TRS inventories and air dispersion modeling for odor reduction at a kraft mill with an activated sludge treatment plant.

Application: Detailed knowledge of a mill's atmospheric TRS emissions, coupled with air dispersion modeling, can be an effective way to plan odor reduction strategies.

For this study, we conducted a complete inventory of the potential sources contributing to TRS emissions at a kraft mill using conventional stack sampling protocols and a flux chamber for emissions from area sources. We entered the data into the Industrial Source Complex Short-Term Version 3 (ISCST3) air dispersion model developed by the U.S. Environmental Protection Agency (EPA). That allowed us to estimate the maximum 1-hour ambient TRS concentrations to expect in the mill area at ground level. We also ran several different modeling scenarios to identify areas that might significantly affect ambient TRS concentrations.

The modeling data indicated that emissions from the treatment system were having the greatest, and most frequent, impact on ambient TRS in the Surrounding community. Further modeling of individual sources suggested that a small innocuous vent from the sludge dewatering building was a major contribution to ambient TRS. The model also indicated that eliminating the TRS from this simple source would significantly reduce the contribution of odors from the treatment system.

Detailed knowledge of the mill's atmospheric TRS emissions, coupled with air dispersion modelling, proved an effective way to plan odor reduction strategies. Recent mill trials also demonstrated that the TRS emissions from the small vent source could easily and consistently be reduced to near zero.

O'Connor is group leader, environment, Paprican, 570 Boulevard St-Jean, Pointe-Claire, Quebec H9R 3J9 Canada. Contact O'Connor by email at [e-mail]; Ledoux is steam plant technical assistant, Fraser Papers Inc., 284 Elizabeth, Thurso, Quebec JOX 3B0 Canada.