Struvite scale prevention tested on and off at Walla Walla
Struvite scale prevention was tested at the City of Walla Walla Waste Water Plant by switching treatment on, then off, on the same metal. Two 12 x 12 inch sections of the belt press drum and pan were chiselled back to bare metal, and a HydroFLOW® Custom 1 inch unit was installed on 31 May 2013. With it running, the cleaned drum section took no new scale for eight weeks and the pan deposits softened enough to wash off with a hose. With it off, pan scale returned within four weeks, and by seven weeks the drum carried an eighth of an inch and the pan a quarter inch.
The Challenge
- Struvite scale prevention had to be tested directly against untreated regrowth on the same equipment
- Hard deposits covered both the belt press drum and pan
- Deposits were firmly bonded to the metal surfaces
- Each 12 x 12 inch test section needed a chisel to expose bare metal
- Limited water flow around the drum restricted deposit removal
The Solution
- Unit installed: one HydroFLOW® Custom 1 inch unit
- Installed: 31 May 2013, signal verified at 41.2 V peak-to-peak
- Trial: inspections at five and eight weeks on, then four and seven weeks off
Struvite scale prevention was judged against untreated regrowth on the same equipment. The drum and pan sections were chiselled clean and the unit was switched on. The sections were inspected after five and eight weeks with the unit running, then after four and seven weeks with it deliberately switched off, so the same metal served as both the treated and the untreated surface.
