Optimizing Filter Performance in Drinking Water Treatment

Filter Monitoring for Better Long-Term Filter Health and Efficiency

Flow rates, timing, and environmental changes can affect filtration media performance. When the flow rate is too high, there’s a higher likelihood of washing out media. When the wash duration is longer than necessary, valuable treated water is wasted both during the wash and during the filter ripening time post-wash.

Media age, pump performance, and other backwash characteristics can change seasonally and over time. Mud ball formation, a result of accumulated buildup on the filter media, can decrease efficacy. Adequate media expansion ensures proper cleaning of the filter media, can increase filter run times, and prevents mud ball formation.

However, 24/7 filtration monitoring can address these issues before they happen, alerting operators for proactive management of the drinking water treatment process. With current data on filter performance instead of just a one-time calculation, operation is optimized.

A Clear Picture of Turbidity

The FilterSmart Backwash Monitor directly measures media expansion and turbidity. These two trends together present a clear picture of what’s going on during backwash, allowing operators to see into the process like never before. FilterSmart simplifies filter optimization because its 24/7 monitoring takes the place of countless manual hours of data collection.

The FilterSmart sensor is installed in the top of a gravity filter just below the top of the wash trough. This in-filter turbidity measurement provides immediate feedback during a backwash on when the filter is clean. During a backwash, the ultrasonic sensor tracks the level of the media and the turbidity sensor measures how clean or dirty the wash water is as it flows into the wash trough. These two measurements produce trends that together provide an extremely accurate profile of the backwash and become a powerful tool for optimizing filter performance.

With this information, operators can virtually eliminate media loss and mud-ball formation, in most cases reduce water usage, and improve overall filter health and efficiency.

Real-World Monitoring Example: Punta Gorda, Florida

The Punta Gorda Water Treatment Plant is a 10 MGD surface drinking water facility located just east of Punta Gorda, Fla. The process includes floc tanks, and four Solids Contact Units (SCUs) (which are a form of upflow clarifier), which then feed two Greenleaf Filters with four cells each. The filters are backwashed every 70 hours regardless of head loss. High backwash flow rate is 5200 gpm. The total cost of treating 1,000 gallons of drinking water is $1.73 (£1.37).

During a field trial with FilterSmart monitors, it was noted that the loading in the filters was very light, with relatively low turbidity measured during the backwash. Since the backwash schedule was based on time and not head loss, the suggestion was made to incrementally increase the Filter Run Times (FRTs) until the head loss value was reached. FRTs were increased to 120 hours, an adjustment that resulted in a 42% decrease in backwash water consumption annually; and cost savings of approximately $65,000 (£50,400).

Once the instruments were purchased and installed, backwash data also indicated that the high rate portion of the backwash was longer than necessary, and was reduced by four minutes. This adjustment resulted in a savings of approximately 22,100 gallons of wash water per wash, at a value of $21,000 (£16,000) annually.

“We love these instruments,” said Brian Fuller, Utilities Director, Punta Gorda Water Treatment Plant. “They’ve given us data that we can use to make decisions that have saved us a lot of money.”

Together, these two simple adjustments to the backwash process optimized filtration and resulted in $86,000 (£66,700) in savings the first year.

Final Thoughts

Optimizing filter performance in drinking water treatment is critical for ensuring particle removal and efficient filtration processes. With the implementation of 24/7 filtration monitoring, such as the FilterSmart Backwash Monitor, operators can achieve real-time insights into filter performance, allowing for proactive management and significant cost savings. The success at the Punta Gorda Water Treatment Plant highlights the financial and operational benefits of smart sensor technology.