A cautionary tale about HTT …

Mystery surrounded what was being built just up the road in Derwenthaugh, near Gateshead. Our MRF had been running for over a year and we were proud of this system, but could we be getting some serious competition?

We soon found out it was to be an autoclave plant similar to the one in Rotherham operated by Sterecycle. This meant that we could have some real problems in winning a MSW contract from Sunderland City Council if it worked as they said it would.

I had a contact in the company which was supplying the post-autoclave segregation machinery. They called me and asked if Alex Smiles Ltd. could help with an analysis of the product coming out of the thermal treatment. Of course we were willing to help (especially if we could have a look around the plant.)

The problem was ‘crocodiles.’ What? The rivers Tyne, Derwent and Wear have been cleaned up a lot recently, but I hadn’t heard of crocodiles following the salmon upstream!

The crocodilians in question were, in fact, an artifact of the thermal treatment process which consisted of tightly wrapped fabrics and other materials which retained many of the recyclables that the plant was designed to segregate. This solid mass was simply rolling over the screening machines with very little result.

We determined that by running these ‘crocodiles’ through our trommel, which co-incidentally rotated in the opposite direction to the autoclaves, we could unwind the fabrics, releasing the recyclate and allowing the following screens to segregate the wastes as designed. Another effect of this rotation was to release the retained heat in the form of steam. Another success for a little bit of lateral thinking.