Quaternary ammonium biocides are commonly used in cooling water systems to control organisms associated with microbiologically induced corrosion and microbial fouling. These compounds while being highly efficacious and low cost have, in general, high foaming tendencies which can limit their range of application. A new quaternary ammonium compound, decylisononyldimethylammonium chloride (DIDMAC), was developed to prevent foam problems while maintaining the advantages of standard quat treatments.

Laboratory evaluations showed DIDMAC to produce significantly less foam than a standard alkyldimethylbenzylammonium chloride (ADBAC), approaching that of a polymeric quat. Bactericidal and algicidal evaluations showed DIDMAC to provide efficacy greater than the polymeric quat and similar to the ADBAC.

Field evaluations confirmed the laboratory results showing DIDMAC to foam significantly less than the ADBAC and similar to the polymeric quat. In the field, DIDMAC bactericidal and algicidal efficacies were evaluated in combination with other nonoxidizing biocides. Optimized programs, consisting of weekly additions of 10-30 mg/L DIDMAC with semiweekly applications of 1.5 mg/L isothiazolone, exceeded the algicidal and matched the bactericidal performance of control thione/isothiazolone programs. The DIDMAC-containing programs, in addition to providing enhanced bactericidal and algicidal efficacy, reduced treatment costs by 27 to 43% compared to the control.

Subject
Field performance, Algae, Costs, Water, Materials, Quaternary ammonium, Dosages, Isothiazolone, Efficacy, Aerobic bacteria, Towers, Biocides, Chlorides
Keywords:
biocides, algicides, quaternary ammonium compounds, cooling water, foam
© 1994 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
1994
Association for Materials Protection and Performance (AMPP)
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