At Palm Beach County Water Utilities Department (PBCWUD) Water Treatment Plant (WTP) 11, hydrogen sulfide was stripped from the treated water using degasifiers and blowers, producing a hydrogen-sulfide-laden exhaust air stream that was sent to a chemical odor scrubber. The scrubber was capable of removing 90% of the hydrogen sulfide gas before the air stream was released to the atmosphere.
PBCWUD wanted to replace the existing chemical odor scrubber with a biological odor scrubber to remove more hydrogen sulfide gas, improve odor, increase safety, and decrease maintenance. Under a continuing design-build services contract, PBCWUD retained Globaltech to design, permit, procure, and construct the improvements.
The new biological odor scrubber system included three larger replacement blowers, two BioAir odor scrubber towers, two irrigation booster pumps, nutrient tank, nutrient feed pumps, and ductwork modifications to connect the new biological scrubbers to the existing degasifiers. The new biological odor scrubber system removes 99% of the hydrogen sulfide from the exhaust air. And whereas the chemical scrubber system required the use of a hazardous chemical (sodium hydroxide), the biological scrubber requires only a non-hazardous nutrient feed similar to plant food.
Project Achievements / Benefits
- Substantial reduction of odor at the plant and surrounding areas
- Improved plant safety
- Reduced maintenance associated with sodium hydroxide storage and feed equipment
- In addition to the new scrubber system, Globaltech designed and installed a dedicated lift station for the scrubber’s waste stream, which turned out to be low pH and very corrosive to the plant’s process concrete wetwell and lift station pumps. The new, corrosion-proof lift station contains an Armorock wet well (constructed of polymer concrete with fiberglass rebar) and two 7.5 HP thermoplastic vertical centrifugal pumps.