Membrane systems provide significant value to operations by lowering cost of additional water treatment, saving energy in utility operations, or meeting various purity needs for process applications. Membrane systems’ impurity removal is further defined by application need and the membrane technology being utilized. Micro filtration (MF) and Ultrafiltration (UF) will effectively remove most suspended solids and bacteria, and other large biologicals. Nano filtration (NF) and Reverse Osmosis (RO) will remove dissolved minerals; but are more susceptible to permanent fouling from larger impurities. Despite their benefits, membrane systems represent significant capital and O&M expense.
The membrane elements that perform the impurity rejection are one of the largest portions of the system investment, and are prone to fouling at varying rates depending on the quality of the water feeding the system. Properly timed cleaning will prolong the life of the membrane elements, but, if foulants are allowed to build, the impact can be repeated cleanings costing significant manpower and chemical, or in the worst case, a complete replacement of the membranes. Replacement of RO membranes is typically driven by fouling that cannot be cleaned effectively causing higher than desirable mineral passage, decreased flows, or excessive energy usage. Replacement should however be driven by membrane age and expected flux decline.
For a 100 GPM RO system, the membrane elements represent a roughly $20,000 investment. Not included in this figure is the manpower for replacement (approx. 12 man-hours) and possible downtime / “impure” water impact. Finally, factor in additional risk to unplanned downtime in operations or negative impact on products and you’ll see it is imperative to properly monitor and maintain an RO system.
Impacts of a poorly managed membrane system:
- Effluent quality negatively impacts operations or products
- Increased energy usage
- Increased manpower
- Increased chemical usage
- Asset replacement
Possible benefits:
- Increased control
- Energy savings
- Reduced downtime
- Consistent product quality
- Reduced labor
The raw data collected by the sensors throughout the membrane system cannot be used directly to determine the performance of the system. RO systems require data to be normalized in order to determine the extent of fouling. The normalized key performance indicators (KPI’s) are based on a reference condition and take into consideration variations in conditions that do not impact fouling. Closely monitored, these KPI’s can help drive continuous improvement on the RO cleaning process and drive longer term decisions, such as membrane replacement planning.
While the normalized KPI’s may be monitored through user input into complex spreadsheets, they can also be monitored remotely with U.S. Water’s SMART (Service Maintenance And Routine Treatment) Care™ for Membranes program. This program provides monitoring of the membrane system KPI’s and notification of their approach to action limits by email. The SMART Care™ program also provides dashboards to your email or on demand providing analysis of all KPI’s including calculations of KPI rate of change and projected conditions at dates in the future. The program can be further enhanced by the monitoring of additional KPI’s such as pretreatment chemical usage, totalized flow rates, runtimes, recoveries, and cleaning events.
U.S. Water wraps their integrated offerings around the SMART Care™ program with their comprehensive product line of chemicals, consumable equipment, service, and engineering. Periodic service visits by certified and experienced technicians provide a human element to the program allowing for local review of the program along with verification of all sensors and conditions. SMART Care™ dashboards are reviewed by U.S. Water’s engineers periodically to ensure proper performance of the system. These reviews can also uncover valuable improvement projects with documented Return On Investment (ROI).