This method makes effective use of ability of metals to float on surfaces of leachates on their own. Due to the high proven efficiency of this method, it is widely used for removal of heavy metals such as iron and humic acid from leachates in many parts of the world.
Removal of Plastic from Municipal Waste
Plastic is a non-biodegradable waste that has low recycling margin. Unfortunately, plastic is widely used in everyday products is heavily present in the municipal waste. The environmental threat posed by the presence of plastic in municipal waste is another major issue. Major plastic types that are commonly found in UK municipal waste include PET, high density polyethylene, polyvinyl chloride, low density polyethylene, polypropylene, polystyrene, and other plastics such as melamine. Major source of these types of plastic are fizzy drink bottles, bottles of detergents and washing liquids, plastic plates cups and spoons, bin bags, microwavable trays, margarine tubs, food trays and packaging material for some toys and electronic items. According to Waste Online (2002), approximately three million tones of plastic waste are generated in United Kingdom every year. There are various alternatives to remove and recycle plastic e from municipal waste. According to Foster (2008), Film Separation is an efficient method to separate plastic from municipal waste.
Thermal methods such as Gasification can also be used to remove plastic waste from municipal wastes.
The most common method of removing plastic from municipal is physical collection. Labor can be employed to collect plastic ways physically from the municipal dumps and bring it to the recycle plants. Plastic can be removed and recycled using a combination of various processes including Film separation, whole item separation, Fake dry cleaning, Flake separation. This is a mechanical recycling method and is technically and economically feasible. A major constraint involve wit this mechanical removal and recycling method is that it is not effective for bottled plastic wastage. As mentioned earlier that a large amount of plastic waste that is present in the municipal waste dumps is comprised of bottle plastic waste. The limitation of mechanical method that is only effective for non-bottle waste implies that this method cannot be completely depended upon for effective and complete removal of plastic from the municipal dumps.
Considering the limitation of mechanical techniques of removal and recycling plastic waste. It is more feasible to contract physical labor in order to collect and remove solid plastic waste from the municipal dumps.
There are other forms of mechanical separation processes available too. The contaminants separation method is used where waste is put into cyclone separators and the turbines are rotated at very high speed. The contaminants are then separated from plastic in the separator. This is a very easy to use method and is also cost efficient and environment friendly. The extrusion method involves feeding the flakes into an extruder. This is a thermal treatment method where the flakes are pushed through a die which converts plastic flakes in long polymer products. This bring plastic in a re usable form.
Plastics can be a good alternative for energy resources. They store immense amount of energy and treating plastic on high temperatures can generate energy that can be effectively used in electricity generation and in many other manufacturing processes. This will reduce dependence on mainstream electricity generation methods such as fossil fuels. This will also prove to be more economical as fossil fuel such as oil and gas are expensive while waste plastic is available in great quantities in municipal dumps and landfills.
Untreated sewage and industrial waste emits harmful toxic substances into the environment and pose serious threats such as global warming, climate change and depletion of ozone layer. The industrial waste can harm marine species and human lives that are living around the vicinity of garbage and waste dumps. Untreated domestic waste such as plastic and aerosol substances also adds to global warming. Although United Kingdom has implemented a recycling and waste management system, but it is heavily dependent on conventional incineration techniques. These incineration techniques include thermal treatment of waste and have high emission content. This method is not feasible as far as environmental sustainability is concerned. On the other hand countries of European Union have much more cost efficient and environmental friendly waste management systems in place, while United Kingdom lags far behind. Since Waste management systems are employed in order to make environment safer for human sustainability and to create a balance in eco system, it is important that when designing and developing waste management systems, these constraints and potential threats are taken into account.
Colls, J 2002, Air Pollution, Spon Press, London.
Friends of Earth 2009, Briefing Pyrolysis, Gasification and Plasma, Friends of Earth Limited Company, viewed 25 January 2011, < http://www.foe.co.uk/resource/briefings/gasification_pyrolysis.pdf>.
Hill, T 2010, Pyrolysis and Gasification briefing, UK without incineration, viewed 25 January 2011, < http://www.foe.co.uk/resource/briefings/gasification_pyrolysis.pdf>.
Fantom, I 2005, Should I replace my ESP with a Fabric Filter? Filtration Society, Birmingham, England.
Fay, J & Golomb, D 2002, Energy and the environment, Oxford University Press, London.
Kneese, a & Bower, B 1979, Environmental quality and residual management, Resources for the Future, Baltimore.
Robinson, H & Maris D, 1985, 'The treatment of leachates from domestic waste in landfill sites' Water Pollution Control Federation, vol. 52, no. 1, pp. 30-38.
Ifeanyichukwu, M 2008, New leachate treatment methods, Lund University, Sweden,