Troubleshooting

Loss of salt rejection and loss of permeate flow are the most common problems encountered in reverse osmosis. If the salt rejection and/or the permeate flow decreases slowly, this may indicate a normal fouling / scaling which can be handled by proper and regular cleaning. A rather fast or an immediate performance decline indicates a defect or misoperation of the plant. In any case, it is essential that the proper corrective measure is taken as early as possible, because any delay decreases the chance of restoring the plant performance.

Keeping Data Records

A prerequisite for early detection of potential problems is proper record keeping and plant performance normalization. This includes proper calibration of all instruments. Without accurate readings it might be too late before a problem can be detected and corrected. Another key to successful troubleshooting is understanding the effects of changing system parameters on system performance. Some apparent plant problems are simply the normal reaction of the plant to changing feed or other operating parameters.

Identify the Cause

Once a performance decline has been identified, the first step in solving the problem is to localize the problem and to identify the cause(s) of the problem. This can be done using the data of the record keeping logsheet or by the use of some additional on-line measurements. If these data are not sufficient to determine the cause(s) and to recommend corrective action, one or more membrane elements must be taken from the plant and analyzed. Dow DIRECTOR^SM Services program offers an extensive array of membrane and element analytical tests which will help not only determine the cause(s) of a problem, but can help with detailed solutions as well.

Interactive Membrane Troubleshooting Guide
Consists of a set of tables which describe the symptoms and causes of typical problems that may arise and offer solutions or suggestions to improve the system operation. There are links to additional information such as cleaning procedures, etc., where appropriate.

Typical Troubleshooting Operations
Provides details of typical troubleshooting operations like profiling, probing, cleaning various foulants and data normalization.

Technical Field Support
Identifying and solving problems when they arise is critical to efficiently operating a reverse osmosis or nanofiltration system.  Using these tools can assist you in quickly identifying, understanding and solving your system problems.

Troubleshooting Introduction (27KB PDF)

Evaluation of System Performance and Operation (46KB PDF)

System Tests - Visual Inspection, Most Effective Cleaning, Profiling, and Probing (76KB PDF)

Membrane Element Evaluation

Sample Selection (23KB PDF)

DIRECTOR Services (24KB PDF)

Visual Inspection and Weighing (23KB PDF)

Vacuum Decay Test (32KB PDF)

Performance Test (37KB PDF)

Cleaning Evaluation (24KB PDF)

Autopsy (24KB PDF)

Membrane Analysis (27KB PDF)

Symptoms of Trouble, Causes, and Corrective Measures

Low Flow (339KB PDF)

High Salt Passage (117KB PDF)

High Pressure Drop (162KB PDF)

Troubleshooting Grid (47KB PDF)