To see the other types of publications on this topic, follow the link: ]+[628.4.
Dissertations / Theses on the topic ']+[628.4'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic ']+[628.4.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Winfield, Jonathan. "Scale-up of microbial fuel cells for wastewater treatment." Thesis, University of the West of England, Bristol, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.572852.
Full textAbstract:
For decades microbial fuel cells (MFCs) have offered the potential to treat wastewater while concomitantly producing power, but to date scale-up has not been achieved. The goal for this thesis was initially to explore the capabilities of MFCs in the laboratory and then to test the technology in the wastewater treatment environment. The aim was to operate the demonstrator in an existing process, without altering infrastructure or adding extra energy (Le. pumping). Laboratory work yielded novel findings helping to achieve the thesis objective while also contributing to MFC knowledge. Investigations into the anodic development period revealed that inoculating while in continuous-flow primed MFCs for operation in conditions of high flow-rate. The phenomenon 'power overshoot' was described and its occurrence explained in terms of the internal resistance of the MFC. A new miniature tubular MFC was designed and up to seven units were connected in fluidic series (cascade) to mimic the trickling filter process. These efficiently removed up to 90% COD, to levels that comply with European guidelines. The influence that fluidic connection had on MFCs in terms of flow-rate and external resistance was described for the first time. To mimic hostile flocculating conditions, MFCs were fed feedstock with varying ferric chloride concentrations. Power production, COD treatment, metal reduction and increased pH were all achieved suggesting the technology could supplement and improve existing processes. Utilising experience gained in the laboratory and following visits to Wessex Water, the trickling filter was selected as test location for the demonstrator. Using a variation on the novel tubular design, under field conditions at the Saltford treatment plant, MFCs demonstrated the ability to produce power while reducing COD to levels acceptable for release into the environment. These results strongly support the hypothesis that MFCs are becoming ready to be incorporated into the wastewater treatment process.
2
Brown, N. W. "Adsorption of organics in wastewater on nyex and electrochemical regeneration : development of a process." Thesis, University of Manchester, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556317.
Full textAbstract:
The removal of low concentrations of aqueous phase organics using adsorptive techniques has traditionally used high capacity adsorbent materials, for example activated carbons. The drawback of these materials is that regeneration can be costly and complex. An alternative approach reported in this thesis involves the use of a highly conductive material, a graphite intercalation compound (GIC), as an adsorbent. This material, which has been shown to be non-porous with a low surface area, is capable of electrochemical regeneration. This electrochemical regeneration is achieved by the oxidation of the organics in the anodic compartment of a simple, divided cell. In comparison with activated carbons, it has been demonstrated that adsorption is quick, with up to 88% of equilibrium loading being achieved within 2 minutes. 100% electrochemical regeneration can be achieved in a simple divided electrochemical cell with 10 minutes treatment, by passing a charge of 25 C g-1. The efficiency of electrochemical regeneration depends on a range of variables including charge passed, current density, treatment time, electrolyte concentration and composition and the adsorbent bed thickness. Multiple adsorption and regeneration cycles indicate that there is little loss of adsorptive capacity on regeneration. Whilst a number of modes of operation are potentially possible, the m4jority of the work reported in this thesis is based on separate adsorption and electrochemical regeneration. However, some work on a process involving continuous adsorption coupled with continuous and simultaneous electrochemical regeneration is presented. A third design involving continuous adsorption and regeneration within separate zones IN a single unit is given as an area for further research.
3
Tang, S. L. "An optimization model - preliminary selection of appropriate technology in wastewater treatment alternatives." Thesis, Loughborough University, 1989. https://dspace.lboro.ac.uk/2134/10484.
Full textAbstract:
This research is concerned with the use of techniques of system analysis/operations research in the selection of the optimal - or most appropriate - wastewater treatment techniques in any given situation. An extensive investigation of existing treatment system optimization models, applying techniques of linear programming, dynamic programming and non-linear mathematical programming, has been carried out. None of these existing models deals with the socio-cultural and environmental conditions but merely with the economy of treatment. In this work the more subjective or intangible factors are included in the proposed optimization model in which twenty parameters are identified. These parameters are considered to be most important in the selection of appropriate alternatives for treating municipal wastewater. They include technical, economic, environmental and socio-cultural factors. The model was developed to rank a definite number (n) of wastewater treatment alternatives (decision variables) by the evaluation of the twenty parameters [ ... continues].
4
Hewings, Guy. "Design and management of composting systems." Thesis, Cardiff University, 2007. http://orca.cf.ac.uk/55167/.
Full textAbstract:
Composting is an effective method of removing a large proportion of biodegradable waste from landfill. The CO2 produced by microbial activity demonstrates the rate of decomposition, and was measured in green waste composting in windrows, a forced aerated bay, an aerated test rig and related to the volatile solid content. The peak respiration rates were 35gC02kgVS",day"1 in windrows, and 290gCO2kgVS"1day"1 in the test rig. Knowing the rate of microbial activity, allows the volume of air required to supply sufficient oxygen to a composting matrix to be determined. Recently introduced treatment regulations require 100% of the waste in a composting system to be maintained above 60 or 70 C for minimum periods. Aeration management methods were evaluated that maximise the rate of temperature increase and distribute the heat generated by microbial activity. Managing re-circulated gases between set CO2 limits was demonstrated to an effective method of encouraging rapid temperature increase. Whilst the lowest recirculation rate of 40m3hr l per m3 of compost was required to ensure 100% of the compost matrix in the test rig was greater than 60 C. The research presented in this thesis demonstrates methods that will aid the design and management of any composting system, especially those treating catering waste.
5
Owen, Nia Elin. "Effects of increased kerbside provision and materials recovery facility development on recycling rates in a rural community." Thesis, Cardiff University, 2009. http://orca.cf.ac.uk/54763/.
Full textAbstract:
Traditionally, the UK has relied heavily on landfill as a means of dealing with its MSW, However, the UK waste management industry is undergoing a significant period of change as a result of legislative drivers implemented on an European level. The key driver is the Landfill Directive, which has set targets for the reduction of the quantity of biodegradable waste sent to landfill. This Directive has been implemented in Wales by the Landfill Allowance Scheme (LAS), which essentially sets each local authority an annual tonnage of Biodegradable Municipal Waste (BMW) which it can landfill. Failure to comply with the annual target can result in significant financial penalties which are set at £200 per tonne landfilled over the target. This driver coupled with the ever increasing landfill tax, which is set to increase by £8 per annum, is making alternatives to landfill become more economically viable. As well as these statutory drivers, there are also non-statutory drivers. In Wales, the Welsh Assembly Government (WAG) issued the non-statutory requirement for local authorities to achieve 40% recycling and composting by 2009/10, with a minimum of 15% recycling and 15% composting. It has also been announced that post 2010, the targets are likely to increase rapidly, culminating in a 70% recycling and composting target by 2024/25. This thesis uses a case study authority to investigate whether a Materials Recovery Facility (MRF) coupled with changes to its kerbside provision could assist the region to meet its LAS and WAG targets. Key aspects of the thesis include: a compositional analysis of household waste within the case study authority, to ascertain the quantities of material available for diversion via a dry recyclate and organics collection scheme a review of a variety of different MRFs within the UK and overseas to determine best practice operations the development of a MRF conceptual design based on the information obtained from compositional analysis and the process reviews conducted on other MRFs the efficiency testing of the MRF commissioned within the case study authority to determine its performance and areas which could be improved and, the modelling of various scenarios to determine what changes could be made to waste management practices so as to maximise the quantity of material diverted from landfill, and assist the authority to meet its LAS and WAG targets. The compositional analysis study identified that the average household waste generation within the Case Study Authority was 14.9 kg/hhAvk, which was lower than the Welsh average figure of 17 kg/hh/wk. Participating households typically segregated 4.7 kg/hhAvk and 3.0 kg/hh/wk of dry recyclate and organic material respectively. It was also interesting to note that the compositional analysis established that the average BMW content within the Case Study Authority was 72%, which was significantly higher than the 61% used to define MSW for the LAS purposes. An efficiency study carried out on the first phase of the MRF implementation highlighted that when processing a residual waste (black bag) stream 11.2% was recovered in the form of dry recyclate, and 27.7% in the form of a mechanically segregated fine organic stream (less than 50mm fraction). When processing a dry recyclate stream, the efficiency study identified that 95% of the material was recovered for recycling however, two-thirds of this was in the form of a low grade paper product, which was sensitive to market changes. The thesis highlights that a MRF has a significant role to play in an integrated solution for municipal waste management however, it is clear that ultimately some form of thermal process will be required for the residual waste stream in order for local authorities to comply with the LAS targets.
6
Notton, David. "Theoretical and experimental determination of key operating parameters for composting systems." Thesis, Cardiff University, 2005. http://orca.cf.ac.uk/54547/.
