ng the field pilot-scale implementation, the news release says.
The technology also can be used for other applications, including algae dewatering, process water, cooling towers, bilge water, mining water, separation of oil or other emulsions from water, distributed/onsite water treatment, and recovery of resources from water, the news release says.
Carbon nanotubes threaten aquatic species
Researchers have determined that carbon nanotubes (CNTs) can be toxic to aquatic animals. University of Missouri (Columbia) and U.S. Geological Survey researchers conducted a joint study showing that CNTs can reduce growth rates or even kill some species of aquatic organisms, according to a university news release.
CNTs are used to strengthen composite materials, such as those used in tennis rackets, and have potential uses in everything from medicine to electronics to construction. The thin, long cylinders of carbon atoms can contain impurities of nickel, chromium, and other metals used in the manufacturing process, the news release says.
Researchers studied CNTs’ effects on mussels, small flies’ larvae, worms, and crustaceans and found that the metal impurities and CNTs themselves can have a negative effect on these species, the news release says.
The study, funded by a $400,000 grant from the U.S. Environmental Protection Agency, was published in the journal Environmental Toxicology and Chemistry. Researchers noted the need for additional studies of CNTs.
Achieving disinfection by combining ozone and ultraviolet radiation
Researchers conducted bench-scale experiments with municipal wastewater effluent samples to examine the feasibility of the combined application of ozone and ultraviolet (UV) radiation for disinfection. The November issue of Water Environment Research contains an article on this work.
Researchers studied effluent samples from the City of Indianapolis’s Belmont and Southport water resource recovery facilities. Effluent samples were subjected to ozonation in semibatch reactors to enable measurement of ozone demand and ozone transfer efficiency, the article says. This yielded high ozone-transfer efficiency and rapid initial ozone demand. Ozone demand resulted in relatively inefficient and variable inactivation of Escherichia coli and required ozone doses of approximately 10 mg/L to approach compliance with discharge permit limitations. Ozonation also yielded small improvements in UV transmittance of effluent samples; preozonation yielded only modest benefits with respect to subsequent UV254 irradiation, the article says.
The study found that compliance with discharge permit limitations could be achieved consistently with a UV254 dose of 12.4 mJ/cm2 at a preozonation dose of 2 to 3 mg/L. Without preozonation, consistent compliance was achieved with a UV dose of 16.5 mJ/cm2. And according to the article, “no evidence of synergism between ozone and UV254 radiation was found in the measured inactivation responses of E. coli.”
The article, “Ozone and UV254 Radiation for Municipal Wastewater Disinfection,” appears in the November issue of Water Environment Research and can be downloaded free at http://goo.gl/PFqHm.