The increase in global carbon dioxide emission has raised concerns about climate change. This has caused nations to consider different carbon dioxide mitigation pathways to reduce emissions. The iron and steel industry contributes to approximately 30% of total global CO2 direct emission in the industrial sector. It is an energy intense industry. Many steel mills are operating close to thermodynamic limits in efficiency. Therefore decarbonising the steel industry through process improvements is limited. Breakthrough technologies such as carbon capture and storage (CCS) is an alternative and attractive solution. In this research I have explored the application of a retrofit carbon capture technology to an existing steel mill. The steel mill chosen, combusts gases arising from the steel making processes. Different locations within the steel mill were analysed, the in-house power station and the turbo blower house were chosen for retrofit post-combustion carbon capture. Two different separation technologies were process modelled to capture the carbon dioxide from the flue gas of the in-house power station and the turbo blower house. The technologies were chemical absorption and adsorption. The two technologies were techno-economically studied. Chemical absorption, with solvent MEA, showed capability of recovering 86% of CO2 with a purity of more than 99 mol%. Adsorption using sorbent zeolite 13X was able to achieve 82% recovery with purity of 96 mol%. Sorbent activated carbon showed a capability of recovering 67% of carbon dioxide with a purity of 95 mol%. The cost of CO2 avoidance for the process using chemical absorption (MEA) was equal to $44.92/tonne CO2. For the process using adsorption (zeolite 13X) the CO2 avoided cost was equal to $44.90/tonne of CO2. Activated carbon was the most expensive capture process, out of the three processes studied. It costs $45.81/tonne of CO2 avoidance.

Bioclogging can be defined as the reduction of hydraulic conductivity and porosity of a saturated porous medium due to microbial growth. Wastewater disposals, artificial groundwater recharge, in-situ bioremediation of contaminated aquifers, construction of water reservoirs, or secondary oil recovery are all affected by this process. The potential for soil and groundwater contamination may increase by the rapid movement of the solutes through soil due to the presence of preferential flow which resulted in increasing bypassing of soil matrix and increasing pore water velocities. On the other hand the presence of preferential flow could affect the clean-up process of the contaminated land by extending the remedial time. The reason behind that is the relatively quick contaminant clean-up in the high permeable zones compared to the slow contaminant clean-up in the low permeable layers. Therefore, this study aims to investigate the bioclogging process in porous media and the factors that can affect this process, also to understand how all aspects of flow are affected by the clogging process, and finally to investigate the potential of biological growth to control direction and location of subsurface hydraulic flow to overcome the problems of preferential flow. The bioclogging process was investigated through a series of sand column experiments in homogeneous and heterogeneous porous media. Six sand fractions ranging from 63-1180 μm were selected as a porous media. Two bacterial strains (P. putida mt-2 and B. indica) were used in this study. Different analytical methods such as loss on ignition and the total number of cells were used to analyse the soil samples. iv The outcomes of this study showed that the growth of bacteria in porous media can reduce the heterogeneity of the porous media, thereby reducing the impact of the preferential flow which could affect the clean-up process of the contaminated land. Pore throat model with the incorporation of different bioclogging models such as the biofilm or plugs (Vandevivere et al., 1995), micro-colony (Okubo and Matsumoto, 1979), and macroscopic (Clement et al., 1996) models were applied to evaluate the results of the experimental work in heterogeneous porous media. The changes in hydraulic conductivity and the porosity of porous media were modelled by assuming that the bioclogging occurs in the small pores which connect the large pores of the porous media. Generally amongst the three bioclogging models, the current study showed that the measured values of the hydraulic conductivity relatively coincide with the predicted values obtained by using Vandevivere et al. (1995) model. Nevertheless, the predicted values of the hydraulic conductivity coincided to some extent with the measured values of the hydraulic conductivity for the large sand fractions. This corresponds with the findings of several previous studies which also confirmed that bioclogging models can only predict the change of the hydraulic conductivity for the large sand fractions. The failure of these models could be related to the assumptions made by each model, which could be less appropriate in fine-textured materials than they are in coarse textured ones. The second possible reason for the disparities between observations and model predictions is related to the assumption made in some of these models that the microorganisms which are responsible for clogging form biofilms of constant thickness which uniformly coated the surface of soil particles.