Full textAbstract:
The combination of increasing quantities of Municipal Solid Waste (MSW) and increased legislation for the disposal of this type of waste have created a need to develop different disposal or treatment routes for waste. Approximately 60% of MSW by mass is biodegradable and many disposal routes for this waste allow energy recovery. However the waste hierarchy presented in the National Waste Strategy for Wales emphasises the importance of materials recovery over energy recovery. It has been shown that the only way to achieve these targets is through the recovery of catering waste, which requires an in-vessel composting facility. In order to gain an insight into the aeration requirements for in-vessel composting, calculations were performed to ascertain the required airflow for the supply of oxygen, the removal of excess moisture and the removal of excess heat. It was found that approximately 450kJ are released for each mole of oxygen utilised whilst 500kJ are released per mole of carbon dioxide evolved. It was found that the air requirement for removal of heat from the process was approximately 100 times greater than the air required to supply oxygen to the system. In order to determine the power of aeration equipment required for composting facilities a static pressure test rig was constructed. From the results gained a model relating the static pressure to the bulk density of compost was developed. Initially a windrow composting system processing green waste at the Carmarthenshire Environmental Resources Trust (CERT) composting facility was studied. A canopy system was developed to monitor the respiration rate of this system and allow comparison between different feedstocks and control strategies. For a green waste only windrow the highest recorded respiration rate was 38gC02kgVS"1day"1. The respiration rate was observed to reduce with temperature above 55 °C. In addition to the green waste windrows a temperature managed windrow and a windrow constructed from a mixture of green waste and chicken litter were also tested. The final series of trials involved the testing of the ability of a containerised composting system to meet the Animal By-Products Regulations. The vessel was fed various mixtures of green waste and factory waste. Airflow and insulation within the vessel were analysed and a composting rate of over 45gC02kgVS'1day1 was achieved. If this had been sustained then the vessel may have met the Animal By-Products Regulations.
7
Woollam, Tom. "Increasing the diversion of household waste through kerbside recycling systems." Thesis, Cardiff University, 2006. http://orca.cf.ac.uk/56072/.
Full textAbstract:
Kerbside recycling schemes in the UK are voluntary. In 2003/4, 61% of households in Wales had some form of kerbside recycling scheme collecting at least one material. Householders are encouraged in a variety of ways to segregate targeted recyclables from their general waste and to put this at the kerbside in any number of separate receptacles. There are many ways of increasing the diversion of household waste into kerbside recycling systems. A plethora of incentives, penalties and communications can be offered and many awareness raising schemes can be employed. This thesis uses a case study authority to trial, then subsequently examine the effectiveness of specific methods to increase the diversion of household waste into kerbside recycling systems. A public waste awareness campaign and a schools waste education programme are implemented within the authority a range of incentives were used, some using voluntary approaches and others financial carrots. Key aspects of the work include a legislative overview of household waste in Wales, a quantitative examination of the scale of the household waste problem and a study of attitudes towards waste, actual recycling behaviour and the effectiveness of a waste awareness campaign and a schools waste education programme. It is thought local authorities which implement kerbside recycling and composting schemes, and still have significant tonnage to divert to meet their 2010 diversion targets, will not meet them by implementing voluntary/carrots and financial/carrots incentives alone. Ultimately, alternative waste treatment technologies that do not require households to participate in segregation or a significant change in kerbside recycling behaviour (thought only possible through financial/stick incentives or alternate weekly collections) will be needed for local authorities to meet the 2010 Wales Waste Strategy targets and reach the required BMW diversion set in the Landfill Allowance Scheme. Waste awareness campaigns and schools education campaigns have a role to play, but, should not be solely relied on to meet short term diversion targets.
8
Cowie, Claire. "The use of rhizogenic 'Agrobacterium' strains to improve phytoremediation of inorganic and organic pollutants." Thesis, University of Newcastle Upon Tyne, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436167.
Full text
9
Adelopo, Abdulganiyu Omobolaji. "Conversion of landfill composite to activated carbon as an approach to sustainable landfill management." Thesis, De Montfort University, 2017. http://hdl.handle.net/2086/14532.
Full textAbstract:
Landfilling of municipal solid waste is a major waste disposal method, especially in developing countries despite its pressing environmental challenges. Reuse of the landfill composite has been suggested as a sustainable management option that could limit its negative effect. This research evaluated the compositional trend and characteristics of landfill composites with depth in order to assess its suitability as a precursor for activated carbon. A bulk system classification was used during analysis of the composite parameters (‘more degraded’ and ‘less degraded’ components). Both landfills had similar waste constituents, but varied in relation to moisture, TOC, and heavy metals contents. The elemental and chemical constituents of an active and a closed landfill were compared using Fourier transform - infrared (FTIR) spectroscopy, scanning electron microscope/energy-dispersive X-ray (SEM/EDX) spectroscopy, and proximate analysis. The two landfills had similar major elemental constituents representing 96.5 % and 98.4 % of elemental composition for the closed (O > C > Si> Fe > Ca >Al) and active(C > O > Si > Al > Ca > Fe) landfill samples respectively. A single step chemical activation process of precursor was applied involving irradiation with microwave energy and KOH as the activation agent. The average percentage yield of activated carbon (AC) from active landfill precursor was higher than that from closed landfill for all three depths of sampling (upper, 23.8 and 19.3 %; mid, 52.4 and 34.7 %; lower 35.7 and 27.0 %). Methylene blue adsorption capacity and BET surface analysis indicated adsorption capacity and surface area of AC from degraded precursor increased with depth. All AC conformed to a multilayer adsorption model and a pseudo second order kinetic. Carbonyl and hydroxyl groups were the major functional group on the surface of activated carbon. The AC properties indicated that precursors from both landfills are potentially suitable for generation of adsorbent suitable for removal of cationic dyes and pollutants.
10
Mohammed, Alya. "Development of an engineered wetland system for sustainable landfill leachate treatment." Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/105531/.
Full textAbstract:
Sustainable and effective treatment of landfill leachate has become one of the most important environmental problems due to the fluctuating composition and quantity, as well as its high concentrations of pollutants. High-tech solutions applied for the leachate treatment are expensive and energy consuming, and in addition they are not suitable at many landfill sites, especially those in rural areas. Hence there is need to develop novel and sustainable low-energy systems for the effective treatment of landfill leachates. Constructed wetlands (CWs) are inexpensive simple to operate and they have the potential to remove not only organic carbon and nitrogen compounds, but heavy metals. This study focussed on the design, development and experimental investigation of a novel CWs for the treatment of landfill leachate. The CWs employed dewatered ferric waterworks sludge (DFWS) as the main substrate. The overall aim of the study was to design and assess the novel configuration of the CWs, whilst also contributing to advancing the understanding of pollutant removal from the landfill leachate in the CWs, through the development of models to explain the internal processes and predict performance. The key design and operational variables investigated were: the primary media used, i.e. the DFWS, and the wetting and drying regimes. The CWs was configured as 4-stages in series which was operated for 220 days. Thereafter, an additional unit was added due to clogging and the CWs was operated for 185 days in this second period. Results and experimental observations indicate that the chemical treatment processes (adsorption and precipitation) contributed to the clogging. The DFWS used served as adsorbent for heavy metals removal in the system. Results of heavy metals, organic matter (COD), ammonia and total nitrogen removal indicate average removals of 99%, 62%, 83% and 81%, respectively in first period; and 100%, 86%, 90% and 82% in second period, with an average heavy metals loading rate 0.76 g m-2 day-1, organic loading rate 1070 g m-2 day-1, ammonia loading rate of 178 g m-2 day-1 and total nitrogen loading rate 192 g m-2 day-1. Results were supported through mathematical analysis using STELLA model for heavy metals transformation in CWs and numerical modelling using HYDRUS CW2D, which enhanced understanding of the internal processes for organic matter and nitrogen 4 removal. The result from STELLA modelling showed that up to 90% of the removal of heavy metals was through adsorption, which is highly significant. While HYDRUS CW2D results showed that the main path of nitrogen removal was through simultaneous nitrification and denitrification. Overall, results have shown that CWs design has great potential for reduction of metals and nutrients in landfill leachate. Results of this study can contribute to future CW research and design for landfill leachate treatment, through the increased understanding of long-term pollutant removal in these systems. In time, this may result in the wider application of CWs for landfill leachate treatment to better protect the environment.
11
Rutter, P. J. "The application of clean technology to waste management : innovative technologies and engineering in waste management." Thesis, University of Surrey, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395347.
Full text
12
Hu, Windy Chiung Wen. "Anaerobic digestion of liquid wastewaters from food industry using continuously stirred tank reactors." Thesis, University of Birmingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531076.
