Pollution
Humain
Environnement
Economique

For four days, residents living near a cheese factory were bothered by foul odours coming from the factory’s wastewater pretreatment plant. One of the residents complained of the smell. The operator checked the flare stack and the scrubber tower associated with its biogas plant and found a significant air handling failure. After conducting a comprehensive assessment of the facility, the operator identified the following problems:

  • a significant imbalance in the operation of the biogas plant due to the fact that some of the effluent to be treated arrived directly at the pumping station;
  • the cold weather had frozen the sodium hydroxide used to adjust the pH entering the biogas plant because the feed system temperature hold clip was no longer working;
  • the significant increase in the amount of odorous gases caused the initial air handling control to fail.

The foul odours were thus caused by the combination of cold weather and failure of the sodium hydroxide feed system temperature hold clip. The situation was compounded by an increase in effluent fed into the biogas plant due to the shutdown of some operations.

The operator conducted frequent visual checks of the entire facility and replaced the feed system temperature hold clip. The municipality organized a meeting with the neighbouring community. Several malfunctions had previously occurred at this pretreatment facility in July 2016 (ARIA 49095).