Veolia Water Technologies recently helped a food manufacturer to eliminate hydrogen sulphide in its wastewater treatment.
VWT had previously supplied effluent treatment chemicals to the business, and helped with servicing the Dissolved Air Flotation (DAF) water treatment plant at its facility.
In July 2023, the site began experiencing an issue with a foul odour. Staff at the factory had begun reporting a sulphur smell in certain corridors and staff areas within the building, which was initially believed to be an issue with the drains leading from the staff facilities.
The on-site team tried to solve the problem by cleaning and surveying the pipe network. The problem was eventually traced back to the wastewater treatment system on site, some distance from the factory.
As the manufacturer’s water treatment partner, VWT was contacted to help the team find a solution. They identified the cause as hydrogen sulphide build-up in the sump where treated water from the DAF unit is stored before being discharged to the public sewer. The low flow and long retention times in the system meant that hydrogen sulphide had developed in the water. Although the on-site team carried out daily testing of the water from the DAF plant, the presence of hydrogen sulphide downstream could not be detected.
Hydrogen sulphide is created by microbes breaking down organic matter under anoxic (oxygen-free) conditions. It often occurs in water that stagnates for a long period of time.
VWT recommended adding its Hydrex 6935 water treatment chemical to the wastewater stream to correct the issue. Formulated specifically for this purpose, it breaks down the hydrogen sulphide into more inert substances, which eliminates the odour. It also stabilises the water to prevent further formation of hydrogen sulphide. It requires no specialist dosing equipment and is easy to manage, meaning minimal cost and disruption to the site.
The first step was to carry out a trial of the Hydrex 6935 chemical and the result was immediate. Within 30 minutes, the smell had reduced substantially. The VWT team set up the dosing equipment and provided training to allow the on-site team to manually add the small doses required. Since implementing this, there has been no recurrence of the issue.
Brian Jones of Veolia Water Technologies said: “Some facilities use aerosol spray systems to mask the odour, but this is often ineffective and does not treat the underlying cause. Hydrex 6935 safely and quickly neutralises the compound and can be easily applied on a range of different water treatment systems.”
