With the European Union’s Landfill Directive targets for 2020 fast approaching, local authorities in the U.K. are finding it necessary to devise innovative ways to deal with household waste, including the use of treatment methods.
This is the situation in Milton Keynes, where its council has taken the groundbreaking decision to implement not one, but three separate waste management systems under one roof at a brand new facility, the Milton Keynes Waste Recovery Park.
Milton Keynes currently has a no-mass-burn policy but has also committed to reducing its current landfill percentage to less than 5 percent by 2019/2020. In a move which will showcase the first facility of its kind, the new Milton Keynes Waste Recovery Park incorporates mechanical treatment (MT), advanced thermal treatment (ATT) and anaerobic digestion (AD) in one site.
The town already enjoys considerable recycling success. The percentage of household waste being recycled in the area stands at 53.5 percent (2012/13), well above the U.K. average of 42 percent for the same period. However, the Milton Keynes Waste Recovery Park is an important component in Milton Keynes Council delivering on its ambitious goal of achieving a 70 percent recycling rate by 2024/25. To achieve this, the new facility, which is positioned as a waste treatment plant as opposed to a recycling plant, will treat 132,000 metric tons of residual municipal waste collected in the area each year.
Winning combination
Once inside the facility, any recyclable materials not yet removed will be mechanically separated before the waste moves on to either ATT or AD treatment. By combining these three methods, the new plant will contribute to the local authority delivering effectively on both its “no burn” and its landfill reduction aims.
This is where Stadler UK—the U.K. arm of the Germany-based sorting and processing equipment supplier—comes in. Stadler UK was commissioned for the design and build of the new MT plant by AmeyCespa, the Cambridge, U.K.-based firm responsible for the construction and operation of the facility.
Importantly, as well as recovering viable levels of valuable resources from waste, the plant will significantly contribute to Milton Keynes meeting its targets to reduce waste sent to landfill to less than 5 percent by 2020. In addition, the ATT facility will produce enough electricity to power 11,000 homes, with the AD plant producing renewable energy and a compost-like product which will be used on brownfield sites around the region. Overall, Milton Keynes Council anticipates savings of what translates to $75 million against the cost of landfill over the life of the facility considering the current landfill cost of around $120 per metric ton.
Back to the basics
While the new plant’s design is complex, Trevor Smart, U.K. sales manager for Stadler UK, says he believes that the first steps in designing every sorting system are answering two basic but crucial questions.“We first need to ascertain what is coming into the plant, i.e., what is the composition of the feedstock, before moving on to then identifying what the plant operator wants the end product to be.”
Smart continues, “The primary consideration when designing this plant was taking into consideration that the MT process sits in between the other two processes and had to be flexible in order to be able to keep processing the waste if the ATT or AD processes are full or offline.”
Municipal waste deliveries do not stop if part of the system needs servicing, upgrading or repairing, notes Smart, and therefore the MT plant design has had to ensure it can cope with a number of operational possibilities. “In response, we have included additional equipment within our design to ensure the process is robust in order to fulfill the service delivery requirements of Amey Cespa to Milton Keynes Council,” he says.
Another significant challenge for the design is keeping the plant clean. As Smart explains, “If you imagine what the bottom of your household waste bin would look like if no refuse bags were used and your rubbish was just piled in, and then multiply this by the sheer volume of household waste that will be heading to the plant, then you have some idea of the challenge we faced in the design.”
In order to keep the plant as clean as possible, Stadler has incorporated a number of features, such as scrapers to clean the machinery and special chutes for getting rid of sludge.
