Sludge Cleaning Machines

2003/03/28 Andonegi Beristain, Garazi - Elhuyar Zientziaren Komunikazioa

• Ingurumena
• Energia

This legislation proposes the opening of new facilities in Gipuzkoa. In addition, the amount of water
and organic matter of the waste will be limited due to the problems generated in the treatment plants.

All this will lead, on the one hand, to an increase in the amount of sludge and, on the other hand, the treatment of these sludge must be carried out right here. Therefore, it is important to remove most of the water contained in these sludge and recycle the organic matter contained therein.

Sludge drying and gasification

As mentioned, most sludge concentrates on water, specifically 90-95%. Mechanical treatment of this water is currently used in all treatment plants, but the results are not desired. For this reason, a plan has been put in place for replacing these systems with heat treatment systems. Specifically, thermal drying systems allow more water to be removed from sludge and a solid waste containing only 15-20% water.

INASMET gasification prototype.

These dry sludge are used in the gasification prototype developed by Inasmet. In this prototype, sludge is
gradually introduced into a bed of sand that is bordering between 800 and 900°C. This bed of sand has a height of one meter and makes it circulate through the air that passes through it. Specifically, the temperature and the air are those that evaporate the organic matter and the water that contain the sludge and, therefore, those that produce the gasification. In addition, at all times the amount of oxygen in bed is controlled to prevent combustion.

Gasification produces mainly carbon monoxide and hydrogen, but in addition to these gases carbon dioxide, methane and water vapor are obtained. Finally, the result of gasification is a group of gases suitable for combustion. This group of gases is very useful for entering a combustion process and obtaining heat or electric energy.

This is another possibility offered by the prototype: in addition to sludge treatment, it produces an energy-exploitable raw material. In addition, it should be noted that the new sludge drying systems installed in the treatment plants, with heat treatment, will increase the consumption of electric energy, and if this energy is obtained from the gasification plants, the energy balance will balance it.

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