Advances in Water Treatment and Enviromental Management

WATER TREATMENT TECHNOLOGIES FOR THE NINETIES 159The bulk of the R&D in the drinking water area, however, seems to be ratherconservative: it focuses more on a better understanding of the intimate mechanismand a better control of existing processes than on the development of new ones. Alarge portion of the effort is also spent in pilot experiments, which are usually localdemonstrations, of a proven technology. As an example among the papers selectedin the journal AWWA for their 1989 best paper award,30% were on activated carbonabsorption, 25% were on ozone oxidation, 10% were on filtration, 10% were onmembrane separation, 10% were on air stripping, and 10% were on sludgedewatering.These papers represent research projects which were probably started several yearsago and the current reality may be somewhat different. We can see, however that inthe area of drinking water, carbon absorption and ozone oxidation still representmore than half of the research efforts. This is a rather general situation, but newtechnologies such as membrane separation are now appearing heavily in theprograms and some research organizations are deliberately putting the majority oftheir strengths on these innovative areas.THE DRINKING WATER AREA: A FOCUS ON ORGANIC MATTERREMOVALIt is needless to say, that water treatment will, in the years to come, continue tofocus on an improvement of the removal of the organic constituents. The push forreinforced standards following the U.S. SDWA, the need to eliminate all the newsynthetic organics appearing in the environment, the attempt to avoid the formationof disinfection by-products, the requirement to control the bacterial regrowth in thedistribution systems,…All these reasons will lead to technologies more and moreeffective in organics removal. This does not mean of course that local problemscaused by other substances may not arise. Compounds such as Radon, heavymetals, radioactive metals, barium and of course calcium, sodium, potassium, willalways generate treatment technology improvements. The main thrust will howeverremain on the organics, for the years to come.Together with treatment technologies tremendous efforts and progress will be madein the areas of water analysis, identification of the mechanisms of formation of theby-products, health effects assessment and the next decade might see thedevelopment of toxicity bio-assays.ABSORPTION, OXIDATION AND DISINFECTIONThese treatment technologies which are traditionally being used for the reductionof organic matter will naturally continue to grow in importance. A better usage ofthe granular activated carbon (G AC) through a better modelling of the absorptionmechanisms seems to be the surest evolution of current practice. Alternatives toGAC such as activated alumina, which raised some interest in the mid eighties isnow fading out. New carbons, with various shapes (fibers?) might appear, betterreactivation technologies will develop, but altogether this will result only in minorchanges over the technologies which have been in use for the past fifteen years.Powdered activated carbon (PAC) will probably regain importance over GAC,particularly in conjunction with floe blanket clarifiers and new membrane reactors.The development of ozone will continue. It will be more and more systematicallyapplied together with GAC, but again, this is not a really new trend! The technology