Dual Scales Cause Frequent Cleans and Membrane Replacement - Avista Membrane Treatment Solutions
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Case Studies
September 17, 2018

Dual Scales Cause Frequent Cleans and Membrane Replacement

Membrane scaling triggered an on site visit by Avista. Review of operations indicated that membrane cleaning occurred every 2 weeks. An updated water analysis revealed that the well water quality had changed with a marked increase in sulfate.

BACKGROUND
Rapid reverse osmosis (RO) membrane scaling from silica and sulfate. Well feedwater was high in silica, sulfate, and calcium.

SYSTEM DESCRIPTION
System Information: Array 3:2:1

Pretreatment: 5 micron cartridge filters

Feedwater: Well water

Application: Resort

 

ACTION/APPROACH
Membrane scaling triggered an on site visit by Avista. Elements were removed for visual inspection, and heavy scaling was observed. Review of operations indicated that membrane cleaning occurred every 2 weeks. An updated water analysis revealed that the well water quality had changed with a marked increase in sulfate. A membrane autopsy identified dual scales, silica and calcium sulfate (see CEI).

To temporarily control the high silica and sulfate in the water, two antiscalants were injected at two dose rates; one to inhibit silica and one to inhibit sulfate scale. Concurrently, the lab developed Vitec 7400, a single inhibitor to effectively control both silica and sulfate scale with one dosage rate (see Avista™ Advisor™Ci projection).

Vitec 7400 has provided consistent performance for over one year. Cleaning frequency decreased from twice monthly to only one annual maintenance clean.

Avista trained on-site personnel to collect membrane performance data and monitor the system performance during the Vitec 7400 run period. Ongoing data collection and twice-yearly site visits by Avista ensure the RO continues to run at optimal levels.

 

Case Study
Dual Scales Cause Frequent Cleans
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