Hong Kong is vulnerable to energy and economic security due to the heavy dependence on imported fossil fuels. Waste has also been a major environmental management problem due to the amount of rubbish produced every year but lacking the technology and capital to manage different types properly. The objective of the dissertation is to study the feasibility of the use of biofuel in Hong Kong by recycling local waste. Current government policies in Hong Kong and overseas are being investigated on the appropriateness for domestic use. Literature reviews and stakeholders’ questionnaires are accounted to analyse the adaptability and popularity of the biodiesel application. The methodology of the dissertation is to firstly examine literature reviews regarding biodiesel’s environmental aspect, technical efficiencies, economic aspect, government incentives and tax constraints. The consensus outcome of these researches advocated high popularity of biodiesel consumption and production in Europe and U.S. due to lower environmental impact, equivalent output efficiency and strong government support. Their successful implementation is a good example to improvise biodiesel domestically in Hong Kong. Secondly, interviews were conducted with Hong Kong’s limited stakeholders. Respondents such as Hong Kong International Airport, Hong Kong Jockey Club, Fairwood Fastfood MTR Maritime Square were interviewed as these participants have been the pioneers in Hong Kong by recycling waste into biodiesel. On the production side, two out of three bio-refineries in Hong Kong provided their business sustainability and feasibility comments to pursue a long term goal. The limitation on responses might be focused solely on a few peer groups, and not the appropriate stakeholders with proper sampling size. However, the results are concurrent that biodiesel is one of the best alternative energy in Hong Kong. The dissertation draws positive results based on the following factors. Biodiesel can diminish the tremendous cost on waste management and landfill dumping. Using local food waste and industrial wastes from restaurants and food factories as feedstock to produce biodiesel is positive. This will also minimise the heavy reliance on imported fossil fuels to diversify energy sources. Refuelling of biodiesel fuel can be performed in any gas stations with the use of the existing infrastructure without any further requirement of new investment. Nonetheless, in order to facilitate the use of biodiesel, incentives programmes initiated by Hong Kong Government and the biofuel producers have to coherently promote this alternative fuel. The conclusion states that Hong Kong is completely feasible to adopt the use of biodiesel in medium to heavy sized vehicles and vessels in the commercial sector. The environmental benefit of Hong Kong using biodiesel stood out compared to other form of renewable energy. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

There are many factors affecting the hotel energy consumption, such as hotel classifications, floor area, numbers of guest rooms, nos. of room guests, mix of guest segments, level of occupancy (guest nights), scale of meeting facilities, laundry, retails operations, building features, facilities features, fuel mix, year of construction, year of retrofit, numbers of staff, weather conditions, management arrangement, etc. In Hong Kong and Singapore, the traditional method of benchmarking by Energy Use Index (EUI) per particular factor however was not able to effectively analyze such multiple inputs and multiple outputs environment. From the previous research papers, the Data Envelopment Analysis (DEA) was applied for the hotel management study in other countries recently, such as Portugal, Africa, Italy, Taiwan and Korean. Recently, the application of DEA to building energy analysis was only limited to residential buildings in US, government buildings in Taiwan, and hotel buildings in Turkey. The study provides a simple and basic DEA model (CCR-I CRS) for the evaluation of hotel energy consumption analysis of a sample hotel in Hong Kong for the tourism /hospitality industry. The DEA model was established with multiple input variables (electricity, Towngas, water, outdoor temperature and relative humidity) and multiple output variables (numbers of room nights, numbers of room guests, and numbers of food & beverage cover). The models successfully identifies the relative efficiencies of efficient decision-making units (DMUs) and inefficient DMUs, therefore the potential of saving areas are shown for further improvement action by hotel management strategic planning. Benchmarks are provided for improving the operations of poor-performing DMUs – months and F&B outlets respectively. Several interesting and useful managerial insights and implications from the study are discussed. Peer groups and slacks were identified among the efficient operations for the inefficient DMUs to adjust themselves in order to reach the efficient frontier. The study suggests a framework which enables the hotel management to develop a strategic action plan with energy conservation measures in different priorities. At the end, the hotel will be able to deliver a high degree of guest service standard and at the same time to preserve the environment by reducing the energy consumption. It is concluded that my area of study is a fit to “the gap”. The end results will form the extension of overseas researches and the foundation of the local researches in this knowledge area. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

