The inactivation of C. parvum and spores of Cl. perfringens by ozone treatment in natural water in a lab-scale continuous-flow system was compared. In addition the inactivation of the natural occurring spores of sulphite-reducing clostridia (SSRC) in this water was monitored in one of the lab-scale systems as well as in a full-scale ozonation process. The survival ratio of C. parvum oocysts was determined using the CD-1 neonatal mouse infectivity test and for Cl. perfringens and SSRC the survival ratio was assessed with the standard anaerobic colony count on the iron-sulphite medium. The results of the lab-scale experiments revealed an inactivation rate constant k (Chick-Watson modelling) at 10°C for C. parvum of 0.14 (SD=0.014; P<0.001) and for Cl. perfringens of 0.25 (SD=0.01; P<0.001). Moreover, first results of monitoring the SSRC inactivation in full-scale ozonation processes indicated that the inactivation rate constant for these wild strains was in the same order of magnitude as determined for Cl. perfringens. Further research is needed to compare inactivation ozone kinetics for Cl. perfringens D10 and SSRC at different temperatures and in other natural waters. Results of additional lab-scale experiments with Cl. perfringens strain D10 indicated that the CT of the gas-feed chamber should be incorporated in the design of a full-scale ozonation. Moreover, setting theCT with the contact time was not as effective for the inactivation capacity as setting the CT with the ozone dosage.

Started in 1948, Kiwa Water Research has developed into an internationally respected research center in the field of drinking water and related environmental issues. The 120 scientific specialists conduct the joint research program of the water supply companies in the Netherlands, and also provide research services for other national and international clients.While the major focus is on drinking water supply, Kiwa is also involved in projects addressing the integration of the water chain, including water for industrial and other use. Core tasks of the division include innovative research and transfer of knowledge and know-how.Other divisions of Kiwa provide a range of certification, inspection and management consultancy services for water businesses and other sectors of industry.More information can be found on www. The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for errors or omissions that may be made. DisclaimerThe information provided and the opinions given in this publication are not necessarily those of IWA, KIWA or the editors, and should not be acted upon without independent consideration and professional advice. IWA and the editor will not accept responsibility for any loss or damage suffered by any person acting or refraining from acting upon any material contained in this publication. British Library Cataloging in Publication Data SUMMARYWater quality management requires knowledge about all aspects that can have an impact on water quality. From toxicological point of view the presence of organic micro-pollutants in raw water and consequently drinking water, is one of these aspects. Taking into account that these compounds are usually found in relatively low concentrations, the main research attention of drinking water industry is focused on the (suspected) presence of mutagenic and carcinogenic compounds. Up to now only lipophilic (= less soluble in water) compounds were analysed within research on the occurrence of mutagenic and carcinogenic compounds in water. These compounds were isolated from water using XAD-resins. It was proved that they contain approximately half of the total organic material present in water. A clear mutagenic effect was demonstrated for these compounds using the Ames test.Up to now, the hydrophilic (= very good soluble in water) part of the organic material could be hardly included in the research. This material is namely difficult to isolate and analyse due to its high solubility. The high solubility means also that the hydrophilic compounds are mobile in conventional treatment systems and in water conveying (ground) pockets. They can easily penetrate into drinking water. Because of this, it is very important to know, what is the toxicological meaning of this hydrophilic material.Eight different water types, including strongly polluted industrial water, were examined to determine the role of hydrophilic material. A method was developed to ...