POWDERED CARBONS.

.When using powdered carbon, this is added to the product that is being purified in a tank that has enough agitation in order to get an homogeneous suspension. After giving the adequate contact time, the carbon is removed either by sedimentation or filtration. For the latter, it is advisable to use a helping filter to get a more efficient filtration. When possible, it is recommended to have a small tank where the activated carbon suspension is prepared -with water or with a clean liquid- and the powder is allowed to moisten perfectly.

The suspension is later added to the treatment tank.

The powdered carbon operation is more versatile because the dosage can be modified depending on the quality of the liquid that is being purified, so reducing variations in the process. In addition, the equipment needed is very simple and conventional, therefore the required investment is low.

The dosage range can be determined by using Freundlich isotherms described before. In general, it can be said that the carbon dosage in most of the applications is lower than 2%. Sometimes, the isotherm for a certain application shows a very steep slant that means that to achieve high purification levels, a high dosage of activated carbon is needed. Such being the case, to improve the use of the carbon and to reduce its dosage, the double countercurrent contact is a good option. This process consists in a first treatment with activated carbon that has been "used once". Then, the liquor obtained is treated again, but now with virgin carbon.

The final liquor would have a better quality than the one that only had one contact. The carbon that is collected from this second filtration is precisely the one that is used again for the first treatment.

The result of the double contact means important saving of carbon that can amount to 50% or more. Yet, before making a decision, the need for more equipment and more labor must be considered. An approximation to double contact is achieved by taking one of the filters used to filtering liquor with carbon, and instead of throwing away the cake and washing it, use it to filter the untreated liquor before sending it to the carbon treatment tanks. This double contact, although not as sufficient as the one mentioned above, requires less additional equipment.

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[ The Mystery of Activated | Activation Process | Classification of Activated Carbon | Liquid Fase Purification | Gas Fase Purification ]