Full textAbstract:
This thesis describes an investigation on the application of anaerobic contact process treating a variety of wastewaters from food industries (raw molasses, purge wastes, ice-cream and diary wastewaters). The raw molasses is one of the wastes produced from the sugar industries, which contains high concentrations of organic matters and high concentrations of sulphate and was firstly investigated in this work. A series of batch experiments were carried out to establish a suitable feedstock for pilot scale digesters. A 1% mass molasses medium with a COD: N: P ratio of 200: 5: 1 in a buffer system has been shown to give a successful digestion of molasses with a methane yield of 0.36 l/g CODrem and a COD removal of 89 % from the batch experiment 3. Two pilot scale digesters (14.13 1) were fed with the molasses medium that was established from the batch experiment 3 as suitable for this work. Several organic loading rates were investigated. After feeding with the molasses medium for about 30 days, both pilot digesters have reached steady-state conditions with respect to a COD removal in excess of 90 % and methane yield in excess of 0.321/g CODrem. The process kinetics of anaerobic contact reactor for treating four different wastewaters was investigated. The Monod equation and the Contois equation were used to develop two basic steady-state models. The kinetic parameters required for the application of the steady-state models were determined by using the results obtained from four individual experiments for treating four different wastewaters. Both models were evaluated with four experimental results obtained in this work and a set of routine analysis data obtained from a full scale anaerobic contact reactor treating the ice-cream wastewater for Birds Eye Walls Ltd., (Gloucester). It is found that the Contois model would be more suitable than the Monod model for express the process kinetics of the anaerobic contact process in full scale due to the reason that the Contois model considers the effect of variable influent substrate concentration into the prediction. In addition, the Contois model was found to be better than the Monod model to express the process kinetic when treating the wastewater containing the organic matters, which has a slow rate of hydrolysis (i. e. lipids/proteins).
13
Sia, Hung-Ing (Anna). "Landfill lining engineering designs : a probabilistic approach." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/35657.
Full textAbstract:
Uncertainty and variability are prevalent in any engineering design. In this study, the uncertainty of input parameters for the stability of a landfill veneer cover soil and the integrity of a lining system were treated probabilistically using Monte Carlo simulation. Statistical information required to postulate the distribution types of input parameters, taken as random variables, were identified and characterised using available data from literature survey and a designed laboratory repeatability testing programme. The variability and uncertainty of interface shear strengths (τ) and the derived strength parameters for three generic interfaces, commonly found in a landfill lining system, were computed and compared using these types of information. The variability of τ computed using the combined global database were three-to-five times and could reach up to seven times higher for the derived strength parameters when compared to laboratory repeatability test results. Additionally, a normal distribution was recommended for interface shear strengths and derived parameters (except interface adhesion with high COV) for good quality data based on subjective and objective statistical test methods.
14
Acomb, Jonathan Christopher. "Simultaneous production of carbon nanotubes and hydrogen gas from the thermal treatment of waste plastics." Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/11534/.
Full textAbstract:
In this work a two-stage reaction system was used for the simultaneous production of carbon nanotubes (CNTs) and hydrogen gas from plastic feedstocks. Initial pyrolysis was undertaken in the first stage heated at 600 C, before the evolved gases were passed to a second stage where a catalyst was held. Carbon deposition builds up on the surface of the catalyst, whilst hydrogen and other gases are then collected downstream. A series of analytical techniques were used to characterise the carbon deposition on the catalysts, as well as any oils or gases produced. Initially, a two stage pyrolysis-gasification process was undertaken with plastics from waste electrical and electronic equipment for investigation into hydrogen production. The introduction of a nickel catalyst led to increased hydrogen production, with small amounts of CNTs observed in the carbon deposits on the catalyst surface. In order to increase the yield of CNTs, different plastics including polyethylene, polypropylene and polystyrene were investigated. The rate of steam injection into the two stage pyrolysis-gasification process was also investigated, and proved significant to obtaining high yields of CNTs and hydrogen. All of the plastics produced CNTs, with the largest yield obtained from the pyrolysis gasification of polystyrene at a steam injection rate of 0.25 g h -1 . Additionally, the use of different catalysts was investigated, with iron, nickel, cobalt and copper catalysts all tested. CNTs were produced on the iron, nickel and cobalt catalysts, with the iron catalyst producing the largest yield. The calcination temperature and metal loading on the nickel catalyst was also studied, with catalyst support interactions of intermediate strength and a higher metal loading producing larger CNT yields. Finally, investigations into the temperature of the second stage where the catalyst was held were undertaken, along with using different ratios of catalyst: plastic sample. These too proved important in achieving large yields of both CNTs and hydrogen.
15
Almustapha, Muhammad Nurudeen. "Modification of a sulphated zirconia catalyst using calcium carbide for conversion of plastic waste into non-aromatic liquid hydrocarbons." Thesis, Heriot-Watt University, 2016. http://hdl.handle.net/10399/3112.
Full textAbstract:
Plastic consumption has increased 8% annually since the 1950 reaching an estimated 300 million tonnes in 2014, where more than 50% was discarded after single-use. Many recycling methods have been proposed to manage this growing waste, but most have practical, environmental and economic limitations. Catalytic conversion, a chemical recycling method using a suitable catalyst, has been suggested as a viable option since it can return plastic to a chemical feedstock, which is the aim of this work. Four potential catalysts, namely sulphated zirconia SZ, calcium carbide CC, molybdenum carbide MC and zirconium oxide ZO were tested for HDPE conversion, which was selected from five different polymer samples due to its high thermal resistance. It was found that only calcined SZ and calcined CC showed some impact HDPE conversion. However, SZ was marked with high coke yield while calcined CC had low conversion with virtually no coke. Therefore a hybrid catalyst was considered, where the SZ and the CC were mixed together on equal weight bases forming the hybrid catalyst SZ1CC1. Fixed bed pyrolysis showed an excellent HDPE conversion of virtually 100wt% using the hybrid catalyst at 410oC with 66.0wt% liquid yield against a 98.0wt% conversion with only 39.0% liquid yield for the pure SZ and no conversion in the case of HDPE only. The hydrocarbon composition of the liquid fraction obtained changed significantly from 58% aromatic and 16% paraffinic for the SZ to 74% olefinic and 23% naphthenic for the SZ1CC1. The improvement in liquid yield and selectivity to non-aromatic liquid was strongly linked to a modification in the acidic strength of the hybrid catalyst SZ1CC1. The moderation in acidity and textural properties, such as surface area and porosity were found to suppress excessive cracking and limiting secondary cracking reactions, that promotes high gas yield and aromatisation in the SZ. Overall, it is concluded that the SZ on its own, which had high acidic strength and large surface area, promoted secondary reactions during HDPE cracking that yielded aromatics. However, the hybrid catalyst SZ1CC1, which had moderate acid strength and low surface area halted any secondary reaction and terminated the cracking reaction at stages that produced only olefinic and naphthenic hydrocarbons.
16
Miller, Lorraine Anthea. "Investigating stakeholder priorities and preferences for the restoration of containment landfill sites through the application of an ecosystem services approach." Thesis, University of Nottingham, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.727948.
Full textAbstract:
In recent years the concept of ecosystem services has been becoming increasingly important within environmental policy and decision making. A range of ecosystem services can be provided through the restoration of containment landfills but research to date has tended to focus on constraints rather than what can be provided by them. This study investigates the ecosystem service priorities of stakeholders for grassland and woodland as conventional landfill restoration land uses, and willow SRC as a new restoration land use. The overall priorities of stakeholders, and priorities with regard to trade-offs between ecosystem services are considered. This study also investigates the land use preferences of stakeholders for the delivery of ecosystem service priorities. It identifies conflicts and synergies between stakeholders and how these can be used to enhance sustainable land use planning and management in the context of the restoration of containment landfill sites. Data was collected through a combination of questionnaires and interviews. The study identifies major conflicts between stakeholders over the provision of recreation on sites, and over access being provided to landfill gas infrastructure. The study also identifies that local authority planning requirements, health and safety and the need for access to landfill gas infrastructure, are all potential barriers to the delivery of ecosystem service priorities. In order to maximize the ecosystem services prioritized by stakeholders, several suggestions are made. It is argued that there is: a need for changes in local authority planning requirements; a need for landfill gas managers to be included in decision making, and as statutory consultees in the planning of the restoration of sites, and a need for research into improving the design of landfill gas infrastructure, to enhance its suitability for use on sites that are to be opened to the public. The study also shows how an ecosystem service-based approach can be useful for identifying interests and conflicts and synergies between stakeholders in the context of the restoration of containment landfill sites.
17
Pickering, Rheanne Lisle. "How hard is the biomass working? : can cell specific uptake rates be used to optimise the performance of bacterial biomass in wastewater treatment plants?" Thesis, University of Newcastle upon Tyne, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548009.
Full text
18
Peter, Gwom. "Planning for municipal solid waste management : the case of Greater Jos, Nigeria." Thesis, Heriot-Watt University, 2016. http://hdl.handle.net/10399/3156.
