As Tesco and its waste management company DS Smith incorporated food waste segregation and backhauling into its reverse logistics operation, they needed a solution to empty 350kg roller cages full of food waste into a walking floor trailer for transportation to an anaerobic digestion facility.
John Masters, procurement manager at Tesco, explains: “We wanted to use this waste stream to generate green energy. With the introduction of a plastic liner, the four-side roll cages allowed segregation and removal of the 700+ compactors at stores, and consolidated the waste at our recycling service units.
“But the material needed to be decanted into the walking floor trailer for further treatment off-site. This needed to be done efficiently and safely.”
Nicholas Power, DS Smith recycling division’s account director, adds: “We had a number of conversations with companies large and small, but it wasn’t until we spoke to Whitham Mills Engineering that we felt we were moving in the right direction.
“When we saw the simplicity of their proposal, it looked right and sounded right. With a few tweaks, we had a working design and an operational prototype within a few weeks.”
The newly designed cage tipping system sees much of the process being automated, with operator input kept to a minimum. To tip the cage on to the conveyor, the operative presents the cage, door open, into the housing of the tipper system. With the safety guard in place, the system is activated from the control panel on the external wall.
The cage is lifted in two stages. In the first lift, the base of the cage is raised in an arc so that it comes to rest higher than the top of the cage. After a couple of seconds, hydraulics push the front of the cage upwards to a horizontal position, parallel with the floor but 2m higher. Held in this position for a few seconds, the waste is guaranteed to be deposited into the conveyor.
The system then operates in reverse with the empty cage still locked in place, before being removed. The whole process takes around 70s.
Ben Smart, managing director of Whitham Mills, says: “We have now installed this system in 10 of Tesco’s recycling service units, and our design is proving to be a valuable addition to their recycling operations. It was a challenging brief which tested the mettle of our best brains, but it is pleasing to see the system in operation across the country.”