Removal of organic micropollutants by coagulation and adsorption

The factors which affect removal of organic micropollutants by coagulation, sedimentation, filtration and activated carbon adsorption will be reviewed. Removal of specific compounds by coagulation, sedimentation and filtration is often slight, unless the pollutants adsorb on particles or associate with humic substances which are then coagulated. By comparison, removal of humic substances by these processes can be substantial, depending upon the water chemistry and the process conditions. Activated carbon may be applied in both the powdered (PAC) and granular (GAC) form. PAC and GAC have been used successfully throughout the world to remove odorous compounds. PAC has been used to a much smaller extent for removal of other micropollutants, but there is much potential for improvement of the application procedure so that good results can be achieved. GAC is widely used to remove micropollutants other than odor in Europe but has not been extensively used for this purpose in North America. The compounds which can be removed by GAC are presented and process monitoring procedures are discussed. Factors which limit its use include incomplete knowledge about which compounds must be removed and what effluent concentrations are acceptable.