techbulletin care handling bacteria carbon

8/10/2019 TechBulletin Care Handling Bacteria Carbon

1/3

Carbon Resources

2535 Jason Ct. Oceanside, CA 92056 760-630-5724 fax 760-630-9930 www.carbonresources.com

Technical Bulletin

TM

Activated Carbon Products

THE CARE AND HANDLING OF ACTIVATED CARBON

Activated carbon adsorbent media is easy to use and easy to handle. If stored properly, it has an indenite shelf life. Iis non-toxic and relatively nonammable. If it has become wet or damaged through improper storage, it usually can bdried out or restored easily. After it has become saturated with contaminants, it often can be reactivated to virtually itsoriginal adsorptive capacity with only a slight volume loss during reprocessing.

Activated carbon is a form of commercially pure carbon typically manufactured from coal, wood, peat or coconut shelhaving a microscopic physical structure. Each granule contains millions of tiny passageways or pores, which provide tremendous internal surface area and which accounts for its adsorptive power. The surface area of activated carbon istypically 600 to 1200 square meters per gram depending upon the type and grade of product. It is used to purify air

and water, recover valuable vapors and liquids, catalyze chemical reactions and aid in the manufacture of highly purieproducts. Activated carbon is available in a wide variety of granular sizes, powders, beads, shaped pellets, cloth, padsbers. The physical form used is dictated by the service application and in some cases, pressure drop considerations.

HANDLING AND STORAGE: Activated carbon is stable and can be stored for many years in its shipping container package if protected from contaminating vapors and liquids. Typical packaging options include large supersacks (100-2000 pounds), mini-supersacks (200 500 pounds), small bags (20 55 pounds), Gaylord type boxes (200-1000pounds) and steel or ber drums (50 200 pounds). Activated carbon deteriorates only by doing work, that is, by actias a catalyst or adsorbing vapors, gases and dissolved substances. Because it is relatively pure carbon, it is resistant toacids, alkalis, chemicals, and corrosive substances. Repeated heating and cooling has little effect on its physical struct(In solvent recovery plants, the adsorbent has been subject to as many as 10,000 heating and cooling cycles with noappreciable breakdown of the granules or pellets.)

The best grades of granular activated carbon are hard and abrasion resistant, but methods of handling that tend togrind the product should be avoided. In vapor treatment systems, a high-velocity or non-uniform air ow may causemovement of the particles and rapid wear or breakage of the granules, particularly if the top of the carbon bed is not hein place by a screen. Upward ow of uid at high velocities during adsorption should be avoided, because it tends tolift the granules and causes channeling. The method of handling activated carbon must be suited to the exact characterof the product being used. For example, a powder has different considerations in connection with its handling thandoes a granular material. Impregnated carbons generally have somewhat lower ignition points than non-impregnatedcarbons. There are exceptions to this, but one must give special attention to ignition points in connection with carbons which have been impregnated or given other special treatments. Manufacturer product specication sheets and MSDSinformation provide important details such as carbon ignition temperature.

For the purication of air in living and working spaces, the adsorbent should be reasonably dry. It is not sensitive tomoisture, but if it is dripping wet, its capacity will be reduced. If it has become saturated, it can be dried in an ovenat 200F to 250F. Wet activated carbon tends to corrode mild steel, aluminum, and some other metals. For wetapplications, stainless steel, monel nickel, plastic, glass or ceramics can be employed satisfactorily for container vesseFor most dry applications, ordinary steel, aluminum, plastic or paper are suitable for container materials.


2/3

Carbon Resources


Technical Bulletin

TM


If a particular grade of granular carbon contains too much dust or ne granules for a given application, they may beremoved by screening, air-hosing, or water-washing. The dustiness of most powdered carbons can be reduced by addi10 to 30 percent moisture.

HEALTH AND SAFETY: Activated carbon is not toxic. Many types meet FDA Codex requirements for food gradeapplications and many are also approved by AWWA and NSF for drinking water treatment. In addition, some grades oactivated carbon are USP certied and are taken internally for various medicinal treatments. Dust exposure is a conce with some activated carbons and normal dust handling procedures should be used such as eye protection and dust masfor personnel handling the carbon and room dust lters to keep dust level under control.

Activated carbon is combustible, but not easily ignited. In the absence of a forced draft, even hot activated carbonsupports combustion with difculty and, under some conditions, will extinguish on its own accord. It should not besubjected to a blast of air at temperatures above approximately 400F, however. Where high concentrations of vapors adsorbed, the heat of adsorption (adsorption is an exothermic reaction) may be sufcient to raise the temperature of thcarbon appreciably. In such cases, it may be best to operate with the carbon partially wet with water, as is typically doin solvent recovery plants, or to reduce the vapor concentration by adding additional air.

