Municipal and industrial water managers have many test methods at their disposal to analyze physical and chemical parameters (e.g. pH, temperature, turbidity, color, etc.) associated with water samples. However, the options available for biological testing have been significantly more limited. Conventional culturing methods require several days worth of incubation, and even then less than 1% of the total microbial population can be quantified with a single test.
A technology that has historically shown promise is the measurement of Adenosine Triphosphate (ATP). ATP is the main energy carrying molecule found in all living cells, thereby making the measurement of ATP a direct indication of total microorganisms in a given sample. While this technology has been historically used for surface testing for hygiene and surface cleanliness monitoring, recent advances now allow ATP monitoring to provide fully quantitative results in essentially any industry where microbiological monitoring and control is needed. Drinking water, cooling water, industrial process streams, and wastewater are all non-conventional ATP testing markets that are now within reach.
This "2nd Generation" ATP measurement technology offers a dramatic improvement on conventional culture testing for the purposes of microbiological condition monitoring in water treatment and distribution systems as well as industrial process water systems. This test provides more complete information on total microorganisms in a portable package that allows for testing anywhere while generating results in only a few minutes after sample collection.
Rapid test results provide operators with a tool that can not only allow them to troubleshoot microbiological issues on-site, but it can also guide treatment initiatives and assess their efficacy. This usually eliminates the need for subsequent troubleshooting or validation visits, and more importantly prevents the problem from escalating any further – microbiological contamination events are most economically solved in their earliest states of evolution.
Other techniques that focus on the quantification of indicator organisms such as Total Coliforms or E. Coli are helpful to reveal when gross contamination has occurred, but it would certainly be more desirable to be aware of problems in their early stages so that the impacts of contamination events are minimized or avoided altogether.
While ATP monitoring should not be considered a replacement for regulated tests or indicator organisms, it fills an important need in the form of a rapid non-specific measure of the total microbial population.
Monitoring the total microbial population of a water system enables the user to assess overall water cleanliness, and can be used to assess the threat of biofilm formation. As biofilms develop, they may harbor additional microbial threats such as Legionella, Mycobacteria, and pathogenic amoebae, anaerobic microorganisms associated with corrosion and odor issues, and nitrification-related microorganisms.
Municipal Water Applications
- Uncover system vulnerabilities – Due to the speed that results are made available, source-to-tap surveys of water distribution systems can be completed in a matter of hours. When problems are identified, users can "trace up the line" to identify pathways of entry or hotspots in order to isolate and mitigate the problem.
- Reveal and characterize accumulation and regrowth hotspots – A key deficiency of culture tests is the number of species that are left out and can go undetected. A common example of this is the emergence of nitrifying bacteria in water systems treated with monochloramine. Since ATP is in all cells including those that are not easily cultured, nitrifying bacteria will be detected among the indigenous population, thereby detecting nitrification issues in their earliest stages of evolution.
- Optimize flushing cycles – The lack of tools available for assessment of line flushing can result in significant wastage of water and time since it is difficult to tell how much flushing is enough. When water operators use traditional microbiological methods, equipment can be left in the field for several days until results are known. ATP monitoring not only allows the operator to tell how much flushing is enough, but also permits flushing crews to move on to the next location as soon as the cycle is complete with no waiting. This has obvious economic benefit.
The Canadian company LuminUltra (www.luminultra.com) offers ATP test kits suited for use in drinking water and wastewater applications. Its Quench-Gone Aqueous (QGA) kit is appropriate for testing source waters, treatment process effluents, treated water, water tanks, water distribution systems and point-of-use samples. It can also be used for disinfected wastewater effluents and systems using intensive tertiary treatment.
The company's QuenchGone21 Wastewater (QG21W) kit is designed for testing aerobic or anaerobic bioreactors, raw influents and collection system samples. The company also offers a Deposit and Surface Analysis (DSA) kit suited for testing slimes and deposits as well as quantifying attached growth on biologically active filter media.
Conclusion
2nd generation ATP technology is a game-changer for a multitude of industries – including the municipal and industrial water markets. The economic advantages of shortening test response times from days to minutes are many, and offer the opportunity to dramatically improve safety, security and environmental impact.
One of the greatest advantages to this technology is the capability of quantifying total microorganisms, including those for which culture tests are not equipped to measure (ie. nitrifying bacteria, many corrosion-related bacteria, some protozoa, and Archaea). Along with other molecular biology techniques, the field of microbiological measurement is rapidly changing, shifting away from the old culture-based techniques to new techniques that together operate as a ‘tool box' that will lead to more rapid and effective anti-microbial initiatives in municipal and industrial processes.
