Avista™ | Membrane Autopsy with CEI
Membrane Foulant Identification
The Avista Membrane Autopsy is one of the most powerful tools available to identify, prevent and correct membrane performance issues to improve system maintenance and operation.
Troubleshooting Membrane Systems
The Avista™ Membrane Autopsy includes a physical dissection of an element to remove samples and supporting materials for laboratory and foulant analysis. This procedure identifies scaling or fouling problems, determines the proper cleaning regimen, verifies system operating conditions and improves system performance.
Avista Chromatic Elemental Imaging℠ (CEI℠) is used to identify the location and relative concentration of elements in a foulant sample to resolve the primary sources of membrane fouling. In the CEI process, a beam of focused electrons is accelerated across the surface of a foulant sample causing each element to emit electrons. The X-ray patterns emitted are specific to every element, enabling each one to be individually identified. CEI then assigns a color to each element and produces a three-dimensional, high resolution image of the foulant sample. Element concentration is indicated by color intensity.
- CEI provides insight into the layering characteristics of foulants deposited on a membrane. By analyzing the layers, it is possible to understand the fouling sequence.
- When used in combination with Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS), CEI can reveal the interaction between inorganic, organic, metal oxide and colloidal compounds.
AVISTA MEMBRANE AUTOPSY WITH CEI: UNIQUE ADVANTAGES
Troubleshooting: CEI is unmatched in its ability to successfully determine the primary membrane foulants which can help identify process deficiencies to prevent or minimize future fouling.
Product Innovation: CEI accelerates the development of new antiscalants, cleaners and biocides by replacing the process of trial and error with scientific validation of formulations targeting specific foulants.
CEI showed both silica and carbonate which resulted in the proper antiscalant recommendation to protect the membranes from future scaling. Additionally, it provided information on a cleaning sequence that removed the calcium carbonate layer first followed by silica scale.
The reverse osmosis (RO) element was received for an Avista membrane autopsy to determine why a second stage RO system had experienced a rapid increase in pressure after only six months of operation.
- The tail element weighed almost 50 pounds (22 kgs) more than a new element, a clear indication of severe scaling.
- The Avista membrane autopsy revealed crystals on the membrane surface.
- CEI identified the crystals as calcium carbonate scale layered on top of silica deposits.
Based on a review of an original feedwater analysis, the Avista membrane autopsy determined that both calcium carbonate and silica were within the inhibition capabilities of the on-line antiscalant.
- The antiscalant injection rate was correct, and the system recovery was within design parameters.
- A new feedwater analysis was completed and revealed that the silica values had doubled over the summer.
- The higher silica values exceeded the capabilities of the scale inhibitor, which led to the extreme scaling.