Stephen Burnley

Energy implications of the thermal recovery of biodegradable municipal waste materials in the United Kingdom

Waste management policies and legislation in many developed countries call for a reduction in the quantity of biodegradable waste landfilled. Anaerobic digestion, combustion and gasification are options for managing biodegradable waste while generating renewable energy. However, very little research has been carried to establish the overall energy balance of the collection, preparation and energy recovery processes for different types of wastes. Without this information, it is impossible to determine the optimum method for managing a particular waste to recover renewable energy. In this study, energy balances were carried out for the thermal processing of food waste, garden waste, wood, waste paper and the non-recyclable fraction of municipal waste. For all of these wastes, combustion in dedicated facilities or incineration with the municipal waste stream was the most energy-advantageous option. However, we identified a lack of reliable information on the energy consumed in collecting individual wastes and preparing the wastes for thermal processing. There was also little reliable information on the performance and efficiency of anaerobic digestion and gasification facilities for waste.

The impact of the European landfill directive on waste management in the United Kingdom

The European Union Landfill Directive calls on member states to reduce the amount of biodegradable municipal solid waste disposed of to landfill. In addition, national waste strategies will require the constituent parts of the United Kingdom to achieve increased household waste recycling and recovery rates. Both these measures will require the development of the infrastructure to support national high-intensity recycling and composting schemes and the construction of at least 35 new municipal waste to energy incinerators. Before plans can be developed for meeting the targets several areas relating to municipal solid waste need to be clarified. Depending on the definition of municipal solid waste, its composition and likely future growth rates the number of incinerators required could be up to 170.

Towards Sustainable Operations Management Integrating Sustainability Management into Operations Management Strategies and Practices

Sustainability is an increasingly relevant issue for a wide range of organizations, and therefore sustainability management strategies and practices are of growing significance. Because many sustainability impacts are strongly influenced by operations management decisions it is critical that the operations management function embraces the requirements of sustainability management. This has implications for decisions and processes associated with all aspects of operations management including strategy, design, planning and control, and improvement. For example, appropriate environmental and social performance objectives, targets and indicators need to be integrated with quality, cost and other more conventional performance measures. The closed loop supply chain perspective must be adopted and the requirements of other stakeholders in addition to the customer must drive operations decisions. The scope of any given “operation” is thereby expanded considerably and the nature of the operations management role altered, with implications both for the professional development of managers and the research needed to support the manager in this changed role.

A multi-criteria decision analysis assessment of waste paper management options

The use of Multi-criteria Decision Analysis (MCDA) was investigated in an exercise using a panel of local residents and stakeholders to assess the options for managing waste paper on the Isle of Wight. Seven recycling, recovery and disposal options were considered by the panel who evaluated each option against seven environmental, financial and social criteria. The panel preferred options where the waste was managed on the island with gasification and recycling achieving the highest scores. Exporting the waste to the English mainland for incineration or landfill proved to be the least preferred options. This research has demonstrated that MCDA is an effective way of involving community groups in waste management decision making.

Factors influencing the life cycle burdens of the recovery of energy from residual municipal waste

A life cycle assessment was carried out to assess a selection of the factors influencing the environmental impacts and benefits of incinerating the fraction of municipal waste remaining after source-separation for reuse, recycling, composting or anaerobic digestion. The factors investigated were the extent of any metal and aggregate recovery from the bottom ash, the thermal efficiency of the process, and the conventional fuel for electricity generation displaced by the power generated. The results demonstrate that incineration has significant advantages over landfill with lower impacts from climate change, resource depletion, acidification, eutrophication human toxicity and aquatic ecotoxicity. To maximise the benefits of energy recovery, metals, particularly aluminium, should be reclaimed from the residual bottom ash and the energy recovery stage of the process should be as efficient as possible. The overall environmental benefits/burdens of energy from waste also strongly depend on the source of the power displaced by the energy from waste, with coal giving the greatest benefits and combined cycle turbines fuelled by natural gas the lowest of those considered. Regardless of the conventional power displaced incineration presents a lower environmental burden than landfill.

