Division BAT 27: In order to reduce the waste water volume and the organic load discharged to waste water treatment, BAT is to use an appropriate combination of the techniques given below.
United Kingdom
| Technique | Description | Applicability | |
|---|---|---|---|
| a. | Water-free vacuum generation | Use mechanical pumping systems in a closed circuit procedure, discharging only a small amount of water as blowdown, or use dry-running pumps. In some cases, waste-water-free vacuum generation can be achieved by use of the product as a barrier liquid in a mechanical vacuum pump, or by use of a gas stream from the production process | Generally applicable |
| b. | Source segregation of aqueous effluents | Aqueous effluents from aromatics plants are segregated from waste water from other sources in order to facilitate the recovery of raw materials or products | For existing plants, the applicability may be restricted by site-specific drainage systems |
| c. | Liquid phase separation with recovery of hydrocarbons | Separation of organic and aqueous phases with appropriate design and operation (e.g. sufficient residence time, phase boundary detection and control) to prevent any entrainment of undissolved organic material | Generally applicable |
| d | Stripping with recovery of hydrocarbons | See Section 12.2. Stripping can be used on individual or combined streams | Applicability may be restricted when the concentration of hydrocarbons is low |
| e. | Reuse of water | With further treatment of some waste water streams, water from stripping can be used as process water or as boiler feed water, replacing other sources of water | Generally applicable |