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MRBT or MBHT - The case for enhanced residual waste treatment

Updated: Aug 11, 2023

The Biocentre process is advanced Mechanical, Biological and Heat Treatment (MBHT), which is a type of 'second chance' recycling, recovering resources for valuable use from residual waste. Sometimes also called pre-treatment. Zero Waste Europe emphasise the importance of this enhanced treatment of residual waste and call this type of process MRBT - Materials Recovery and Biological Treatment

Many resource and circular economy experts have emphasised the importance of 'second chance' recycling of residual waste and enhanced treatment prior to landfill or incineration. Both landfill and incineration represent leakages from a circular economy, that is resources are lost, typically causing pollution and emitting CO2 as a bi-product of this wasteful industry. Incineration of plastics also causes very significant CO2 emissions - typically resulting in the burning of plastic derived from a fossil fuel to produce electricity at very low levels of efficiency.

Zero Waste Europe have been at the forefront of promoting the case for enhanced residual waste treatment and the avoidance of landfill and incineration of untreated residual waste. Their paper on MRBT can be found here and a 2022 panel discussion on the subject "Sorting Recyclables From Residual Waste" here

Note. This figure replaces a similar figure A from the Zero Waste Europe article at the request of a third party copyright holder ​

It is essential in this type of process that as ZWE put it: "With that in mind, the definition of “acceptable pre-treatment” should primarily consider ​a significant reduction in fermentability."

This because biodegradability of food and other organic matter in residual waste causes the release of methane (a significant greenhouse gas) , harmful leachates and odours.

This is achieved through a "Biological" process - either aerobic or anaerobic digestion with capture and use of the methane. The Biocentre process utilises aerobic digestion, or composting, achieved at accelerated rates in managed vessels.

Residual waste: just a load of valueless stuff?

The majority of material in residual waste is recyclable, and contains valuable resources, heavy metals and other materials which can be used in place of virgin material, yielding considerable benefits to the environment. The advanced MBHT process from Biocentre is particularly good at extracting high grade materials from the residual waste stream, leaving only a very small proportion (less than 10%) of stabilised waste for landfill or incineration.

Global Warming Gas Emissions Benefit of MRBT - Moving Towards Net Zero Carbon

Zero Waste Europe set out the benefits to CO2 (equivalent) reduction by simply pre-sorting residual waste prior to landfill or incineration using an MBRT process. The Biocentre process gives even greater benefits, as we have set out in other blogs on this website.

Figure: GHG emissions from treating 1 tonne of residual waste through different treatments assuming different carbon intensities of energy being avoided (0,22kg CO2/kWh) (MWS = mixed waste sorting).

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