Full textAbstract:
Among the greatest challenges of the twenty-first century is the rapid growth of cities. The growth of most municipalities has remained unplanned and uncontrolled. Unmanageable development in developing countries has given rise to environmental disorders in the built-up settlements. Municipal solid waste management in particular, is now a fear-provoking assignment for the municipal establishments who are lacking in capacity to confront the municipal solid waste issue. The main objective of carrying out this research is to see how urban planning can help improve municipal solid waste issues in Greater Jos municipal area. It defines the municipal solid waste problem and identifies a number of specific planning drivers as the factors responsible for lack of improvement in the municipal solid waste management situation. A mixed method approach was used for the empirical analysis which combined both interviews and questionnaire data from senior government officials, industry stakeholders and residential neighbourhoods, collected with observational and documentary data, in order to investigate the solid waste issue. Major problems identified in this research are: (i) municipalities are undergoing deterioration of solid waste conditions but the local, state and federal governments are lacking adequate planning to deal with the circumstances (ii) apart from quite a lot of causes of the municipal solid wastes crisis can be known, the political commitment to urban planning is lacking which serves as the basis of the deteriorating situation in Nigerian municipalities and (iii) relationship exists between poor planning and municipal solid waste management delivery of collection services and disposal amenities. Individual municipal solid waste management strategy alone was found to produce unplanned and uncoordinated management of waste issues. Collaboration to produce a joint municipal solid waste management plan has been recommended as a good practice.
19
Song, He. "Anaerobic digestion of source-segregated domestic food waste." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/402998/.
Full textAbstract:
Anaerobic digestion (AD) is an attractive waste treatment process in which both pollution control and energy recovery can be achieved. Source-segregated domestic food waste (FW) has a high organic content on a dry weight basis and is rich in lipids and proteins, indicating the potential for a good biogas yield with high methane content. Process instability, however, has often been reported in food waste digesters, which was mainly manifested by the accumulation of volatile fatty acids (VFA) and reduction of specific methane production. Trace element (TE) supplementation has been proved to be an effective way to rectify this problem and has been applied to industrial AD plants. This practice, however, was usually characterised by a trial-and-error approach due to the lack of a clear understanding of the impact of TEs on AD under different process conditions. The aim of this study was therefore to optimise TE dosing strategies for FW digestion at different loading rates, with particular attention to the role of cobalt (Co) and selenium (Se). The limiting concentrations of Co and Se were studied in long-term continuously stirred tank reactor (CSTR)-type digester experiments at organic loading rates (OLR) from 1.8 to 5 kg volatile solids (VS) m-3 d-1. In a digester operated at OLR 1.8 kg VS m-3 d-1 without TE addition, dosing of Co at a strength of 1 mg Co kg-1 fresh matter was effective to stimulate the complete degradation of accumulated VFA. Around 2500 mg L-1 VFA built up, however, after OLR increased to 2.5 kg VS m-3 d-1; then dropped slightly by addition of Se at a strength of 0.05 mg Se kg-1 fresh matter. After stepwise increases in Se concentration to 0.2 mg kg-1, VFA reduced to less than 1000 mg L-1. In another 2 digesters, at OLR 3 and 4 kg VS m-3 d-1 respectively, TE washing-out was introduced for determination of the limiting Co concentration. All TE supplementation was ceased in these 2 digesters for around 300 days with the exception of continuous addition of 0.2 mg kg-1 of Se. VFA accumulation up to 30000 mg L-1 occurred in one digester immediately after the OLR increased from 4 to 5 kg VS m-3 d-1 and later up to 22500 mg L-1 in the other digester when OLR increased from 3 to 4 kg VS m-3 d-1. By gradually increasing Co concentration in both digesters to 0.3~0.5 mg kg-1, VFA started to be consumed. At the end of test, the recovered digester with OLR 5 kg VS m-3 d-1 was running stably with 0.2 mg kg-1 Se and 0.3~0.5 mg kg-1 Co addition, with a pH of 7.8, IA/PA ratio 0.4, specific methane production (SMP) 0.47 standard temperature and pressure (STP) m3 CH4 kg-1 VS d-1, volumetric methane production (VMP) 2.37 STP m3 CH4 m-3 d-1, and VFA concentration less than 500 mg L-1. To further understand the effect of trace elements on VFA production, short-term trials were carried out to assess their function in VFA production. The results indicated that with accumulated VFA, supplementation of trace elements stimulated VFA production to a greater extent than VFA consumption. Effect of organic loading rate on TE dosing strategy and digester performance was studied in 5 digesters, all of which had stable operation but different trace element addition histories. One pair digesters was run as control at OLR 5 kg VS m-3 d-1 over the course of the experiment, another pair operated with a gradual loading increase to 6, 7, 8 and 9 kg VS m-3 d-1. A SMP of 0.46±0.02 STP m3 CH4 kg-1 VS d-1 at OLR 8 kg VS m-3 d-1 was achieved. Volatile solids destruction (VSD) rates were similar between OLR 5 and 8 kg VS m-3 d-1, at approximately 0.74~0.75, but reduced to 0.71~0.72 at OLR 9 kg VS m-3 d-1. Residual methane production (RBP) test results showed that biogas production of digestate from OLR 5 and 7 kg VS m-3 d-1 were similar, whereas digestate from OLR 9 kg VS m-3 d-1 generated more biogas than OLR 5 kg VS m-3 d-1, indicating lower conversion efficiency was achieved at OLR 9 kg VS m-3 d-1. Nitrogen mass balance equations were developed to distinguish nitrogen distribution in digesters. These showed that microbial biomass density increased along with OLR increase, which in turn requires an increase in TE addition. The specific rate of biomass increase at OLR 9 kg VS m-3 d-1, however, was lower than at 8 kg VS m-3 d-1, reflecting the decrease in specific methane production and VSD rate. The results indicate that FW digester was able to operate at OLR 8 kg VS m-3 d-1, without loss of performance when compared with OLR 5 kg VS m-3 d-1. Loading 9 kg VS m-3 d-1 was regarded as overloaded due to the lower hydrolysis and acidification efficiency. The fifth digester, in which the same TE dosing was applied, was operated with random loading: a daily load between 2.5~7.5 kg VS m-3 d-1 was randomly introduced while weekly average OLR was maintained at 5 kg VS m-3 d-1. Stable performance was observed in this digester with 2.27 STP m3 CH4 m-3 d-1 of 30-day rolling average VMP and 76% of VSD rate, and VFA concentrations less than 500 mg L-1. Further research on essential TE supplementation for stable FW digestion at high loading was carried out. All TE additions were ceased except 0.3 mg kg-1 of Co and 0.2 mg kg-1 of Se, in two pairs of digesters at loading 5 and 8 kg VS m-3 d-1, respectively. VFA accumulation occurred in digesters at the higher loading, which finally failed. VFA fluctuated around 4000 mg L-1 in digesters at OLR 5 kg VS m-3 d-1, until the rest of trace elements in a full 11 trace elements recipe were reintroduced, when VFA degraded quickly to below 1000 mg L-1. The research provided new insight on optimising essential TE supplementation to FW digestion, especially at moderate and high loading rates, to ensure stable and high productive biogas production.
20
Dalton, Clare. "Influences of landfill leachate dissolved organic carbon on the attenuation of toluene and naphthalene by Oxford Clay." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/393695/.
Full textAbstract:
The uncontrolled release of landfill leachate poses a significant threat to the environment and is prevented in part by the landfill liner. The attenuation of contaminants by the liner material may be crucial in limiting environmental damage should the containment of the landfill fail. While the sorption of hydrophobic organic contaminants (HOCs) to clay materials is well documented in the literature in terms of the organic carbon content of the sorbent in a variety of solution phases, a knowledge gap exists in respect to the influence of landfill leachate dissolved organic carbon (DOC) on the attenuation of HOCs. A laboratory based batch sorption study was undertaken, using leachates with five differing DOC characters and origins, at various dilutions, to establish the influence that DOC present in landfill leachates had on the attenuation of the HOCs toluene and naphthalene by Oxford Clay. The aim of this work was to increase the understanding of attenuation of toluene and naphthalene to Oxford Clay in the presence of leachate DOC and to elucidate the role of DOC chemical composition and concentration in landfill leachates on the sorption of HOCs to the Oxford Clay. The objective of this work was to provide more reliable data for predicting the contribution of attenuation of HOCs by sorption in the risk assessment of landfills and recommending updates to the selection process of Kd values for landfill risk assessment models such as LandSim. The chemical character of the DOC was found to affect how the DOC interacted with the solid phase and humic substance-like (HSL) DOC was observed to preferentially sorb to the Oxford Clay. The sorption of DOC was reversible, indicating that DOC, and so DOC-HOC complexes, had the potential to desorb from the clay. The addition of DOC to the aqueous phase resulted in deviation from the sorption and desorption isotherms in a DOC free leachate in the case of both toluene and naphthalene. While DOC effects on toluene sorption and desorption behaviour were not clear cut, with both increases and decreases in sorption and desorption observed with the addition of DOC; a uniform decrease in sorption and an increase in desorption relative to the DOC free leachate was observed for naphthalene sorption and desorption behaviour. No desorption was observed for toluene in three of the leachates. In all other DOC containing leachates sorption was reversible and exhibited hysteresis. The alteration in sorption and desorption behaviour of HOCs due to DOC could not be explained solely by the maturity or the concentration of DOC in solution, and was attributed to a complex interaction of both factors. Increasing the hydrophobicity of the HOC resulted in increased sorption (naphthalene > toluene). Recommendations were made for the selection of a Kd value to model HOC attenuation on the basis of a ‘worst case’ scenario. Implications for the post closure monitoring and containment of the landfill and the relevance of commercially available humic acid as a leachate DOC surrogate are also presented.
