Water Online

SEP 2016

Water Innovations gives Water and Wastewater Engineers and end-users a venue to find project solutions and source valuable product information. We aim to educate the engineering and operations community on important issues and trends.

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Page 16 of 46

By J. Michael Trapp A cross the U.S., municipalities and industries are forced to deal with an increasing number of contaminated waterways. These impairments, including 303(d) listings and Total Maximum Daily Loads (TMDLs), stem from a variety of pollutants, including metals, sediments, organic chemicals, and trash. However, with each of these potential impairments presenting unique challenges, the most prevalent issue involves fecal indicator bacteria, which accounts for 13 percent of all impairments nationwide — or roughly 10,781 impairments. California is a prime example of the widespread nature of this issue. The state alone has 627 bacteria- impaired watersheds that comprise 26,000 square miles — or 16 percent of the state's land area. Bacterial contamination is not only most prevalent but also one of the most complex types of contamination for which to develop and implement plans to achieve permit compliance. This is a result of the diverse nature of bacterial sources and sinks and their ability to reproduce in varied environments. To further compound the issue, the bacteria used for regulatory compliance are not the organisms that directly pose the public health concerns that regulatory permits are designed to protect. Rather, they are indicators of pathogens that epidemiology studies have linked directly to human health concerns. As a result, there has been a growing focus on research and innovation to develop technologies and tools to help managers and planners identify bacteria pollution sources, assess their relative health risks, develop new advanced treatments, and deploy GIS tools to help effectively place treatment. Advances In Bacterial Source Tracking Over the past decade, there have been significant advancements in the identification of sources of bacteria pollution in surface waters. Early efforts to reduce bacteria concentrations focused on wastewater discharges, as they frequently represent a major point source to a receiving waterbody that can be effectively managed. In many cases, the near-complete elimination of bacteria from these effluents was not sufficient to reach water quality goals, which left questions about the sources of the bacteria, particularly human sources, as they represent the greatest risk to public health. To understand where the contamination is coming from, the field of microbial source tracking (MST) developed a toolbox of resources ranging from chemical tracers of human activities (such as optical brighteners or caffeine) to assays focused on the bacteria themselves. The earliest of these tools looked at ratios of fecal bacteria types and antibiotic resistance. More recent developments have provided genetic tools that are able to identify the specific host organisms of the bacteria and quantify an estimated contribution to the total load. The most common and widely used of the host-specific tests utilizes quantitative polymerase chain reaction (qPCR) technology to focus on the genetic code of the Bacteroides 16S rRNA gene. Small mutations in this gene have been found to be specific to populations of humans, birds (general avian, Canada geese, sea gulls, chickens), cows, pigs, horses, rodents, canines, and other common bacteria sources, which allow their discernment and quantification. These tests have been successfully deployed in hundreds of source tracking programs around the country in either single-site temporal studies or across multiple watersheds to identify both host sources and geographical hot spots. This testing has been particularly successful in helping to identify failing septic tanks and leaking sewer infrastructure, as well as distinguishing other important sources to provide insight into their relative importance to the overall pollution load. Quantitative Microbial Risk Assessment Regulatory fecal indicator bacteria can come from many sources, representing a very different level of risk to public health. This is a result of the nature of the tests used, which focus on several species of indicator bacteria (e.g., E. coli, Enterococci, and fecal/total coliforms) as they are much easier to detect than the actual pathogens (bacterial and viral) that infect humans. While bacteria from human waste contains the highest concentration of human pathogens, and thus pose the largest threat for illness, other sources with high amounts of 12 wateronline.com n Water Innovations Modern Technology For Combating Bacterial Water Contamination Mobile-enabled geographic information systems (GIS) herald a new age for bacterial source tracking, allowing increased stakeholder involvement, more informed decision-making, and enhanced water quality. Cause of Impairment Group Name Number of Causes of Impairment Reported Pathogens 10,261 Nutrients 7,174 Metals (other than Mercury) 7,045 Organic Enrichment/Oxygen Depletion 6,464 Polychlorinated Biphenyls (PCBs) 6,061 Sediment 5,993 Mercury 4,479 pH/Acidity/Caustic Conditions 4,318 Cause Unknown - Impaired Biota 4,066 Temperature 3,069 Turbidity 2,910 Salinity/Total Dissolved Solids/Chlorides/Sulfates 1,904 Causes of Impairment for 303(d) Listed Waters

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