ADVANCED OXIDATION PROJECT

St. Anthony Village, MN

ACKNOWLEDGEMENTS

Owner: Village of St Anthony

Engineer: WSB & Associates

Manufacturer: Trojan Technologies

Supplier: Great Northern Environmental

General Contractor: Gridor Construction

PROJECT BACKGROUND

As early as the 1940’s, chemicals and other wastes were being disposed of in the region by the Twin Cities Army Ammunition Plant (TCAAP). In 1987, TCAAP was positively identified as the source of Volatile Organic Compounds (VOC) contamination in several community water supplies. The contamination at the time consisted of Trichloroethylene (TCE). Trace amounts of 1,4 Dioxane were discovered in 2015 by the City of St Anthony Village and neighboring communities. 1,4 Dioxane is a chemical stabilizer added to chlorinated solvents to prevent their acidification and breakdown.

PROJECT HIGHLIGHTS

St Anthony Village is the 35th public water system in North America to specifically treat 1,4 Dioxane using Advanced Oxidation with UV-Peroxide.The six (6) Trojan UVPhox Reactors each contain 144 low-pressure high-output UV lamps. The overall system can remove more than 99% of 1,4 Dioxane at Peak Flow Conditions of 3,000 GPM. Due to its high solubility and limited sorption to soils, natural degradation of 1,4 dioxane in water is limited. Further, it’s low Henry’s Law Constant makes 1,4 dioxane resistant to traditional treatment methods used for removal of VOC’s.

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LOW UVT WASTEWATER IS STILL NO MATCH FOR THE TROJAN UV3000PLUS

SUPERIOR, WI

The Environmental Services Division of Public Works (ESDPW) for Superior WI is comprised of ten (10 Sanitary Sewer Districts and carries four discharge permits. The main WWTF treats an average of 3-4 million gallons per day with peak flows hitting 11 million gallons per day during storm events. Several years ago, the City was faced with a decision to rehabilitate the existing Chlorine disinfection facility or convert to another form of disinfection. After evaluating all of the alternatives, Superior chose UV disinfection over chemical disinfection for several reasons:

Location of the WWTF was close to several high population density areas
The City could eliminate the need for additional Risk Assessment Reports and Emergency Action Plans typically associated with feed chlorine gas
The City was required to dechlorinate with sulfur dioxide and the existing S02 system was also at the end of it’s useful life

The City evaluated several different types of UV systems and manufacturers and ultimately chose the Trojan3000PLUS with the Automatic Chemical and Mechanical Cleaning System. The WWTF has at times a ( generally about 50 and at high flows down to 30’s) relatively low Ultra-Violet Transmittance (UVT) combined with using Ferric Chloride as a Coagulant for Phosphorus Removal. For these reasons, the chemical and mechanical cleaning system is vital to the performance of the UV System. According to Mark Simmonds the Operations and Maintenance Supervisor, “when having a UVT of less than 40%, we are typically seeing non-detect or single digit E-Coli counts in our sample. We are very happy with our switch to UV Disinfection.” The Operations staff removes the modules twice per year to recharge the chemical cleaning solution since they have a year-round disinfection permit.

Contact GNE about TROJAN 3000 plus

SURFACE WATER TREATMENT PLANT

City of Thief River Falls, MN

APPLICATION

Surface Water Treatment

TREATMENT SYSTEM

Gravity filter upgrade

FEATURES

BLEU™ underdrain
Simul-Wash™ backwash system
Reduced backwash waste
State-of-the-art technology

CONTACT GNE TO LEARN MORE

PROJECT

The City of Thief River Falls, Minnesota was in need of a water treatment plant upgrade including the replacement of the underdrain, media, and troughs in four existing gravity filters. The plant was originally built in 1954, with a refurbishment of filters and controls in 1980. The plant had been well maintained, but the equipment had reached the end of its life. The project provided an opportunity for The City to upgrade its system with the latest technology, including stainless steel underdrains and simultaneous air and water backwash. Tonka Water proposed the BLEU™ underdrain paired with the Simul-Wash™ backwash system, which allowed for all filter components to be supplied by one manufacturer. Tonka Water was selected to supply this equipment for the gravity filter upgrade.

PROCESS

The City treats a river water source using lime softening followed by media filtration. The water flows through solids contact clarifiers, then into media filters to capture any unsettled solids. The filter is bedded with dual media, directly retained by the BLEU™ underdrain system. During backwash, water flows back through the underdrain laterals while air is applied simultaneously through separate slotted pipes between them. Adding air between the laterals ensures that the media is uniformly cleansed, eliminating dead zones. The Simul- Wash™ backwash troughs prevent media loss while sustaining a simultaneous air and water backwash. Only one trough is required per twelve-foot wide filter due to its unique design.

SIMUL-WASH™ BACKWASH SYSTEM

The treatment plant also includes Tonka Water’s value-added Simul-Wash™ backwash system. This unique backwash system uses air and water simultaneously, at sub-fluidized rates, within the collapse-pulse range for the selected media, resulting in the most effective means of backwashing granular filter media1. Tonka Water’s media rejecting Simul-Wash™ trough enables the air and water backwash cycle to continue indefinitely without media loss. This results in optimal filter cleaning efficiency and prolonged filter runs while saving approximately 50 percent of backwash wastewater compared to conventional methods.

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