ANSI AWWA B605-18 pdf download.Reactivation of Granular Activated Carbon
The supplier shall determine how effectively the spent GAC can be reactivated, as measured by the iodine number or other characteristics agreed to by both the purchaser and supplier, using their own procedures. The supplier will report these results to the purchaser to determine whether to continue contract negotiations.
Further contract negotiations should then be predicated on whether this reactivated quality is satisfactory to the purchaser. If the reactivator determines that the material cannot be reactivated to a suitable quality, the water utility should consider how to dispose of the spent GAC. (Options may include selling it to a reactivator for use in a different application, e.g., industrial waste treatment, or it may be landfilled or incinerated.)
4.4.1 Removing spent material. The drained level of the filter shall be marked before GAC is removed. Proper Occupational Safety and Health Administration procedures shall be followed when entering a confined space. Warning: Wet GAC will remove oxygen from the surrounding environment within a confined space, resulting in a lack of oxygen.
4.4.1.1 Eduction. If the filter vessel is an open-type gravity filter, eduction is the preferred removal method. The main barriers to educting GAC from the filter are the water pressure available as a motive force and the distance the GAC must be moved. Care shall be taken to minimize the amount of filter support material (sand or gravel) removed with the spent GAC. This procedure could also be included in the contract as a service provided by the supplier.
4.4.1.2 Vessel pressurization. Where the adsorption vessel is a pressure vessel with the proper drain connections included at the base of the vessel, the preferred method of spent GAC transfer shall be to apply air pressure to the vessel filled with water to move the GAC slurry to the truck or other source of transportation. Trucks receiving the spent material shall be equipped with a screened drain and screened overflow, so excess water can be removed without loss of GAC.ANSI AWWA B605-18 pdf download.