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MERC ER02-10
21
Live Microbes
cfu = colony forming units
E. coli
T0
cfu/100ml
TF
cfu/100ml
Control
10.33 (9.29)
2.67 (2.52)
Treated
0 (0)
0 (0)
Enterococci
T0
MPN/100ml
TF
MPN/100ml
Control
5.13 (2.05)
8.9 (2.88)
Treated
0.33 (0.58)
0.33 (0.58)
MPN = most probably number estimate determined by the Idexx Enterolert kit.
V. cholerae –
No detectable culturable toxigenic
Vibrio cholerae
were detected in any
samples during any of the trials.
Heterotrophic
Bacteria
T0
cfu/1ml
TF
cfu/1ml
Control
2,180 (383)
631.67 (218.68)
Treated
3.5 (6.06)
0 (0)
Toxicity Summaries
Residual Chlorine
Analysis
–
On June 9-10, 2010, MERC assisted Siemens with the
testing of their dechlorination system. A 24-hour trial resulted in successful dechlorination of
the treated tank using sodium bisulfate (a decline in total chlorine levels from 0.59 ppm to below
0.1 ppm – the EPA discharge standard). Note that using a sodium thiosulfate treatment resulted
in a final total chlorine level of 0.22 ppm.
Chronic Toxicity
– Ballast water was tested after treatment with a higher concentration of
chlorine followed by an in-line de-chlorination. Ballast water was collect in the same manner
and location as previous tests. All three species (mysid, fish and algae) were tested for toxicity.
There was no statistically significant toxicological effect seen in any of these three test species.