Research Report 9 Three Surface Waters with Differing Character
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Impact of Ozone on Disinfection By-Products: Comparison of Research Report 9 Three Surface Waters with Differing Character Research Report 9 Impact of Ozone on Disinfection By-Products: Comparison of three Surface Waters with Differing Character Chris Kostakis and Brenton C. Nicholson Cooperative Research Centre for Water Quality and Treatment Research Report no. 9 November 2001 CRC for Water Quality and Treatment Research Report 9-2001 © CRC for Water Quality and Treatment, 2001 ISBN 1 876616 10 5 DISCLAIMER • The Cooperative Research Centre for Water Quality and Treatment and individual contributors are not responsible for the outcomes of any actions taken on the basis of information in this research report, nor for any errors and omissions. • The Cooperative Research Centre for Water Quality and Treatment and individual contributors disclaim all and any liability to any person in respect of anything, and the consequences of anything, done or omitted to be done by a person in reliance upon the whole or any part of this research report. • The research report does not purport to be a comprehensive statement and analysis of its subject matter, and if further expert advice is required the services of a competent professional should be sought. The Cooperative Research Centre for Water Quality and Treatment can be contacted at: CRC for Water Quality and Treatment Private Mail Bag 3 Salisbury South Australia, 5108 AUSTRALIA Phone: 61 8 8259 0337 Fax: 61 8 8259 0228 ii CRC for Water Quality and Treatment Research Report 9-2001 FOREWORD This report is the result of work carried out in CRC Project 3.2.3 “Alternative Disinfection Regimes” and was also submitted by Chris Kostakis to fulfil the requirements for the degree of Master of Applied Science in Chemistry at the University of South Australia. The degree was conferred in November 2001. Research Officer: Chris Kostakis Project Leader: Dr Brenton C. Nicholson Research Node: Australian Water Quality Centre CRC for Water Quality and Treatment Project No. 3.2.3 – Alternative Disinfection Regimes iii CRC for Water Quality and Treatment Research Report 9-2001 Executive Summary The provision of microbiologically safe drinking water is still commonly achieved by chlorination in most water treatment plants. The discovery of chloroform and many other halogenated organic compounds in drinking water as a result of chlorination has sparked public concern and the introduction of stringent regulations on maximum contaminant levels of these disinfection by-products in treated water. Water utilities overseas, and possibly Australian utilities in the future, are being compelled to adopt alternative water treatment regimes in order to reduce the level of these chlorinated disinfection by-products. The use of ozone in water treatment for the management of various water quality issues including disinfection by-product control has increased in popularity and is becoming a widespread practice. Ozone is shown to react with natural organic matter present in water to form lower molecular weight oxygenated compounds such as aldehydes, ketoacids and carboxylic acids. Analytical procedures for the determination of these classes of ozonation by-products were optimised and validated in this work. Bench scale ozonation experiments were performed on waters collected from the Myponga, Hope Valley and Tod Reservoirs. Doses of 0.5, 1, 2, 3 and 5mg of ozone per mg of dissolved organic carbon content were applied and aldehydes, ketoacids and carboxylic acids were found to generally increase with increasing ozone dose. The formation of these compounds was shown to depend on the organic and inorganic character of the water. Bacterial regrowth potentials were determined and the biodegradability of the organic matter was shown to increase in ozonated waters. Raw waters and their ozonated samples were subsequently chlorinated to determine the effects of pre-ozonation on the formation potentials of trihalomethanes, chloroacetic acids and other chlorinated disinfection by-products. The effects of ozone dose on chlorinated by-product formation following chlorination differed in each water, illustrating the dependence on source water characteristics. The character of the organic matter and high bromide levels are shown to significantly contribute to the outcome of halogenated by-product formation. Finally, water samples were collected at each stage of the water treatment process from the Edenhope water treatment plant in Western Victoria, Australia. The plant utilises advanced treatment technologies such as ozonation and biologically activated carbon. Aldehydes, ketoacids, chlorinated disinfection by-products and other water quality parameters were monitored