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TOC Article - Brent Stewart - Applications Engineer TOC stands for Total Organic Carbon, it includes all organics that contain carbon except for CO2, bicarbonate and carbonate. TOC is common on the NE coast of America where vegetative matter leaches tannins into the water giving it a tea like color (water softeners). The naturally occurring TOC is typically negative charged colloids or suspended water. Ideally, RO feed water would have less than 3 ppm of TOC. Anthropogenic (man-made) sources of TOC can contribute significantly higher levels.

Oxidation of TOC in potable water supply creates THM's which is carcinogenic. Municipalities require TOC reduction before chlorination to remain under the THM target set by the EPA. There are a number of techniques for the removal or reduction of TOC including, coagulation/flocculation, activated carbon, oxidation, ion exchange, reverse osmosis and nanofiltration.

For low levels of TOC, RO/NF technology is ideal, with the combination of post UV treatment, TOC levels can be lowered to trace amounts. Nanofiltration (NF) membranes are well suited for TOC reduction while maintaining minerals in the water. The selection of RO or NF membranes is a function of the molecular weight (size) or the organic molecules, their distribution and rejection requirements. As a general rule, Hydranautics states a molecular weight of less than 200 are rejected at levels greater than 99%.

Pure Aqua, Inc. specializes in RO/NF technology, to see Pure Aqua's standard line of packaged RO equipment visit our website:

TOC Article - Brent Stewart