In Tunisia, the National Agency for the Environment is encouraging the creation of a carbon footprint method specifically adapted to the Tunisian context. In cooperation with the French National Agency for the Environment, the adaptation of the French carbon footprint method is realised and has to go along with an adaptation of the emission factors. In this framework, this master thesis aims at presenting the emission factors adaptation process led to adapt the accounting tool. First, a literature review enables to present the main notions useful to understand the precise definition of emission factor. Then, a preliminary study of the main carbon footprint tools is presented so as to identify the main characteristics of a carbon footprint method. A comparison is then done to present the differences which can occur between the previous methods. Finally, for each category of emission factor, the adaptation process is presented showing three different ways to adapt emission factors: a replacing of the data in the calculations, an adaptation based on local studies and a more difficult adaptation requiring to develop a new method.

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Sustainability is increasingly becoming a significant part of strategic asset management worldwide. Road agencies are providing guidelines to assess the relative sustainability of road projects. Unfortunately, environmental features of a road project are still considered as stand-alone evaluations, an added value. Very little has been done to integrate environmental impacts as a part of pavement management systems and other decision support tools to choose between different strategies. In this way, being awarded with a "green" certificate for a specific road project could result in the belief that recognition would correspond to the optimal strategy. Furthermore, a road project awarded with a "green" rating during the construction phase does not mean that the project results "green" if a life cycle approach is considered. Indeed, the most environmental friendly strategies may not be the ones with the highest performance. Using "greener" materials or performing recycle-related practices may lead to a lower performance over the life cycle and therefore produce an increase in maintenance needed, which could in turn result into more congestion due to work zones and higher total emissions. Therefore, construction and maintenance strategies should be analyzed according to three main parameters: cost, performance or effectiveness, and environmental impacts. The cost analysis part takes into account outflows over the service life of the pavement according to the well-known Life Cycle Cost Analysis methodology. The cheapest maintenance technique over the analysis period was expounded and sensitivity analyses to involved factors were conducted. Performance assessment was developed according to experimental on site data gathered and analyzed over several years to develop deterioration pavement models. Effectiveness of maintenance treatments is further provided and compared to the volume of traffic. In addition, environmental impacts related to maintenance and rehabilitation strategies were analyzed. Emissions were computed over the life cycle of the pavement from the manufacture of raw materials for the initial construction, placement, and maintenance phase. Finally, an optimization procedure was developed for including environmental impacts into a Pavement Management System. A methodology to set a multi-attribute approach system, computing costs, performance, and eco-efficiency over the life cycle of the pavement, is therefore proposed. / Ph. D.

Nearly half of Britain’s carbon dioxide emissions result from the activity of households, both within the home and from personal transport. This research examines how the carbon dioxide emissions of households can be reduced, particularly through the calculation of carbon footprints and testing the public’s reaction to the concept of personal carbon allowances (PCAs). Two data collection stages were used - a postal survey providing quantitative data, followed by semi-structured interviews producing mainly qualitative data. The research was carried out in a largely rural district which is run by a council noted for its work on sustainable energy, Newark and Sherwood. The survey looked at PCAs as well as a variety of contemporary issues that might influence household footprints such as energy efficiency grants and information, as well as relationships with gas and electricity suppliers. Each interview involved the calculation of a household carbon footprint, the identification of measures to reduce it, and the gathering of attitudes about personal carbon allowances, in order to identify challenges and opportunities with respect to reducing household carbon emissions. Support for PCAs was higher than anticipated, and tended to be associated with those who were prepared to use public transport or cycle more, or were supportive of renewable energy in homes. Interviewees had much to say about individual carbon reducing measures. Opposition was associated with those who envisaged that they would be unlikely to sell carbon units. Regarding personal transport, long commutes were common, and the cost of public transport was of concern. Specific findings were made about domestic heating, insulation, lighting, refrigeration, water use, commuting, public transport, and rail as an alternative to short-haul flights. There was more interest in monetary savings than carbon savings. Recommendations about policy and regarding further research are made.

