Part one of this article appeared in the July issue and discussed microfiltration and utrafiltration. This article discusses nanofiltration and reverse osmosis.
Once considered a viable technology only for desalination, membrane processes are increasingly employed for removal of bacteria and other microorganisms, particulate material and natural organic material that can impart color, tastes and odors to the water.
Goulston Technologies has practiced evaporator techniques over four years to separate water from oil and surfactant mixture. A joint development effort was pursued with a local company, Recovery Technologies Corporation (RTC), Charlotte, N.C., to take the evaporation process one step further in terms of dewatering, and also toward active product recovery and potential recycle.
Public Water Supply District #7 in Cass County, Mo., has combined an ultrafiltration membrane system with a ballasted flocculating/clarification system to deliver higher-purity water than ever before. The two treatment systems were designed by Koch Membrane Systems and Kruger of Denmark, respectively.
"Current and upcoming EPA regulations focused us directly towards new treatment techniques," Leonard Whiting, Cass County superintendent, said. "Many plants will not meet the regulations using current treatments.
Products At Work
The membrane processing technologies of microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) are widely used to separate suspended and dissolved materials from water solutions in numerous industrial, medical and drinking water applications.
The increasingly broad range of requirements for water quality has motivated the water treatment industry to refine existing techniques, combine methods and explore new water purification technologies including desalination.
The removal of impurities and contamination from water supplies or industrial chemicals is a process existing all over the world to varying degrees of sophistication. Filtration systems vary enormously according to location, the type of purification required and funding available.
An overview of various filtration methods and their applications
Membrane filtration, widely used in chemical and biotechnology processes, is already established as a valuable means of filtering and cleaning wastewater and industrial process water.
This paper summarizes ozonation and by-product formation chemistry as well as ways to control by-product formation.
"In four years, half of San Diego may be filling its glasses with tap water that once ran through its toilets."