21
Turner, David. "Evaluating the life cycle climate impacts of solid waste management." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/398127/.
Full textAbstract:
This thesis comprises three papers that address the evaluation of potential climate impacts of solid waste management (SWM) systems and processes from a life cycle perspective for purpose of decision-support. Paper I presents a critical review of the carbon footprint quantification and communication practice of large UK-based waste management companies. Results indicated a lack of methodological consistency and transparency in current practice, emphasising the need for a robust, transparent, and standardised approach to corporate carbon footprint quantification and reporting. Paper I also describes the importance of greenhouse gas (GHG) emission factors (EF) in helping stakeholders better understand and address the potential climate impacts of their SWM activities. However, existing EFs were reviewed in Paper II and were found to lack transparency and breadth. Consequently, Paper II presents an original and fully transparent series of GHG EFs for the recycling of a wide range of source-segregated materials . Results showed that materials recycling generally leads to (often substantial) climate benefits, due to avoided primary material production. However, results also highlighted the dearth of available high quality materials recycling life cycle inventory data, which are essential to support effective SWM decision-making. Paper III presents a novel, practical framework for evaluating the potential climate impacts of complex SWM systems through the innovative use of publically-available waste flow data and a combined material flow analysis (MFA) and LCA approach. The performance of a complete, meso-level SWM system was evaluated and the potential effectiveness of real world waste policies was analysed. Results showed that landfilling was the greatest source of potential impacts for the existing system, whilst the increased diversion of food waste from landfill lead to the greatest reduction in potential impacts. Overall, this thesis presents an original, practical analytical framework and valuable information to support decision makers at multiple levels in evaluating the potential life cycle climate impacts of their SWM activities.
22
Fernando, Eustace. "Treatment of azo dyes in industrial wastewater using microbial fuel cells." Thesis, University of Westminster, 2014. https://westminsterresearch.westminster.ac.uk/item/8yq85/treatment-of-azo-dyes-in-industrial-wastewater-using-microbial-fuel-cells.
Full textAbstract:
Due to the extensive use of xenobiotic azo dyes in the colour industry and their proven mutagenic and cytotoxic nature, their treatment prior to discharge is essential and is legally enforced. However, currently used wastewater treatment technologies such as activated sludge systems, anaerobic digestion, electrochemical destruction, adsorption and membrane filtration are ineffective in removing azo dyes due to reasons such as inefficient dye degradation, slow degradation kinetics, toxic metabolite formation, inhibitory costs and generation of secondary waste streams. Therefore, in this study, microbial fuel cells (MFCs) were studied as possible systems that could effectively degrade azo dyes with an additional benefit of concomitant biogenic electricity generation. The co-metabolic degradation of the model azo dye Acid Orange-7 (AO-7) using Shewanella oneidensis and mixed anaerobic cultures in MFC was carried out with particular emphasis on AO-7 degradation kinetics in the initial study. The effect of using various carbon sources including cheaper complex ones such as molasses and corn steep liquor as electron donors for azo dye degradation in MFCs was also investigated. The outcomes of this study demonstrated that fast AO-7 reductive degradation kinetics using cheap, sustainable co-substrate types can be achieved with concomitant bioelectricity generation in two-chamber MFCs. Power densities up-to 37 mWm-2 were observed in the two-chamber MFC system during AO-7 decolourisation. Co-metabolic reductive degradation of azo dye mixtures using dye acclimated mixed microbial populations under industrially relevant conditions (high temperatures and salinities) and changes in microbial community structure in the MFCs in presence of complex azo dye mixtures in two-chamber MFCs was investigated. The outcomes of this work demonstrated that efficient colour and organic content removal can be achieved under high temperatures and moderate salinities using azo dye adapted mixed microbial populations in two-chamber MFCs. Microbial community analysis of the original anaerobic consortium and the azo dye adapted microbial culture following MFC operation indicated that both cultures were dominated by bacteria belonging to the phylum Firmicutes. However, bacteria belonging to phyla Proteobacteria and Bacteroidetes also became selected following MFC operation. Peak power densities up-to 27 mWm-2 were observed in this study during decolourisation of complex azo dye mixtures. The complete degradation of the azo dye AO-7 using a sequential reductive – oxidative bioprocess in a combined MFC-aerobic bioreactor system operating at ambient temperature in continuous mode was studied. The outcomes of this study demonstrated that the azo dye AO-7 can be fully decolourised and degraded into non-toxic and simpler metabolites. Maximum power densities up-to 52 mWm-2 were observed during azo dye degradation. A modular scale-up version (with a volumetric scale-up factor of 6) of the two stage integrated bioreactor system demonstrated the capability to efficiently treat two types of real wastewater originating from colour industry without any apparent deterioration of reactor performance in terms of dye decolourisation and COD removal. The use of applied external resistance (Rext) and redox mediators as tools for enhancing azo dye degradation kinetics in dual chamber MFCs was studied. The outcomes of this work suggest that azo dye reductive degradation kinetics in MFC anodes can be influenced by varying Rext. Furthermore, AO-7 reductive degradation kinetics was improved in a concentration-dependent manner by exogenous addition of two electron shuttling compounds anthraquinone-2,6-disulfonic acid and anthraquinone-2-sulfonic acid in MFC anodes. The overall outcomes of this study implies that MFCs could be successfully applied for achieving enhanced azo dye reductive biodegradation kinetics in MFC anodes coupled with concomitant bioelectricity generation. It further demonstrated that MFC systems can be successfully integrated with existing wastewater treatment technologies such as activated sludge systems for complete degradation and toxicity removal of azo dyes and their biotransformation metabolites.
23
Dri, Marco. "Utilization of industrial waste for value-added permanent sequestration of CO2." Thesis, Heriot-Watt University, 2014. http://hdl.handle.net/10399/2804.
Full textAbstract:
Mineral carbonation allows to permanently store CO2 into materials rich in metal oxides. However, mineralization technologies still suffer of slow reaction rates and low carbonation efficiencies and, to improve them, there has been increasing interest in employing waste streams as feedstocks. In light of this, the aim of this thesis was to determine the potential use of wastes for permanent sequestration of CO2. It was found that waste streams available for mineral carbonation in the UK have a capture potential of 1Mt/year, and in many cases, waste resources are located close to the CO2 emitters. A novel closed-loop, multi-step mineralization process was developed. The process consists of extracting calcium from the feedstock followed by its precipitation as crystals of calcium sulphate, which are then converted into calcium carbonate. Carbonation efficiency of the process increased when temperature was raised and solid to liquid ratio and particle size reduced. A 74%, 67% and 59% of carbonation efficiency was achieved for steel slag, ground granulated blast furnace slag and phosphorus slag, respectively. Finally, a real case scenario, where the mineralization process would be retrofitted to a steel plant, was investigated. It was found that, because of the thermal and electrical energy required to run the process, the mineralization system would be carbon negative (i.e. storing more CO2 than the amount emitted during the process) when the solid to liquid ratio would be 240g/l or higher.
24
Farrar, Siân Marjorie. "The use of short rotation coppice (SRC) willow for the bioremediation of landfill leachates." Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.705916.
Full textAbstract:
Landfill leachate is a growing problem in both Ireland and the rest of U.K. Methods of treating landfill leachate are often costly and ineffective but SRC willows are extremely capable of the bioremediation of landfill leachate. When screening Salix genotypes (120 in total) with landfill leachate, the majority of genotypes, responded well, with minimal stress. The data suggests that a number of genotypes maybe more suited to leachate than others. Commercial genotypes such as Nimrod and Olaf were particularly tolerant to leachate application. Various loading rates of leachate were applied to eight selected genotypes. The application rates were based on nitrogen content of the leachate. When evaluated, rates of around 1000 kg - 2000 kg N/ha/yr were optimal for biomass production with minimal phytotoxic effects. Application equivalent to 4000 kg/ha/yr produced a significant reduction in biomass yield and led to increased potassium concentration in the soil. Risk evaluation of the technology using simulated rainfall confirmed that the presence of willow actively reduces risk of N leaching and P run-off. Sulphate concentration was elevated in the willow planted plots. The application of leachate produced a small but significant effect on the combustion of the lignocellulosic biomass produced by willow. The minor changes to combustion did not significantly reduce the overall combustibility of the material. This suggests that pairing the bioremediation with methanogenic leachates with biomass production may be possible. This technology could be the sustainable and cost effective solution to a growing leachate problem, provided it is made accessible to landfill operators and local authorities. To increase uptake, it is necessary for policy to support bioremediation as a credible solution. Possibly, incentivising the use of phytoremediation in the way green technologies have been incentivised in recent years, could insure that landfills are not left with leachate treatment issues in the future.
