The company’s emissions result from the process of coating circuit boards. When heated during the curing process, some of the chemicals release volatile organic compounds (VOCs).
The route to abatement
The route to abatement was simple: remove the trace amounts of VOCs from the airstream. The process would have to be continuous, as the firm's operation is on a twentyfour hour, seven day schedule. Croll-Reynolds Clean Air Technologies of Westfield, NJ, evaluated technologies for the application. The technologies considered and conclusions reached include:
- Direct thermal oxidation: Burning VOCs in a high-temperature incinerator. It is simple and effective as a destruction method, but highly uneconomical in Photocircuits’ circumstances. Typical temperatures of destruction are on the order of 1500 F. This level would have to be reached almost entirely by burning purchased fuel, as the low VOC concentrations would contribute very little toward heating the airstream. Thermal incineration was, however, considered cost-effective for endpoint destruction following another remediation process.
- Catalytic incineration: A catalyst is coated onto the surface of a ceramic packing material. The catalyst increases the rate of conversion of pollutants to non-pollutants. However, catalytic incineration was considered entirely too costly. In addition, effluent stream contamination may quickly poison the expensive catalyst.
- The biofiltration method: In the process of biofiltration, airflow is directed through a peat bed seeded with microorganisms which consume the VOCs. The process is effective, but only in a narrow operating range as it is highly sensitive to moisture, heat, and concentration of organics and solids in the gas.
- Activated carbon adsorption: This method removes VOCs from the airstream and concentrates them to higher levels, permitting cost-effective regeneration followed by incineration in a nearly self-sustaining process.