Ferric dosing reduction on a food plant DAF
A ferric dosing reduction was needed at Maple Leaf Foods’ Heritage plant, where the dissolved air flotation system ran on a fixed ferric dose of 200 ppm. The chemical cost was high, so was the carbon footprint that came with it, the system was near its operational limits, and there was a real risk of fines if discharge limits were exceeded. In October 2023 two HydroFLOW® Custom units, 12 and 14 inch, were fitted to the DAF feed lines for a 90-day trial, and ferric was reduced in stages. Dosing fell by 50% with discharge compliance held throughout, saving $47,500 a year.
The Challenges
- A ferric dosing reduction was needed with the dose fixed at 200 ppm
- Chemical cost and carbon impact were both high
- The DAF system was running near its operational limits
- Exceeding discharge limits carried a risk of fines
- Any reduction had to be staged and proven against compliance
The Solution
- Units installed: two HydroFLOW® Custom units, 12 inch and 14 inch
- Installation point: DAF feed lines
- Installed: October 2023
- Trial: 90 days, with ferric reduced in stages
- Previous treatment: fixed ferric dose of 200 ppm
Ferric is dosed for compliance, so the ferric dosing reduction was taken in stages rather than in one cut. With the two units fitted to the DAF feed lines, the dose was lowered step by step over the 90-day trial, and discharge compliance was tracked against each step. The signal improves flocculation, so the lower ferric dose still held compliance.
