GE chemical scavenger removes sulfides, solves water conformance for Australian refinery

• GE provides a refinery in Australia with a chemical scavenger to remove sulfides and solve water conformance issues.

TREVOSE, PA, Oct. 17, 2006 -- In late 2004, a refinery in Australia was having a problem with the effluent water from its wastewater treatment plant. Despite treating the water before discharge to the local water authority, the water occasionally contained a high level of sulfides. The problem was that the local water authority had set a limit on the sulfide concentration in the effluent from the lagoon, which was a non-negotiable figure. As a result of the high sulphide levels in its effluent, the local water authority downgraded the refinery's designation from level 1 conformance to level 2. At level 3, the water authority threatened to stop taking the effluent from the refinery, effectively shutting it down. The challenge, then, was to reduce sulfide levels in the effluent stream consistently below the target limits.

The Solution
GE Water & Process Technologies (W&PT) was brought in to help remedy the problem in the short-term -- essentially a band-aid solution -- until the root cause of the excess sulfides was discovered. It was identified that the high sulfide levels were due to two causes:
-- High inlet sulfides entering the lagoon, due to operations upstream in the refinery
-- Sulfide generation over the lagoon, due to bacteria (SRB) present in the lagoon

After carefully considering the options and explaining them to plant management, GE elected to target the second cause by adding a sulfide scavenger (Prosweet OC 2543), which would counteract any sulfides generated inside the lagoon by the bacteria. Administered at a constant rate, this chemical would safely and effectively transform the sulfides into sulphur.

The Results
Using the Prosweet sulphide scavenger, in conjunction with the Six-Sigma process, GE achieved significant improvement in the effluent sulfide levels. In fact, the following results were obtained in a comparison between summers from 2003, 2004 and the 2005 trial:
-- Median sulfide levels improved dropped by 0.8ppm, enough to bring the refinery consistently into control.
-- DPMO was reduced from 509,434 to 61,538

While the problem still exists, it isn't nearly as critical as before the trial. As a result of these impressive results, the water authority returned the refinery to level 1 conformance. In addition, the odor that is characteristic of high sulfide levels was dramatically alleviated.

Currently, GE is working to determine the origin of the sulphide problem and provide a more permanent solution. For more information, see the GE Water & Process Technologies website: www.gewater.com

Also see: "ProSweet essential oil technology controls odor from biosolids plant"

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