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[December 2007]
Testing - No Waste of Time
The UK produces approximately 434 million tonnes of waste every year and, despite the fact that recycling has dominated the news agenda so much in recent times, these levels continue to rise.
But just because reducing waste production is a slow process doesn’t mean the environmental battle is lost. As Malcolm Rose of CERAM explains, there’s a lot you can do to manage waste and use it more effectively, particularly if you make use of the latest testing technology available. Anyone that says otherwise is talking rubbish.
By the time waste has been generated and sent on its way to landfill sites there is often the erroneous belief that little else can be done - pleas to recycle have gone unheard and all that is left is to ‘keep the mess contained’. This couldn’t be further from the truth.
In fact Municipal Solid Waste (MSW), if managed correctly, can prove a valuable source of fuel thanks to advanced thermal treatments designed to extract the energy it contains. It is a concept that many local authorities across the UK are only really just beginning to take notice of. But why now particularly?
The primary reason is legislation. The safe and cost effective disposal of waste is becoming increasingly important in Europe - EU demands for higher environmental standards of waste disposal are now in place. Together with the lower carbon emission targets set by the Kyoto protocol this means three things for UK municipalities:
- They are under pressure to reduce total waste produced
- Emissions produced by waste on landfill sites must be limited and monitored
- Processes employed to utilise waste emissions and the energy it contains as fuel must also have limited impact on the environment.
Reducing total waste, is proving a tough enough challenge but even when looking at points two and three in isolation it seems local authorities face an uphill struggle when it comes to waste, particularly when you consider one important issue –landfill composition varies dramatically from one site to another. It is here that testing has an important role to play.
Despite the fact that most landfill sites emit the same ‘core’ gases, namely methane, carbon dioxide, hydrogen, nitrogen and oxygen, the landfill testing team here at CERAM frequently find that the ratio in which these gases are produced can be hugely different from site to site, even when composite elements of the waste itself are theoretically similar.
When you add into the mix the other trace concentrations of gases and vapors also present at most sites, which again also vary according to the specific landfill composition, it becomes clear just how sensitive the testing procedure needs to be simply to monitor general emissions.
But detecting potentially harmful gases/contaminants is one thing, ensuring that landfill can be used efficiently, and with minimum impact on the environment, is quite another.
The main issue here is that actually ‘releasing’ useable energy from landfill is itself a process which requires energy and can therefore have an undesirable effect on the environment.
The reason for this is that traditional incineration techniques require very high temperatures, often in excess of 850°C, and are therefore relatively energy inefficient. To achieve suitable combustion levels the amount of oxygen needed to oxidize the fuel (the waste material) is also significant, again an undesirable aspect of the process. Until now however, local authorities have not really had an alternative if they wanted to convert landfill waste into energy.
Thankfully, help is now at hand in the form of advanced thermal treatments such as Pyrolysis and Gasification. The reason for this is that they rely on less or no oxygen to fuel the combustion process and require much lower heat levels than traditional incineration methods.
Both processes produce what is known as syngas, a mixture of carbon monoxide, hydrogen, methane and a variety of other volatile organic compounds and it is this which has significant potential in terms of energy recovery.
Burning syngas to generate steam is one, and indeed the most common, route to harnessing its energy. In this process, the steam produced is passed through a turbine in order to generate electricity. Alternatively, the gas produced can be used to power engines specifically designed to accept the alternative fuel. So, if generating power from waste is so straightforward, what’s the problem?
The problem with both these processes, and indeed most other systems which utilise syngas in this way, is that they require very specific filtering and cleaning stages in order to achieve their objectives (in terms of energy utilisation) and also in order to comply with the requirements of the Waste Incineration Directive. Once again, the importance of testing becomes evident.
Our dedicated landfill team at CERAM has, on a number of occasions, been contacted to carry out extensive testing on syngas which has theoretically been filtered, only to discover that trace levels on contaminants have ‘made it through’ and have subsequently impaired turbine/generator performance dramatically. If turbine/generator performance is hindered, this significantly impairs the whole process’ performance when it comes to effectively utilising energy.
Of course performance is just one side of the coin. When you talk about detecting contaminants you are also highlighting potential environmental and health threats which also require immediate action. No form of technology, even if it makes good use of waste material, is going to develop if threats such these cannot be detected and eliminated.
This is why advances in technology designed to harness the energy in waste material must be accompanied by a willingness to explore and utilise the latest in testing technology – only the two together can ensure that this is an area that moves forward as a concept rather than remaining simply ‘a good idea in principle’.
The equipment, expertise and knowledge now available to local authorities, and the organisations they employ to process waste, means that emissions/content can be analysed to the finest detail, that energy conversion rates can be maximised and that process failures caused by contaminants can be identified and appropriate solutions produced.
By doing all this, not only will local authorities be a step closer to meeting increased legislative demands when it comes to landfill waste, they will also be playing a significant role in helping to reduce the current impact waste has on the environment.
Demonstrating a willingness to tackle the issue of waste management in this way also gives local authorities a much stronger standpoint from which to encourage consumers to play their part in reducing waste levels, an outcome that would benefit everyone. With opportunities such as this on the table, talking about testing is certainly not a waste of time.
PRESS CONTACT: Catherine West-Robinson, Marketing Co-ordinator
Tel: +44 (0)1782 764344 Fax: +44 (0)1782 412331 Email: catherine.west-robinson@ceram.com
ENDS