throughout the treatment process and the observed distribution of the various products is discussed. iv CRC for Water Quality and Treatment Research Report 9-2001 Acknowledgments This work was funded by the CRC for Water Quality and Treatment and supported by SA Water as part of CRC Project 3.2.3 “Alternative Disinfection Regimes” The contribution of the other supervisors in this project, namely Associate Professor Dennis Mulcahy and Dr Gunter Klass of the University of South Australia is gratefully acknowledged. The support and cooperation of co-workers and postgraduate students at the Australian Water Quality Centre is also acknowledged as without this, work of such quality would not have been possible. Chris Kostakis would also like to thank Mr Noel Sims, Mr Peter Felgate, Dr Hilton Kobus and Dr Paul Kirkbride of State Forensic Science for their encouragement, motivation and for some necessary time off given to complete this report. v CRC for Water Quality and Treatment Research Report 9-2001 Table of Contents Page FOREWORD…………………………………………………………………………………………..………..iii EXECUTIVE SUMMARY…………………………………………………………………………………..….iv ACKNOWLEDGMENTS……………………………………………………………………………………….v TABLE OF CONTENTS……………………………………………………………………………………….vi LIST OF TABLES…………………………………………………………………………………………......viii LIST OF FIGURES…………………………………………………………………………………………….ix LIST OF ABBREVIATIONS………………………………………………………………………………......xi 1 INTRODUCTION………………………………………………………………………………….…..1 1.1 Overview………………………………………………………………………………………….……1 1.2 Natural Organic Matter in Water………………………………………………………………….....1 1.3 NOM: Precursors to Disinfection By-products………………………………………………….….3 1.3.1 Chlorine and its Use in Water Treatment………………………………………………....3 1.3.2 Chlorinated Waters in South Australia……………………………………………….……6 1.4 Alternative Disinfectants…………………………………………………………………………..….7 1.4.1 Effectiveness of Disinfection……………………………………………………………..…7 1.4.2 Chloramines……………………………………………………………………………….…7 1.4.3 Chlorine Dioxide……………………………………………………………………….…….8 1.4.4 Ozone……………………………………………………………………………………..…..8 1.5 Reactions of Ozone…………………………………………………………………………….….….8 1.5.1 Reactions of Ozone With Organic Compounds…………………………………………..8 1.5.2 Reactions of Ozone With NOM……………………………………………………………..9 1.5.3 Aldehyde and Ketoacid Analyses…………………………………………………………11 1.5.4 Biodegradable Organic Matter…………………………………………………………….11 1.6 Research Objectives…………………………………………………………………………………12 2 THE WATER SOURCES AND THEIR CHEMICAL CHARACTERISTICS………………………………………………………………………………...13 2.1 Hope Valley Raw Water……………………………………………………………………………..13 2.2 Myponga Raw Water………………………………………………………………………………… 14 2.3 Tod Raw Water……………………………………………………………………………………….15 2.4 Reagent Water……………………………………………………................................................16 3 OZONATION: APPLICATION AND BY-PRODUCT ANALYSIS…………...............................17 3.1 Ozonation Experiments………………………….................…………….............................……17 3.2 Raw Waters and Their Ozone Demand…………………...........................................…………18 3.3 Ozonation By-Products and Evaluation of The Methodology……...........................................21 3.3.1 Determination of Aldehydes in Water……………………...........................................…..21 3.3.1.1 Analytical Procedure………………………………............................................22 3.3.1.2 Sample Dechlorination…………………………..........................................…..22 3.3.1.3 Background Contamination………………………............................................23 3.3.1.4 Recoveries and Limits of Quantitation……………..........................................24 3.3.2 Determination of Ketoacids in Water………………………..............................................25 3.3.2.1 Buffering the pH of the Reaction…………………............................................26 3.3.2.2 Decarboxylation of Oxalacetic Acid……………..........................................….26 3.3.2.3 Analytical Procedure…………………………….............................................…27 3.3.2.4 Recoveries and Limits of Quantitation…………........................................…...27 3.3.3 Determination of Carboxylic Acids in Water………………...............................................28 3.3.3.1 Identification of Carboxylic Acids………………...............................................30 3.3.3.2 Developmental Work…………………………...….............................................30 3.3.3.3 Analytical Procedure…………………………….............................................…31 3.4 Determination of Bacterial Regrowth Potentials…………………..............................................32 4 CHLORINATION: APPLICATION AND BY-PRODUCT ANALYSIS……………..........………..34 4.1 Chlorination Experiments…………………………………...............................................……….34 4.2 Chlorination By-Products and Methodology………………….............................................……34 vi CRC for