Solid Waste Management Case Study In Bristol Environmental Sciences Essay

The management of Municipal Solid Waste (MSW) is a major environmental crisis throughout of the World, which everyone is concerned about. In the United Kingdom, the quantity of municipal waste has increased and 46.9 per cent of the total collected waste has disposed of in landfill in 2009/10 (DEFRA, 2010b). In comparison, the Netherlands and Denmark have disposed of almost no municipal waste to landfill and other members of European Units such as Germany and Sweden have less than a quarter of municipal waste to landfill (DEFRA, 2010b). Therefore, the UK Government published Waste Strategy for England 2007 on 24th May 2007 in order to meet EU strategy and set out a sustainable method for hierarchy of waste management options within climate change and population growth. The fundamental goals of the strategy are to set out a blueprint for waste prevention, reduction, re-use, recycling and recovery and improving environmental and economic outcomes through increased recycling of resources and recovery of energy from residual waste using a mix of technologies. There are some actions of the proposal strategy outlined, for example, energy from waste is expected to account for 25% of municipal waste by 2020 compared to 10% in 2007 and the standard rate of landfill tax increase by eight pounds per year from 2008 until at least 2010/11(DEFRA, 2010c).

As a result, it is necessary to set up a variety of waste treatment for recovery material in the UK, such as Mechanical Biological Treatment (MBT) and Energy from Waste (EfW). There is no doubt that a number of local authorities face major challenges when they manage residual waste sustainably. Take Bristol for example, 59% of waste has been sent to landfill and 40% has been recycled or composted in 2009/10 (DEFRA, 2010d). According to Bristol City Council (2000), 100,000 tonnes of household waste will remain to be treated if 40% waste is recycled or composted. Thus, the council wants to make a 25 years Residual Waste Management Contract with company to treat 100,000 tonnes of Residual MSW by one of three options which include MBT with composting or anaerobic digestion and Energy from Waste. In this paper, the environmental impacts of each option will be assessed in order to find a sustainable method for residual waste management in Bristol. Furthermore, some relative mitigation measures and remediation approaches for chose option will be mentioned, focusing key issues of development and land redevelopment after 25 years.

2. The Description of Development and Site

Bristol city council aims to set up a waste treatment plant in the city in order to not only meet their recycling needs but also make efficiently recover value from the residual waste produced. There is no doubt that a hundred thousand tonnes of rubbish send to the new plants for processing in the coming years rather than dumping it in landfill sites. The possible potential site is assumed as previously used land which locates in the main industrial estate (Avonmouth) in the northern part of Bristol. It would generally be preferred in planning terms, as no new land would be used and contaminated land restored. In addition, the facility has good transportation infrastructure, which results from closely primary road network and alternatively rail access. Figure 1 shows some potential previously land in the potential area, which have several large chemical manufacturing plants and also has a significant residential area in Avonmouth between the industrialised zone and the M5 motorway. Moreover, a large scale of green sites and water body around the assumed site.

Figure 1. The Potential Site for Waste Treatment Plant in Bristol

alll sites.jpg

(Source: Google Map)

There are three potential options including MBT using composting (In Vessel Composting) or anaerobic digestion (AD) or EfW provided in following details. The local waste strategy officers assume that:

100,000 tonne residual MSW will be treated;

the detailed value of treatment for each option is described in Figure 2;

Figure 2. The Value of Waster Treatment Process

mixed recyclates are worth on average £50/tonne;

all plants operate 90% of the 8760 hours in a year;

both digestate and compost are disposed to landfill at the full tax rate; however, the digestate is charged the full dispose cost, compost is disposed for free;

bottom ash can be processed and used as a secondary aggregate, making profit at £5/tonne;

gas cleaning residues are hazardous waste and landfilled at £100/ tonne plus landfill tax at £48/tonne;

electricity from AD is worth £135/MWh, electricity from EfW and In Vessel Composting is worth £60/ MWh.

