Plant Applications: System helps galvanizer meet zinc benchmarks for stormwater

June 15, 2011

Situation

The galvanizing facility at Emerald Galvanizing Inc., Puget Sound, Wash., consists of about 8,700 sq. ft. of paved area with a building measuring about 4,300 sq. ft. The stormwater collects at one catch basin and discharges directly into Lake Union Ship Canal, which flows into the Puget Sound.

The galvanizing site had been struggling to meet the action-level benchmarks set in place for zinc by the facility's Washington Industrial Stormwater General Permit.

Resolution

Emerald Galvanizing connected with StormwateRx LLC, which helped the facility with a design to divert the building roof runoff to a reuse tank for use as process water. The rest of the site sheet flows to one central catch basin. Here the stormwater is pumped to an above-ground StormwateRx Purus™ 50SBE with an ion exchange option. In this application, the Purus delivers filtered water to an ion exchange polishing system.

The system uses a combination of buffering, inert, and sorptive media for the removal of suspended solids and heavy metals. It then pumps to a wastewater ion exchange system. Ion exchange resin canisters were installed to assist with dissolved metals removal.

The changes have helped Emerald Galvanizing achieve 99 percent average zinc removal efficiency, which meets the benchmark. The company also has achieved benchmarks for oil and grease, pH, turbidity, lead, and copper.

StormwateRx LLC, 122 S.E. 27th Ave., Portland, OR 97214, 800-680-3543, www.stormwaterx.com