Division BAT 25 In order to reduce total emissions of VOCs and dust emissions to air, to reduce emissions to water and to improve the overall environmental performance, BAT is to use techniques (a) and (b) and a combination of techniques (c) to (i) given below.
United Kingdom
| Technique | Description | Applicability | |
|---|---|---|---|
| Waste and waste water management | |||
| (a) | Segregation of waste and waste water streams | Docks and slipways are constructed with:
| Only applicable to new plants or major plant upgrades. |
| Techniques relating to preparation and coating processes | |||
| (b) | Restrictions for adverse weather conditions | Where the treatment areas are not fully enclosed, blasting and/or airless spray coating are not carried out if adverse weather conditions are observed or forecast. | Generally applicable. |
| (c) | Partial enclosure of treatment areas | Fine nets and/or water spray curtains are used around areas where blasting and/or airless spray coating are carried out to prevent dust emissions. They may be permanent or temporary. | Applicability may be restricted by the shape and size of the area to be enclosed. Water spray curtains may not be applicable in cold climatic conditions. |
| (d) | Full enclosure of treatment areas | Blasting and/or airless spray coating are carried out in halls, closed workshops, areas tented with textiles or areas fully enclosed with nets to prevent dust emissions. Air from the treatment areas is extracted and may be sent to off-gas treatment; see also BAT 14 (b). | Applicability may be restricted by the shape and size of the area to be enclosed. |
| (e) | Dry blasting in a closed system | Dry blasting using steel grit or shot is carried out in closed blasting systems equipped with a suction head and centrifugal blasting wheels. | Generally applicable. |
| (f) | Wet blasting | Blasting is carried out with water containing a fine abrasive material, such as a fine cinder (e.g. copper slag cinder) or silica. | May not be applicable in cold climatic conditions and/or in enclosed areas (cargo tanks, double bottom tanks) due to the heavy mist formation. |
| (g) | (Ultra-)High-Pressure ((U)HP) water jetting or blasting | (U)HP blasting is a dustless surface treatment method using extremely high-pressure water. There are options with or without an abrasive. | May not be applicable in cold climatic conditions, or due to surface specifications (e.g. new surfaces, spot blasting). |
| (h) | Stripping of coatings by induction heating | An inductor head is moved over the surface, causing localised fast heating of the steel to lift old coatings. | May not be applicable for surfaces with a thickness of less than 5 mm and/or for surfaces with components sensitive to induction heating (e.g. insulation, flammable). |
| (i) | Underwater hull and propeller cleaning system | Underwater cleaning system using water pressure and rotating polypropylene brushes. | Not applicable for ships in full dry dock. |
Table 12
BAT-associated emission level (BAT-AEL) for total emissions of VOCs from the coating of ships and yachts
| Parameter | Unit | BAT-AEL(Yearly average) |
|---|---|---|
| Total VOC emissions as calculated by the solvent mass balance | kg VOCs per kg of solid mass input | < 0,375 |
The associated monitoring is given in BAT 10.