3. Introduction of Three Processing Options for the Residual Municipal Solid Waste Management

This section focuses on introduction of the process and principals of three options including In Vessel Composting, Anaerobic Digestion and Energy from Waste. MBT mainly follow two processes including mechanical sorting and biological process. Mechanical sorting is to sort ‘mechanical’ element such as metal, plastics, glass & paper, which is made by hand and is a basic process in both composting and anaerobic digestion. However, the biological processes are different because of the variety of treatment principals. Anaerobic digestion, which is the biological treatment of organic waste without oxygen, utilise microbial activity to break down the waste in a controlled environment with mesophilic and thermophlic digestion and produce biogas (e.g. Methane and Carbon Dioxide) and digestate at the same time. In Vessel Composting is an enclosed compost system and is the treatment of organic matter with aerobic microorganism to produce a mixture of stable humic substances and inorganic plant nutrient (Agrivert, 2010). In comparison with AD, there is no green energy produced through the system, therefore, the extra energy will be used in the processes. Energy from Waste is process incorporation the thermal decomposition of the waste include waste reception and storage, combustion system, heat recovery, flue gas cleaning, power generation and process control and monitor. Compared with MBT, EfW can disposal of all types of waste without other pre-treatment and the temperature has a minimum requirement of 850oC for 2 seconds (March, 2010a). Additionally, incineration offers a further option for the treatment of residual MSW and is already proven and bankable technology in the UK with 26 EfW plants (March, 2010a). However, there is no incineration in Bristol at the moment.

4. Environmental Impacts Assessment of Three Processing Options

In order to achieve the UK government’s fundamental goals and Bristol waste strategy, assessment of the environmental and economic impacts of each processing option should be undertaken in the following section. Local facilities of waste treatment would provide much local employment opportunities. Moreover, the number of legislation and planning policy comprising international, national and local policy will also be introduced to make sure the sustainable development. Therefore, this section focus on the key issues of waste treatment options such as air emissions / health effects, dust / odour, noise, water resources, visual intrusion and public concern. According to analysis of environmental impact assessment, one of the options will be identified as the Best Practicable Environmental Option for Bristol City Council.

4.1 Planning Policy and Context

i) International Policy

The European Union has instigated a range of Directives at a European level that should be suitable for each EU member and transposed into national laws in order to adopt the local environment. The following International policies provide the European framework for Waste applicable to the United Kingdom.

• European Community (EC) Landfill Directive 1999/31/EC;

• EC Framework Directive for Waste 75/442/EEC as amended by 91/156/EEC;

• Waste Incineration Directive 2000/76EC (WID).

ii) National Policy

The Waste Strategy for England (2007) sets out the Government’s vision for sustainable waste management. The key objectives and targets of the strategy are to reduce the amount of waste produced and increase the rate of recovery of municipal waste. There are also some other legislation created to achieve the target in the following:

Landfill Allowance Trading Scheme (LATS);

Planning Policy Guidance Notes (PPG) and Planning Policy Statements (PPS);

Planning Policy Statement 1 (PPS1): Delivering Sustainable Development (2005);

Planning and Climate Change (PCC): The purpose is to set out how climate change considerations should be taken into account at different stages of the planning process.

Planning Policy Statement 10 (PPS 10): Planning for Sustainable Waste Management.

During Annex E of PPS 10, the main factors have been taken into account by waste planning authorities when testing the suitability of a site for waste management purposes.

iii) Regional and Local Planning Policy

Planning policies for Bristol are set out in the Statutory Development Plan which includes the following documents (South Gloucestershire Council, 2010):

Regional Planning Guidance for the South West (RPG10) (September 2001)

Joint Replacement Structure Plan (as saved) (September 2002)

Bristol Local Plan (as saved) (1997)

Regional Planning Guidance for the South West (RPG10) (2001)

RPG10 comprises the Regional Spatial Strategy for the South West and the Regional Transport Strategy, and aim to meet sustainable development in terms of environment, economy and society.

