Existing water treatment plants are not very effective for the removal of a growing list of organic compounds that pollute our waters. One treatment technique that is highly effective for organic removal is adsorption on granular activated carbon (GAC). Cost has been a major obstacle to expanding the use of GAC treatment and adsorption systems which must be optimized if they are to provide cost effective municipal water treatment. One of the process cost factors having the greatest potential for savings is the loss of granular activated carbon. Make-up carbon alone accounts for 30%-50% of the total annual cost of adsorption systems. As pointed out by others, this can be reduced by optimizing the adsorption step and reducing the frequency of regeneration. However, a greater potential for savings appears in a reduction in carbon losses: (1) during the thermal regeneration process, (2) created during the slurry transport of GAC from the adsorber to the regeneration furnace and return. In order to achieve the greatest reduction in the cost of GAC treatment emphasis must be placed on those components of the treatment process that (1) are common to all GAC system designs, (2) constitute the greatest portion of the cost, and (3) cannot be easily changed once the system has been built. These criteria suggest that studies be directed toward optimizing the design of carbon transport systems. The proposed research in Phase I will develop head loss curves and equations for the slurry transport of different types and sizes of granulary activated carbon as a function of pipe size, velocity and carbon concentrations. This information is needed to replace the erroneous data previously disseminated and will greatly improve the design of carbon transport system. The head loss curves and equations developed in Phase I will find immediate application in the design of carbon transport systems to replace the erroneous data presently available.
