| 210 / | HD | LIQUID PURIFICATION OR SEPARATION |
| 600 | DF | PROCESSES {14} |
| 696 | DF | .~ Preventing, decreasing, or delaying precipitation, coagulation or flocculation {2} |
| 698 | DF | .~.~ Utilizing organic agent {2} |
| 699 | | .~.~.~ Phosphorus containing {1} |
| 700 | DF | .~.~.~.~> Nitrogen containing |