How your local council is planning to waste you
THREE sites across South Yorkshire are firmly in the sights of three borough councils – Barnsley, Doncaster and Rotherham – to host plants that will handle a quarter of a million tonnes of waste every year. The potential sites have been well publicised, and in due course they will be picked.
Yet staggeringly when they ARE chosen, even the councils picking them will NOT know exactly what will be going on them! In this special report, Liam Hoden looks at the various projects that might just end up on YOUR doorstep.
THE most controversial choice remains that of an incinerator – an option that has raised the blood pressure of many members of the public at consultation meetings over the past year.
INCINERATOR
What it does:
The main task of an incineration plant is to burn waste and turn this into energy, in the form of electricity or heat.
Power can be easily distributed and sold via the national grid. This is by far the most common form of energy recovery.
Anyone wanting to buy the heat generated would of course have to be close by to the facility and a dedicated distribution facility would also be required.
Unless ALL the available heat can be used, the generating facility will not always be operating at optimum efficiency. Combining heat and power helps increase the overall energy efficiency.
Regulations:
The Waste Incineration Directive (WID) has the most stringent controls in the EU, and aims to minimise the impact from emissions to air, soil, surface and ground water on the environment and human health.
All incineration plants in the UK must comply with the WID. Combustion conditions are required to ensure the waste is completely burned.
What is needed:
Incineration plants will typically require the following elements to function:
Waste reception and handling – generally untreated municipal waste will be delivered by waste collection vehicles and tipped into a bunker. However, pre-treated waste that has been dried, and has had recyclable objects removed can also be used.
Combustion chamber – four main combustion technologies are available, with the most common being moving grate which sees waste slowly moved in one side and ash discharged at the other.
Energy recovery plant – the standard approach is to use a boiler to generate steam, either to generate power through turbines or to be used for heating.
Emissions clean-up for combustion gases – to comply with regulations, combustion processes have to be correctly controlled, and flue gases cleaned, prior to final release. Chemicals are injected
to neutralise many harmful
emissions.
Bottom ash and air pollution
control residue handling – processes are required to deal with the side products of emission cleaning and combustion. For example, there will likely be metals suitable for recycling among the ash.
A staff of between six-18 are needed to operate a facility dealing with 50,000 tonnes per year.
Examples:
Sheffield's incineration plant near Park Square deals with 225,000 tonnes each year and is both an energy and heat producing facility.
Marchwood incinerator in Hampshire is sized to accept 165,000 tonnes per annum and exports 14MW to the local grid to power up to 14,000 homes. The facility is clad in a 36m high aluminium dome with a chimney stack 65m high.
Key issues:
Incinerator emissions have reduced substantially over the past two decades and most are less than 10 per cent of the level of 20 years ago. Yet a facility dealing with 230,000 tonnes of waste per year will produce the following equivalent emissions:
Nitrogen oxides and articulate matter equivalent to a four miles-plus (7km) stretch of motorway
Dioxides and furans ( toxic and cancer-causing compounds) equivalent to accidental fires in a town the size of Milton Keynes
About one 20th of the cadmium produced by a medium sized coal fired power station.
Incinerators are not normally sources of dust and smell.
Noise is likely, from vehicles, mechanical processes such as waste preparation, ventilation systems, steam turbines and condenser units.
Up to 20 HGVs per day can be expected at a plant dealing with 50,000 tonnes per year.
Local likelihood:
Rotherham, Barnsley and Doncaster Councils are together looking for three sites estimated at dealing with 250,000 tonnes a year and any incineration facility would likely be a moving grate plant of around four hectares, with a 70m high chimney.
Up to 100 heavy goods vehicles could be expected each day, and a staff of 30-90 would be required.MECHANICAL BIOLOGICAL TREATMENT PLANT
What it does:
The main task of a mechanical biological treatment plant is to divert waste from landfill.
It is not a stand-alone technology, but forms part of an integrated waste management system – for example it would compliment recycling or composting facilities.
Facilities either separate then biological treat waste, or visa versa. Initial preparation can include removal of large items, or shredding the waste.
Sorting of mixed waste is done by mechanical processes – it may be sorted by size, weight and magnetism before undergoing recycling; biological treatment; energy recovery through fuel production; and landfill. Most facilities use a combination of techniques.
Biological treatment can involve composting of waste to yield organic, rich compost, and waste headed for landfill could be mechanically divided into biodegradable and non-biodegradable waste.
Biodegradable waste can then be dried to reduce its size and turned into compost-like material for use on the land. Waste can also be converted into bio-gas or dried to produced a rich material for use as a fuel.
Output:
Recyclable material – generally of lower quality than from collection systems where the waste is pre-separated. Metals will almost always be involved and, for many plants, they may be the only recyclable material. However other materials not normally be collected from households – such as batteries – can also be recovered.
Glass, textiles, paper and plastics – the most common being glass, which can be mixed with stones and ceramics for a low grade aggregate which could be used to top off landfill. The other materials are unlikely to be of value once sorted.
Compost – suitable for improving low quality soils on former industrial land or for landscaping landfill.
Bio-gas – this renewable energy would be a product of anaerobic digestion where air is not used. It can be used as a substitute for natural gas or vehicle fuel, but is most commonly used to fuel boilers or heat and power generators. Energy generation may be done on site and sold via the local grid while excess heat generated can also be sold if there is local demand. For use as vehicle fuel or natural gas it would require further treatment.