25
Ramachandran, Rohit. "Multi-scale population balance modelling and controllability of granulation processes." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/7213.
Full textAbstract:
Many continuous granulation plants operate below their design capacity, suffering from high recycle rates and instabilities. Thus, there is an immediate economic incentive for effective operation and control of granulation units. The overall granulation process is integrated and interacting, with limited manipulated variables available (e. g. binder addition, nozzle locations and mixing rate). Hence. the complex process dynamics and operational challenges presented warrant a fundamental model-based strategy for design, operation, control and scale-up that is well supported by experimental analyses. A realistic model of the granulation process has to account for the granule size, the binder content, and the porosity (or related parameter bulk density), thereby necessitating a three-dimensional population balance model to yield a good representation of the process. While this multidimensional population balance model is warranted by the physics of the problem. it is a bigger challenge to derive kernels (rate laws) for the key granulation mechanisms. Most kernels in the literature are empirical and/or semi-empirical and provide little insight into the intricacies of the granulation mechanisms. This effectively results in an inability to make the necessary engineering decisions to improve control of the granulation process. Hence, this thesis is concerned with a more systems-centric approach to enhance the design, control and scale-up of granulation processes. Experimental studies on a lab-scale batch drum granulator for a Calcite/PVOH-H20 system were performed to assess granulation kinetics and model development of the granulation process. Effects of process /material properties and liquid binder distribution on granule properties, illustrating the non-homogeneity of key particle attributes and which justify the need for multi-dimensional population balances, were studied. Process sensitivities, manipulations and potential disturbances were identified, formulating a comprehensive control configuration for granulation processes, with application seen in a continuous drum granulation of limestone. While carrying out experiments, multiple granule attributes were characterised and this presents a challenge, which this research addresses accordingly. A population balance model incorporating nucleation, aggregation, breakage and consolidation was developed in this research. Novel aspects are the mechanistic formulations of the nucleation, aggregation and breakage kernels which are derived from first-principles. Such mechanistic descriptions of the rate processes lend themselves to a more in-depth understanding of the granulation process, contributing fundamental knowledge to the design, control and scale-up of these processes. A sensitivity analysis of the model was then performed to ascertain the influence of model parameters on the particle density distribution. Continuing from this, a compartmentalised version of the combined population balance model was developed, for the purpose of controllability analysis. Results obtained were used to identify suitable control-loop pairings to facilitate enhanced control-loop performance. Experimental validation of the population balance model is an integral part of this research. The model was quantitatively validated using lab-scale experimental data for granule size, binder content and porosity. The tuned model was then able to predict evolutions and distributions of granule attributes for different operating conditions and formulations. The model was also validated for different granulation systems. This illustrates the robustness and flexibility of the model and these results are promising toward the longer-term step of a first-principles based predictive model for the granulation process that can help alleviate the need for large number of experiments. As an alternative to deriving the above-mentioned mechanistic kernels, a discrete element modelling (DEM) approach was also undertaken in this thesis. Based on a Volume of Fluid (VOF) method, the analysis carried out provided useful information to help understand the effect of primary particle morphology on granulation kinetics making it possible to establish relationships between material and process/design properties and granulation process behaviour
26
Hanotu, James. "Development of a fluidic oscillator-driven flotation system." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/4635/.
Full textAbstract:
Treatment of liquid effluents is a serious challenge owing to the high stability and colloidal nature of the particles. In many applications, microbubbles (< 150 µm) are employed for separation purposes due to their buoyancy and increased surface area to volume ratio. This property has been exploited in the water treatment industry for separation in a process known as dissolved air flotation (DAF). Though practically efficient, the process is energy intensive operating at >5 bars and consequently consuming ~90% of the total energy required in water purification plants. Other approaches in generating microbubbles for separation are not without challenges. One example is dispersed air flotation, which generates bubbles several orders of magnitude larger than the bubble exit pore and consequently unsuitable for flotation of these colloidal particles. These two concerns have been addressed in this research with the designing and development of a microbubble diffuser driven by a fluidic oscillator to facilitate microbubble generation suitable for flotation as well as investigating its performance for flotation applications. This fluidic oscillator converts continuous air supply into oscillatory flow with a regular frequency to generate bubbles of the scale of the exit pore. Bubble characterisation results showed that average bubble size generated under oscillatory air flow state from a 50 µm pore membrane was 86 µm, ~ twice the size of the diffuser pore size of 38 µm. In contrast, continuous airflow at the same rate through the same diffusers yielded an average bubble size of 1059 µm, 28 times larger than the pore size. In the first application, fluidic oscillator generated microbubbles were investigated for the separation of emulsified oil using Aluminium sulphate as the coagulant. The effect of surfactant concentration on oil droplet size was investigated. It was found that oil droplet size varied inversely proportional to surfactant concentration. In addition, it was found that the oil removal efficiency also depends on the surfactant concentration. The maximum oil removal efficiency by Microflotation was found to be 91% under lowest surfactant concentration tested (0.3 wt%) whilst at highest surfactant concentration used (10 wt%); lowest recovery efficiency (19.4%) was recorded. In the second application, the separation of algal cells under fluidic oscillator generated microbubbles was investigated by varying metallic coagulant types, concentration and pH. Best performances were recorded at the highest coagulant dose (150 mg/L) applied under acidic conditions (pH 5). Amongst the three metallic coagulants studied, ferric chloride yielded the overall best result of 99.2% under the optimum conditions followed closely by ferric sulphate (98.1%) and aluminium sulphate with 95.2%. The third application investigated the performance of Microflotation for the recovery of yeast cells from their growth medium at different pH levels, flocculant dose and varying bubble sizes. In this study, the food-grade-constituent- Chitosan was used as the flocculant. Results reaching 99% cell recovery were obtained under various conditions examined. Bubble size profiling showed an increase in average bubble size with diffuser pore size. Also, cell recovery efficiency was a function of both bubble size and particle size (cell size). For smaller particles (<50 μm), relatively smaller bubbles (<80 μm) were found to be more effective for recovery, otherwise, relatively larger bubbles (80-150 μm) proved to be efficient in recovering larger particles (particle size: ~250 μm). Acidic and neutral pHs were effective in separation as hydrophobic particles were formed. As pH tends towards alkalinity, flocs become more hydrophilic, leading to low recovery from the aqueous solution. In addition, separation efficiency was dependent on flocculant dose as increase in concentration improved flocculation and consequently, yeast recovery. However, above a critical concentration, overdosing occurred and inadvertently, recovery efficiency decreased. The results compare well with conventional dissolved air flotation (DAF) benchmarks, but has a highly turbulent flow, whereas Microflotation is laminar with several orders of magnitude lower energy density.
27
Poggio, Davide Antonio. "Modification and experimental calibration of ADM1 for modelling the anaerobic digestion of solid wastes in demand driven applications." Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/13299/.
Full textAbstract:
This thesis is an exploration into the modelling of anaerobic digestion (AD) with a focus on its integration into a microgrid for rural electrification. The work investigated the improvement of Anaerobic Digestion Model No 1 (ADM1) in order to better describe the kinetics of biogas production in an AD system with particular focus on substrate characterisation, codigestion and the mechanisms of inhibition. The resulting model was used to investigate the possible role of AD in microgrid systems. A novel biochemical and kinetic fractionation method was developed in order to fully characterise any substrate and produce the required input parameters into the a modified version of ADM1. The method uses a combination of analytical and digestion batch tests and was applied to food waste, green waste, pig manure and oat processing residues. The fractionation method was validated using measurements from semi-continuous laboratory scale digesters, operated with varying substrate combinations and loading rates. The model was able to suitably predict the methane production rate and the typical off-line measurements in AD systems, except during periods of high organic loading rate where biochemical inhibition became an important phenomenon. Possible inhibiting mechanisms were investigated by model based analysis of the experimental data characterised by inhibition, and a possible inhibition mechanism was proposed and integrated in the ADM1 model. Microgrid modelling software HOMER was used alongside the updated version of ADM1 in order to perform a benchmark of various operational and control strategies for the demand-driven operation of an AD system integrated in a microgrid. Different biogas demand profiles were considered. In the case of a biogas demand profile with low variability it was found that simple operational strategies could be used, with limited required biogas storage buffer and without causing process instabilities. With more variable demand profiles, an expert control system was needed in order to reduce the biogas storage requirements and guarantee process stability.