Highway clients are increasingly concerned with the environmental consequences and sustainability implications of their highway maintenance service. This is because the service consumes a significant amount of natural resources, is financial and energy-intensive and is a large Greenhouse gas (GHG) emitter responsible for global warming and climate change. This has placed the highway maintenance sector, including its supply chain under increasing pressure to deliver well-maintained low-carbon maintenance service, whilst addressing its climate change impacts. The highway stakeholders increasing focus on carbon footprinting is a direct response to the legal obligation presented by the enactment of the UK s Climate Change Act (2008) and the Carbon Reduction Commitments. Investment decisions on highway infrastructure must now account for carbon and financial costs in a balanced manner. Highway clients now require their supply chains to demonstrate the capacity to reduce both direct and indirect carbon, and provide carbon footprint information relating to the work done or being tendered for. This is driving the sector to re-think its business operations within environmental, economic and social limits, which inherently presents risks and opportunities poorly understood by the stakeholders. It requires an in-depth understanding of the business operations, inputs and outputs. These business requirements are compounded given the lack of an agreed industrial methodology standard focusing on carbon footprinting, the knowledge and skill gaps, system boundary definitions, credible industrial data and their collection approach. The aim of this study is to develop a project-focused and process-based carbon footprinting methodology that includes a decision-support and carbon management tool to assist carbon management decision-making in highway maintenance planning and operation. This study then explored how the PAS2050 protocol can enhance the highway maintenance service delivery carbon footprinting and identify opportunities for reduction. It briefly reviews carbon emissions performance and the UK s highway maintenance sector, and developed a methodological framework that includes a carbon evaluation tool (the sponsor s business focus tool) based on the PAS2050 protocol. The framework developed is specific to highway maintenance planning and operation. It offers a carbon Life Cycle Assessment (LCA) tool that can identify emission hotspots across the process value chain, and inform a carbon reduction hierarchy. The implementation of the PAS2050-compliant methodology framework and the carbon evaluation tool for core highway maintenance processes (for example, pavement resurfacing, pavement marking, bulk lamp replacement and grass cutting), in addition to carbon footprinting across different site locations (urban, semi-urban and rural) are presented. The results indicate that materials production and their delivery to site (embodied carbon) are areas of carbon hotspots. This represents an important decision point for highway designers, managers and maintainers in order to deliver low-carbon service. These carbon hotspots suggest a less energy-intensive or green materials manufacturing process, responsible sourcing, use of recycled and secondary materials sourced locally (closer to sites) and delivered in bulk. The step-by-step carbon footprinting approach presented in this study is unique. It can be used by other sectors within the built environment as a pragmatic means of identifying and prioritising areas of potential carbon reduction through informed decision-making.

Pathogenesis of enterotoxigenic Escherichia coli (ETEC) and Shigella flexneri relies predominantly on members of the AraC/XylS family of transcriptional regulators, Rns (or its homolog, CfaD) and MxiE, respectively. Rns/CfaD regulate the expression of pili, which allow the bacteria to attach to the intestinal epithelium. Better understanding of the role Rns plays in virulence was attained by expanding our knowledge of the Rns regulon, revealing that it functions as an activator of cexE, a previously uncharacterized gene. By in vitro DNase I footprinting two Rns-binding sites were identified upstream of cexEp, both of which are required for full activation of cexE. The amino terminus of CexE also contains a secretory signal peptide that is removed during translocation to the periplasm. Though the function of CexE remains unknown, these studies suggest that CexE is a novel ETEC virulence factor since it is regulated by Rns/CfaD. In Shigella flexneri, the expression of a subset of virulence genes (including, ipaH9.8 and ospE2) is dependent upon the activator MxiE and a cytoplasmic chaperone IpgC. To define the molecular mechanism of transcriptional activation by this chaperone-activator pair, an in vitro pull down assay was performed revealing that MxiE specifically interacts with IpgC in a complex. Additionally, IpgC recognizes three polypeptide regions in MxiE: within MxiE(1-46), MxiE(46-110) and MxiE(196-216). Furthermore, it seems that MxiE and IpgC regulate transcription of ipaH9.8 and ospE2 promoters differently. In the bacterium, the formation of the MxiE-IpgC complex is initially prevented because IpgC is sequestered in individual complexes with effector proteins, IpaB and IpaC. Upon contact with an eukaryotic host cell the effector proteins are secreted, thereby freeing IpgC to form a complex with MxiE and activate the expression of virulence genes. This new characterization of the role of Rns and MxiE in virulence gene regulation in ETEC and S. flexneri, respectively will give new insights into the pathogenesis of the regulators.