With the growing urbanized population, cities have become a major contributor to global energy consumption and greenhouse gas (GHG) emission. The urbanization processes also cause local climate change through excessive anthropogenic heat emission and modification of the land biophysical properties. The resultant urban heat island (UHI) effects and aggravating human heat stress have become key environmental issues in city management. Cities can be designed to be climate-conscious and energy-efficient not only to contribute to urban sustainability, but also address global climate-change issues at the local level. Green roof presents a feasible strategy for climate-conscious urban design (CCUD). With the notable thermal effects in microclimate amelioration and energy conservation, it has great potential to help cities tackle local and global climate issues. Understanding the status and underlying mechanism of green-roof thermal effects can inform optimal design and management, and provide scientific basis to promote green-roof application. This study formulates a multidisciplinary framework to assess green-roof thermal effects at building, neighborhood and district scales, based on a case study in Hong Kong. Firstly, the building-scale field measurement found that the 484 m^2 experimental extensive green roof can significantly ameliorate rooftop microclimate and cut building energy consumption. The peak surface and air temperature can be reduced by 11℃ and 4.5℃ on sunny summer days, and 7.2℃ and 2.3℃ on cloudy days, leading to an electrical energy saving of 2.80×〖10〗^4 kWh for a summer of air conditioning. The thermal performance was sensitive to background environmental factors. Solar radiation and relative humidity governs the seasonal and diurnal variation of air and surface temperatures reduction. Substrate moisture can significantly regulate the subsurface temperature but has limited effect on evapotranspiration (ET). Based on correlation and scenario analyses, this study has formulated an irrigation scheme which could balance between plant growth, thermal performance and water efficiency to achieve sustainable management of tropical extensive green roofs. Secondly, the neighborhood-scale modeling revealed that greening all roofs in residential communities can extend the cooling effects from the rooftop to the entire neighborhood. Urban design factors such as building height, distance, site coverage and orientation can affect the diurnal, horizontal and vertical pattern of the “cool-islands” created by green roofs. Green roof can also enhance the rooftop thermal comfort by alleviating the intensity and duration of heat stress. The findings suggest that compact cities can green the roof and podium space to provide thermally comfortable and recreational venues for urban residents. Thirdly, the district-scale cost-benefit analysis found that large-scale construction of green-roof infrastructure in Hong Kong can be well justified by its thermal benefits. The extensive green roof has an annual monetary benefit of HK$0.9–1.7 billion, and the intensive, HK$1.4–2.6 billion, in terms of energy saving, CO2 and air pollutant reduction. The life-cycle benefit-cost ratio (BCA) is 3.7–7 for extensive green roof, and 1.4–2.7 for the intensive, indicating the high cost-effectiveness of both types, with the extensive being more economically attractive than the intensive. / published_or_final_version / Geography / Doctoral / Doctor of Philosophy