Fuel – produced for intensive industrial users, such as cement kilns, purpose built incinerators, power stations for use alongside coal and to generate heat.
Examples:
Mechanical biological treatment is an established system in Germany, which houses more than half of the sites in Europe – but it has yet to take off in the UK.
One home example is Shanks East London on Frog Island – a fully enclosed bio-drying system accepting 180,000 tonnes of mixed waste per year.
Waste is shredded before being put in the drying area, treated for two weeks then separated to remove metals, glass and aggregates. The remaining waste is used as a fuel, currently in a cement kiln.
Key issues:
Traffic – for a plant dealing with 50,000 tonnes per year, expect 20-30 HGVs each day, though this would be reduced if bulk transport systems are used.
Emission and health issues – no studies have been carried out on such facilities but investigations around composting facilities have found no increased in cancer or asthma in local populations.
Dust, pests and smell – an odour control system may be needed to limit smell; meaning air would be treated or released high in the air. As such facilities are generally enclosed, dust, vermin and scavenging birds should not be problems – though flies may be, during hot weather.
Noise – centres mainly on vehicle movements and mechanical processes such as shredders, and ventilation systems.
Water resources – because of the enclosed plant, environmental impact on local waterways should be limited, though waste water would have to be managed using a dedicated drainage system
Staffing – two to eight people would be required at any one time to operate a plant dealing with 50,000 tonnes per year with more required if manual picking of waste were used. A shift system could ensure 24-hour operation and would increase the workforce.
Local likelihood:
As mechanical biological treatment plants are tailored to deal with specific supplies of waste or for specific ends, it is difficult to say what type of plant would be used for the joint waste management plan for Barnsley, Doncaster and Rotherham.
The councils are looking for three facilities, each dealing with 250,000 tonnes per year – so a staff of at least 10 will be required, though it is likely that the workforce will be larger. Some 100-150 HGVs can be expected each day at such a site.ADVANCED BIOLOGICAL TREATMENT PLANT
What it does:
This processes waste that has been segregated at source, to produce quality compost.
Can also be used as the biological part of Mechanical Biological Treatment.
Can act only on biodegradable organic materials and will turn these into bio-degrable, rich organic material.
The method aids diversion of landfill into products such as compost that can safely be applied to agricultural land and reduction of landfill waste sizes on material unsuitable for use on the land.
Food and green waste are suitable for use but input levels of other materials – such as card, paper and wood – are limited to longer degrading times.
Options:
All biological waste treatment involves decomposition, but there are several ways to achieve this:
l Tunnels – either permanent or temporary large scale rectangular structures are used to process waste.
Air is blown in through a slatted floor, perforated pipes, or special channels on the tunnel floor.
l Vertical towers – waste is continuously fed into the top of a sealed tower or silo and processed as it falls.
l Bays, piles or extended beds – waste is fed into a large enclosed building and placed in long, concrete-walled bays, pile or beds. It is then turned while being held.
l Rotating drums – continuous processing in which waste is aerated as it passes along the drum.
This is often used as pre-treatment alternative to shredding to aid sorting of waste.
l Bio-drying – the mass of waste is reduced by drying it .
Outputs:
Compost for use on land. The quality will vary but it can be used in a number of sectors including land restoration, landscaping, domestic and commercial gardening and agriculture.
A grading system has been developed to determine the quality of compost. Bio-gas and fuel can also be produced.
Examples:
The main examples of composting technology in the UK have been open-air facilities but following changes to the handling of meat and dairy waste products, there have been an increase in in-vessel systems – such as the Terra Eco Systems facility in High Wycombe.
This currently deals with 15,000 tonnes of kerbside-collected waste per year but plans are in place to expand to 40,000 tonnes.
Input waste is shredded and has water added, before being loaded into the first composting bay where air is drawn into it via pipes and re-circulated through an odour control system.
The compost is then moved into a second bay before finally maturing in an open area. It is then distributed for use on farmland and in landscaping.
Bio-gas production technology is normally used in the UK on sewage sludge across the water industry, but the South Shropshire Bio-waste Digester has dealt with commercial waste – taking 5,000 tonnes per year of separated kitchen and garden waste.
This is shredded and wet before being put in a tank employing
moisture and heat control. By-products include soil conditioners and bio-fertiliser.
Key issues:
Traffic – for a plant dealing with 50,000 tonnes per year up to 20 HGVs per day can be expected.
Emissions and health issues – even well-run open facilities can emit micro-organisms and dust.
Studies have indicated a possible link between commercial-scale open composting and respiratory symptoms in people living nearby – though this was concerned a single facility and is being re-evaluated.
No studies have been published suggesting adverse health effects of anaerobic facilities though potential effects would be similar to those of composting facilities.
Smell – control of odour is very important though, as most plants are enclosed, smell can be controlled through treatment or careful release.
Some smell will be unavoidable.
Pests – as such facilities are generally enclosed, dust, vermin and scavenging birds should not be problems... though flies may be, during hot weather.
Noise – mainly vehicles and mechanical processes such as waste preparation, ventilation systems and operations associated with turning and airing biomass.
Plant size – most facilities will have capacities in the range of 10,000-60,000 tonnes per year.
If used in a mechanical biological treatment plant, capacity is usually 50,000-200,000 tonnes per annum.
Local likelihood:
Due to the many variables it is impossible to predict what might be used in the joint waste management plan.
However, given the requirements of the three councils, an advanced biological treatment plant would most likely be part of a mechanical
biological treatment facility.
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Sunday 05 February 2012
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