Milton Keynes Waste Recovery Park is a world-class waste treatment facility, which is due to be fully operational in 2016. The facility aims to deal with Milton Keynes’ black bag waste in a sustainable way by incorporating three different types of treatment on one waste treatment site: mechanical treatment (MT), advanced thermal treatment (ATT) and anaerobic digestion (AD). Annually, an estimated 132,000 tonnes of residual municipal or black bag waste will be processed at the facility.
As well as setting an ambitious 70% recycling target by 2024/25, Milton Keynes Council has introduced a ‘no mass burn’ policy and set a target to reduce the volume of waste it sends to landfill to around 3% by 2019/20. Key to achieving all three of these objectives is its ground-breaking Waste Recovery Park, which is being built and will be operated by Amey.
Once fully operational, the MT plant within the facility, which has been designed by Stadler UK, will process some 70tph of black bag residual waste. This waste stream contains a variety of valuable, recyclable materials including mixed plastics, PET/HDPE, bricks and rubble, cardboard, film and metals.
Milton Keynes Council and Amey have chosen to focus on the recovery of three grades of plastics: PET, HDPE and mixed plastics. In order to maximise the recovery of these materials, the infeed material will firstly be screened to separate out the organic fraction (fines of 70mm or below). The high content of organic material is one of the biggest challenges when treating MSW and can significantly affect the quality of the recyclables output, so this organic matter will be targeted and removed early on in the process, to be treated in an Anaerobic Digestion process on site.
Once the infeed material has been screened, air knifes will separate the light items from the heavy and ballistic separators will be used to separate the 2D (flat) material from the 3D (rolling) items. The aim, in following this process, is to ensure that the material is in the best condition possible for going on to the next stage in the process.
Once this upfront mechanical treatment has taken place, near infrared (NIR) sorting technology supplied by TOMRA Sorting Recycling (TOMRA) will be used to separate out three grades of plastic: PET, HDPE and mixed plastics. Given the nature of the black bag infeed material at the plant, it would be virtually impossible to sort and recover materials such as plastics using manual labour methods, both from health and safety and a practical perspective. However, optical sorting overcomes these challenges and is able to operate at 7tph despite the dirty nature of the infeed material.