By definition:

Low fouling water: (TOC <2% total anions)

Moderate fouling water (TOC = 2 - 5% total anions)

High Fouling water (TOC >5% total anions)

Another test for measuring organics in water is COD = Chemical Oxygen Demand which is a test that oxidizes organics in water using Di-chromate. VOC's = volatile organic compounds are another category or organic pollutants that are volatile. Some common VOC's are BTEX = Benzne, Toluene, Ethylbenzene and Xylene which are petroleum products.

Removing organics from water can be done using several technologies depending on the nature of the organic pollutant:

1. Coagulation and Flocculation (if the organic pollutants are coagulable) and this treatment methodology can be supplemented by using PAC. In previous power stations where I used to work at, we used to do a test at a lab in Germany called DOC Labor in which the organics are classified according to different groups and according to that, they would be either removable by coagulation or PAC adsorption.

2. Activated Carbon Filtration using GAC

3. Advanced Oxidation Processes: using UV light and oxidants such as Fenton's Reagent. This tecnique is also used for removing VOC from polluted soils

4. WBA (Weak Base Anion) Ion Exchange resins

5. Specialized organic trap resins

6. Using Chromatographic Columns in Normal Phase or Reverse Phase (Lab Scale). I have used TLC = Thin layer Chromatography before to separate organic molecules it is a fascinatung technique.

7. If the organics are immiscible fluids like kerosene or benzene or diesel, then oil separators can be used.

8. RECAM from SA Envitech is a material based on graphene with very exciting properties for water treatment

9. Biological degradation (if the organics are biodegradable). Ofcourse genetic engineering allows the development of custom bacteria that degrade even persistant organica pollutants.

10. Demulsifiers: if the organic pollutant is in the form of an emulsion, then an emulsion breaker can be used. Sometimes, applying electrical fields can help with that.

11. Reverse Osmosis technology can be used to reject large size organic molecules from water. In this case, it is advisable to use high pH in a process known as HERO where organic molecules exist in the anionic rather than caroboxylic acid form and are less sticky to the RO membrane thus causing less fouling.

12. Ozone can be used to oxidize some organics but it is an expensive gas to generate.

Compiled by Rami E. Kremesti M.Sc.