Cyanotoxins and Cyanobacteria Cell Accumulations in Drinking Water Treatment Plants with a Low Risk of Bloom Formation at the Source

Hi all…a study looking at the extent of cyanobacterial cell accumulation and presence of five cyanotoxins across the treatment trains of four drinking water treatment plants in the Great Lakes region considered to be at little-to-no risk from cyanobacteria and their toxins has just been published in the journal ‘Toxins’. It was reported that significant cell accumulations of up to 240,000 cells/mL occurred despite low cell concentrations in the raw water (under 1000 cells/mL) and that while microcystins and anatoxin-a were detected across the treatment trains, toxin concentrations did not correlate with cell counts. They also report that “anatoxin-a was detected in a drinking water sample. This is concerning because if accumulated cells release anatoxin-a, it could have adverse consequences for public health, given that it is resistant to degradation by chlorine.”

The authors conclude that their “results show that plants receiving a low influx of cells can be at risk of toxic cyanobacterial accumulation, and therefore, the absence of a bloom at the source does not indicate the absence of risk.”

This is an open access article: https://www.mdpi.com/2072-6651/10/11/430

Bill

Cyanotoxins and ​Cyanobacteria Cell Accumulations in Drinking Water Treatment Plants with a Low Risk of Bloom Formation at the Source

Husein Almuhtaram, Yijing Cui, Arash Zamyadi and Ron Hofmann
Toxins 2018, 10, 430; doi:10.3390/toxins10110430

Abstract: 

“Toxic cyanobacteria have been shown to accumulate in drinking water treatment plants that are susceptible to algal blooms. However, the risk for plants that do not experience algal blooms, but that receive a low influx of cells, is not well known. This study determined the extent of cell accumulation and presence of cyanotoxins across the treatment trains of four plants in the Great Lakes region. Samples were collected for microscopic enumeration and enzyme-linked immunosorbent assay (ELISA) measurements for microcystins, anatoxin-a, saxitoxin, cylindrospermopsin, and β-methylamino-L-alanine (BMAA). Low cell influxes (under 1000 cells/mL) resulted in significant cell accumulations (over 1 × 10⁵ cells/mL) in clarifier sludge and filter backwash samples. Microcystins peaked at 7.2 µg/L in one clarifier sludge sample, exceeding the raw water concentration by a factor of 12. Anatoxin-a was detected in the finished drinking water of one plant at 0.6 µg/L. BMAA may have been detected in three finished water samples, though inconsistencies among the BMAA ELISAs call these results into question. In summary, the results show that plants receiving a low influx of cells can be at risk of toxic cyanobacterial accumulation, and therefore, the absence of a bloom at the source does not indicate the absence of risk.”