The genome sequencing projects have generated a wealth of genomic data and the analysis of this data has provided many interesting findings. However, genome wide analysis of bacteria for promoters has lagged behind, because it has been difficult to accurately predict the promoters with so much background noise that are found in bacterial genomes. One approach to overcome this problem is to predict phylogenetically conserved promoters across multiple genomes of different bacteria, thus filtering out many of the false positives, which are predicted by the current methods. However, there are no programmes capable of doing this. Therefore, the work presented in this thesis has developed a position weight matrix (PWM) based programme called Multiscan that predicts conserved promoters across multiple bacterial genomes. Since Chlamydia is one of the most sequenced bacterial genera and has a high level of conservation of genes and large-scale conservation of gene order between species, Multiscan was developed and tested on Chlamydia. When Multiscan analysed a genome wide dataset of equivalent non-coding regions (NCRs) upstream of genes, from Chlamydia trachomatis, Chlamydia pneumoniae and Chlamydia caviae for σ66 promoters that are phylogenetically conserved, Multiscan predicted 42 promoters. Since only one of the 42 promoters predicted by Multiscan had previously available biological data to confirm its prediction, an additional subset of 10 of the remaining 41 σ66 promoters were analysed in C. trachomatis by mapping the 5' end of the transcripts. The primer extension assay synthesised cDNA products of the correct length for seven of the 10 genes chosen. When the performance of Multiscan was compared to one of the accepted method for genome wide prediction of promoters in bacteria, the &quotstandard PWM method", Multiscan predicted 32 more promoters than the &quotstandard PWM method" in Chlamydia. Furthermore, the promoters predicted by Multiscan were up to three more mismatches from the Escherichia coli σ70 consensus sequence than the promoters predicted by the standard PWM method. Although Multiscan predicted 42 promoters that were well conserved across the three chlamydial species, the analysis was unable to identify the 14 known σ66 promoters in C. trachomatis. These promoters were missed (1) because they were dissimilar to the E. coli σ70 consensus sequence and/or (2) because the promoters were poorly conserved across the three chlamydial species. To address the second possibility, the 14 false negatives were analysed by another phylogenetic footprinting method. Fourteen sets of equivalent NCRs located upstream of the homologous genes from the three chlamydiae were aligned with the computer programme Clustal W and the alignment analysed &quotby eye" for evidence of phylogenetic footprints containing the 14 false negatives. The analysis identified that seven of the 14 false negatives were poorly conserved across the chlamydial species. Analysis of two of the seven promoters that could not be footprinted, the promoters of ltuA and ltuB, by mapping the transcriptional start sites in C. caviae, confirmed their poor conservation across C. trachomatis and C. caviae. This analysis showed that substantial differences exist in chlamydial σ66 promoters from equivalent NCRs upstream of genes. This study has developed a new computer programme for genome wide prediction of promoters that are phylogenetically conserved and has shown the value of this programme by identifying seven new well conserved promoters and seven candidate poorly conserved promoters in Chlamydia.

