Installation of Automatic Backwashing Strainers for Sand Removal from BWRO Feedwater in Fort Myers, Florida

Pretreatment for sand removal upstream of Reverse Osmosis (RO) membrane systems is a major inland brackish water challenge. Many RO water treatment plants (WTP’s) need to efficiently remove sand produced by wells that can otherwise plug the membrane system, severely reduce membrane productivity and possibly cause permanent membrane system damage. A few different options are available to reduce or eliminate sand problems. Centrifugal-type processes are often used to remove sand from RO feedwater, but are limited by their operating flow range, removal efficiency of small sand particles, constant high differential pressure, large waste volumes, and high capital cost. Newly available multielement sand strainers are one option that has successfully worked to mitigate feedwater sand problems. This paper will discuss the City of Fort Myers, Florida wellfield sand issues and how they impacted the RO system operation. This paper will also give an overview of the progression of the wellfield solutions, starting with the addition of basket strainers, to well redevelopment, and eventually to the installation of automatic backwashing sand strainers. The overview will include a summary of the evaluation of the sand strainer options, the design concepts related to adding backwashing strainers, and actual operating data from the Fort Myers RO water treatment plant.

This presentation is available to AMTA Members only.