The marine environment is likely to experience profound climate change in the coming 100 years and beyond. Ocean acidification (OA) is one of the climate change issues attracting the attention of researchers all over the world. The decreasing pH of the oceans might threaten marine biofouling organisms. However, climate change is not only involved with ocean acidification (OA) but the change of other environmental variables, such as temperature and salinity. These environmental factors act as multiple stressors and synergistically affect shell-forming biofoulers, in which, the calcium carbonate skeleton structure plays an important role of protection. Previous studies regarding the response of marine biofoulers to the environmental stressors were generally summarized in this article. Then a calcifying biofouling tube worm, Hydroides elegans, were reared from larval stage to early juvenile stage under control and treatment conditions to examine the combined effects of temperature (24, 30°C), pH (8.1, 7.7) and salinity (34, 27ppt). Juvenile growth and chemical composition (Mg/Ca and Sr/Ca) of their calcareous tubes were tested and used as assessment of effects of the three environmental stressors. The experiment revealed that H. elegans was robust to the environmental change because juvenile development positively responded to temperature and the interaction between temperature and salinity. Other combinations did not exert significant effect. The results suggest the need of further study of proteomics and transcriptomics to reveal the mechanisms of calcification as well as long-term studies to examine the energy costs of adaptation. In addition, the non-significant chemical composition (Mg/Ca and Sr/Ca) of the tube of this organism suggest a need of further exploration of the same animal but not only focus on three factors but the seawater chemical composition as well. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

To have better understandings of the partial pressure of carbon dioxide (pCO2)in northern South China Sea(NSCS), the pCO2readings from 1999-2012 were reviewed. Both the pCO2in NSCS and in the atmosphere also showed an increasing trends and the pCO2in NSCS varied across the seasons. There are many important processes that influenced the pCO2in NSCS, which were the rise of the temperature, biological production, seasonal upwelling, Pearl River discharge, increase in the concentration of atmospheric pCO2and the rate of calcification. These six mechanisms extend different strengths on the resultant sea surface pCO2in NSCS. The impact of induced sea water acidification on the marine phytoplankton by the high pCO2in NSCS would also be discussed. The drop of pH in the seawater would change the community of phytoplankton from diatom to dinoflagellate as a resistance to the change of pH of dinoflagellate that was better than the diatom. DMS, which was one of the climatically important gases, would also affected by the high pCO2induced seawater acidification. Hong Kong (HK) was studied as a case to estimate whether NSCS also faced the same impacts upon by the marine phytoplankton. The study showed that the diatom was relatively sensitive to the drop of pH in HK waters. The DMS producing marine phytoplankton was also affected by the drop of pH in HK waters. It was concluded that the NSCS might also face the same situation with HK. Finally, three instruments were recommended to have a better management in NSCS, namely, knowledge gaps and NSCS research priorities, valuing the NSCS as well as decision making team. Firstly, filling the knowledge gaps and NSCS research priorities aim to enhance the ability of the ocean sequestration to absorb and store the largest amount of anthropogenic CO2as possible. Afterwards, valuing the NSCS aims to protect the marine organisms, such as the phytoplankton, form the negative impacts of the decrease of ocean acidity. Last but not least, a good decision making team aims to balance the conflicts between those various options to reduce the anthropogenic CO2with ocean sequestration and impacts result from the ocean sequestration. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Plastics are cheap and convenient materials that are widely adopted in our daily applications. High production and consumption of plastics, however, are resulting in the issue of marine plastic pollution. Plastic debris is often divided into two categories: macroplastics and microplastics. Macroplastic is a well-known international problem to the world’s oceans, while microplastics often receive less attention. Many coastal areas and remote islands are suffering from plastic pollution. Marine plastic debris is responsible for negative impacts on organisms and the environment, including entanglement, ingestion, absorption of toxic chemicals, and transportation of invasive species. Human society and the economy may also be threatened. It is noticed that impacts caused by microplastics are comparatively more critical than those caused by macroplastics. Microscopic size and large surface area to volume ratio increase the potential for microplastics being ingested or used as vectors to absorb chemicals. Micro particles may enter the circulatory system, cause damage to cells and tissues, and release contaminated chemicals to the body, and hence result in health and safety issues. Ingested plastics may undergo bioaccumulation and pass up the food web, which may influence the entire ecosystem as well as human populations. Guangdong province is the largest plastic production centre in Mainland