The following EngD thesis presents research on the potential for short term deployment of carbon dioxide utilisation technologies within the context of the European steel industry, in collaboration with Tata Steel Europe. The aim of the project was to identify options for short term utilisation of CO2 directly from steelmaking process exhausts and then evaluate them in terms of their technical feasibility, CO2 reduction potential and economic sustainability. An initial review of steel production processes and CDU routes resulted in the selection of two potentially promising processes for further investigation; production of precipitated calcium carbonate (PCC) from steelmaking wastes, and combined biomass production and steelmaking wastewater remediation using microalgae. Each technology was investigated experimentally to determine its technical feasibility, and then via a techno-economic evaluation in order to estimate the scale of potential CO2 mitigation and economic viability. Although both technologies were deemed to be technically feasible, when techno-economic evaluations were performed it became clear that neither technology is likely to be able to achieve significant CO2 emissions reductions (reduction is limited to less than 1% of typical integrated site emissions). Despite this, economic estimates for a scaled up PCC production process were promising; a moderate payback on capital expenditure of around 5.51 years was estimated under baseline conditions, with a significant additional revenue potential if the process were credited under the European Union Emissions Trading Scheme. In contrast, the microalgae based process was found to be highly uneconomical when using technology which is currently available at a commercial scale, and the CO2 mitigation potential was determined to be limited by the indirect CO2 emissions from very high electricity demands as the process is scaled up.

Amine functionalised silica adsorbents are promising materials for post combustion carbon capture. They exhibit high CO2 equilibrium adsorption capacities and selectively adsorb CO2 in the presence of water. A practical method of regenerating these materials in fossil fuel power stations is to utilise steam regeneration. There is a lack of understanding of the long term stability of amine functionalised silica in the presence of steam. This thesis explored the deactivation mechanism of impregnated and covalently tethered amine adsorbents under steam regeneration and humid adsorption conditions. The adsorbents were characterised using organic analysis and nitrogen sorption before and after aging. The effect of steam regeneration aging led to a significant decrease in the CO2 adsorption uptakes of the adsorbents. Impregnated amine adsorbents were deactivated by leaching of the impregnated amine component from the largest pores of the support. Steam aging also led to diminished amine accessibility caused by amine polymer agglomerating within pores below 8 nm. To address this issue of instability in the presence of steam amine impregnated silica adsorbents were post functionalised with organosilanes. Under certain conditions this silane functionalisation was shown to selectivity occur at the exterior and pore mouths of the adsorbent. The presence of silane coatings preserved the CO2 adsorption capacities of the adsorbents after aging. A compromise exists between adsorbent stability and CO2 uptake behaviour as silane functionalisation led to a reduction in the CO2 uptake capacity. Post functionalisation of amine impregnated silica with hydrophobic silanes limits the intrusion of water within the pores of the adsorbent. This reduction in water intrusion limits the rate of solubilisation of the amine polymer, thus preventing leaching. The impregnation of amine polymers onto porous silica supports typically leads to agglomerations and significant pore blocking. This limits the rate of adsorption and uptake capacity of the adsorbents. The introduction of aminesurfactant mixtures into the adsorbent was found to increase accessibility of the adsorption sites leading to enhanced rates of adsorption and CO2 equilibrium uptakes. The addition of surfactants also yielded a reduction in the regeneration requirements of the adsorbents, by the formation of favourable thin films of amine within the pores of the adsorbent.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1906 (first author), and Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Civil and Sanitary Engineering, 1906 (second author). / by Norman P. Gerhard and Charles F. Breitzke. / B.S.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [212]-293).

