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October 23, 2007

Better recycling plants planned for the UK

BY 2011 all the broken kettles, potato peelings, smashed glass, holey socks, margarine pots, dirty tissues, light bulbs and pet litter thrown away by the 1.4 million people who live in Lancashire, UK, will be whisked away to two recycling plants near Preston.

Conventional recycling handles about 50% of household waste. The new plants would handle 70% and eventually 85% of household waste.

Mechanical biological treatment plants (MBTs) aim to "mine" all waste. But they have struggled to convert the organic-rich mush into a marketable product. The problem with composting it, a seemingly obvious solution, has been contamination.

Using a patented process for decontaminating and separating waste, the Lancashire plants will transform this goo into high-grade compost. What's more, burning the methane produced by the bacteria that feed on this waste will fuel the plant and return electricity to the national grid.

The two Lancashire plants are in the early stages of preparation and will be run by the Australian company Global Renewables (GRL), whose first plant in Sydney was up and running in 2004. Companies like GRL are fast becoming the commercial face of a trend towards "zero waste" a future in which every last gram of waste is reused and landfill is a thing of the past.


As waste enters the plant, workers wearing protective gear sift through it by hand to remove most of the 3 per cent of waste deemed toxic, such as kidney dialysis tubing, paints, gas cylinders, asbestos, computers and car batteries. The remaining organic-rich matter is then piped to a percolator, which washes and aerates it, removing specks of glass, metal and plastics and dissolving some carbon.

The carbon-rich liquid is then fed to a digester, where anaerobic bacteria break it down to produce methane. In Lancashire, the methane will be used to generate 25,000 megawatt hours of electricity each year, which will run the plant, with any excess going to the national grid.

The solid residue, meanwhile, is composted for a couple of months. Initially, GRL plans to use it to plant 100,000 trees a year to rehabilitate old industrial land. To go mainstream though, the compost will need to be sold widely, which could be hard.

The International Biochar Initiative, a group of scientists, policymakers and farmers, believes that organic-rich waste can be used to make a biofuel whose by-product is both a soil improver and a carbon sink.


FURTHER READING
The Lancashire recycling project is a 25 year deal worth more than A$5 billion (£2 billion) over the full term

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