The membrane-based ARoTech Module developed by APTwater of the USA and aimed at removing specific oxidised contaminants in drinking water has received certification from NSF International.
The first full-scale commercial module, an ARoNite plant to treat nitrates, finished construction in late 2011, and is now running in conjunction with California Department of Public Health approval testing in Rancho Cucamonga, California.
Andrew Simon, for APTwater, told D&WR that the company was piloting and moving towards commercial development with its ARoChrome (chromium VI reduction), ARoPerc (perchlorate) and ARoSel (selenium), and will explore other oxidized contaminants after that.
“The technology is virtually identical across the company’s entire line, but we target specific contaminants by slightly altering the environment within the modules,” said Simon.
The ARoNite process uses a fixed-film bacterial culture to biologically reduce contaminants from the influent stream. At the heart of every system is the ARoNite module: serving as both a growth medium and hydrogen delivery substrate in support of the active biological culture.
The ARoNite system cultivates a naturally occurring bacteria culture on the surface of a proprietary membrane media. The autotrophic bacteria assimilate inorganic carbon from the alkalinity, phosphorus, and other trace nutrients directly from the influent stream to build cell mass. Nitrate from the influent stream is reduced using hydrogen gas as an electron donor in the respiration process to produce harmless nitrogen gas and clean water.
Over time, cell mass is discarded from the downstream filtration process. The end result is a biological process that directly removes nitrate without producing waste.
Hydrogen is delivered to the sealed ARoNite media under slight pressure. The growing biomass exerts a demand for hydrogen which then diffuses directly across the membrane and is immediately consumed in the respiration process.