Total Reduced Sulphur Compounds (TRS) What are they?
Total Reduced Sulphur Compounds (TRS) are gases that result from various steps in the manufacturing of kraft pulp. These compounds are recognizable by their distinctive odour, which is similar to that of rotten eggs. The most common TRS compound is hydrogen sulphide.
Why do they matter?
The concern with TRS emissions is the undesirable odour they create. The smell associated with these compounds can be sensed even at incredibly low levels. Exposure to these low concentrations has a negligible impact on human health and the environment. However, the odour is unpleasant to most people and needs to be controlled.
How do we measure it?
We use on-line equipment to monitor TRS concentrations in the stack before it enters the atmosphere. Continuous monitoring allows us to track TRS emissions and to take action if the emissions begin to rise. In addition frequent testing is carried out in the community by the regulatory agencies and us to make sure that ground-level TRS concentrations are in compliance with provincial guidelines.
How do we control it?
TRS emissions are reduced using a variety of methods. Improvements to the burning efficiency of our chemical recovery system and the introduction of low odour boilers have significantly reduced the formation of TRS compounds. The addition of oxygen to the sulphur-containing liquor before it is burned prevents the formation of TRS compounds in the boiler. Scrubbers can also be used to reduce TRS compounds emissions to the atmosphere.
The Thunder Bay mill has a comprehensive Air Improvement Program that has identified a number of projects to reduce TRS emissions from the facility.