Carbon and life cycle implications of thermal recovery from the organic fractions of municipal waste

PurposeThe aim of this research was to determine the optimum way of recovering energy from the biodegradable fractions of municipal waste. A part-life cycle study was carried out on the following wastes: paper, food waste, garden waste, wood, non-recyclable mixed municipal waste and refuse-derived fuel. The energy recovery processes considered were incineration, gasification, combustion in dedicated plant, anaerobic digestion and combustion in a cement kiln.MethodsThe life cycle assessment (LCA) was carried out using WRATE, an LCA tool designed specifically for waste management studies. Additional information on waste composition, waste collection and the performance of the energy recovery processes was obtained from a number of UK-based sources. The results take account of the energy displaced by the waste to energy processes and also the benefits obtained by the associated recycling of digestates, metals and aggregates as appropriate.Results and discussionFor all the waste types considered the maximum benefits in terms of climate change and non-renewable resource depletion would be achieved by using the waste in a cement kiln as a substitute fuel for coal. When considering the impacts in terms of human toxicity, aquatic ecotoxicity, acidification and eutrophication, direct combustion with energy recovery was the best option. The results were found to be highly sensitive to the efficiency of the energy recovery process and the conventional fuel displaced by the recovered energy.Conclusions and recommendationsThis study has demonstrated that LCA can be used to determine the benefits and burdens associated with recovering energy from municipal waste fractions. However, the findings were restricted by the lack of reliable data on the performance of waste gasification and anaerobic digestion systems and on the burdens arising from collecting the wastes. It is recommended that further work is carried out to address these data gaps.

The use of virtual reality technology in teaching environmental engineering

Abstract The Open University (OU) provides a Diploma in Pollution Control as part of its undergraduate degree programme. The courses that make up the Diploma are presented in distance learning format using the OU’s supported open learning system that has been developed over several decades. Teaching environmental engineering by distance learning presents several challenges in terms of ensuring that students gain an appreciation of the technology in action and receive the motivation and support more readily available to students taught in a campus setting. The OU has developed a multimedia resources DVD to help meet these challenges for students undertaking an environmental impact assessment project. The DVD contains virtual reality views of the proposed site, maps of the region, supporting technical data, interviews with experts and advice from a virtual tutor. A survey of students using the DVD found that the overwhelming majority found the DVD to be “very useful” or “useful”. Understandably, the material that is essential for completing the project received the highest rating, but the background material was still considered to be useful by most students. Similar resources could benefit all students in many areas of engineering and technology.

The environmental and financial benefits of recovering plastics from residual municipal waste before energy recovery

A life cycle assessment was carried out to investigate the environmental benefits of removing dense plastics from household waste before burning the waste in an energy from waste (EfW) facility. Such a process was found to improve the climate change impacts of the waste management system by 75% and the non-renewable resource depletion impacts by 18%. A preliminary financial assessment suggests that the value of the plastics recovered in this way would be less than the reduction in electricity income for the EfW leading to a loss of £2-5 million per year. However, if the plastics were separated by householders for a kerbside recycling scheme, the higher price commanded by the higher-quality reclaimed plastics and lower processing costs means that overall the operation would be financially viable giving a net present value of £768 000 at a 5% rate of return. In both cases, there is a further financial benefit to the EfW operator resulting from the additional gate fees for processing waste to replace the plastics removed. Further work is required to assess the costs and effectiveness of using both kerbside collections and mechanical recovery to reduce the plastics content and carbon intensity of EfW feeds.

The Immobilisation of Flue Gas Treatment Residues Through the Use of a Single Staged Wash and Crystalline Matrix Encapsulation (CME) Treatment Process

All incineration and other thermal treatment technologies produce flue gas treatment residues (FGTR) that require specialised treatment and disposal. In the United Kingdom the FGTR arising from municipal solid waste incineration is classified as a hazardous (special) waste. This is primarily due to the irritant properties of chloride, but also due to the content of heavy metals. These wastes must be handled, transported & disposed of in accordance with the Special Waste Regulations 1996 and are disposed into highly engineered landfill sites, which isolate the material from the environment. The low levels of trace elements in the FGTR mean that the recycling of the metallic elements is not economic. Control through stabilisation and encapsulation in a crystalline matrix converts the FGTR primary form from a powder into solid block form. The use of a novel metal matrix encapsulation (MME) process allows low level engineering processes to be employed, increasing a range of reuse options combined with long-term improved storage.Copyright