difficulty of identifying the most relevant impact parameters. This paper, seeks to inform LCSA...

Sustainability assessment of resource recovery from waste is an important prerequisite for informed and sound decision-making. Life Cycle Sustainability Assessment (LCSA) has been developed to support this process, yet its use is still constrained by the difficulty of identifying the most relevant impact parameters. This paper, seeks to inform LCSA...

Malaysia has a plethora of biomass that can be utilized in a sustainable manner to produce bio-products for circular green economy. At the 15th Conference of Parties in Copenhagen, Malaysia stated to voluntarily reduce its emissions intensity of gross domestic product by upto 40% by 2020 from 2005 level. Natural resources e.g. forestry and agricult...

The replacement of traditional process design approach by a more holistic approach is exigent in view of developing sustainable industrial systems and effectively reducing the energy and emission intensities in the process industries. Polygeneration systems are flexible and integrated multi-product systems that can potentially enhance energy effici...

The economic and environmental sustainability can be enhanced by polygeneration of added value chemicals and materials through process integration opportunities. Reuse and recycle of carbon dioxide (CO2) rich as well as lean streams can generate syngas, hydrogen, formic acid, methane, ethylene, methanol, Fischer-Tropsch liquid, succinic acid, etc....

Due to the huge amount of sago biomass generated and discharged to the environment from sago industry without proper treatment, serious environmental impacts are caused. In order to reduce such environmental pollutants, sustainable conversion of biomass into value-added products is of paramount importance. However, up-to-date, sago-based biorefiner...

Development of clean coal technology is highly envisaged to mitigate the CO 2 emission level while meeting the rising global energy demands which require highly efficient and economically compelling technology. Integrated gasification combined cycle (IGCC) with carbon capture and storage (CCS) system is highly efficient and cleaner compared to the...

Process to process material and heat integration strategies for bio-oil integrated gasification and methanol synthesis (BOIG-MeOH) systems were developed to assess their technological and economic feasibility. Distributed bio-oil generations and centralised processing enhance resource flexibility and technological feasibility. Economic performance...

This chapter discusses conceptual designs of coprocessing of bio-oil in a crude oil refinery and refining of bio-oil in a novel membrane based multifunctional reactor. Stable bio-oil from biomass pyrolysis can be coprocessed with refinery middle distillates in a hydrocracker to produce renewable diesel, lowering the CO2 emission compared to crude o...

Thermochemical processing is one of the main biorefinery platforms, where biomass is converted into high value intermediate products. This chapter gives a comprehensive overview of the thermochemical processing technologies relevant to biorefineries. Thermochemical processes are highly favorable platforms for conversion of any lignocellulosic mater...

The two approaches, value analysis and environmental impact (EI) analysis, are coupled into an economic value and environmental impact (EVEI) analysis approach. Equivalent to the cost of production (COP) and the value on processing (VOP) of intermediate streams, the impact cost of production (ICP) and the credit value on processing (CVP) concepts c...

This chapter discusses the fundamental concepts of economics germane to chemical engineering process design and the methodology for performing economic analysis of process technologies. The learning outcomes from the chapter are: 1) to assimilate the fundamental economic terminologies and concepts. 2) to perform a capital and operating costs evalua...

This chapter discusses the value analysis methodology which is used to solve large-scale combinatorial process optimization problems based on economic margins, without mathematical programming. It evaluates economic margins of individual streams and processing pathways in a process network, such that aggregation of their individual economic margins...

This chapter focuses on mathematical programming based optimization. An optimization problem is concerned with the maximization or minimization of an objective or even simultaneous maximization and minimization of several objectives. Nonlinear optimization problems involve one or more nonlinear terms in the objective function and/or constraints. So...

Designing the thermochemical conversion processes of biomass involves the assessment of process performance with respect to material utilization and energy efficiency. Modeling of these processes requires the application of fundamental concepts of reaction thermodynamics, and thereby identification of key operating parameters and performance indica...

Data uncertainty in life cycle assessments (LCA) can result from imprecise measurements of inventories, average or even outdated data using proxies and incomplete data. Various assumptions are made when deducing life cycle inventories (LCI), such as linear correlations and averaged data over time and across regions. The LCA results include the foll...

Polymers are present in almost every aspect of human daily life, in textiles, automobile, computer parts, insulation, and food protection and packaging. Polymers have contributed to energy saving and environmental impact reduction by more efficient energy use in lightweight automobiles, insulation of houses and refrigeration. Polymers with differen...

Industrial plants encompass a large number of heat exchanger equipment and involve many heating and cooling duties. Heat integration using pinch analysis is a well-established methodology and has been demonstrated in many projects in the oil and gas industry throughout the world. Biorefineries need to adopt a process integration analysis at the out...

Bio-oil can be produced in a centralized site consisting of a number of pyrolysis plants integrated with other processing plants. There are two main types of bio-oil upgrading process in practice, that is, physical and chemical catalytic upgrading. Other emerging technology includes the biological upgrading method via fermentation. Bio-oil can be c...

Several decarbonised polygeneration schemes exploiting carbon capture and storage (CCS) or CO2 reuse technologies for the generation of clean fuels, chemicals, electricity and heat have been systematically analysed for techno-economic feasibility. Process simulation, energy integration and economic analysis were undertaken to analyse the effect of...

Development of clean coal technology is highly envisaged to mitigate the CO2 emission level whilst meeting the rising global energy demands which require highly efficient and economically compelling technology. Integrated gasification combined cycle (IGCC) with carbon capture and storage (CCS) system is highly efficient and cleaner compared to the...

The biofuel mix in transport in the U.K. must be increased from currently exploited 3.33% to the EU target mix of 10% by 2020. Under the face of this huge challenge, the most viable way forward is to process infrastructure-compatible intermediate, such as bio-oil from fast pyrolysis of lignocellulosic biomass, into biofuels. New facilities may inte...

Integrated gasification combined cycle (IGCC) power generation systems have become of interest due to their high combined heat and power (CHP) generation efficiency and flexibility to include carbon capture and storage (CCS) in order to reduce CO2 emissions. However, IGCC's biggest challenge is its high cost of energy production. In this study, dec...

The objective of this work was to design a heat integrated, cost-effective, and cleaner combined heat and power (CHP) generation plant from low-cost, fourth-generation biomass waste feedstocks. The novelty lies in the development of systematic sitewide heat recovery and integration strategies among biomass integrated gasification combined cycle pro...