After initially developing our Deposit & Surface Analysis (DSA) test kit many years ago to quantify sessile build-ups on pipe or tank walls, we stumbled upon drinking water treatment via biologically active filtration as a process that could benefit greatly from this monitoring technology. As this type of pre-treatment emerged in North America following more widespread use in Europe, people struggled to determine how biologically active their biologically active filters were. Quantifying attached growth, especially on granular media, is very difficult using conventional culture-based techniques in addition to their tendency to be very selective (typically < 1% of total microbial content measured). As such, the benefits of ATP monitoring in this situation were huge considering that all cells are measured and the tests can be completed in minutes by anyone.
To date, ATP monitoring has proven most effective in biofilter media analysis by showing the biomass’ response to process changes such as nutrient supplementation, pre-oxidation/treated backwash, or backwash cycle frequency/duration. However, recent research done at the University of Colorado (Boulder) has taken biofiltration process monitoring to another level. Ph.D. candidate Leigh Gilmore Terry from CU Boulder has tied biological activity as measured using ATP analyses together with filter empty bed contact time (EBCT) to produce an effective model for total organic carbon (TOC) removal(1). Mathematically, the model is as follows:
Ceff = Total Organic Carbon (TOC) Concentration @ Filter Effluent
Cinf = Total Organic Carbon (TOC) Concentration @ Filter Influent
k’’ = Contamination Utilization Rate Constant as ml*(pg ATP*min)-1
[ATP] = Biological Activity as pg ATP/g media
The impact of temperature was reflected in changes in ATP. This work was published recently at AWWA’s Water Quality Technologies Conference (WQTC) in Salt Lake City. This research continues to mature but is very promising so far.
(1) Gilmore, P. Leigh; Summers, R. Scott. “Organic Matter Removal via Biological Drinking Water Filters: Removal Efficiency Based on Quantifiable System Factors”. 2015 ©American Water Works Association. AWWA WQTC Conference Proceedings.
An introductory overview of 2nd Generation ATP monitoring in biological filters.
See slide deck below: