Removing Silica Scale - Avista Membrane Treatment Solutions
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Removing Silica Scale

Case Studies
April 4, 2021





A plant on Tenerife in the Canary Islands was suffering from fouling. A raw water analysis was taken and found to have high levels of silica present that had not been considered when designing the plant. It was concluded that the cause of the loss in performance was due to silica scaling.

The system design consisted of 3 pressure vessels, each containing 5 Hydranautics CPA-3 low-pressure membranes. The initial flow was 100m3/day, but due to fouling this had reduced to 81m3/day. The initial permeate quality was 225uS/cm, and this had increased to 270uS/cm.

RoClean P112 has been developed as a specialty cleaner to remove colloidal matter when other cleaners have failed. The high pH and strong
dispersants present work together to disperse colloids from the membrane surface and hold them in suspension until they are clear of the system.
The product contains no EDTA, making it environmentally friendly, and is buffered to maintain the optimum pH during the cleaning cycle. The cleaner
readily dissolves and is easily prepared into a cleaning solution.

Site Trial and Cleaning Support

A 2% solution of RoClean P112 was applied to the system at a temperature of 35°C and recycled for 30 minutes. It was then allowed to soak for 24 hours. Following this, the cleaner was recycled for 30 minutes.

The system was then flushed and returned to operation. Once stabilized, the system flow rate was found to have increased back to 100m3/day. The permeate quality had reduced from 270uS/cm to 235uS/cm.







Case Study
Removing Silica Scale