China. Any discharge from Guangdong province will enter the Pearl River and move downstream to the mouth of the estuary where Hong Kong is located. Hong Kong, especially it’s western waters, is directly susceptible to discharge from Mainland China. Data of plastics collected from beaches illustrated that higher quantities of plastic pellets have been collected from the western part of Hong Kong. This implies Hong Kong is suffering from plastic pollution generated from the Pearl River. Hong Kong may also receive overseas plastics carried by ocean currents and monsoon winds, which may have a stronger effect on the southern and eastern waters. There are many valuable marine biota and environments in Hong Kong. The presence of microplastics may pose a significant threat to the entire marine ecosystem and food chain. It is necessary to take action on the prevention and mitigation of the impacts of microplastics. Efforts should be made at national and international levels, and all sectors are responsible to take appropriate actions. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

X-ray diffraction (XRD) has become one of the most powerful techniques for crystal structure studies and phase composition identifications. In this thesis, using the quantitative XRD (QXRD) technique to assist the development of reliable engineering strategies of stabilizing hazardous lead pollutants into ceramic matrix and resource recovery will be introduced. Metal stabilization strategies have been sought to replace the traditional disposal methods for the management of waste metal sludge. To demonstrate the unique capability of QXRD in monitoring the lead incorporation behavior, different ceramic precursors was used to react with lead oxide to investigating metal transformation mechanisms during the sintering process. When heating with alumina, influences of Pb/Al molar ratio, temperature, and treatment time on lead incorporation efficiency on the formation of PbAl2O4and PbAl12O19phasesweresuccessfully revealed by QXRD. Moreover, the influence of silica on lead stabilization effect was analyzed by blending amorphous SiO2 and quartz with -Al2O3 as the precursors. The results suggest that both silica precursors could crystallochemically incorporate lead into the lead feldspar (PbAl2Si2O8) structure in significant quantities. In addition, by sintering clay-based precursors with lead oxide, a complete lead incorporation into lead feldspar occurred above 950℃. Lead glass-ceramics were produced by thermally treating waterworks sludge with lead oxide, and amorphous contents in the products were quantified using QXRD. When hematite was used as a Fe-rich precursor to treat lead oxide, three types of lead ferrite crystals were observed and quantitatively determined. Furthermore, the mechanism of incorporating lead-zinc tailing with P-rich municipal waste sludge ash was investigated under different thermal conditions. By detailed X-ray diffraction analysis, Pb was crystallochemically incorporated into the Ca5.5Pb4.5(PO4)6(OH)2 crystalline structure and Zn was stabilized into Zn(Al0.5Fe1.5)O4 spinel phase. The stability of lead in all the product phases was evaluated byprolonged acid leaching, and the results indicated the lower intrinsic lead leachability of the product phases. The progress in optimizing experimental parameters in resource recovery suggest an opportunity of using QXRD technique to investigate the feasibility of extracting Pb from CRT and recycling P by struvite precipitation. A novel process of thermal reduction treatment with the addition of metallic iron (Fe(0)) to recover lead from cathode ray tube (CRT) funnel glass was introduced. The optimal operational parameters for the thermal extraction of lead from CRT glass were determined by QXRD technique as 50 wt.% Fe addition, heating at 700 °C for 30 min. Struvite crystallization for phosphorus recovery from wastewaters has gained strong attention. While the aspects of application and modeling have been widely studied, the phase composition of recovered phosphorus products was rarely reported. The obtained high degree of accuracy supports the validity of Rietveld method for the quantification of both amorphous and crystal phases in the products. QXRD results suggest the amount of increase of struvite in the products with the elevated N/P molar ratio from 0.2/1 to 1.2/1. All the results have demonstrated the capability of QXRD in contributing to the advancements of both material and environmental technologies. / published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