Activated sludge treatment systems rely on a microbial consortium structurally organized in bioflocs to treat pollutants present in wastewater. The treatment process efficiency in these systems can be severely affected by toxic chemicals present in the influent wastewater. The effects of chemical toxins at the treatment process level are determined by the mechanisms that occur at the biofloc and cellular levels, which can be physical, chemical and physiological in nature. We believe that the overall process effects of chemical toxins on activated sludge systems likely result from a combination of all three types of mechanisms and that they are interdependent, in the sense that specific bacterial stress response mechanisms (physiological mechanisms that protect the cell from toxic conditions) may lead to physical/chemical alterations at the floc level, and vice-versa. Ultimately, understanding the mechanisms that occur at the floc and metabolic scales will help to design more robust and efficient treatment systems, and to develop tools to prevent and mitigate the effects of toxic chemicals on activated sludge systems. In this research, we set out to establish the link between the effects of chemical toxins on activated sludge cultures at the process, floc and metabolic scales. First, the effects of shock loads of different toxic sources (1-chloro-2,4-dinitrobenzene (CDNB), cadmium, 1-octanol, 2,4-dinitrophenol (DNP), weakly complexed cyanide, pH 5, 9 and 11, and high ammonia levels) on activated sludge process parameters (biomass growth, respiration rate, flocculation, chemical oxygen demand (COD) removal, dewaterability and settleability) were studied. For all chemical shocks except ammonia and pH, concentrations that caused 15, 25 and 50% respiration inhibition were used to provide a single pulse chemical shock to sequencing batch reactor (SBR) systems containing a nitrifying (10 day solids retention time – SRT) and a non-nitrifying (2 day SRT) biomass. We found that cadmium and pH 11 shocks were the conditions that most detrimentally affected all the processes, followed by CDNB. DNP and cyanide primarily led to effects on respiration, while pH 5, 9, octanol and various ammonia concentrations did not impact the treatment process to a significant extent. Additionally, there was a clear correlation between biomass deflocculation and increases in the effluent soluble COD of the shocked reactors for different chemical sources. With this study, we were able to establish a source-effect matrix linking classes of chemical toxins to their potential inhibitory effects on activated sludge processes, thereby contributing to a better understanding of the potential effects of toxic industrial discharges into biological treatment systems. The findings of the first phase of the research, specifically the correlation between chemical-induced deflocculation and increases in soluble COD, served as a motivation to explore the role of floc structure in the response of activated sludge cultures to toxic compounds, and to conduct a more in-depth analysis of the supernatant (soluble phase) of toxin-exposed activated sludge. In one study, we evaluated the respiration inhibition induced by octanol, cadmium, N-ethylmaleimide (NEM), cyanide and DNP on activated sludge biomasses with different floc structures but similar physiological characteristics, with the objective of assessing the role of the extracellular polymeric substances (EPS) in flocs as a protection barrier against chemical toxins. Mechanical shearing was applied to fresh mixed liquor to produce biomasses with different floc structure properties and specific oxygen uptake rate assays were conducted on the sheared and unsheared mixed liquors. The results showed that the respiration inhibition by octanol and cadmium was more intense in sheared mixed liquor (which had less EPS material available in the flocs and smaller floc sizes) than in the unsheared biomass. Conversely, the respiration inhibition induced by NEM and cyanide was similar for the different mixed liquors tested. These results allowed us to conclude that the EPS matrix functions as a protective barrier for the bacteria inside activated sludge flocs to chemicals that it has the potential to interact with, such as hydrophobic (octanol) and positively-charged (cadmium) compounds, but that the toxicity response for soluble, hydrophilic toxins (NEM and cyanide) is not significantly influenced by the presence of the polymer matrix. In the final study that was conducted, we used the metabolomics-based technique metabolic footprinting to assess if the soluble phase of mixed liquor exposed to different chemical toxins exhibited a toxin-specific biochemical composition. We hypothesized that toxin-specific effects could be distinguished through footprint patterns of those soluble samples. The impact of cadmium, DNP and NEM shock loads on the composition of the soluble fraction of activated sludge mixed liquor was analyzed by liquid chromatography-mass spectrometry (LC-MS). The results from this study indicated that there was a significant release of biomolecules (proteins, carbohydrates and humic acids) from the floc structure into the bulk liquid due to chemical stress. More importantly, using a multivariate statistical method called discriminant function analysis with genetic algorithm variable selection (GA-DFA), we were able to show that the soluble phase samples from the different reactors could be differentiated, thereby indicating that the footprints generated by LC-MS were different for the four conditions tested and, therefore, toxin-specific. These footprints, thus, contain information about specific biomolecular differences between the samples, and we found that only a limited number of m/z (mass to charge) ratios from the mass spectra data was needed to differentiate between the control and each chemical toxin-derived samples. In addition, since the experiments were conducted with mixed liquor from four distinct wastewater treatment plants, the discriminating m/z ratios may potentially be used as universal stress biomarkers. These results are promising and indicate that LC-MS may be used for the discovery of activated sludge stress biomarkers, to allow the development of new toxin detection technologies for prevention of upset events in activated sludge systems. / Ph. D.