Agency starts again with MBT diversion rate tests

The Environment Agency is going back to the drawing board with its guidance on landfill diversion rates for mechanical-biological treatment plants. The current tests, it has concluded, are too complex and expensive.

The Environment Agency has belatedly decided to revise how it measures the amount of biodegradable municipal waste diverted from landfill by mechanical-biological treatment (MBT) plants – further delaying introduction of the technology.

The Agency issued guidance on how to monitor diversion rates from MBT plants back in 2005 (ENDS Report 367, p 41 ). However, two years later few plants have been built and not one has had its rate approved.

Many local authorities are seeking to invest in MBT plants to cut the amount of biodegradable municipal waste they send to landfill and meet their targets under the landfill allowance trading scheme (LATS).

Somewhat late in the day the Agency has decided that the current tests are too complex and expensive. For one of the tests – for biochemical methane potential (BMP) – there is only one UK laboratory with the necessary resources, said policy manager Fran Lowe. Another problem is that it takes 100 days to conduct the test – a long time for clients to see if a plant performs properly.

Two plants are currently having their diversion rates calculated. Tests for East London Waste Authority’s facility at Frog Island, which is operated by Shanks, have cost over £100,000, according to ELWA executive director Tony Jarvis.

New Earth Solutions published diversion rates for its plant in Poole almost a year ago (ENDS Report 381, pp 17-18 ) but has only recently had the plant’s monitoring plan approved by the Agency and has yet to start the tests in conjunction with the Agency.

Other MBT operators, such as Biffa and Premier Waste Management, do not need to have landfill diversion rates established for their facilities because none of the outputs are being deposited in landfills. Some material from their plants is being used in landfill restoration, but this is not classified under LATS as material sent to landfill. Premier is undergoing the tests anyway, but not in conjunction with the Agency.

The Agency and the Environment Department (DEFRA) will host a stakeholder meeting in November to discuss revising the tests, which could be followed by a consultation paper. Changes to the testing methodology would come into force for the 2008/09 year of the LATS.

According to Wolfgang Mueller of the Organic Resource Agency (ORA), which has helped several MBT firms understand the UK’s approach, the BMP test provides a fair reflection of the performance of MBT plants, but it could be simplified. ORA is developing a modified version of the test for presentation at the Agency/DEFRA meeting.

Alternatively, the UK could adopt a different biological test, such as the AT4 test used in Germany and Austria that only takes four days. However, this can not be used reliably on the “fresh” inputs to MBT plants – only on their stabilised outputs – and would need to be combined with other tests.

Any new test used would not lead to a significant change in the diversion rate of plants, Dr Mueller said.

According to Global Renewables, which is to build two MBT plants for the Lancashire Waste Partnership, the advantage of changing the current tests are obvious. “There’s a huge pool of data about diversion rates achieved by MBT plants in Europe using different tests,” said technical director Staphis Papadimitriou. “Changing to them would make it easier for authorities… to forecast diversion rates themselves.” This would give local authorities more confidence in the technology.

For the Lancashire contract, Global Renewables provided the partnership with data based on tests undertaken at its plant in Australia (CHECK ENDS Report 386, p 16 ). Its plants will achieve a diversion rate of at least 60%.

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