Atmospheric carbon dioxide (CO2) has increased due to human activity from a pre-industrial value of about 280 ppm to the present level of 399 ppm. The ocean acts as an important natural carbon sink that effectively removes 1/3 of this anthropogenic CO2 from the atmosphere, buffering global warming effects. However, the dissolution of CO2 causes a dramatic change in seawater chemistry and ultimately results in the phenomenon commonly known as "ocean acidification" (OA). As a consequence, the pH value and the saturation states for calcium carbonate decline in the surface seawater, posing a threat to calcareous marine organisms that build their shells using exquisite biomineralization mechanisms. Biological minerals produced by marine organisms are compositionally and structurally more complex than geological minerals. Although changes in biomineral formation in response to OA has been intensively investigated, the features of calcified products in terms of their composition, architectures and mechanical properties have been overlooked in climate change research. The tubeworm is a favourite marine model organism in larval biology. Its life cycle is well understood hence provides a good opportunity to study OA impacts on the stochastic early life. In addition, the model enables comprehensive observation of the sophisticated biomineralization events. In this thesis, four studies on the biomineralization of Hydroides elegans, using a multidisciplinary collaborative approach combining larval biology and material science were conducted. (1) The tube mineral composition at different juvenile stages (4, 11, 18, 25 days) were characterized. (2) The impacts of different predicted OA scenarios (pH 8.1, 7.9, 7.6, and 7.4) on the resultant calcification products were compared. (3) A multiple-stressor investigation of OA (pH 8.1 and 7.8), reduced salinity (33 ‰ and 27 ‰) and increased temperature (25 °C and 29 °C) was conducted to further determine the more environmentally realistic OA impacts. (4) Calcification sites were examined by using a microscopy approach The main findings from each study were: (1) H. elegans produced both calcite and aragonite forms of CaCO3, which have distinctive physical and chemical properties. Thus, the tubeworm serves as an interesting model for studying OA impacts on biomineralization. The early juvenile stages are expected to be more sensitive to OA than the later life stages because the juvenile tubes are rich in aragonite and amorphous calcium carbonate. (2) Under experimental OA conditions, the composition and architecture of the tube structures were adversely affected, ultimately producing tubes with weaker mechanical properties. (3) Warming appeared to strengthen the tube structures and mitigated the adverse OA effects. (4) Calcification sites correlated to regions with higher pH values of 8.5 - 9.0. These regions may be sensitive to OA and should be further analyzed to study the mechanisms of OA impacts on calcification. This series of experiments study biomineralization and larval biology using a variety of modern multidisciplinary approaches provided new insights into the impacts of OA and climate change impacts on marine organisms and also helped us to project which species might adapt or succumb to future scenarios. / published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

Zero valent iron (ZVI) has demonstrated its reactivity and effectiveness for in-situ groundwater and soil remediation. The potential of the high reducing activity of nanoscale ZVI (nZVI) for environmental decontamination has attracted more attentions in recent years, as nZVI may be injected with water to the pollution sites for in-situ remediation. However, rapid oxidation and instant agglomeration of nZVI make it difficult for large-scale engineering application. Effort has been made to improve the stability and mobility of nZVI for effective in-situ remediation. In the present study, a novel Ca-based surface coating method has been developed for protection of nZVI and enhancement of its transport in environmental applications. A simple thermal deposition method was employed to coat a Ca-based layer on the surface of micro- or nano- ZVI particles in water or methanol environment. According to microscopic observations, Ca(OH)2 nano-layer was formed on the ZVI surface. A clear core-shell structure was observed for the coated nZVI/Ca(OH)2 particles based on the TEM observations. The Ca(OH)2 coating layer had a thickness about one fifth of the nZVI diameter and the Ca to Fe ratio was below 0.2. With the Ca(OH)2 shell, nZVI particles can be effectively protected against corrosion according to the standard natural spray corrosion tests. Thus, the Ca(OH)2 coating layer is able to greatly improve the stability of nZVI during storage, transportation and application. In addition, based on the result of the dissolution tests, the Ca(OH)2 shell could be readily dissolved in water with a low Ca content or a low ionic strength. After dissolution of the Ca(OH)2 shell, the reactivity of nZVI was found to be at the similar level as bare nZVI, which could remove Cr(VI) from water by more than 90% in about 20 min. The