What MBT is

MBT stands for Mechanical Biological Treatment.

MBT is a technology which maximises the recycling and reuse and recovery of materials and energy. It complements the existing recycling activities, such as the dry recyclable waste already collected from households, which will continue to be collected and processed at NEWS' modern waste recycling facility in Costessey.

MBT uses a three stage process:

• Mechanical Pre-Treatment - The mixed household waste is subject to a number of screening and separation processes to recover materials for recycling such as metal and plastic bottles. Organic material is also prepared for the next stage - biological treatment.
• Biological Core Treatment - gravity-fed dry anaerobic digestion. Anaerobic digestion reduces organic waste to a solid residue similar to compost in an oxygen free environment. The mixed waste is introduced into large vessels for a period of 21 days which allows biological breakdown of the organic fraction (food waste, paper, cardboard). Methane gas is generated.
• Mechanical Biological Post-Treatment - Gas generated in the anaerobic digestion vessels is collected and transferred to gas engines which use the gas as fuel to generate electricity. The material leaving the digestion vessels is subjected to further separation techniques to remove sands and minerals for recycling. The remaining material is finally moved to in-vessel composting tunnels for further stabilisation through aerobic composting.

This series of proposals has been chosen to provide a resource recovery approach to waste management and will complement existing and future opportunities on re-use and recycling.