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