Electricity key to waste treatment
15 Jan 2000
A new process from EA Technology could help companies convert toxic liquid wastes into harmless carbon dioxide, nitrogen and water. The process, using electrochemical technology, is suitable for a wide range of organic wastes that are usually treated by biological methods.
`Until now,' explains EA's Ged Barlow, `most problematic organic effluent streams have required costly additional treatments before they can be disposed of safely - or, in cases where conventional treatments are ineffective, they must be incinerated.' The dished electrode membrane (DEM) cell provides an effective, environment-friendly and comparatively cheap alternative, he claims.
The DEM cell generates electrons which oxidise organic molecules in two ways: either by a direct reaction at the electrode surface, or by forming a secondary oxidising species, such as hypochlorite, which reacts with the waste and is then regenerated.
The unit uses dish-shaped electrodes clamped into a frame. This design allows a large number of electrodes to be mounted in-line, which means the unit can cope with a wide variation of flow-rates.
The DEM system can handle high COD streams including ammonia, organocyanides, phenols, amines, and nitro- and chloro-compounds, says EA. It can be used alone; as a pretreatment in conjunction with conventional water treatment methods; or as a final `polish' before discharge.