28
Orozco, Angela Maria. "Dilute acid hydrolysis of municipal solid waste using phosphoric acid." Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501392.
Full text
29
Muvundika, Alick Bulala. "Development of a framework for assessing sustainability benefits of landfill gas Clean Development Mechanism (CDM) projects." Thesis, University of Central Lancashire, 2015. http://clok.uclan.ac.uk/12874/.
Full textAbstract:
The twin objectives of the Clean Development Mechanism (CDM) are to assist developing country host nations in achieving sustainable development, and to assist developed countries in meeting their greenhouse gases (GHG) emission reduction targets. This is achieved through implementing GHG abatement projects in developing countries. There has been increased attention in the contribution of CDM projects to sustainable development in host nations. Previous research has suggested that, when left to market forces, the CDM does not contribute effectively to sustainable development. One likely reason is that host nations define and evaluate projects contribution to sustainable development. This has led to a “race to bottom” with regard to setting sustainability standards triggered by a concern that project developers prioritise CDM investments in countries with lower sustainability standards. Researchers have identified the need for an international standard for assessing sustainable development benefits of CDM projects. The main aim of this research was to develop an international level framework for assessing sustainable development benefits of CDM projects with a specific focus on landfill gas (LFG) projects. An in-depth literature review was carried out to establish the link between sustainable development benefits of CDM projects in general, and LFG CDM projects in particular. A case study methodology was used to develop an understanding of landfill management practices at three existing landfill sites both in developed (n=1) and developing countries (n=2). The results from the literature review and case studies were utilized to develop the framework for assessing sustainable development benefits of LFG CDM projects. The developed framework comprises three sustainable development dimensions and 12 criteria with 16 matching indicators. Such a project specific assessment framework has not previously been developed. The results from the validation of the framework suggested that technology transfer is the most likely benefit of any LFG CDM project while balance of payments is the least likely benefit. The proposed framework can be utilised at two stages in a CDM project lifecycle. It can be used as: (i) a template to guide host nations’ Designated National Authorities (DNAs) on how to review projects before issuing Letters of Approval (LoA); and (ii) Designated Operating Entities (DOEs) can also use the developed framework to validate and verify that sustainable development benefits stated in project proposals have been realised at the project level.
30
Hitchin, Suzanne. "Perceptual methods for environmental assessment : odour and landfill." Thesis, Cranfield University, 1998. http://dspace.lib.cranfield.ac.uk/handle/1826/11024.
Full textAbstract:
This thesis investigates the phenomenon of environmental annoyance from waste management, specifically landfill odours. The research study identifies the scope and significance of parameters that influence the extent of impact and includes these in a framework that can be used to influence the design and development of a population response model for odours. The research design considers the physiological, lifestyle and location factors that influence exposure and response to landfill odour and addresses three research objectives: • To produce a framework within which a community based population response model could be developed. • Determine and demonstrate the variability of response within a popUlation exposed to landfill odour. • To determine and demonstrate how spatial and temporal factors also contribute to the differential exposure and response of individuals to odour pollution. The research activity involved the design and implementation of an odour monitoring panel. Volunteers were recruited in the vicinity of two landfill sites where they monitored daily for odours for three months. This programme provided information on their routine activities and exposure to odour at the time. The thesis concludes by noting the following: • Location and climatic factors may generate more variability (at this scale of sample) than interpersonal differences. • The results from laboratory experiments examining hedonic properties were not repeated in the external environment. • The response levels between males and females were inconsistent with current knowledge and research assessing gender differences in the ability to detect odours. Additionally, the research demonstrates how data on the detection of odour in communities could be included in research activity that links olfactometry and the experience of odour in the environment.
31
Gottberg, Annika. "Product service systems for household waste prevention." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/8630.
Full textAbstract:
Waste prevention is the prioritized waste management option within EU waste policy. There is however a scarcity of research on and policy measures for waste prevention. Improved resource productivity in consumption practices may prevent waste. Literature suggests that Product Service Systems (PSS, ‘a marketable set of products and services capable of jointly fulfilling a user’s needs’ (Goedkoop et al. 1999)) have potential for increased resource productivity compared with self-servicing (households owning material artefacts and using them to perform household tasks themselves), and therefore potential for waste prevention. However, the potential of PSS is uncertain due to a lack of well-reported quantitative assessments. Moreover, the potential is predicated on particular behaviours of self-servicing households and PSS providers concerning their choice and management of material artefacts. This research, therefore, aims to assess the utility of the PSS concept for achieving household waste prevention in the UK with a view to informing policy-makers. Three objectives address the aim, namely to: identify attitudes towards PSS adoption and behaviours concerning choice and management of material artefacts which influence the waste prevention and wider environmental performance of PSS; the waste prevention potential of experimental PSS; identify the environmental potential of experimental PSS. An exploratory mixed-methods research design was used to address the objectives, comprising focus groups, interviews, a survey, document studies, development of a model for waste prevention assessment and a simplified life cycle approach using life cycle indicators. The context was a national property development firm and households on new housing developments built by the firm. Experimental PSS, for potential provision by the property development firm were developed for four household tasks to enable the assessments, namely garden maintenance, home improvement, house cleaning and laundry. The households, the property development firm and its supply chain expressed reluctance towards adopting PSS. Reported behaviours concerning choice and management of material artefacts partly confirmed and partly diverged from the propositions in the PSS literature. For almost all propositions, there were diverging behaviours. PSS for all household tasks except house cleaning had some although modest waste prevention potential. PSS led to increases in some types of emissions in most of the assessed scenarios. Increased emissions mainly arose from the transport for the delivery of PSS. Due to the increase in some emissions, it is uncertain whether PSS qualifies as waste prevention according to the legal definition. The waste prevention and environmental potential depend on the organisation of PSS. Moreover, the behaviours of service providers in particular are uncertain. Despite the modest potential for household waste prevention PSS could have a role as one in a suite of waste prevention measures. However, due to the uncertainty of the potential it might be inappropriate for policy-makers to promote adoption of PSS currently. Adoption of household services provided by local service providers may however increase. Policy-makers should consider promoting the environmental sustainability of both self-servicing households and of commercial household services. Policy-measures are proposed. The PSS concept is critiqued and the term PSS rejected. It is suggested PSS are services.
32
Berkhout, F. "Radioactive waste : Institutional determinants of management and disposal policy in three European countries." Thesis, University of Sussex, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234039.
Full textAbstract:
The objective of this thesis has been to write a detailed historical account of the policy and practice of radioactive waste management in Britain. Sweden and West Germany, and to draw out implications for theory and public policy. The research was motivated by the perception that many of the technical and socio-political problems of dealing with radioactive wastes had not been resolved. and that these had a critical bearing on the political viability of civil nuclear programmes. By comparing the evolution of the policy process in three countries it has been possible to develop a better understanding of the particular operational. regulatory and political factors determining policy in each case. In addition. fundamental issues in the regulation of radwastes - the setting of standards and criteria for management and disposal, the institutional structure for oversight and policy-making, research policy and its relation to storage. treatment. disposal and siting policy. and the validation of disposal techniques according to performance goals amid great long-term uncertainty - have been clarified through their analysis in a comparative framework. The main conclusions are three-fold. First. the presence or absence of commitments to the reprocessing of spent fuel for a wide range of strategic, industrial and legal reasons have been critical to the success in finding an acceptable radwaste management and disposal policy (or strategy). Politically it is not possible to make a clear distinction between radwaste management and policy for the rest of the back-end of the nuclear fuel cycle. Analytically It is also not possible to separate the two. Second, because of this complex but intimate relationship to reprocessing policy, the dynamism and consistency of radwaste policies are highly dependent on the industrial and political contexts of the drive to reprocessing. Traditionally a view on reprocessing has been virtually synonomous with a faith or scepticism in the future of nuclear power. Experience in the three countries covered in this research shows that there may be a basic conflict between integrated and viable radwaste policies and strong nuclear policies. In this sense radioactive waste could turn out to be the achilles heel of the nuclear industry. Third, the policy process, and indeed its goals, was rather unique to national circumstances (the legal and institutional framework, industrial and political structures). This demonstrates one of the principle arguments of the thesis which is that the innovation process for radwaste management and disposal technologies cannot be seen merely as a technical process, but has to be seen as a process of political and institutional negotiations. There are no perfect' solutions'. Questions of procedure and the context of policy have to be considered as central to the innovation process. Generalizing the patterns which emerge is however difficult, and conclusions must be applied with care under conditions of continuing change and uncertainty.
33
Oiarzabal, Lierni. "Miscibility study of polyolefin blends." Thesis, Imperial College London, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360505.
Full text
34
Angus, M. J. "Radioactive wase immobilisation in cement-zeolite and other cement-based matrices." Thesis, University of Aberdeen, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372609.
Full text
35
Curry, Robin. "The contribution of recycling to the integrated management of domestic wastes in Northern Ireland." Thesis, University of Ulster, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390058.
