Yes / Theory predicts that the voluntary or community sector will contribute a range of services that are not delivered by the state or private sectors. This paper examines the changing contributions of the community waste sector in the UK to reflect upon these claims. A rosy picture of the community waste sector is presented from research on the sector in 2002, with a growing number of organisations carrying out a range of services, drawing on multiple and diverse sources of funding. More recent evidence, and information drawn from outside the sector, however, suggests that regulation, competition, and changes to funding regimes are putting the sector under considerable pressure, such that it is likely to change, and that some parts of it will contract. In terms of the claims from theory, the paper finds evidence that the community sector can and has been innovative in the services it provides and the way that it provides them, though similar innovations may emerge from the private and public sectors. The sparse evidence on participation and recycling rates in kerbside and civic amenity sites are equivocal on whether the sector provides enhanced communication as theory would predict. Overall, the paper highlights the difficulty in achieving direct comparisons between the waste sectors without specific focused research for this purpose. It concludes that the challenge for European, national and local government is to influence the necessarily constructed waste markets in a way which will enhance rather than discourage service providers to innovate in the waste material collected, and to communicate effectively with the public whom they serve. Such policies promise to encourage the effective delivery of sustainable waste services from all three - public, private and community - sectors.

Engineering problems frequently require solving a sequence of dual linear systems. This paper introduces recycling BiCG, that recycles the Krylov subspace from one pair of linear systems to the next pair. Augmented bi-Lanczos algorithm and modified two-term recurrence are developed for using the recycle space. Recycle space is built from the approximate invariant subspace corresponding to eigenvalues close to the origin. Recycling approach is extended to the CGS and the BiCGSTAB algorithms. Experiments on a convection-diffusion problem give promising results. / Master of Science

In conjunction with Atlantic Pacific Engineering and the Henry County Public Service Authority, Virginia Tech’s Environmental Engineering program measured the emissions from an experimental scrap tire incinerator/wastewater treatment plant sludge dryer. This report recounts the techniques used and the results obtained during this testing. The Virginia Department of Environmental Quality supplied a list of pollutants of permitting interest which included a variety of criteria pollutants, toxics, and metals. Sampling for all the listed compounds required adherence to EPA Methods 5, 201A, 29, 0010, 0011, 0030, 6, 7D, 26A, and 18. Emissions testing transpired during the incinerator’s 72-hour test burn: 0800 October 30th to 0800 November 2nd, 1995. Due to time constraints, only part of one nonpotable water sampling series was completed rather than the proposed duplicate testing using both drying agents: nonpotable water and sludge. High particulate (57 lb/hr) and metal (21.4 lb/hr total) emissions indicate a fairly significant amount of air pollution control equipment will be necessary for a commercial plant. Both nitrogen oxides and sulfur dioxide had low emission rates: 1.73 lb/hr and 0.64 lb/hr, respectively, due to the nonpotable water spray acting as a fairly efficient scrubber removing a great deal of nitrogen oxides, sulfur dioxide, and some metals. Because of sample analysis preparation problems, no organics results were obtained. Commercial development of this incinerator will have to include a sizable quantity of air pollution control equipment: a $5 million plant will need approximately $1 million worth of control equipment. / Master of Science

Eddy current separation aims to recover non-ferrous metals from non-metals utilizing electromagnetic interactions. In order to describe the separation process, a representative model is needed that can accurately calculate the induced forces. Such a model can be used to optimize the efficiency of current equipment as well as designing ones that can offer new capabilities. Models proposed so far for the separation process, using traditional approaches to calculate forces, had limited success due to complex nature of electromagnetic interactions. In this dissertation, a novel method for calculating the magnetic force acting on non-ferrous metal particles was developed. By this method, force calculations can be carried out accurately using intrinsic parameters of particles such as size and shape, as well as its orientation within the field. The method also takes into account the operating parameters of the equipment such as the rotational speed of the magnetic element and the speed of the belt. In order to verify this method and collect empirical data, a novel data acquisition and interpretation approach was developed. A computer simulator was also developed that can calculate trajectories of particles based on operating parameters of the eddy current separator and characteristics of the material being processed. The accuracy of the simulator was verified using empirical data obtained by the novel data acquisition method. This contribution provides a viable option for reducing the cost of analyzing; optimizing and designing eddy current separators. / PHD / As technological advances in chemistry, material science, engineering and manufacturing lead to building of items with smaller parts and complex components, recycling them is becoming more challenging. Production of raw materials, especially metals, from fresh ores in mining has become a challenge due to rising costs and depletion of high grade deposits. Thus, in order to sustain growth of the economy and advances in technology, recycling is of utmost importance. Iron and iron containing metal alloys such as steel can easily be separated with magnets. In order to separate metals that do not contain iron, such as aluminum, copper, brass, lead and zinc, eddy current separators are used. Until now, it was not possible to define the separation process as a whole fundamentally based on the characteristics of particles and operating parameters of eddy current separators. In this research, new methods to analyze the separation process as well as a new technique to calculate the magnetic force acting on metal particles were developed. These will provide great help to optimize current equipment and raise the efficiencies of operations and at the same time serve as a tool to design new and better equipment to increase overall recycling performance.