pseudo-first order rate constants for Cr(VI) reduction by bare nZVI and nZVI/ Ca(OH)2 after shell dissolution were 0.064 and 0.072 min-1, respectively. Moreover, the Ca(OH)2 coating shell would not only function as a protection layer but also improve the mobility of nZVI particles in in-situ applications. The aggregation and sedimentation of nZVI/Ca(OH)2 particles became considerably slower compared to bare nZVI without the coating. Clean-bed water filtration tests were conducted with sand and glass columns to evaluate the mobility and transport of nZVI in porous media. The results show that bare nZVI in the particle suspension deposited mostly at the top of the filters with little penetration. In comparison, the nZVI/Ca(OH)2 particles were able to penetrate through the filter media during the filtration process, and the dark iron particles could fill up the entire filter columns. The penetration rate increased from nearly 0 m/hr for bare nZVI to 0.43 m/hr for nZVI/Ca(OH)2 through the filter media. The Ca-based coating materials are known as of low cost and environmentally friendly. Thus, the new coating method developed in this study provides a cost-effective means for both the protection of nZVI and improvement of its transport and delivery in porous media for environmental decontamination. / published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

To implement green supply chain, a company has to consider sustainability impacts in assessing potential suppliers. Thereby, the supplier evaluation and selection criteria would include various key performance indicators such as price, quality, delivery, as well as environmental and corporate social responsibility aspects. Researchers have proposed numerous multi-criteria decision making (MCDM) approaches for evaluating the multiple conflicting criteria in supplier selection. However, most of the existing approaches have ignored some important issues in business environment such as supplier qualification, supplier autonomy, negotiation between manufacturer and supplier, etc. In this thesis, a multi-agent system (MAS) is proposed for supplier selection in green supply chain. It comprises two types of autonomous agents, namely, buyer agent and seller agents, to represent the interests of manufacturer and suppliers, respectively. The proposed MAS presents three prominent features. First, the proposed supplier selection criteria incorporate the conventional, environmental and social aspects in the supplier selection process. The criteria are classified into negotiable and non-negotiable criteria. Initially, all criteria are included to evaluate and rank all the candidate suppliers. Subsequently, the top-ranked candidates are invited to participate in the bargaining process. In this regard, the negotiable criteria are used for assessing the quality of an offer, while the non-negotiable criteria, i.e. environmental and social criteria, influence the manufacturer’s negotiation attitude to candidate suppliers. The classification enables the manufacturer to fully utilize the performance values of all criteria. Secondly, supplier selection is implemented in a two-stage methodology. The TOPSIS method is devised in the first stage to shortlist some suitable candidate suppliers for entering negotiation in the next stage. In the second stage, the agent-based negotiation process is adopted for selecting the final supplier. Representing the manufacturer and the shortlisted suppliers respectively, the buyer and seller agents bargain on a number of negotiable issues in the multi-round negotiation. A multi-issue and multilateral agent interaction protocol, which is an extension of the contract net protocol, is implemented in the MAS. Accordingly, the buyer agent coordinates with the seller agents to exchange offers and counteroffers. Thirdly, a novel preference-based negotiation strategy is used to govern the behavior of agents during negotiation. A heuristics model with the Particle Swarm Optimization (PSO) algorithm and Adaptive Penalty Function has been designed and implemented to realize the proposed negotiation strategy. The strategy guides the autonomous agents to narrow down the discrepancies in the values of the negotiable criteria (price, delivery days, contract length) in their offers, and simultaneously search a mutually beneficial and acceptable agreement. The negotiation payoffs and negotiation time are improved. Experimental results indicate that the proposed agent-based model could help the manufacturer to identify the most appropriate supplier and improve the quality of final agreement. In addition, the model successfully integrates supplier qualification and automated negotiation, and promotes supplier autonomy in the supplier selection process. / published_or_final_version / Industrial and Manufacturing Systems Engineering / Master / Master of Philosophy