B3.2 continued…
On average, each person in the UK, throws away seven times their body weight (about 500kg) in rubbish every year.
Composting
Composting is the breakdown of biodegradable waste by micro-organisms. Technology in composting has improved and it is now estimated that over 1 million tonnes of waste are composted every year.
The key problems with composting are the space required, the quality of the material provided to be composted (free from contaminants etc) and the potential odour problems.
Babies’ nappies makes up about 2 % of the average household rubbish. This is equivalent to the weight of nearly 70,000 double decker buses every year. If lined up front to end, the buses would stretch from London to Edinburgh.
Fluidised Bed Technology
Fluidised bed technology is a new system that operates by feeding waste onto a bed of ‘fluidised’ sand particles. Combustion is considered to be more thermally efficient than incineration and the production of pollutants is lower.
Anaerobic Digestion
Anaerobic digestion is an established technique for the treatment of wet organic wastes, such as sewage sludge and slurries. The process is similar to the anaerobic breakdown of biodegradable material in landfill sites. However the anaerobic digestion is operated under controlled conditions so that the biogas produced is captured and the breakdown of matter is rapid. The process can achieve an 80% reduction in weight.
Fermentation
Fermentation is considered an emerging technology. This is the same process as that used in brewing beer or wine. Anaerobic organisms break down the waste into a stable solid ready for disposal, and a liquid fuel. This option is mainly used for agricultural waste but could be extended in the future to municipal solid waste.
Feedstock Recycling
Feedstock recycling, another emerging technology, involves using polymer cracking, a chemical process, to break down plastic. This may be a limited solution as the operation should be located near to petrochemical facilities, due to the environmental impacts relating to transport.
Feedstock Substitution
This is another emerging technology, although it has been used in Germany since 1996. This process uses the mixed plastic as a substitute for coal or natural gas in the iron and steel-making process.