An Integrated Rapid Monitoring Protocol for Taste and Odor Compounds and Cyanotoxins

Oral Presentation

Prepared by H. Adams, A. Cottrell, S. Reeder, M. Southard
CITY OF WICHITA FALLS, 4801 BIG ED NEAL DR, WICHITA FALLS, TX, 76310, United States


Contact Information: HUNTER.ADAMS@WICHITAFALLSTX.GOV; 940-691-1153


ABSTRACT

Climate conditions are conducive to both harmful algae blooms (HABs) as well as taste and odor (T&O) events with increasing frequency and intensity. As a result, EPA regulations are moving toward requiring cyanobacteria monitoring. Proactive drinking water agencies are seeking a streamlined approach to monitor cyanobacteria and nuisance algae. Unfortunately, there is no single method that answers all the fundamental questions needed to make treatment decisions and ensure a safe water supply.

The City of Wichita Falls, TX, has designed and implemented a comprehensive integrated rapid monitoring protocol for two surface water reservoirs and one holding reservoir, which includes algae speciation and enumeration by imaging flow cytometry, T&O monitoring by GC-MS/ECD, and cyanotoxin monitoring by qPCR and LC-MS/MS.

Imaging Flow Cytometry: A Fluid Imaging Technologies FlowCam is used to analyze samples 3-5 times per week in warm months and 1-3 times per week in cooler months. This allows rapid enumeration and classification/identification of T&O nuisance algae and toxin-producing cyanobacteria. When triggers are hit for either T&O or cyanotoxin-producing algae, increased testing by the three following methods is implemented.

GC-MS: A Thermo Scientific GC-MS/ECD is used when T&O algae counts are elevated to analyze samples by SPME or HS for T&O compounds as listed in Standard Methods 2170. Powder Activated Carbon (PAC) and Potassium Permanganate treatment is initiated when T&O compounds, such as Geosmin and MIB, are detected above trigger levels.

qPCR: A Cepheid SmartCycler is used weekly to rapidly analyze samples for cyanotoxin-producing genes in source water and treated plant effluent. Phytoxigene’s CyanoDTec kits are a molecular assay produced for the simultaneous detection of hepatotoxins – Microcystin, Nodularin, and Cylindrospermopsin, and neurotoxin – Saxitoxin. Detection by qPCR indicate the presence of cyanotoxin-producing genes, but do not confirm toxins. For toxin confirmation, samples are analyzed by LC-MS/MS.

LC-MS/MS: Samples are sent to a contract lab for analysis when samples are found positive by qPCR. To this point, no samples have been found to confirm toxins over EPA guidance limits.

By using an integrated laboratory approach to monitoring, the City of Wichita Falls has successfully mitigated several
episodes before water containing T&O compounds was discharged to the City’s residents. Customer complaints have been all but eliminated. To date, it has been 778 days since this new strategy was implemented, with no failures.