Pipelines 2018 768 © ASCE Qualitative Investigation of Microbially Induced Corrosion of Concrete in Sanitary Sewer Pipe and Manholes Vinayak Kaushal, S.M.ASCE 1 ; Mohammad Najafi, F.ASCE 2 ; and Johnny Love 3 1 Graduate Research and Teaching Assistant, Center for Underground Infrastructure Research and Education (CUIRE), Dept. of Civil Engineering, Univ. of Texas at Arlington, Box 19308, Arlington, TX 7601. E-mail: vinayak.kaushal@mavs.uta.edu 2 Professor and Director, Center for Underground Infrastructure Research and Education (CUIRE), Dept. of Civil Engineering, Univ. of Texas at Arlington, Box 19308, Arlington, TX 7601. E-mail: najafi@uta.edu 3 National Product Manager, ConShield Technologies Inc., Atlanta, GA 30318. E-mail: jlove@conshield.com ABSTRACT Microbially induced corrosion (MIC) of concrete is a major cause of deterioration in sanitary sewer systems and requires considerable amount of rehabilitation investment every year. MIC is caused by the production of hydrogen sulfide by sulfur oxidizing microorganisms present inside the sanitary sewers. The objective of this paper is to investigate solutions for reduction and/or elimination of MIC in the concrete sanitary sewers. This study reviews the cement chemistry, basic science behind concrete deterioration, and MIC production that takes place due to various biological processes which lead to the production of dilute sulfuric acid. Historical attempts to fortify concrete along with methods to reduce odors and corrosion by treatment of raw sewage are discussed. Experimental testing as per ASTM D4783 standard shows resistance of concrete samples to microbial attack with the use of antimicrobial additives. INTRODUCTION Concrete remains one of the fundamental materials of choice in sanitary collection and treatment systems (Taylor 1997). From the large tanks needed in treatment plants to manholes, pipes, pump stations and various tunneling techniques, it is one of the most cost effective, durable and adaptable of construction materials. However, concrete’s intrinsic lack of chemical resistance to dilute acids results in its corrosion and destruction. As a result of this type of corrosion, concrete structures have a persistent, costly, unpredictable and disruptive maintenance history often times calling for expensive difficult repairs or complete replacement (EPA 2010). Microbially Induced Corrosion (MIC) or Hydrogen Sulfide Corrosion is the main source of concrete deterioration in the sanitary sewer structures. The destruction is caused by dilute sulfuric acid continuously being generated by bacteria that digest Hydrogen Sulfide gas (H2S). This foul smelling gas is produced by Sulfur Reducing Bacteria (SRB) present under the waterline inside the sanitary sewers. Over the past 70 years, attempts to fortify concrete against direct acid attack have proven fruitless (Cheng 2014). The objective of this paper is to study corrosion by hydrogen sulfide and investigate solutions for its reduction and/or elimination in the concrete sanitary sewers. Pipelines 2018 Downloaded from ascelibrary.org by University of Texas at Arlington on 07/15/18. Copyright ASCE. For personal use only; all rights reserved.