Today the water industry faces a huge challenge in supplying a sustainable, energy efficient and safe supply of drinking water to an increasing world population. Slow sand filters (SSFs) have been used for hundreds of years to provide a safe and reliable source of potable drinking water, with minimal energy requirements. However, a lack of knowledge pertaining to the treatment mechanisms, particularly the biological processes, underpinning SSF operation, has meant SSFs are still operated as “black boxes”. This lack of knowledge pertaining to the underlying ecology and ecophysiology limits the design and optimisation of SSFs. This thesis represents the most comprehensive microbial community survey of full-scale SSFs to-date. Using traditional microbiological methods alongside up-to-date molecular techniques and extensive water quality analyses, specific taxa and community metrics are linked to changes in water quality production. Furthermore, it has been verified that laboratory scale SSFs can mimic the microbial community and water quality production of full-scale filters. This allowed rigorous experiments pertaining to operational differences, pathogen and novel contaminant removal to be performed. This has revealed, for the first time, that multiple trophic interactions within SSFs are integral to optimal performance. This thesis has shown that SSFs are phylogenetically and metabolically diverse systems capable of producing high quality water, with the ability to adapt to remove novel contaminants. Using the information gathered, improvements to filter maintenance and operation can be achieved. Future work will apply the microbial and macrobial community dynamics and impact of novel contaminants on filter performance discovered in this thesis into predictive models for water quality.

With a rising demand for nanomaterials and their continual increase in production, the release of nanoparticles (NPs) into the environment is inevitable (Petosa et al., 2010). Problematically, NPs can have a wide range of toxic effects, which are exacerbated by their size (at least one dimension smaller than 100 nm)(Engineering., 2004). Detrimental effects include brain, intestinal and respiratory injury, delayed embryonic development, DNA damage which ultimately lead to increased mortality (Trouiller et al., 2009), (Handy et al., 2008). Natural and manufactured NPs also have the ability to bind and transport chemical pollutants, thus enhancing their toxicity (Moore, 2006). While an array of techniques are available for in situ remediation of numerous groundwater contaminants, there are currently none for in situ remediation of nanoparticles. This fundamental technology gap means we are poorly prepared to deal with nanoparticle pollution events. The aim of this PhD was to develop mechanisms to immobilise and remove nanoparticles from water and waste water in order to prevent the transport of nanoparticles to sites where they have the potential to cause harm. Experiments conducted demonstrate the potential of microbially mediated mineral formation to immobilise nanoparticles from water. The ureolytic bacteria Sporosarcina pasteurii was used to induce calcium carbonate precipitation in batch and column experiments. Nanoparticle immobilisation was tested as a function of nanoparticle size and surface charge. The results demonstrate the successful immobilisation of negatively charged nanoparticles (both large and small, 150 and 35 nm respectively), while failing to remove positively charged nanoparticles from solution. In order to capture positively charged nanoparticles a second mineral, struvite, was tested. The precipitation of struvite successfully immobilised positively charged nanoparticles. However, in comparison to the calcite precipitation experiments the removal of positively charged nanoparticles was found to be pH and ionic strength dependant. Finally, the ability of Bacillus subtilis, a common groundwater bacterium and wastewater treatment biofilm to adsorb and remove nanoparticles from solution was examined. Here both biosorbent materials were highly efficient at removing positively charged nanoparticles from solution whilst negatively charged nanoparticles remained in suspension. The research presented here demonstrates that microbially induced mineral precipitation may be used as a tool to immobilise nanoparticles from contaminated groundwater. In addition, bacteria and wastewater treatment biofilm were found to be highly efficient biosorbents of positively charged nanoparticles. These findings hold implications for the fate and transport of nanoparticles through environmental systems and wastewater treatment plants.

