Electrochemical Detection of Polyphosphate Accumulation by Phosphate Accumulating Organisms for Wastewater Treatment
URI
Date
July 2024
Access
2026-07-01
Authors
Cobb, Davis D
Journal Title
Journal ISSN
Volume Title
Publisher
East Carolina University
Abstract
Inorganic phosphates are a very common additive to fertilizers used in industrial
agriculture. While these additions result in larger healthier crop yields the runoff from these
macronutrients ends up within local water ecosystems. The discharge of phosphate to water
systems can lead to eutrophication and long-term damage to the local environment. To treat
phosphate, local wastewater treatment systems (WWTP) often use bacteria to remove phosphate
from the water. These phosphate treatment organisms are termed phosphate accumulating
organisms (PAO) and sequester phosphate by converting it into long chains of polyphosphate.
The efficiency of this process can vary due to myriad factors; therefore, the ability to monitor if
the biological processes are occurring normally is a significant WWTP need.
To this end, an electrochemical biosensor was developed using Layer-by-Layer (LbL)
methodology to immobilize films containing Pseudomonas putida, a model PAO, to detect
polyphosphate uptake following soluble phosphate exposure. The bacterial films were exposed to
electroactive methylene blue and phosphate with electrochemical monitoring using square wave
voltammetry to determine methylene blue reduction currents. Currents at several potentials (vs.
SCE) increase as a function of phosphate exposure, which were significantly elevated in the
presence of P. putida vs. E. coli films. ICP-MS was used to show that P. putida sequesters
phosphorus in significantly higher amounts than E. coli, which shows that the electrochemical
output is due to poly-P accumulation on the electrode surface. The sensor was challenged with
interfering ion solutions and at varying temperatures to model conditions that might be
encountered at the WWTP. Overall, this study lays the groundwork for the eventual biosensor
use to measure PAO health and function at WWTP.