The term, abbreviated as MBT, refers to a process for handling waste that serves as an alternative to landfilling or incineration, or a process that reduces substantially what waste has to be landfilled or incinerated. In MBT, certain constituents of a waste stream, and it is most often applied to household or municipal waste, are separated by mechanical means and certain constituents are biologically treated. The intent is to re-use, recycle or treat the waste in part to reduce the organic content before the residue is landfilled.
The mechanical treatment includes sorting out different kinds of metals, shredding or reducing the size of materials and other forms of screening materials. The process separates out metals, glass and what is called a high heat value fraction also known as Refuse Derived Fuel (RDF) used to generate energy.
The amount of waste remaining can be subjected to a biological treatment that includes aerobic decomposition and anaerobic digestion that reduces the volume and organic content of the remaining waste. Anaerobic digestion breaks down the biodegradable component of the waste to produce biogas and soil improver. The biogas can be used to generate electricity and heat. Some of this material can be used for landfill cover. Biological treatment can also refer to a composting stage. Here the organic component is treated with aerobic microorganisms. They break down the waste into carbon dioxide and compost.
Some of the waste still has to be landfilled, or incinerated, but this waste is generally inert and it reduces the waste volume to be deposited to at least a half thus extending the lifetime of the landfill.
Some further ideas to explore on Mechanical Biological Treatment:
Identify the constituents of municipal waste that can be subjected to MBT and which process (mechanical or biological) is applicable.
For each constituent identified above, what waste remains after treatment and how is that waste disposed?
Can we eliminate incineration by adopting MBT?
Northern Ireland Environment Agency, Guide to the Regulation of Outputs from the Composting and Mechanical Biological Treatment of Waste, January 2009.
Guinan, B. Kristiansen, T. Milton, D. “Critical Analysis of the Potential of Mechanical Biological Treatment for Irish waste Management”. Associated datasets and digital information objects connected to this resource are available at: Secure Archive For Environmental Research Data (SAFER) managed by Environmental Protection Agency Ireland erc.epa.ie/safer/resource?id=d22d6f8a-217b-102c-b381-901ddd016b14
European Environment Agency, Diverting waste from landfill: Effectiveness of wastemanagement policies in the European Union (Report No 7/2009).