ID and weigh system avoids ‘paying for fresh air’

Sulo reports that the use of its container identification and weighing system has allowed the University of Derby to improve dramatically the cost-efficiency of its waste collection operations. The new Sulo system now enables the University to pay for waste collection service by weight, rather than by number of bin lifts.

The data generated by the Sulo system is also helping the University to better plan and manage its waste collection operations, and is improving its recycling rates.
The instigator of the new regime, within the University of Derby’s environmental and energy office, Jo Seabrook, said: “Previously bins were emptied regardless of whether they were full or not. We were effectively paying for fresh air. With the new arrangements, using the Sulo weigh and ID system, we are only charged for the waste in the containers.”

The combination of the new waste collection regime and good recycling practice has given annual savings of around 10% (approximately £10,000), has reduced weekly bin empties by more than 20%, and has enabled the average number of bins needed on site to be cut by 13%.

Microchips on containers

Sulo’s system works with microchips, fitted to the wheeled waste containers, which carry unique electronic identification numbers indicating the size and type of waste contained. The comb-lift device on the collection vehicles is fitted with an antenna which reads the chips, together with an automatic digital “catch weigher” to weigh the bins as they are being lifted – a process called dynamic weighing because it does not interrupt the lifting operation.

The container identification number and weight is fed automatically into an on-board computer in the truck cab where the information is stored together with the date and time of the emptying. At the end of each round a data card (RAM card) is removed from the vehicle computer and the data downloaded on to an office PC. The data is processed, using software written by White Space Computers, and is used to prepare monthly invoice.

The data generated by the Sulo system also provides the University with a host of useful management data. Identifying the nature and volume of the waste going into each individual bin is particularly useful; the refuse from halls of residence, for example, is very different to that from the tutorial buildings. “We now know where the waste is coming from,” explains Jo Seabrook. “This allows us to match collections with demand. We now have, for instance, less frequent collections in the summer months when students are away and more frequent collections at the end of term when refurbishments are undertaken. But thanks to the Sulo system we are still only paying for the weight of waste removed.”

Most of the 30-plus companies invited to tender for the University of Derby’s new-style waste management contract were reluctant to adopt a ‘pay-by-weight’ arrangement. “Shanks Waste Solutions was the only company prepared to accept the ‘open book’ method of charging”, Jo Seabrook reports, “because they knew that the robustness and accuracy of the Sulo weigh & ID system would be up to the job.”

The system, which went into operation at Nottingham University at the same time as Derby, has proved so successful that it has been rolled out across all of the East Midland Universities consortium, with Nottingham Trent, Loughborough and Leicester universities now coming on stream. Leeds Metropolitan, Bradford and Harrogate Universities have also adopted the Sulo-base scheme, again with Shanks as the chosen contractor.