Microbiologically influenced corrosion (MIC) has occurred in activated sludge effluent treatment systems in several Canadian mills. Carbon steel recycled activated sludge (RAS) piping and type 316L stainless steel clear effluent piping have perforated in less than 10 years of service due to corrosion by sulfate reducing bacteria (SRB). In the vapour space of bioreactors sulphuric acid produced by sulfur oxidizing bacteria (SOX) has caused severe corrosion of concrete and type 304 stainless steel agitator shafts in one mill.

In the case of SRB corrosion of carbon steel RAS piping and 316L stainless steel clear effluent piping the current state of understanding does not provide a correlation with process variables. The situation is more understandable in the case of SOX and sulfuric acid attack of bioreactor concrete and stainless steel agitators and waste sludge lines. Experience from several mills is reviewed to illustrate common and divergent experience.

Subject
Sulfur, Corrosion rate, Sulfuric acid, Effluent, Carbon steel pipes, Acidity, Nutrients, Sludge, Roofs, Bacteria, Carbon steel, Stainless steel, Concrete
© 2004 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).
2004
Association for Materials Protection and Performance (AMPP)
You do not currently have access to this content.