Anaerobic Digestion"s Popularity and Fame Rising Due to BBC Radio 4"s Archers Programme
It remains a fact that, even now, more than 65% of all Municipal Solid Waste (MSW) thrown out in England and Wales is disposed of in landfills.
The European Commission has set targets to reduce the levels of biodegradable materials going to landfill in the EC landfill directive which means that the.
The most significant challenge facing the management of Municipal Solid Waste is now the huge task of finding ways for treating the biodegradable component of MSW and disposing of it away from landfills, and AD processes can help greatly here.
Biodegradable Municipal Waste (BMW) is the part of the waste that will break down naturally in the environment, and it is the part of the rubbish that goes into landfills which causes the bad neighbour problems experienced around landfills.
This type of waste also generates odours, and attracts birds etc.
This organic waste includes: kitchen wastes, green or garden wastes, cork, paper and non man-made textiles (eg cotton and wool).
The need to reduce the levels of biodegradable materials going to landfill is based on concerns over greenhouse gas emissions that contribute to global warming.
The decomposition of biodegradable materials within landfill sites results in the production of methane, a potent greenhouse gas.
One of the best options for dealing with the biodegradable fraction of municipal solid waste is Anaerobic Digestion.
It is a natural process.
It is simply rotting or composting in the absence of air.
The magic is though that it produces methane, and methane is a raw product which can be sued to make biofuels including bio-diesel, and many others.
If you don't believe us about this then listen to the BBC Radio 4's long running soap, the "Archers" in which there is, at present, a storyline about AD.
How does the Anaerobic Digestion Process Work? The waste is delivered to the plant and is sorted mechanically first, to remove as far as possible all non-biodegradable (putrescible) contaminants.
This commonly may involve screens, air classifiers and/or magnets.
The organic waste is then shredded and water is added and the resulting mix is pumped to an enclosed vessel where it is heated, stirred and held for from 1 to 3 weeks whilst bacteria digest the waste and emit a gas consisting of about 60% methane and 40% carbon dioxide.
After this the solid digested material is pressed to recover the added water.
The solid digestate is placed in piles to aerate for about two weeks.
Once the digestate has been aerated it can be used as a soil improver or as part of a growing media, in the same way as compost.
If the material is derived from mixed wastes sources additional sorting may be required to remove contaminates.
The liquid fraction can be recirculated in the process but some excess is generated and depending of the feedstock this can be used as a fertiliser or if the waste is contaminated it has to be disposed of to sewer.
The big appeal of AD is that the main end product (a biofuel) will always find a market for sales, and the value of that market is rising.
The European Commission has set targets to reduce the levels of biodegradable materials going to landfill in the EC landfill directive which means that the.
The most significant challenge facing the management of Municipal Solid Waste is now the huge task of finding ways for treating the biodegradable component of MSW and disposing of it away from landfills, and AD processes can help greatly here.
Biodegradable Municipal Waste (BMW) is the part of the waste that will break down naturally in the environment, and it is the part of the rubbish that goes into landfills which causes the bad neighbour problems experienced around landfills.
This type of waste also generates odours, and attracts birds etc.
This organic waste includes: kitchen wastes, green or garden wastes, cork, paper and non man-made textiles (eg cotton and wool).
The need to reduce the levels of biodegradable materials going to landfill is based on concerns over greenhouse gas emissions that contribute to global warming.
The decomposition of biodegradable materials within landfill sites results in the production of methane, a potent greenhouse gas.
One of the best options for dealing with the biodegradable fraction of municipal solid waste is Anaerobic Digestion.
It is a natural process.
It is simply rotting or composting in the absence of air.
The magic is though that it produces methane, and methane is a raw product which can be sued to make biofuels including bio-diesel, and many others.
If you don't believe us about this then listen to the BBC Radio 4's long running soap, the "Archers" in which there is, at present, a storyline about AD.
How does the Anaerobic Digestion Process Work? The waste is delivered to the plant and is sorted mechanically first, to remove as far as possible all non-biodegradable (putrescible) contaminants.
This commonly may involve screens, air classifiers and/or magnets.
The organic waste is then shredded and water is added and the resulting mix is pumped to an enclosed vessel where it is heated, stirred and held for from 1 to 3 weeks whilst bacteria digest the waste and emit a gas consisting of about 60% methane and 40% carbon dioxide.
After this the solid digested material is pressed to recover the added water.
The solid digestate is placed in piles to aerate for about two weeks.
Once the digestate has been aerated it can be used as a soil improver or as part of a growing media, in the same way as compost.
If the material is derived from mixed wastes sources additional sorting may be required to remove contaminates.
The liquid fraction can be recirculated in the process but some excess is generated and depending of the feedstock this can be used as a fertiliser or if the waste is contaminated it has to be disposed of to sewer.
The big appeal of AD is that the main end product (a biofuel) will always find a market for sales, and the value of that market is rising.
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