4.2 Anaerobic Digestion

In terms of biodegradable waste either by anaerobic digestion or by composting MBT technologies helps to reduce the contribution of greenhouse gases to minmise the impacts of global warming. IPPC (2010) stated that AD technology for various homogenous waste streams is widely proven in Europe, but there are no full scale plants in operation in the UK on municipal derived wastes. Thus, environmental and economic impacts should be assessed in order to develop facilities at present.

4.2.1 Environmental impacts

As we all know that anaerobic digestion is totally enclosed system, which may reduce environmental impacts. As it may achieve a key aim of the landfill Directive and reduce organic wastes from landfill which reduces the production of landfill gas and leachates. Although the facility has pollution control technology in order to control the sustainable processes not only for the company but also for the public, each development has some relevant impacts on air, water resources and local residents. For example, odour emissions should be released during material handling and other air emission (Methane) would be release during the process. This may affect the local living condition if the pollution will not be controlled and visual intrusion, pests and noise problems. In order to predict how odour will be transported, some information such as meteorological conditions (e.g., wind speed and direction, temperature, and inversion conditions) in the proposal site can be obtained from a local weather station. Moreover, contamination of final product is often difficult to avoid, which means digestate from residual MSW connot be used for food growing; only regeneration of contaminated land or landfill cover (McKendry 2010). Therefore, AD also has slightly negative impacts on environment during the handling and processes of the facility. According to Figure 2, net energy (0.5 MWe) will be produced for National Grid, which also can save energy and reduce environmental pollution from power generation. To sum up, compared with no waste treatment in Bristol, AD is a better environmental practical option for waste recovery and also can achieve the UK fundamental target.

4.2.2 Economic impacts

It requires comprehensive pre-processing of the waste or source separation and larger digestion tanks as it does not treat the whole Municipal Solid Waste stream but may be used on residual municipal waste stream with contaminants rejected as part of the process. Thus, AD is more capital intensive than composting and cost more for landfill tax. Moreover, the output of digestates is generally hazardous and set to landfill, which will also cost more for the process than production from composting. However, compared with composting, energy should be produced and is worth £532,170 which is less than profit of net energy from EfW (Figure 3). Someone (City and County of Swansea, 2011) mentions that AD is relatively low capital costs compared to most thermal processes. On the other hand, anaerobic digestion has not enough profit which created from by-products compared to EfW (Figure 3). In terms of economy, anaerobic digestion is the secondary choice in three waste management options for Bristol.

Figure 3. The Analysis of Input and Output of Economy in Proposed Waste Treatment Plant

Anaerobic Digestation

In Vessel Composting

Energy from Waste

Input

£2,380,000 (Landfill)

£ 1,564,000(Digestate)

–

£2,040,000 (Landfill)

£2,880,000(Compost)

–

£408,000 (Landfill)

–

£888,000(Gas Cleaning)

Output

Profit

£1,500,000 (Recyclates)

–

£532,170 (Net Energy)

¹££1,911,830

£1,500,000 (Recyclates)

–

¹££473,040 (Net Energy)

¹££3,893,040

£375,000 (Recyclates)

£185,000 (Bottom Ash)

£3,784,320 (Net Energy)

£3,048,320

4.3 In Vessel Composting

Actually, this technology has only had limited experience in the UK; however, it is rapidly increasing in number due to recent legislation of waste management such as Landfill Directive. The advantage of In-Vessel Composting is that the processes are more controlled and can be designed to achieve specified temperatures of facilitate bacteria destruction.

