The sophisticated energy recovery plants devised by Tidy Planet for DHL are now producing 25,500kW a day of heat from the food waste at London’s Heathrow and Gatwick airports.
The technology hit the headlines in November 2016, and Tidy Planet has now revealed more detail behind the patented technology that tackles 10 tonnes a day of complex material at Gatwick.
“The process begins with pre-sorted organic material being tipped on to a conveyor,” said managing director Simon Webb.
“The material then enters an Untha RS40 four-shaft shredder. Sitting at the front of the line, this machine liberates the organic materials and reduces them to a homogenous 20mm particle size, so that they can be processed optimally by equipment further downstream.
“The shredder includes a foreign object protection mechanism, which means that unexpected contaminants, ranging from teapots to metal drums, can be processed without causing the machine damage.”
The material is then conveyed to a Gobi drying system, where it is exposed to high temperatures to create a powdered biomass fuel. When it reaches a moisture content of less than 10%, it is cooled before a rotary screen sieves out any remaining plastic and foil packaging.
Web added: “The removal of such plastic and foil – which is used in a neighbouring energy-from-waste facility – means the result is a certified high-quality biomass fuel which powers DHL’s biomass boiler.”
DHL’s Flight Catering Centre at Heathrow also has an Untha organic waste shredder at the front end, a RS30, which is tackling five tonnes a day.