Automated waste sortation for councils

An Australian waste sortation specialist has devised a turnkey system for councils and regional bodies that uses automated primary sortation as a fast starting point to separate different types of waste.

Using the trommel can, in many cases, all but eliminate the system of manual sortation at the primary stage, which for a long time has been the solution of choice by most councils and waste-handling authorities around Australia.

Used for primary sortation of comingled products, the trommel sorts beverage containers such as plastic, glass and ferrous items (aluminium cans and steel cans). It has two grades of screens and is 10 m long and approximately 2 m in diameter.

Its two stages of processing involve different screening processes. Stage 1 is the initial fines separation. Using small diameter holes in the screens, stage 1 takes fines out of the system - items such as tiny bits of broken glass and bottle tops - and allows the recyclables to continue on to stage 2.

Stage 2 separates beverage containers and paper. Larger diameter holes in its screen allow these beverage products to drop through, while any paper or cardboard product in the mix is conveyed away to a secondary sorting system. This includes paper-based product such as newspapers, magazines and catalogues as well as some cardboard.

The trommel is a highly effective primary sorter, however, a small amount of carry-through paper is always likely to come through so, at this point, all product that has dropped through the stage 2 screen of the trommel is deposited onto a ‘bounce adherence’ conveyor to find this paper and move it to the main paper stream where it belongs.

The bounce adherence conveyor belt oscillates up and down to make the paper and cardboard products grip, thus moving them up along the conveyor while the remaining beverage container waste travels downwards with gravity.

All paper product taken up by the adherence bounce conveyor again joins with the main paper stream. Product discharged from the bottom of the bounce adherence conveyor gets sorted and separated as glass, steel, aluminium and plastic - an air separation system picks up plastic product while the heavier products such as glass do not.

At the very end of the system, operators physically sort and separate the glass according to colour (clear, green or brown). This task is the only manual element of the entire waste sortation system.

Trommel-based waste-handling systems can be designed and installed as an OEM solution or as a refit to an existing site where space constraints may be limited.