Ultrafiltration being used in Walkerton

Part of OCWA's multi-barrier approach

The second container is lowered onto a concrete pad at Well #7 site.

Zenon delivered one of its mobile containerized Zee-Weed^® ultrafiltration water treatment units to the Town of Walkerton, after responding to a request for proposal from the Ontario Clean Water Agency early in October. The unit will be used in OCWA's interim drinking water clean-up plan which is expected to last six months to two years. OCWA's consultant, R.V. Anderson Associates Limited, will use the ZeeWeed system in a design which features a multi-barrier approach to treating Walkerton's groundwater which is tainted with E. coli 0157:H7 bacteria. This approach includes wellhead protection, ultrafiltration, chlorine disinfection and residual maintenance prior to distribution.

The system is being installed on a new concrete pad at Well #7 site by Stonetown Construction, and will produce a maximum flow of 5,000 m³/day of ultrafiltered water. This transportable system comes complete in two containers, as shown in the picture. The equipment, including process pumps, valves, instruments and control system, is housed in the white container, while the immersed hollow fibre membranes will be installed in the blue steel tank.

On-site work by the contractor consists of civil, mechanical, electrical and control work required to provide the necessary services to deliver raw well water to the unit, chlorinate and provide chlorine contact time for the treated water, and commission high lift pumps to convey the treated water to the town's elevated water storage tank.

The pre-assembled and tested ZeeWeed system minimizes on-site construction time and cost. The on-board Programmable Logic Controller (PLC) monitors the system, and makes necessary adjustments to ensure the plant is operating optimally. The PLC is connected to OCWA's Outpost Supervisory Control and Data Acquisition (SCADA) system, which has recently been integrated with Walkerton's system to oversee operation of the entire system.

Raw groundwater is pumped into the membrane tank where it is filtered by passing through the hollow fibre ZeeWeed membranes, which are attached to the suction side of an ANSI end suction centrifugal pump. Under a partial vacuum, water is drawn through the pores of the membrane to the inside of the hollow fibre, requiring only -2 to -8 psi of suction. With a nominal pore size of 0.04 µm, the membranes form a positive barrier to solids in the water, producing filtered water with less than 0.1 NTU of turbidity.

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