Granular Activated Carbon (GAC)
Carbonair does not manufacture granular activated carbon (GAC) in house, but has over 25 years of experience in developing techniques that effectively uses granular carbon for water treatment. Carbonair has a large inventory of liquid-phase filter vessels and vapor-phase carbon vessels available for temporary projects. Pre-assembled activated carbon treatment systems on skids and trailers are available for mobility at job sites. Carbonair strictly follows the regulatory guideline for the handling and disposal of the spent carbon. In some cases, the spent GAC can be sent back to reactivation facilities for reactivation and reuse. The applications that Carbonair uses GAC to treat contaminated water and air flows are the following: Liquid Phase Carbon Vessels, Vapor Phase Carbon Vessels.
What is Granular Activated Carbon (GAC)?
GAC is basically carbon in a granular form, which is made from raw carbonaceous materials such as coconut shells or coal. In the activation process, heat is used to burn off some of the raw materials and produce microscopic pores which are capable of trapping the molecules of contaminants in water or air – so-called “adsorption”. The activated carbon is then pulverized and sieved into appropriate and uniform particle sizes. Most of organic contaminants can be treated by GAC; however, there are a small portion of organic compounds that cannot be effectively treated.
Those organic compounds are either too small or too large in molecular or globular size. Excessively small organic molecules, such as vinyl chloride, methylene chloride, chloromethane, and chloroethane, etc., can get away from being trapped in the carbon micropores. Oils and greases are present in water as globules, which are too large in size to enter the carbon micropores. Most of inorganic compounds such as iron, manganese, sulfate, and nitrate, etc. cannot be treated by granular activated carbon. Those constituents are typically present in water as ionized forms, which are strongly bound to and difficult to separate from water.
Typical Applications that Require the Use of GAC
- Removal of volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs)
- Dechlorination (chlorine and chloramines removal)
- Total organic carbon (TOC) reduction
- Color removal
- Taste and odor removal
- Reverse osmosis (RO) pre-treatment