In order to prove that perchlorate-laden resins could be bio-regenerated through direct contact with anaerobic microorganisms, two bio-regeneration systems, internal and external, were tested. Anaerobic digestion was demonstrated to be very efficient in degrading perchlorate that had been adsorbed onto A520E resin. The internal bio-regeneration test showed that the fully exhausted resins recovered about 80% of the perchlorate-exchange capacity after 4 weeks of bio-treatment in the anaerobic digester. The bio-regeneration efficiency of the external system increased with the amount of flow passed through the column. Comparison of two perchlorate breakthrough curves obtained from column test, one with virgin resin and the other with bio-regenerated resin, proved that the bio-regenerated resin could be used repeatedly to treat perchlorate in spent or waste brine. The A520E resin was very stable in the anaerobic digester and its perchlorate-exchange capacity was barely changed during 26 weeks of incubation. The most significant contribution of this research is to develop the concept of direct bio-regeneration of exhausted resins by combining physicochemical ion-exchange and biological reduction technology, especially for the removal of perchlorate.

In this study, the performance of powdered activated carbon(PAC) contactor located in the Hakya water treatment plant(WTP) was evaluated. The result of tracer tests showed that the plug flow portion was more than 70 %. According to the total organic carbon(TOC) data of target WTP, there were no clear evidence that the addition of PAC contributed to the removal of organics. However, the results of jar test, conducted with the raw water taken from the Hakya WTP, proved that PAC could remove dissolved organic carbon(DOC) to some extent when the proper velocity gradient was maintained. It was estimated that the production rate of Hakya WTP, defined as the ratio of the operating flow rate to the design flow rate, was only 50 %. Because of this lower production rate, the mixing intensity in the contactor is much less than the designed value and, finally, the performance of PAC contactor was much less than what was expected.

Algae-related taste and odor problems are recognized by the water community worldwide to be major causes of consumer complaints and a loss in confidence of drinking water safety by the general public. Such problems can be arisen by natural and anthropogenic means, even by drinking water treatment processes. Microorganism is a common cause of naturally produced taste and odor. In this connection, the role of microorganisms and their metabolites are reviewed in the viewpoint of taste and odor in drinking water supplies.

Analysis of design parameters of residual treatment process at eight model water treatment plants, which were located in the four major watersheds, showed that there were large differences between those design parameters and the actual conditions. In this background, a new procedure was proposed and applied to the Chungju water treatment plant as an example of the optimum design of residual treatment process based on the characteristics of raw water. In this design example, a filter backwash recycle system consisting of a surging tank and sedimentation basin was newly proposed for more safe recycle of spent backwash water. It is expected that the design procedure proposed in this study would be estimated as a meaningful attempt to develope new design procedure for the domestic water industry.