Application of Advanced Technology for Potable Water Supplies in North Carolina

摘要

Five European water treatment techniques are identified as having a definite potential for application in the United States: ozone, chlorine dioxide, granular activated carbon, biological activated carbon and dissolved air flotation. Ozone is an attractive alternative to chlorine as a primary disinfectant. It may also be useful for pretreatment purposes, trihalomethane precursor removal and overall organics oxidation. Cost considerations and a very short-lived residual are responsible for the limited use of ozone in the United States. Chlorine dioxide is well suited for use both in pretreatment and posttreatment to provide a distribution system residual. Lower chlorinated organics formation, reduced pH dependence and a more persistent residual allow it to compete with chlorine. The major drawback with chlorine dioxide is its relatively high cost. Granular activated carbon is attractive for the treatment of waters contaminated with organic chemicals. Difficulties are presently encountered in assessing the need for such treatment and in evaluating process performance. An additional factor is the significant costs associated with the process, particularly for replacement of exhausted carbon. Biological activated carbon is a new process which is a variation of granular activated carbon treatment. Its potential advantage is the possibility for a significant increase in activated carbon service life. Biological activated carbon is now the subject of considerable research as basic questions about process capabilities remain unanswered. Dissolved air flotation provides an alternative to sedimentation. Advantages over sedimentation include: a sludge thickening capability, a larger hydraulic surface loading and better algae removal.