At what pH range does hydrogen sulfide cause the most serious problems?

Hydrogen sulfide (H2S) poses significant problems primarily in acidic conditions, particularly at a pH level of less than 5. In this acidic environment, hydrogen sulfide is more soluble, which increases its potential to be released into the atmosphere or to cause corrosion in wastewater systems.

At low pH levels, the concentration of H2S in its gaseous form is also much higher, leading to safety risks for workers and enhancing the likelihood of odor problems. Additionally, the corrosive nature of hydrogen sulfide can cause significant damage to infrastructure, such as pipes and tanks, particularly when combined with other factors present in wastewater treatment processes.

In contrast, environments with a higher pH (above 7) or slightly acidic conditions (between pH 5 and 7) often see decreased solubility and the formation of sulfide ions, which are less problematic compared to the gaseous form. Therefore, understanding the relationship between pH and hydrogen sulfide's behavior is essential for controlling its effects in wastewater treatment.