A new Spatial Decision Support System (SDSS) has been designed and developed to address a wide spectrum of semi-structured spatial decision problems. These problems are related to site selection, site ranking and impact assessment. The proposed SDSS is conceptualised as a holistic, informed and impact-based multicriteria decision framework. The system has been developed using the .NET C# programming language and open source geoinformatics technologies such as DotSpatial and SpatiaLite. A combination of existing Multi Criteria Decision Analysis (MCDA) and Artificial Intelligence (AI) techniques, with a few novel variations have been developed and incorporated into the SDSS. The site selection module utilises a theme-based Analytical Hierarchy Process (AHP) and Weighted Linear Combination (WLC). Two site ranking techniques have been introduced in this research. The first technique is based on the systematic neighbourhood comparison of sites with respect to key indicators. The second technique utilises multivariate ordering capability of the one-dimensional Self-Organizing Maps (SOM) to rank the sites. The site impact assessment module utilises a theme-based Rapid Impact Assessment Matrix (RIAM). A spatial variant of the General Regression Neural Networks (GRNN) with a genetic algorithm for optimisation has been developed for the prediction and regression analysis. A number of other spatial knowledge discovery and geovisual-analytics tools have been provided in the system to facilitate spatial decision making process. An application of the SDSS has been presented to investigate the potential of Coalbed Methane (CBM) development in Wales, UK. Most potential sites have been identified by utilising the site selection and site ranking tools of the developed SDSS. An impact assessment has been carried out on the best sites by using Rapid Impact Assessment Matrix. Further analysis has uncovered the spatial variability expected in the potential impacts of the sites, considering key indicators. The application has demonstrated that the developed system can help the decision makers in providing a balanced regime of social, environmental, public health and economic aspects into the decision making process for engineering interventions. The generic nature of the developed system has extended the concept of Spatial Decision Support System to address a range of spatial decision problems, thereby enhancing the effectiveness of the decision making process. The developed system can be considered as a useful modern governance tool, incorporating the key factors into decision making and providing optimal solutions for the critical questions related to energy security and economic future of the region.

The local climate of Malaysia with high air temperature and relative humidity and inconsistent air movement throughout the day provides challenges for architects and designers to design a building including a mosque that can provide better indoor thermal condition. Thermally uncomfortable indoor environment in a typical Malaysian mosque can be sensed due to the poor attendance of believers during communal prayers conducted five times a day at the mosque. A study was carried out in four typical mosques in Malaysia to investigate the thermal comfort level together with what and how the thermal comfort factors affecting the condition. They study also looks at the influence of roof design of the mosque in affecting thermal condition inside the prayer hall since the roof design is a significant feature of the building not only as a filter to the outdoor climate but also as the identity of the building and the society. From the investigation, it has been revealed that air temperature is the primary factor in affecting thermal comfort. When the air temperature is at neutral or comfort temperature, the presence of other factors can be ignored. However, when the primary factor is no longer at its neutral condition, the secondary factors which are air movement and humidity will play their roles in influencing thermal comfort in naturally ventilated mosques in Malaysia. In many cases, air movement is always desirable and able to improve the thermal comfort level. Therefore, the need for the availability of air movement should be particularly considered in designing a mosque to ensure that the mosque is thermally comfortable. The research has also discovered that the pitched and doomed roofs have different abilities to control the distribution of air, for examples, the pitch roof mosque has the ability to circulate the air inside the prayer hall to achieve the equilibrium state whereas the domed roof mosque has the ability to stratify the air according to the temperature where the coolest air located at the lowest level of the space. With the pitch roof, a mosque is able to create air movement inside the space whereas the dome roof mosque will provide stagnant but cooler air at the active level due to the stratification process. Due to these findings, the pitched roof mosque is considered a better option for this climate for its ability to provide natural air circulation inside the space which is desirable by the users. With the understanding on the ability of the roof designs namely, domed and pitched roof in controlling air movement of the interior and the interdependencies of the main factors affecting thermal comfort, strategies for improvement on the design of the mosque can be made to achieve better indoor thermal condition of the prayer hall.