This report provides a review of the literature concerning the current state of knowledge for removing organic chemicals from drinking water. Sources of organic chemicals include humic substances (products form the natural degradation of plant and animal matter), municipal and industrial effluent, agricultural runoff (pesticides, fertilizer and manure), contaminated leachate from landfill sites and lagoons, and accidental and illegal dumping. Humid substances are the products of natural processes and are the most significant class of organics in terms of volume. Because the humic substances are natural, little can be done to prevent them from entering the water, as opposed to other sources that are a result of human activity. Although treatment processes can significantly improve water quality, the cleaner the raw water supply, the simpler and more economical the water treatment is. The effect of organic chemicals on drinking water quality ranges from aesthetic (taste, odour, colour) to threats to human health (carcinogens).
Virtually all organic chemicals can be reduced in concentration by the appropriate water treatment processes. The amount of reduction is a function of the parameters of the chemical of interest, the water treatment process used and the other materials present in the raw water. Coagulation and flocculation, softening, sedimentation, filtration, chlorine, activated carbon (GAC and PAC), resin adsorption, air stripping, reverse osmosis, chlorine dioxide, ozone and UV radiation were evaluated as to their effectiveness in removing organic chemicals from water.
As may be expected, no-one process is capable of treating the whole range of organic chemicals. The effectiveness of a treatment process is a function of the characteristics of the organic chemical in question. For example, physical processes such as coagulation and flocculation can be effective in removing organic chemicals that associate with the organic material in the water.
When designing a water treatment facility extensive testing may be necessary to determine the appropriate processes for treating the raw water. Bench top and pilot plant testing will likely be necessary to estimate the effectiveness of the design treatment processes on treating the water.