The London Borough of Bromley has bought a twin chamber vertical composting unit from Lincoln-based OrrTec which will process over 2,500 tonnes of green waste a year.
The in-vessel composting unit cost 190,000 including shipping and installation costs, but the council could not have bought the unit without the help of London Remade who gave the council a grant to buy a top loading agricultural shredder, a tractor to drive the shredder and a hydraulic trailer. Green waste has to be shredded before it can go through the in-vessel plant and Bromley needed to up-grade its shredding equipment so that the shredder could keep pace with the plant and enable a higher volume of green waste to be processed.
The composting unit at Bromley's Waldo Road transfer station/civic amenity site is currently up and running but will not be working at full capacity until the middle of February when it will be able to process about 20-25 tonnes a week.
Andrew Bale, of Bromley Borough Council, explained that the unit will increase the amount of green waste composted in the borough as currently most of it is although some is transported to a site in Surrey for composting. The composting unit will also save the council green waste transport and disposal costs which currently stand at about 40-50 a tonne.
Kerbside
In February, Onyx takes over the council's collection contract and this will see also the start of a collection of green domestic waste from 10,000 homes. Mr Bale explained that some of this will be fed into the in-vessel system and that the rest of the green waste collected from the kerbside will be composted at local farms.
But Mr Bale said that some of the green waste taken to the civic amenity sites would still have to be landfilled because of the high volume, some 12,000 tonnes delivered annually, the authority was currently “hard-pressed” to compost it all.
The New Zealand-made in-vessel composting system has been brought from OrrTec. Matt Pumfrey, director of OrrTec, explained that the process will see about five tonnes of the green waste that the site receives each day. The rest of the green waste will be landfilled or composted elsewhere.
He said: “Green waste will be dropped off at the site by the general public and this material is then composted on site and used by the council on their parks and gardens. This removes the need for costly transport of material from the site to a windrow plant out of the city.”
Mr Pumfrey added: “This is the first of a number of facilities we are installing this year, including a 5,000tpa facility going into Dublin in the spring. We have also installed a site in Lincolnshire for a company looking to process food waste and we are installing another one in London with a few more awaiting funding.”
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