As paper mills have begun to close up their water systems and move toward zero effluent discharge, they are finding that closing a mill’s water system can lead to changes in a mill’s water chemistry. These can include a build-up of nutrients which can increase the amount of microbes in a mill’s system. In the absence of oxygen that might be found in tanks, chests, and pipes, anaerobic bacteria can thrive.
When certain types of anaerobic bacteria break down the organic material found in a mill, hydrogen sulfide and hydrogen gases can be formed and released. One group of anaerobic bacteria, sulfate-reducing bacteria or SRB, produce hydrogen sulfide gas as a byproduct of their metabolic process. Other anaerobic bacteria, including clostridia, produce hydrogen gas as a byproduct of their metabolic processes.
Both these gases, if present in sufficient amounts, can be a safety concern — particularly for explosions — in a paper mill. Monitoring for these gases can help detect harmful levels of the gases before incident occurs.
RPTA issued Technical Bulletin 16, Hydrogen and Hydrogen Sulfide Gases, which provides guidance on monitoring for these gases.