Waste Types:

People produce a variety of types of waste. Household waste is usually called MSW (Municipal Solid Waste) but this often includes street sweepings and the contents of litter bins as well.

Businesses produce what is known as Commercial and Industrial Waste. Some of this is in the form of food waste. Hospitals produce clinical waste, and there is also farm slurry or Agri-waste. and even Sewage Sludge.

Although not waste, material left out for kerb-side recycling also has to be the responsibility of the local waste management structure. It makes sense if the type of waste process chosen, can deal with as many of these as possible to make smaller units viable.

Transport:

If a method of waste management can only deal with small range of waste streams, then in order to be efficient it needs to transport waste from all over Cornwall.

Transporting waste is bad for the environment due to engine emissions, has a high cost, and causes problems due to road congestion. Therefore the ideal solution should treat the waste close to where it arises to eliminate excessive transport.

Nuisance:

Waste has a number of problems associated with it that can cause nuisance to neighbours. These are the smell of rotting material, the dust which can blow around from waste and ash tips, the noise associated with working machinery, and germs and vermin which feed on waste.

The best system would handle the waste in such a way that it was treated immediately it came onto site rather than being stored.

The handling of waste should be within closed buildings with negative pressure. Large mechanical processes should not take place in the open air where the sound pollution could carry to nearby houses.

Energy Efficiency:

The main driver in the waste processing industry is the energy that is derived from the process. It is the most valuable commodity. However it is the efficiency which is the key point.

There is quite a lot of energy in paper, but there is no point in burning ten pound notes unless you get more than ten pounds worth of energy as a result. Calculations based on efficiency are the main compromise that dogs the waste process.

• How much energy has to be put into the system to start it up?
• How much energy is needed to keep it going?
• Do you have to consume items that have a value as an asset that could be recovered?
• Is the energy produced in a useable form?

Most systems either burn something to produce heat or produce a fuel which can be burned to produce heat. Steam produced from the heat can be used to power turbines, or gas or oil fuel can be used to run engines coupled to generators. The best system would be the one which produces the most power without destroying valuable assets.

Impact:

If only one plant is planned for the whole of Cornwall, then it will be quite large.

Some kinds of technology need a very big structure to house the machinery used in the process.

Those which emit airborne pollution need very high chimneys. If the process is in any way dangerous the perimeter fence needs to be well away from the area of hazard.

If large amounts of waste or residue are to be stored, this also increases the size of the "footprint" of the plant.

In order to reduce the visual and environmental impact on local residents, the size of the plant needs to be kept as small as possible.

Bi-Products:

When the substances contained within waste are rearranged by the treatment process, it is possible that useful bi-products are formed.

Some systems produce glass or ash or stone residues that can be used instead of aggregate in concrete. Others produce products that can be used as soil enhancer or compost.

Where recyclable materials can be sorted from the waste, they too can be reclaimed either for direct reuse, such as whole glass bottles and jars, or to be remade into the same products such as broken glass cullet, and shredded plastic, that can be pressed into new products.

Other recovered materials can have new uses, metals can be recovered as scrap and turned into ingots, paper and wood pulp can have the fibres filtered out and these can be used to make cardboard, wood boards and insulation materials.

The best system would be the one that enabled the most substances to be turned into useful by-products, particularly if this could be done close to the waste plant so that there was no transport involved.

Emissions:

As well as piles of residue that are obvious, some waste processes produce emissions to air land and water which are much more insidious because they largely go unnoticed.

What appears to steam could be a whole cloud of hazardous gas and particles that will eventually fall to the ground. Some substances leach into the water courses and pollute rivers. Most technologies have monitoring devices to check on emissions. However, there is continual debate concerning which substances are harmful, how big the risk could be, and how effective the monitoring is.

In any case, the people who live near to such plants do not like the idea that they are breathing in pollution, or that their property is contaminated by fall out. Therefore it would be advantageous if the process produced little or no emissions.