VOC Emissions from Manufacturing Processes
3. Approaches to Cutting VOC Emissions
Emissions can be grouped depending on how they leave the production facility:
 | in the effluent water or via a wastewater treatment plant |
| in the solid waste hauled away for external disposal |
| in the fumes exhausted to atmosphere or via an exhaust fume treatment plant |
Figure 3.1
Solvent emissions
Wastewater
Wastewater from a plant manufacturing paint and coatings on a solvent basis comprises essentially cleaning effluent from washing the floors of the production buildings and cleaning equipment as well as the transportation and traffic routes. Under the aspect of the solvent balance, this will only be of significance in isolated cases, as the solvent loadings being transported are generally very low, and consequently production modification measures for reduction or prevention will have little influence on the overall emission situation.
For this reason, wastewater as an emission path is eliminated from further consideration in this study.
Solid waste
The solid waste arising in a paints and coatings manufacturing plant comprises essentially disposable packaging, transportation drums as well as sedimentation and filtration residues. These are likewise of importance for the solvent balance and the overall emissions situation only in isolated cases, and are therefore not considered further.
Fume extraction and exhaust
Effective prevention and/or reduction of solvent emissions is only possible in connection with fume extraction and exhaust.
A basic distinction is made between point and diffuse emission sources. A point source is a specific outlet through pipe or stack. Point sources are often established by compulsory ventilation. Diffuse emissions are not related to specific outlets. For instance diffuse discharges, such as emissions from vessels and tanks not furnished with compulsory ventilation.
Causes of emissions
The determining causes of emissions in a paint and coatings manufacturing plant are:
| displacements of solvent-laden air when filling and emptying road and rail tankers |
| respiration losses at tanks in general |
| displacement of solvent-laden air when dosing tanks and dissolvers with feedstocks |
| emissions as temperature rises due to chemical reactions or shearing forces in reactors and dissolvers |
| displacement of solvent-laden air when decanting and filling intermediate and final products |
| diffuse emissions from systems and components that are open or only partially closed |
| cleaning of stationary tanks and dissolvers |
| cleaning of mobile tanks and small parts |
As a rule, the originators of emissions of volatile organic compounds are solvents and binding agents.