Alternative pretreatment tests with UF yield excellent results at Tampa Bay

Abstract

This article discusses problems with the pretreatment system at the Tampa Bay Seawater Desalination Facility. Currently the plant uses a two‐stage dual sand filtration pretreatment system to remove turbidity, algae, organic material, and other particulate matter from the incoming raw seawater and ensure optimum performance of the plant's reverse osmosis (RO) system. The manufacturer's recommended silt density index (SDI) for the RO membranes is typically < 4; however, the current pretreatment has not been able to consistently meet these parameters to protect the RO system. As a result, the RO membranes foul too quickly, and the plant cannot achieve peak water production. The desalination plant also faces more frequent cleaning of the RO membranes, significantly increased operating costs through higher energy consumption, increased chemical usage for cleaning, and more frequent RO membrane replacement. Moreover, the plant only operates intermittently and produces less drinking water than it is designed to deliver. The article discusses the selection of ultrafiltration (UF) membranes as the solution, specifically Veolia Water North America's bid for ZeeWeed membranes, and explains the benefits of ZeeWeed membranes in a RO system.