How A Waste Disposal Unit Can Help The Environment
Food waste that is dumped on landfill sites gets converted into methane which is a very powerful greenhouse gas, 25 times more damaging to the environment than C02 and a major contributor to climate change. Government and local councils in the UK are working towards reducing landfill in order to meet stringent targets to comply with European Union regulations.
The EU Landfill Directive states that all Member States must reduce the amount of biodegradable municipal waste (such as food and garden waste, and paper and paperboard) sent to landfill to: 50 per cent of that produced in 1995 by 2013 and to 35 per cent of that produced in 1995 by 2020. In order to make this happen landfill taxes have been introduced which are now £72/tonne. This is on top of normal landfill fees by businesses and local authorities. This is why local councils in many parts of the country have now introduced charging for bin bags.
A Better Way – Anearobic Digestion
The anaerobic digestion (AD) process is a well proven renewable energy technology. Additionally it reduces greenhouse gas emissions by capturing methane from the decomposition of organic materials, such as livestock manures, slurries, sewage sludge and food wastes. By harnessing the natural process – where organic matter is broken down by bacteria in the absence of oxygen, in a closed vessel – it enables the production of biogas that can be used as a renewable energy source for both for heat and electrical power. The treated digestate from the process can be used as fertiliser. As an additional benefit the presence of food waste from disposal units also improves the efficiency and running of the sewage plant.
Each tonne of food waste that is processed by a WDU and sent to the sewage works will not only avoid the 25 tonnes equivalent of greenhouse gases (by preventing methane being made in the landfill) but will also save a tonne of CO2 from being produced by virtue of substitution, ie by burning 1 tonne of methane and creating electricity it means that the power stations burn 1 tonne less of coal.
AD is the now the method favoured by water companies in England and Wales for dealing with waste water sludge and many have anaerobic digesters attached to water treatment plants. By 2015 85% of the final sewage sludge will be digested into methane and in turn converted into electricity. Studies in Sweden have shown that adding the food waste output of WDUs to the sewage waste stream can increase biogas capture by as much as 46%.
WDU’s offer significant advantages over composting and collection. Most significant are the space savings, avoidance of smell and vermin, and the fact that methane is captured resulting in carbon savings.
Worldwide Use of Waste Disposal Units
In the UK only a small number (about 6%) of householders have adopted this convenient and eco-friendly way to dispose of food waste. Other parts of the civilised World are far ahead of the UK being led by the USA where 50% of households (80% in new homes and 94% in California), Sweden (46%), New Zealand 34% , Australia 20%.