Doctor of Philosophy / This study emphasizes the need to incorporate sustainable practices into urban planning in Saudi Arabia, therefore helping the country's Vision 2030 goals for a greener future. The research focuses on developing a framework for constructing beautiful wall panels using recycled materials, which is critical for solving energy and environmental issues. By integrating several research methodologies, the study creates an initial framework that is subsequently refined with expert feedback. The findings suggest that employing recycled materials for these wall panels not only improves their beauty but also helps to create a more sustainable and environmentally responsible approach to building in Saudi Arabia. This study's findings provide architects and designers with practical suggestions to assist them in creating more sustainable construction practices in the region.

Thesis (PhD (Process Engineering)--Stellenbosch University, 2006. / My applied engineering research and industrial application work of the past 20 years is presented in this dissertation. It is the conjecture of my work that only if thorough first principles knowledge of the depth of process metallurgy and recycling is available, can meaningful first principles environmental models be developed. These models can then evaluate technology, provide well argued and first principles environmental information to our tax paying consumer society as well as to legislators and environmentalists. Only through this path can one estimate the limits of recycling and its technology, hence evaluate the true boundaries of sustainability. My work with students has presently culminated in the detailed modelling and simulation of recycling systems for post-consumer goods. Notably the models are finding an application in the prediction of legally required recycling rates for automobiles. The models provide first principles arguments for less stringent EU recycling legislation and the integration of the first principles models in computer aided design tools of the automotive industry as part of a large EU 6th Framework (project managed by Volkswagen and the other European car producers). Presently these models are also being converted to model the Waste Electric and Electronic Equipment (WEEE) as well as water recycling systems respectively, both for industry in The Netherlands. This unique rigorous integration of systems engineering, reactor technology and process control theory is the basis of all my work to describe recycling systems as dynamic feedback control loops. My large body of acquired industrial knowledge renders these models practical and can hence be used by the automotive and recycling industries. The origins of this work may be found in the various cited publications and reports to industry by myself (due to my close association with industry as well as industrial experience) over the past 20 years as well as the work of my students, covering topics such as: • system optimization models for flotation, mineral beneficiation and recycling systems and applying these for design for recycling and argue for better/improved first-principles based legislation, • industrial measurement, modelling and simulation of industrial extractive process pyrometallurgical reactors as well waste incinerators and recycling plants, • various activities in other areas such as hydrometallurgy, clean and new breakthrough technology, and • process control of industrial metallurgical reactors by among others the application of artificial intelligence techniques. All the ideas of the last years have been worked out with students and have been summarized in our book: “The Metrics of Material and Metal Ecology, Harmonizing the resource, technology and environmental cycles”.