4.3.1 Environmental impacts

Composting can reduce volume of organic waste fraction of MSW by 25-50% and minmise landfill rate (IPPC, 2010), which avoid environmental pollution (Landfill gas and leachate) similar with AD. However, some potential odour and leachate also should be produced, which can result in air and water resources may be polluted to some extent. Although it is suitable for green and kitchen waste, it is potential of co-composting operations with other waste streams such as paper, sewage sludge (IPPC, 2010). On the other hand, it requires careful source segregation of further post or treatment as sensitive contamination of glass and plastics. Furthermore, in comparison with other options, In Vessel composting has no energy output and need extra energy for operation, which will affect more issues from power generation such as air pollution. It is similar with AD that the development is not bad for ecosystem and visual instruction as the proposed site is previously used land which may be contaminated or brownfield site. The technology has a greater ability to control air pollution emissions than mass burn EfW in theory, but this has not yet been demonstrated in practice in the UK (Environment Agency, 2010).

4.3.2 Economic impacts

Although the capital cost is not quite expensive than Energy from Waste, the balance of input and output of waste treatment process is totally different than other options. According to Figure 3, the developer or government should invest more money for rejected waste to landfill and extra energy (£473,040), which means the profits of recyclates cannot make sure the continuously process of operation. Thus, in terms of economic aspect, this technology is not suitable for the UK fundamental sustainable development target and is the worst option.

Energy from Waste

In the UK, Energy from waste has a particularly poor public image and has been debatable by environmental groups on the grounds of perceived health impacts from emissions to air. Combustion of residual MSW can produce or release carbon dioxide and other greenhouse gases. Hence carbon emissions should to be considered in terms of composition of the residual waste stream, the type of energy produced (heat and/or power) and the overall generating efficiency of the facility.

4.4.1 Environmental impacts

Compared with other options, EfW can disposal of a variety of waste without limitation and pre-treatment required. However, dust problem may exist within the waste reception hall or drawn into the furnace. Moreover, there is a WID emission limitation and air quality standards regulated in order to control the air emission especially greenhouse gases from factories. The advantage of this technology is that the state of the art of pollution control technology is completed for global use. In addition, energy recovery includes Combined Heat and Power (CHP) plants and opportunity for district heating programmes. However, the temperature is not easy to control during the operation processes, which may affect the efficiency of residue quality and disposal when combustion is not completed. Although EfW can resolve waste to landfill and emission reduction (methane)from landfill and residual waste, which to some extent may address climate change, air pollution of EfW is more significant than other options (Hong, 2010). The WID emission limits to air shows daily average emissions limit from incineration in the following (Veolia, 2011):

Dust (Particulates) 10mg/m3

Total Organic Carbon 10mg/m3

Hydrogen Chloride 10mg/m3

Carbon Monoxide 50mg/m3

Sulphur Dioxide 50mg/m3

Oxides of Nitrogen 200mg/m3

According to Figure 2, the number of waste can be combusted and bottom ash can be used for construction applications, which reduces the quantity requiring landfill disposal to under 10% of the feedstock mass (IPPC, 2010). In comparison with others, 8MWe net energy should be produced and deliver cheap heat and power either to the National Grid or local users. On the other hand, it also save more energy and reduce pollution from power generation plants. EfW is not long term liability facility, thus, local EfW would provide the best global solution for Bristol depending on the Life Cycle Assessment. Furthermore, the impacts of visual, pests and noise and ecosystem are similar and related to other waste management options and with proper planning can be minimized to acceptable levels. As for the visual impacts, the following factors should be considered: direct effect on landscape by removal of items such as trees; potential of an exhaust stack associated with air clean up systems; screening features and scale of vehicles accessing site.

4.4.2 Economic impacts

There is no doubt that EfW is one of the high capital costs technology, however, it also create net profits from the processes. According to Figure 3, although, gas cleaning residuals are hazardous wastes and landfilled at £148 per tonne, the facility can create £3,048,320 net profit from operation system except the capital investment, which including £185,000 income from bottom ash, £3,784,320 profit from electricity and £375,000 worth from recyclates. Thus, EfW is the best option for waste treatment for Bristol in terms of economy compared to other options. On the other hand, the facility will waste more investment and energy during the process stopped when there is no enough waste for combustion process.

