United States
Environmental Protection
Agency
RESEARCH PROJECT
National Risk Management Research Laboratoi
Water Supply and Water Resources Division
Microbial Contaminants Control Branch
MOLECULAR SURVEY OF MICROBIAL COMMUNITIES INVOLVED IN CONCRETE
CORROSION IN WASTEWATER COLLECTION SYSTEMS
I
IMPACT STATEMENT
Corrosion of wastewater collection infrastructure,
especially concrete sewers, is a significant cause of
deterioration and premature failure. When exposed to the
internal atmosphere of gravity sewers, which is
characterized by high humidity and the presence of
hydrogen sulfide, sulfuric acid corrosion negatively affects
concrete surfaces, mortar, and metal reinforcement
material. Given this universal challenge for wastewater
utilities, this research project will look into an innovative
condition assessment method development that
addresses corrosion-related wastewater infrastructure issues.
BACKGROUND:
One of the U.S. Environmental Protection Agency's (EPA) primary roles is that of an advocate for sustainable water
infrastructure. Condition assessment tools enhance the ability of our external stakeholders, including public and private
utilities, and municipal governments that provide drinking water and wastewater services; state and tribal water and
wastewater programs, to make technically sound judgments regarding structural, operational and performance status of
capital infrastructure assets (asset management).
The deterioration of concrete in wastewater collection systems is caused by biogenic acid (i.e., sulfuric acid) generated
by various microbial species through complex mechanisms that have been described in the literature. To efficiently
control microbial-induced concrete corrosion (MICC), it is necessary to understand the microbial succession of sulfur-
oxidizing bacteria (SOB), as well as other bacteria that enable colonization of the concrete surface leading to sulfuric acid
production. Development of comprehensive databases for bacterial communities in sewer systems with a wide range of
corrosion conditions will be crucial in identifying bacterial groups/species that could form the basis for bioassays useful
in monitoring systems for MICC.
DESCRIPTION:
The Office of Research and Development's (ORD) National Risk Management Research Laboratory has funded this
research project in support of its Aging Water Infrastructure (AWI) Research Program. This project will provide
laboratory data and information that will ultimately be used to develop preventive condition assessment measures. This
project will evaluate MICC as it relates to biodeterioration of wastewater conveyance systems. This project provides
analysis on the application of molecular/microbial "tools" for identifying the presence of MICC bacteria to assess the
probability of crown corrosion in sewers, in support of Innovative Condition Assessment Method Development -
Advanced Techniques. Proper design in new collection systems reduces anaerobic microbial activity and sulfide
National Risk Management Research Laboratory
Water Supply and Water Resources Division
-------
generation. However, efforts to restore concrete sewers will be ineffective without a better understanding of the
fundamental processes of biogenic sulfuric acid corrosion.
The aim of this project is to obtain a better understanding of the succession of microbial community members
responsible for the production of sulfuric acid in order to develop innovative condition assessment tools for monitoring
MICC. In order to achieve this, sequence analysis of 16S rDNA and functional gene clone libraries will be used to describe
the phylogenetic affiliation and function potential of microbial communities associated with MICC. This information will
be used to develop assays that will specifically determine the abundance of MICC bacteria and MICC-related processes
in sites that exhibit different stages of corrosion.
EPA GOAL: Goal #2 - Clean & Safe Water, Objective 2.1.1- Water Safe to Drink
ORD MULTI YEAR PLAN: Water Quality (WQ), Long Term Goal - WQ-3 Source Control
RESEARCH PARTNERS :
Collaborators: The Metropolitan Sewer District of Greater Cincinnati
Contractors: Student service contractors
EXPECTED OUTCOMES AND IMPACTS:
It is expected that this project will result in enhanced acceptance of new and innovative technologies; lowered
operation, maintenance, rehabilitation and replacement costs of aging water infrastructure; extended service life and
functionality of existing conveyance systems; and reduced life cycle cost.
OUTPUTS:
Current and expected project outputs include peer-reviewed journal articles and conference proceedings.
RESOURCES:
Aging Water Infrastructure Research Program: http://www.epa.gov/awi/
NRMRL Microbial Contaminants Control Branch: http://www.epa.gov/ORD/NRMRL/wswrd/mcc.htm
CONTACTS:
Jorge Santo Domingo, Principal Investigator - (513) 569-7085 or santodomingo.jorge@epa.gov
Randy Revetta, Principal Investigator - (513) 569-7129 or revetta.randy@epa.gov
Steven Doub, Media Relations - (513) 569-7503 ordoub.steven@epa.gov
Michelle Latham, Communications - (513) 569-7601 or latham.michelle@epa.gov
L
National Risk Management Research Laboratory
Water Supply and Water Resources Division
www.epa.gov/nrmrl
EPA/600/F-09/012
October 2009
------- |