How positive and neutral NOM are removed?

Ladies and Gentlemen, 

Given we use cationic coagulants ,how positive and neutral Natural Organic Matter (NOM) can be removed on a municipal rapid sand filter?

Taxonomy

• Sand Filter
• Coagulants

3 Answers

1. NOM tends to be negatively charged; hence a cationic coagulant should work well, if not overdosed. However, if you are sure that the NOM particles are positive and neutral  in charge, then you might want to think of using an anionic coagulant.

2. You may test the dosage of cationic ​coagulants by jar test, and know the best to remove the NOM.

   1 Comment

   1. Cationic coagulants will attract or remove positive charged NOM? How?

3. The coagulant etc are removed in the flocculation and sedimentation process before the final filter. There is not a lot of biological activity on a rapid sand filter. There is a lot of removal on a slow sand filter, but you would not have one after coagulation.

   1 Comment

   1. So ,.can be concluded that mainly all positive charge and neutral NOM are removed before filtration step? We have seen no more of 50% removal of TOC, so the other 50% portion escapes  coagulation - flocculation- sedimentation . How to explain this?