Full text
36
Short, Joe. "Composting and vermicomposting waste paper sludge." Thesis, Open University, 1999. http://oro.open.ac.uk/58000/.
Full textAbstract:
Increasing legislative and economic pressure to find more sustainable methods of organic waste management has fuelled innovation in biological treatment technology. By-products of paper manufacturing industries provide a large source of organic waste, which is known to have a high environmental impact. This waste paper sludge has been shown to be amenable to biological treatment. Recent research has confirmed that windrow-composting and vermicomposting techniques have potential to treat these wastes and share many economic and environmental benefits. Many authors have suggested that sludge specific composting methods need to be developed and this research aims to provide fundamental data in this respect. The treatment of specific waste paper sludges was investigated through small and larges calee xperimentsw ith the aim of optimising thesep rocessesw ith minimal intervention. Identical samples of a selected waste paper sludge feedstock were used in large scale investigations into the application of each composting technique, and the performance of each process and resulting products was evaluated. Windrow composting and vermicomposting were found to stabilise and enhance waste paper sludge in very different ways, producing unique products. In terms of processing, windrow composting resulted in more rapid rates of stabilisation and although the performance of the vermicomposting process was less effective in these respects, it afforded additional benefits as a treatment of waste paper sludge. Both processes were found to stabilise and enhance waste paper sludge but the selection of one system or the other will depend largely on the objectives of the project and the criteria required of the finished product.
37
Jan, Mir Ahmed. "Removal and recycling of metals from aqueous systems using fluidised bed electrolysis in combination with other concentrators." Thesis, Brunel University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366225.
Full text
38
Butler, John Hague. "The environmental impact of post-consumer waste recycling initiatives in England and Wales." Thesis, Manchester Metropolitan University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340943.
Full text
39
Hussain, Zaib-un-nisa. "Metal recycle and recovery." Thesis, Brunel University, 1999. http://bura.brunel.ac.uk/handle/2438/7122.
Full textAbstract:
The development of techniques for the removal and recovery of metals from industrial effluent taking account of the consequences of the definition of waste in the Basel Convention on transfrontier shipment of waste is reported. The use of fluidised bed cell electrolysis in the recovery of metals from dilute solutions is investigated, and the conditions for recovery optimised. For the first time the application of a novel activated carbon cloth concentrator cell to recover metals from effluent solutions is reported and the conditions for its use optimised. Comparative studies using conventional mesh and plate electrodes, and novel activated carbon cloth electrode for the recovery of cobalt from dilute solution, and copper from three different hydrometallurgical solutions viz (i) Cu/Zn, (ii)Cu/Zn/Fe and (iii) Cu/Zn/Cd containing effluents were carried out. Application of concentrator cell technology including activated carbon cloth and ion exchange resin to the recovery of metals, including precious group metals, from industrial as-supplied samples is reported. Optimisation leads to successful recovery of iridium and palladium from very dilute solutions. The alternative recovery of metal as added-value chemicals is also investigated. The Basel Convention is concerned with transfrontier shipment of waste from developed to developing countries and has produced a need to investigate the leachability of metals in various forms. In this work the leachability of copper and zinc is studied under various conditions that model environmental situations and the results have been used to develop a methodology to determine whether a metal containing material would be subject to a shipment ban under the Convention. As part of the development of the methodology, leaching studies were also carried out on single chemical compounds of copper, zinc, cadmium and lead, and their bioavailability determined.
40
Cerda, Ruben Osvaldo Bustos. "Microbial extraction of chitin from prawn shell waste." Thesis, Queen's University Belfast, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337646.
Full text
41
Yang, Yunlai. "Study of the mechanical properties of pulverised fuel ash for use in geotechnical applications." Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386970.
Full text
42
Kier, D. "Ion-exchange for radioactive waste treatment." Thesis, University of Salford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376870.
Full text
43
Flanagan, Leslie. "Environmental assessment of the re-use and recycling of unplasticised polyvinyl chloride window profiles." Thesis, University of Brighton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324398.
Full text
44
Pinto, Gilberto. "High pressure - high temperature neutral hydrolysis of amorphous poly(ethylene terephthalate)." Thesis, University of York, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310981.
Full text
45
Mess, Harold. "Sewage sludge disposal constraints and opportunities." Thesis, Aston University, 1985. http://publications.aston.ac.uk/15168/.
Full text
46
Peters, Michael D. "Improving the environmental performance of small and medium sized enterprises : an assessment of attitudes and voluntary action in the UK." Thesis, University of East Anglia, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365135.
Full textAbstract:
The environmental performance of small and medium sized enterprises (SMEs) was chosen to be the topic of study for this thesis. While this policy-relevant research area has gained increased coverage in the literature over the last decade, it has still proved difficult to generate empirical data and information of sufficient quality and quantity. A major aspect of environmental performance involves the management of waste, and waste minimisation was of particular interest to this programme of research. Another area of special interest for this thesis was the extent to which voluntary policy tools (voluntary initiatives, or VIs) could be utilised at the local level to engage with SMEs on the issue of improved environmental performance. The early desk study research revealed the major barriers preventing more environmental action by SMEs to date. The barriers included low-priority attachment to environmental issues, a lack of time/manpower and limited understanding. It also revealed that while VIs have proved successful at the 'macro' level there is little evidence or experience to draw on for their design or implementation at the local scale. The programme of empirical research Involved an original analysis of a recent nation-wide survey into the environmental attitudes of UK manufacturing businesses; the completion of an environmental attitudes survey with approximately 60 SMEs situated in East Anglia; observation of a waste-oriented local authority environment project Involving small businesses and a similar project with a rural village community in Suffolk, and finally the establishment of two voluntary waste minimisation initiatives on Industrial estates in Norfolk and Suffolk. The national survey analysis identified smaller sites as consistently less proactive in most areas of environmental thinking and action. This finding was not strongly confirmed by the survey of East Anglian SMEs which showed that a small business does not have to be a member of an environmental group/initiative to have already adopted certain sound environmental practices, even if primarily these measures were geared towards cost savings/efficiency gains. The industrial estates projects have proved to be particularly useful, demonstrating the potential benefits of this type of voluntary action which capitalises on the close geographical proximity of a number of SMEs sharing common problems. The benefits included a reduction of waste generation, the development of more environmentally responsive business cultures and improved relations with the local authority. The village community project that brought together all elements of the local society from the businesses to the school, in a rural setting, seems to be a sensible way to focus minds on the reduction of waste and consequent benefits.
47
Jackson, Alan. "An investigation into potential methods for the removal/recovery of metals from ceramic wastes." Thesis, Staffordshire University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318341.
Full text
48
Ling, Sarah R. A. "Assessing the effectiveness of landfill restoration and remediation at a closed landfill site." Thesis, Cardiff University, 2007. http://orca.cf.ac.uk/54748/.
Full textAbstract:
This research project was established to investigate the varying environmental impact of a landfill waste mass after the installation of a fully engineered landfill capping system. Nant-y-Gwyddon Landfill Site is a waste disposal site situated in the Rhondda Fawr in South Wales, UK. The site was established on an area of high ground overlooking the densely populated valley floor. The key environmental body at risk from the site was identified as the layered aquifer system supported by the cyclical geological strata dominated by sandstone aquifers separated by less permeable siltstone, mudstone and coal seams. The research adopts an integrated approach, where the understanding of the changes occurring in the waste mass are directly linked to predicted changes in the contamination levels in the groundwater system. Emphasis is also given to the mechanisms for contaminant transport between the waste mass and the environmental systems. As such the entire landfill system including the surrounding environment is considered as a set of closely interconnected systems. A monitoring system was designed to observe the changes occurring to the waste mass in terms of leachate level and saturation conditions after the installation of the landfill cap in an attempt to assess the changing leachate generation rates and quality within the waste mass. The key findings from the waste mass are then used to interpret variations in contaminant levels in the groundwater systems. Geophysical investigations highlight the extent of the leachate contamination detected in the groundwater hydrogeologically down gradient of the waste mass. The findings from groundwater monitoring are then used to develop a hydrogeological numerical model for the site using the program Visual MODFLOW. The key findings from groundwater monitoring and modelling highlight the importance of the unsaturated zone beneath the site in providing a source of contaminants which are mobilised during increased groundwater levels triggered by rainfall events. The majority of the contaminant loading was determined to be sourced from the area where a direct pathway exists between the waste mass and the Main Aquifer system. Predictions for future trends of contamination levels are then made in response to the findings and show a dynamic system intrinsically linked to the development of the waste mass and the meteorological conditions on site.
49
Lloyd, C. J. "The displacement of metals from butylphosphate complexes." Thesis, University of Portsmouth, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380250.
Full text
50
Gandy, Matthew. "The recycling of household waste : urban environmental policy in London and Hamburg." Thesis, London School of Economics and Political Science (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241722.
Full text