January 2011, Vol. 23, No.1

Research Notes

Odors may warn of toxins

The presence of taste and odor compounds, along with the visual evidence of blue-green algae, known as cyanobacteria, could identify the presence of harmful cyanotoxins in lakes or reservoirs, according to a study by the U.S. Geological Survey (USGS). In the study, these compounds that result in earthy, musty odors, were found almost every time cyanotoxins were present, a USGS news release says.

While taste and odor compounds are not toxic, they can accompany cyanotoxins, which are produced by some cyanobacteria and can be poisonous to humans, aquatic life, and animals. Cyanotoxins are on the U.S. Environmental Protection Agency’s drinking water Contaminant Candidate List and tracked in many state freshwater beach monitoring programs, the news release says.

For the study, samples collected from 23 lakes in Iowa, Kansas, Minnesota, and Missouri were analyzed for 13 toxins and two taste and odor compounds, the news release says. Lakes with a known history of cyanobacterial blooms were chosen for the study.

The study indicates that cyanotoxins may be more common than previously thought. Microcystin, often the only cyanotoxin considered when evaluating risks associated with cyanobacteria in water, were found in all samples.

Taste and odor compounds were found in 91% of the samples, which indicates a strong correlation to the presence of cyanotoxins. But since toxins occurred more often, the presence of odor alone does not provide complete warning of presence of toxins, the news release says.

For more information on this ongoing area of study, see http://toxics.usgs.gov/highlights/algal_toxins.  

Bacteria from spoiled pickles clean wastewater

Bacteria resulting from the spoilage of pickles may help clean up dyes in textile industry wastewater, according to a study by the U.S. Department of Agriculture.

Some species of Lactobacilli, which are food-related microorganisms, can cause pickle skin to turn red when combined with tartrazine, a yellow food coloring used to make dill pickles, according to a U.S. Agricultural Research Service (ARS) news release.

ARS microbiologist Ilenys Pérez–Díaz and her colleagues found that some Lactobacilli modify azo dyes into nonmutagenic substances. While many azo dyes are nontoxic, some have been found to be mutagenic and may end up in wastewater if untreated, the news release says.

Azo dyes are used in the textile industry to create vivid and warm reds, oranges, and yellows in fabric.

Pérez–Díaz discovered this phenomenon while searching for the culprit responsible for causing commercial dill pickles to have red spoilage bacteria. She isolated Lactobacilli from spoiled jars of hamburger-dill pickles and used these to inoculate nonspoiled pickle jars. Jars containing brines with tartrazine developed the red hue, while those that contained turmeric or no added coloring did not.

Seven treatments were tested to find a preventive measure, and Pérez–Díaz found that adding sodium benzoate prevented bacterial growth and the development of red-colored spoilage in the pickles.

If food-grade Lactobacilli capable of degrading a range of azo dyes were identified, they might become “organisms of choice for wastewater treatment applications,” the news release says. Findings from this report can be found in the August 2009 Journal of Applied Microbiology. 

Paul L. Busch award recipient works to convert greenhouse gas into fuel

Kartick Chandran, associate professor and director of the Biomolecular Environmental Sciences (CUBES) program at Columbia University (New York), has received the 2010 Paul L. Busch Award.

The annual award includes a $100,000 research grant that will support Chandran and his team of researchers as they work on developing a new treatment technology that transforms methane and carbon dioxide generated from wastewater treatment plants into methanol, according to a Water Environment Research Foundation (WERF; Alexandria, Va.) news release.

Currently, methanol production requires an expensive conversion process that chemically catalyzes the oxidation of methane gas. Chandran’s research takes an alternative and more cost-effective approach through the development of autotrophic microbial reactors. These reactors, which treatment plants could integrate into their normal biological treatment processes, convert the methane in digester gas directly to liquid methanol, avoiding purification and chemically catalyzed conversion.

Successful application of Chandran’s technology could remove nitrogen while addressing the problem of greenhouse gas emissions by converting nitrogen to nitrite using ammonia oxidizing bacteria and then channeling the methanol that these bacteria produce into biofuel or an external carbon source to enhance denitrification. The process could lower the overall greenhouse gas footprint of wastewater treatment plants by reducing both methane and carbon dioxide, the news release says.

The WERF Endowment for Innovation in Applied Water Quality Research presented the annual award to Chandran at WEFTEC® 2010 in New Orleans. This year marks the 10th anniversary of the award, which supports wastewater research. For more information, see www.werf.org/PaulLBusch.


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