Challenge

In 2003, Siemens Water Technologies, formerly USFilter, received a call from the utility asking for help with RO membrane fouling problems.  Upon investigation, Siemens engineers found several issues to address:

• Well water, previously thought to be free of contaminants, proved to have significant quantities of iron.
• The water system was built without any pretreatment equipment to remove iron.
• EDI polishers were producing off-spec water quality due to excess carbon dioxide in the RO permeate.
• Excess capacity expansion in the electric utility caused a capital-spending freeze that precluded the customer from purchasing new equipment to solve system inadequacies.

Solution

Siemens installed a containerized, iron-removal system with six PreFlex® 54 automated multi-media filters to prevent membrane fouling.  Plumbing between the first and second-pass RO units was extended to increase reaction time for the inter-stage caustic and carbon dioxide, thereby preventing its passage through the RO membranes.  EDI performance improved and the final water quality consistently meets customer specification. 

The customer signed a 10-year service contract with Siemens that provides routing and preventative maintenance on the equipment.  The contract includes full operational responsibility for RO membranes, filters and expendables, as well as capital recovery for the filtration system over the life of the contract.

Results

Several benefits have resulted in this project.

• RO membrane fouling problems eliminated.
• Customer's life-cycle labor costs reduced.
• The service contract assures regular on-site service and maintenance for the water system including immediate consultation for problem solving at a known and fixed cost.
• Minimized unscheduled outages.
• No capital expenditure to impact the customer's balance sheet.