Division 1.4.2 Emissions to water
United Kingdom
| Technique | Description |
|---|---|
| Biological treatment | The biological oxidation of dissolved organic substances using the metabolism of microorganisms, or the breakdown of organic content in waste water by the action of microorganisms in the absence of air. The biological action is usually followed by the removal of suspended solids, e.g. by sedimentation. |
| Coagulation and flocculation | Coagulation and flocculation are used to separate suspended solids from waste water and are often carried out in successive steps. Coagulation is carried out by adding coagulants with charges opposite to those of the suspended solids. Flocculation is carried out by adding polymers, so that collisions of microfloc particles cause them to bond to produce larger flocs. |
| Flotation | The separation of large flocs or floating particles from the effluent by bringing them to the surface of the suspension. |
| Dissolved air flotation | Flotation techniques relying on the use of dissolved air to achieve separation of coagulated and flocculated material.. |
| Filtration | The separation of solids from a waste water carrier by passing them through a porous medium. It includes different types of techniques, e.g. sand filtration, microfiltration and ultrafiltration. |
| Oil-water separation | The separation and extraction of insoluble hydrocarbons, relying on the principle of the difference in gravity between the phases (liquid-liquid or solid-liquid). The higher density phase settles and the lower density phase floats to the surface. |
| Retention basins | Large surface area lagoons for the passive gravitational settlement of solids. |
| Sedimentation | The separation of suspended particles and material by gravitational settling. |