Biomass Recovery Method for Adenosine Triphosphate (ATP) Quantification Following UV Disinfection

ABSTRACT

A biomass recovery method was developed to monitor UV disinfection efficacy using adenosine triphosphate (ATP). Typically, disinfection monitoring at wastewater treatment facilities (WWTFs) involves quantifying fecal and total coliforms or colony forming units, the results of which take a minimum of 24 h to produce. ATP quantification immediately before and after UV treatment, which takes only minutes, shows little reduction and often an increase in the microbial population since UV irradiation results in cells that are viable (i.e., still producing ATP) but not culturable. To overcome this, our biomass recovery method incorporates an incubation step to encourage life cycling of microbes. Average log reductions in cellular ATP (cATP) were found to be −0.28 ± 0.19, −0.011 ± 0.153, −0.17 ± 0.32, and 0.065 ± 0.074 using direct ATP measurements on UV-treated samples from WWTFs A, B, C, and D, respectively, while those using the recovery method were correspondingly 0.17 ± 0.34, 1.8 ± 0.8, 0.20 ± 0.35, and 0.72 ± 0.26. The response of the biomass recovery-ATP method indicated a significant direct correlation to the microbial population reduction observed in heterotrophic plate count (HPC) and Colilert® methods using both pure Escherichia coli culture and secondary municipal wastewater effluent.

KEYWORDS:

• Adenosine triphosphate (ATP)
• coliforms
• disinfection efficacy
• luminase
• microbial enumeration
• UV disinfection
• viable but nonculturable

Acknowledgments

The authors would like to acknowledge and extend thanks for the financial support provided through the NSERC/Halifax Water Industrial Research Chair in Water Quality & Treatment at Dalhousie University. Funding partners for this Industrial Research Chair program include the Natural Science and Engineering Council of Canada (NSERC), Halifax Water, LuminUltra Technologies Ltd., Cape Breton Regional Municipality Water Utility, CBCL Ltd., Agat Laboratories Ltd., and Mantech Inc. Additional funding for this work was received from the NSERC Discovery Grant program. Dr. Mackie would also like to acknowledge funding received from NSERC’s Postdoctoral Fellowship program. The authors also thank Heather Daurie, Nicole Allward, and Dr. Ben Trueman for their technical support, experimental assistance, and theoretical support.

SUPPLEMENTAL DATA

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