VESSELS CONTAINING ACTIVATED CARBON: Care must be exercised in entering tanks or other enclosed space which contain large quantities of activated carbon. It is recommended that before entering such spaces, the atmospherbe tested for oxygen content, carbon dioxide or monoxide content, or other contaminants which might conceivably bepresent in the space. As an example of the precautions stated herein; if a vessel which contains activated carbon and which is large enough for the entry of a man needs to be repaired, inspected, or have the carbon replaced; the air spaceshould be ventilated by blowing in air. This precaution should be observed even though the carbon may not have beenused in service.

Activated carbon can react slowly with oxygen under certain conditions even at ambient temperatures and, although thrate is sufciently slow and no important amount of carbon is consumed nor any great weight of oxygen used, it may ban important factor in the oxygen content in a space which has been tightly closed for a long time.

SERVICE LIFE: Activated carbon has a denite life or capacity in performing its function. When the limit has beenreached, the adsorbent should be replaced or reactivated. It is good practice to have at least one spare charge on hand that the original one can be replaced whenever necessary.

SPECIAL SERVICE CONDITIONS: Activated carbon is a powerful adsorbent and catalyst. Although most of itsreactions and properties are reasonably well known, it must be regarded with care in unusual circumstances. Activatedcarbon can adsorb most types of molecules (there is a great difference in degree, depending on the type of molecule

adsorbed and the ambient conditions), and if the conditions change, the carbon can give up these molecules into thesurrounding space.

RESTORATION AND REACTIVATION: If contaminated with low boiling impurities, activated carbon may be eithepartially or completely reactivated in an oven or furnace at 200F to 400F or treated with low pressure steam and thendried. Granular activated carbon usually can be factory-reprocessed (reactivated) to make it almost equal in adsorptivcapacity to the original product.


3/3

Carbon Resources


Technical Bulletin

TM


SPECIAL CARBONS: Carbons impregnated with metallic salts may require special handling because of irritation dueto dust particles. Carbons having especially high purity or low moisture content must be handled carefully to avoidcontamination or moisture pick-up. For special carbons, be guided by instructions furnished for that type or class ofcarbons.

SHIPPING ACTIVATED CARBON: There are some transport regulations and restrictions with regard to the shippingof activated carbon by land, air and ocean and these should be carefully observed. There are no special hazards withmost types of activated carbon, but apparently, there have been a few instances where carbon was the suspected sourceignition which is the reason for the regulations.

Special impregnated activated carbons (used in respirators or for specic applications such as ammonia, formaldehyderadioactive iodine treatment) have chemicals added and require special handling and need to be kept away from oxidizagents and MSDS warnings should be heeded. In general, chemically activated carbon (such as phosphoric acid) needhigher level of attention and should also be stored separately from oxidizing agents. There is no history of well-prepasteam activated carbon causing problems in shipping or storage. Activated carbon should not be compared with crudecharcoal or barbecue charcoal which has entirely different properties and which, from time to time, appears to havespontaneous combustion.

BACTERIAL GROWTH: New, pure activated carbon will not support the growth of bacteria. However, carbon canadsorb nutrients required by bacteria and, after such adsorption has taken place, it is possible for bacteria to grow on thoutside of the carbon granule and, to some degree, within the large pore entrances. Bacteria can be eliminated by heatsterilization, high pH soak, low pH acid soak, or through the use of some other chemicals. There are types of carbonavailable which contain biocides which do not add any poisonous substances to the water, but will control bacteriagrowth. Bacteria which are free-oating in the water can be removed by activated carbon because it can act as a lteriagent also.

APPLICATIONS: Activated carbon should be properly mixed with the uid to be treated (powder form) or suitablysupported in the ow stream (granular form). Where it is used for the purication of liquids in a lter tank, the owsystem should be arranged so that pockets of air are eliminated, permitting the liquid to be in contact with the full charof carbon. Air or water that is to be puried by activated carbon should be free from dust or suspended matter thatmight tend to plug the carbon bed. A particulate lter ahead of the carbon will eliminate this potential problem.

In addition to its use as an adsorptive agent, activated carbon can be used as an electrical conductor, an insulator, a sou

deadening agent, or for the adsorption of light.

Most spent activated carbon can be properly disposed of by sending to a reactivation facility, landll, or incineration.Hazardous spent activated carbon must be handled accordingly and sent to a RCRA approved facility for disposal.

techbulletin care handling bacteria carbon

Documents