4.5 Summary

In summary, each option may achieve the UK and local waste management and recycling target and to some extent reduce waste and air emission such as methane and carbon. However, in terms of sustainable development which related to economic, social and environmental aspects, each option has its own disadvantages and advantages. As for economy except the capital investment, Energy from Waste can make more profit in 25 years than MBT using Composting or Anaerobic Digestion. Although air emission from EfW is more significant than other options, EfW has been used for a long time and is improving or mitigating more sustainable technologies to avoid the negative impacts on environment. It is true that Energy from waste has a particularly poor public image; however, public attitude will be changed within the situation changing. Therefore, Energy from Waste is the best value options for Bristol City Council to reach the waste treatment target and follow sustainable development.

5. Mitigation Measures and Remediation Approach

Energy from Waste is the Best Practicable Environmental Option for Bristol waste management programme based on Environmental Impact Assessment (EIA). As we all know that each option has its limitation, EfW is also a case in point. EIA states that the efficiency of combustion, air emission (flue gas emission and cleaning) and public image are the mainly significant issues of EfW facility implementation for Bristol. Moreover, the land restoration after use should be considered at the beginning of construction in order to be able to use as sustainable as possible. Mitigation measures should aim to avoid, reduce, or remedy any significant adverse effects that a proposed development is predicted to produce. First of all, because it is a smaller scale EfW plants, it is better to maximize the scope for dealing with risk events and other potential adverse impacts. Moreover, more information qualitative and quantitative assessment of impacts such as meteorological conditions and ambient air quality should be collected for the next depth assessment. The recommended mitigation measure for efficiency of combustion is to use more effective techniques. For example, the techniques such as Flue Gas Recirculation (FGR) can control the incomplete combustion in order to increase efficiency and to reduce the flow rate of pollutant emissions (Liuzzo, 2007). In addition, the chimney should be high enough to furnish adequate draft and to discharge the products without causing local sir pollution. There are also some methods to increase positive public image, such as enhancing propaganda or media spread and improving education. The risk management including accident management/plan and security precaution also should be undertaken to avoid the health and safety of employees.

As for the future development after use, the land should be careful managed to avoid potential hazardous components released into the land whether it is current contaminated or not (McKendry, 2010). The first recommendation aims to used less penetrability materials for land construction and reduce pollutants released. Moreover, the regular clean up system is recommended to collect the residual waste during transporting system and clean up the dirty area such as oil releasing sites. Contaminated Land Management Regulation indicates that the polluter or owner has responsible to deal with pollution if the land will be contaminated by human activities. In my view, the proposal site is hard to change to an eco-green site after development, thus, it is better to develop as commercial or industrial use in the future.

6. Conclusion

In conclusion, Environmental Impact Assessment of Anaerobic Digestion, In Vessel Composting and Energy from Waste were analysed in this paper in order to find out one of the best sustainable development for Bristol and also achieve the UK fundamental goals for waste management. It is certainly that each option has both negative and positive impacts on environment and economy. The main aim of them is to reduce waste sent to landfill and achieve the UK waste management target; moreover, they also have same impacts on environment such ac visual intrusion, public image, potential contaminated land after use and air pollution. However, the significant impacts of facilities are different in different technologies; for example, odour emission is more significant during anaerobic digestion approach, visual intrusion, public image and air emission is more significant for Energy from Waste, and energy use and odour and leachate are significant in composting process. In terms of economy, EfW is the best option with highest net profits during the process; on the other hand, In Vessel Compost is the worst approach because of extra energy supply. At the last, EfW has been chose to treat residual Municipal Solid Waste with the additional mitigation measures in Bristol, which results in the development is not only suitable for international, national and local strategy but also meet the Best Practicable Environmental Option which is sustainable and integrated in the further development.