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European WTE plants taking the lead Waste-to-energy (WTE) plants in Europe don’t displace recycling efforts there, nor do they churn out smoke and pollutant-laced emissions. But they do contribute to reduced fossil fuel imports. Those were the messages shared by Ella Stengler, managing director of the Brussels-based Confederation of European Waste to Energy Plants (CEWEP). Stengler delivered these remarks as one of three speakers during a session titled “End of Life Options,” that was part of the Plastics Recycling Conference Europe, held Oct. 29-20, 2014, in Milan, Italy. Commenting on what she said was a widely held but incorrect view, Stengler quipped, “God recycles and the devil burns.” Stengler said although WTE plants may often be regarded in a negative light, statistics from Northern Europe show they work hand-in-hand with recycling facilities, serving as a home for complex materials, preventing those wastes from being landfilled and also contributing to better quality recyclables. Stengler said Europe’s 456 WTE plants provide thermal treatment of leftover municipal and similar waste (including refuse-derived fuel) and represent close to 80 million metric tons of capacity. Contrary to most people’s beliefs about the smog-emitting incineration plants of years past, she said today’s European WTE plants are often aesthetically pleasing, modern structures featuring many technological advancements and are among the most stringently regulated and controlled industrial activities. Furthermore, Stengler said, today’s plants are equipped with sophisticated low-emission filtering systems that can account for as much as half the cost of the entire plant. “That means that we are also more flexible as to the input,” she said, “because the filters can deal with the heterogeneous waste.” Stengler said Europe’s decentralized WTE plants offer baseload power, district heating and cooling and steam for industrial purposes. According to CEWEP, in 2010, WTE produced around 100 terawatt hours (TWh) of energy, and the level is forecast to reach 134 TWh by 2020. “It is affordable and it is local, so it helps to reduce Europe’s high dependence on imports of fossil fuels,” Stengler said, referring to CEWEP calculations showing that the energy content of waste treated in Europe’s WTE plants is equivalent to 19 percent of the 2012 natural gas deliveries from Russia. However, Stengler said Europe’s WTE plants are unevenly distributed, with a heavier concentration in Northern Europe, not many in Eastern Europe, and few or none in some Southern European countries such as Greece and Malta. “Unfortunately these countries still rely heavily on landfilling, and some of them landfill almost 100 percent of their municipal waste,” Stengler said. On the other hand six northern European EU countries with some of the highest recycling rates—Germany, Belgium, Sweden, the Netherlands, Austria and Denmark—still are able to utilize a significant amount of WTE capacity and landfill 3 percent or less of their waste. “These countries more or less do not landfill anymore but they achieve very high recycling rates with the help of waste to energy,” Stengler told attendees. Stengler said the opposite appeared to be true of countries with few or no WTE plants: “They landfill very much, have very low recycling rates and poor or no waste to energy.” Stengler also observed that WTE facilitates quality recycling by treating complex and contaminated wastes and keeping those materials out of the circular economy. “If waste is not good enough for recycling, it should be turned into energy,” she said. To skeptics claiming that Europe’s WTE plants are clamoring for landfill diversion simply to “feed the beast,” Stengler argued that simply wasn’t true. “Member states that achieve high recycling rates—they do it together with waste to energy in order to avoid landfilling,” she observed. Stengler also acknowledged while some Northern European countries have more WTE capacity than they need domestically, these countries are offering the spare capacity to countries that would otherwise landfill. With more than 80 million metric tons of EU waste still landfilled, “taking Europe as a whole, there is no waste-to-energy overcapacity.” Stengler also referred to the European Commission’s 2014 proposal of a landfill ban on recyclable waste by 2025, which she hailed as a positive development but one that CEWEP is working to accelerate. “We think by 2020 would have been better, because there is a European obligation to separate these wastes,” Stengler said. “It doesn’t make sense to separate this waste stream and then bring it to landfills.” — Lisa McKenna |
An integrated approach
Stadler UK also had to meet the needs of the many companies involved in the project. Stadler UK is contracted with AmeyCespa to deliver the sorting system, however, there is also the main building contractor and the process contractors for the AD and ATT plants—all of which have their own inputs and opinions.
Stadler UK’s design at the new plant will see waste passed through trommels before going through ballistic separation. Once the waste has been mechanically sorted, it will be diverted to the appropriate treatment system, either AD or ATT.
“The technology for AD is fairly robust, so from our point of view, it has straightforward requirements,” says Smart. “With regards to the ATT, the system is capable of operating with a wide range of materials but we still have to meet the fuel in-feed specification so it can operate to maximum efficiency.”
Work started at the Milton Keynes Waste Recovery Park earlier in 2014. The plant is due to be commissioned in early 2016 with extensive testing to take place before it becomes fully operational in September 2016.
“We are in the advanced stages of the development of this facility and it is an exciting project to be involved with,” Smart says. “This will be the first fully integrated waste treatment plant Stadler has been involved in and we look forward to progressing the installation and seeing it become fully operational in 2016.”
The article was submitted on behalf of Stadler UK, based in Bristol U.K., a subsidiary of Altshausen, Germany-based Stadler. For more information, contact Diane Kenny at diane.kenny@proteuspr.co.uk.
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