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The global quest for sustainability has intensified the requirement for waste recycling in a number of countries. Waste recycle includes Construction and Demolition Waste (CDW), which emanates from the demolition of buildings and other civil engineering structures. In Europe, the United States, China, and Australia, waste recycling has proven to be successful, both structurally and functionally. In particular, the consideration and /or use of CDW in pavement layers remain on the increase. However, in Southern Africa the use and/or application of CDW and its allied practice is limited; the abundant natural aggregates, the lack of knowledge and technical expertise besides the availability of suitable CDW remain the prominent reasons for its limited consideration. In this research, recycled material infers to Construction and Demolition Waste pertaining to Recycled Concrete and Masonry (RCM). The quality and the type of RCM vary from region to region and as a result, quality control measures aimed at limiting the inconsistency are usually required. Results revealed that secondary crushing influences the physical and mechanical behaviour of RCM aggregates; this information remains insightful in terms of material gradation, performance and viability. The compaction protocol followed and its findings revealed that the initial material grading lightly changed after compaction. However, the 10% FACT results showed that the RCM aggregates exhibit less degradation due to crushing when dry than when they are wet. It is eminent that compaction and/or densification are a cheaper method to improve the pavement layer structural capacity. However, this is reliant on material characteristics, quality, and type. With this cognisance, an experimental program in line with RCM aimed at assessing the mechanical behaviour was developed. The experimental variables include mix composition, mixing and compaction moisture as well as degree of compaction and/or compactive effort. In general, the laboratory evaluation and analysis of the results showed that the mix composition in addition to compaction moisture and the degree of compaction were influential to the obtained shear strength, resilient modulus and Poisson Ratio. Particularly, mix composition exhibited relatively higher influence on the resilient modulus while the compaction moisture effect on the Poisson Ratio dominated other investigated variables such as mix composition and the degree of compaction. Shear strength and resilient response results show that RCM exhibits significant shear strength due to its cohesion, and satisfactory resilient modulus. Pavement analysis and design using multi-layer linear-elastic model and transfer functions in pavement layers where RCM is used also revealed that this material could perform satisfactorily. It was deduced that RCM is a viable material type to consider in the construction of pavement layers that carry low to moderate levels of traffic. / AFRIKAANSE OPSOMMING: Die globale beweging na meer onderhoubare aktiwiteite het gelei tot die ʼn toename in vereistes met betrekking tot herwinning van rommel. Rommelherwinning sluit materiaal van bouwerke en ander siviele strukture in. In Europa, Amerika, China en Australië het die herwinning van afval materiaal tot groot sukses gelei. Spesifiek die gebruik van geselekteerde bourommel in padlae bleik om toe te neem. In Suid -Afrika word die materiaal net in enkele geïsoleerde gevalle gebruik as gevolg van die onderbreking van tegniese kennis met betrekking tot die toeganklikheid en bruikbaarheid van die materiaal. Ook, tans geniet die gebruik van gebreekte klip voorrang omdat die verbruiker glo dat daar nog baie van hierdie materiaal beskikbaar is. In hierdie navorsing verwys bourommel spesifiek na herwinde beton en boustene. Die “kwaliteit” van boustene in verskillende gebiede varieer en as ‘n gevolg moet kwaliteitskontroles toegepas word om hierdie te beperk. Resultate in diè navorsing het gewys dat sekondêre klipbreking/vergruising die fisiese en meganiese gedrag van “bourommel aggregaat” beïnvloed. Die 10% FACT (Fynstof Aggregaat Breekwaarde) resultate het ook gewys dat geselekteerde bourommel minder degradasie ondervind as dit droog is in vergelyking met nat materiaal. Goeie kompaksie van die tipe materiale word erken as een van die goedkoopste maniere om die gedrag daarvan in plaveisellae te verbeter. Dit is wel afhanklik van materiaal karakteristieke, kwaliteit en tipe materiaal. Hierdie faktore is ingesluit in die eksperimentele plan wat eienskappe soos mengsel komposisie, meng en kompaksie voginhoud sowel as graad van kompaksie insluit. Die resultate van die laboratorium analise het gewys dat die mengkomposisie, vog tydens kompaksie en graad van kompaksie ʼn invloed op die skuifsterkte, veerkragsmodulus en die Poisson verhouding het. Veral die mengkomposisie het ʼn merkwaardige invloed op die veerkragmodulus gehad, terwyl die voginhoud tydens kompaksie die grootste invloed op die Poissonverhouding gehad het. Die skuifsterkte (agv hoë kohesie) en veerkragsmodulus van geselekteerde bourommel dui aanvaarbare resultate vir die gebruik in paaie, spesifiek in padlae waar lae spanningsvlakke ondervind word,soos deur liniere elastiese berekeninge gewys is.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

published_or_final_version / Public Administration / Master / Master of Public Administration

This thesis is concerned with developing porous materials from tyre shred residue and polyurethane binder for acoustic absorption and thermal insulation applications. The resultant materials contains a high proportion of open, interconnected cells that are able to absorb incident sound waves through viscous friction, inertia effects and thermal energy exchanges. The materials developed are also able to insulate against heat by suppressing the convection of heat and reduced conductivity of the fluid locked in the large proportion of close-cell pores. The acoustic absorption performance of a porous media is controlled by the number of open cells and pore size distribution. Therefore, this work also investigates the use of catalysts and surfactants to modify the pore structure and studies the influence of the various components in the chemical formulations used to produce these porous materials. An optimum type and amounts of catalyst are selected to obtain a high chemical conversion and a short expanding time for the bubble growth phase. The surfactant is used to reduce the surface tension and achieve a homogenous mixing between the solid particulates tyre shred residue, the water, the catalyst and the binder. It is found that all of the components significantly affect the resultant materials structure and its morphology. The results show that the catalyst has a particularly strong effect on the pore structure and the ensuing thermal and acoustical properties. In this research, the properties of the porous materials developed are characterized using standard experimental techniques and the acoustic and thermal insulation performance underpinned using theoretical models. The important observation from this research is that a new class of recycled materials with pore stratification has been developed. It is shown that the pore stratification can have a positive effect on the acoustic absorption in a broadband frequency range. The control of reaction time in the foaming process is a key function that leads to a gradual change in the pore size distribution, porosity, flow resistivity and tortuosity which vary as a function of sample depth. It is shown that the Pade approximation is a suitable model to study the acoustic behaviour of these materials. A good agreement between the measured data and the model was attained.