Division Description
United Kingdom
The application of an appropriate combination of the techniques described below. The combination of techniques can be implemented on site and/or off site, in two or three stages.
| Technique | Description | Applicability | |
|---|---|---|---|
| a | Mechanical treatment | Screening of gross solids, skimming of fats, oils, and greases and removal of solids by sedimentation. | Generally applicable for on-site and/or off-site treatment. |
| b | Physico-chemical treatment | Sulphide oxidation and/or precipitation, COD and suspended solids removal by, e.g., coagulation and flocculation. Chromium precipitation by increasing pH to 8 or above using an alkali (e.g. calcium hydroxide, magnesium oxide, sodium carbonate, sodium hydroxide, sodium aluminate). | Generally applicable for on-site and/or off-site treatment. |
| c | Biological treatment | Aerobic biological waste water treatment using aeration, including the removal of suspended solids by, e.g., sedimentation, secondary flotation. | Generally applicable for on-site and/or off-site treatment. |
| d | Biological nitrogen elimination | Nitrification of ammoniacal nitrogen compounds to nitrates, followed by the reduction of nitrates to gaseous nitrogen. | Applicable to plants with direct discharge to receiving water. Difficult implementation into existing plants where there are space limitations. |