Membrane and Module Autopsy Services
The physical dissection of a reverse osmosis (RO) element or microfiltration/ultrafiltration (MF/UF) module and the resulting analysis of its foulants can be one of the most definitive methods of troubleshooting a system. Identifying the cause of performance loss is only part of this valuable service. Equally important are the recommendations provided in the Avista report which outlines the best course of action in correcting system problems including frequent cleanings, loss of productivity, reductions in permeate quality, system downtime or premature membrane or MF/UF replacement.
- To identify scaling or fouling problems
- To determine the proper cleaning regimen
- To improve system performance
A membrane autopsy includes a physical dissection of a reverse osmosis (RO) membrane removed for laboratory analysis and can be one of the most definitive methods of troubleshooting an RO system.
Membrane Autopsy Process:
1. Full Element Wet Test
The full element is tested in a single element vessel. Flow, pressure and salt rejection data is collected and then normalized to the original membrane manufacturer’s specification. This full element data is then compared to flat sheet samples harvested from that element to identify mechanical leaks and physical damage such as compaction.
2. External Inspection
The exterior components such as the brine seal, permeate tube, external casing and anti-telescoping devices are inspected for physical damage.
3. Internal Visual Exam
The element is dissected to examine glue lines, membrane folds, and the permeate side of the element. Any foulants or odors are also noted during this inspection.
4. Foulant Analysis
Samples collected from the membrane surfaces are analyzed using a series of tests to identify the composition of the foreign material on the membrane surface.
5. Organic Analysis
Foulant samples are scraped from the membranes surface, Gram stained and examined under a light microscope. The sample is inspected for biological material including bacteria, yeast, fungi, algae and mold. Loss on ignition (LOI) is performed to determine what percentage of the material is organic.
6. Identification of Inorganic Foulants
Energy Dispersive X-ray (EDX) analysis is used to determine the percent of inorganic material in a foulant sample. Scanning Electron Microscope (SEM) produces close and clean images of the foulant layer.
7. Chromatic Elemental Imaging
Chromatic Elemental Imaging (CEI) generates vivid, three-dimensional color images that identify specific elemental foulant constituents, concentrations and spatial locations on a membrane’s surface.
8. Laboratory Cleaning Study
These are performed to determine which of the RoClean or AvistaClean products will restore performance. A membrane sample is placed in a laboratory apparatus and tested for water passage and salt passage before and after cleaning.
9. Identifying Membrane Damage
If damage of the active membrane surface is suspected, a dye test is performed to expose and highlight damaged areas. For polyamide membranes, Fujiwara testing is conducted to indicate exposure to a Group 7 Halogen.