Pilots, Trials and Testing
Florida Drinking Water Plant
Full-Scale Demonstration Objectives
Reduce Sulfide concentration from approximately 3 mg/l in the well water to <0.3 mg/l in the treated water.
Eliminate hydrogen sulfide odor in the treated drinking water caused by high concentrations of sulfide in the raw groundwater.
Reduce Disinfection By-Product (DBP) formation and Total Organic Carbon (TOC) in the finished drinking water storage and distribution system.
Provide cost effective regulatory compliance by replacing existing treatment processes with Ferrate Treatment.
Sulfide was reduced to below the laboratory detection limit of <0.010 mg/l by a Ferrate dose of 6 ppm. The corresponding Finished Water sulfate concentration was 59 mg/l, significantly less than the 250 mg/l Florida Secondary Drinking Water Standard.
There was no hydrogen sulfide odor in the treated drinking water.
Disinfection By-Product (DBP) levels in the Finished Water were below US EPA Stage 1 limits for both TTHM and HAA5.
TOC of 3.6 mg/l in the raw water was reduced 15% to 3.07 mg/l in the Finished Water.
A comparison of current Plant operating costs from 2010 shows that the cost of Ferrate Treatment can be offset by replacing the existing chemicals used for treatment with Ferrate.
Phosphorus Removal Lake Apopka
How Lake Apopka Died
At 48.12 square miles, Lake Apopka is the third largest lake in the state of Florida. It is located 15 miles (24 km) northwest of Orlando. Fed by a natural spring, rainfall and storm water runoff, water from Lake Apopka flows throughout Florida and eventually into the St. Johns River.
Lake Apopka has a history of more than 100 years of human alteration ranging from canals to levees to draining 20,000 acres (80 km2) of shallow marsh for farming. For many years, the discharge of fertilizers and pesticides into the lake decimated game fish populations by created chronic algal blooms that depleted dissolved oxygen and blocked sunlight necessary to sustain plant life along the lake bottom. After several decades, this aquatic abuse caused the sandy lake bottom to be covered by a deep layer of black muck.
Worse yet, in July 1980, the Tower Chemical Company (TCC), a local pesticide manufacturer, caused significant amounts of Dichlorodiphenyldichloroethylene (DDE), a DDT byproduct and known endocrine disruptor, along with other toxic chemicals to spill into Lake Apopka. In December 1980, the US Environmental Protection Agency shut down TCC’s operations and began an investigation. Soon after, the EPA decommissioned the site and designated it as a Superfund clean-up site. DDE has resulted in significant health problems in much of the lake’s wildlife population, and has caused infertility and other sexual disorders in several species, including alligators. In 1996, Governor Lawton Chiles signed the Lake Apopka Restoration Act that provided funding to purchase the farmland responsible for agricultural run-offs that were compounding Lake Apopka’s downward spiral.
Restoring the Lake – A Novel Treatment Process
In 2013, Clean to Green, WesPac Water, and Ferrate Treatment Technologies, LLC came together to create a highly effective treatment process based on Ferrate which removes phosphorus and ammonia nutrients from lake water and allows dredge spoils to be used as feedstock in fertilizer production for beneficial reuse. See a pictorial overview of the process below:
Lake Apopka, Florida
Untreated Dredge Water
Ferrate Treated Dredge Water
The water quality data (shown below) were received and tested by ENCO labs on January 21, 2013. ENCO is a state certified laboratory; certification number E83182-32. Note that several of the contaminants tested were removed down to the limits of the analytical method. Actual removal rates may be even lower.
Pennsylvania Wastewater Treatment Plant
Disinfected Fecal Coliform Bacteria. Fecal coliform were reduced to well below regulatory limits at a dose of 2-ppm ferrate.
Passed Aquatic toxicity. The lab reported that the “No Observable Effects Concentration” (NOEC) for Ceriodaphnia dubia was at the 100% concentration level for a ferrate dose of 3 ppm.
No Harmful Residuals. Residual chlorine and THMs in treated effluent were at trace levels and non-toxic to freshwater aquatic species.
Phosphorus Reduced. Phosphorus in ferrate treated samples at doses of 2 and 3 ppm were consistently lowered by an average of 0.2 ppm.
The Pilot Ferrator® was installed on July 28 and 29 and operated during the period July 30 through August 20, 2008. The Ferrator is shown below in Figure 1. The 25-gpm slipstream showing the in-line mixer, ferrate injection and sampling points, and the prototype ferrate monitor are shown in Figure 2.
Figure 1. Pilot Ferrator
Fecal Coliform Results
Figure 3 shows the untreated fecal coliform concentrations and the resulting concentrations for ferrate doses at both 2 ppm and 3 ppm. The black line at 200 is the plant’s regulatory limit. Excellent disinfection of fecal coliform bacteria was achieved at a ferrate dose of 2 ppm, substantiating the results from previous bench tests. This was achieved over a wide range of untreated fecal coliform levels of between 3,300 and 15,400 CFU per 100 ml, demonstrating very good flexibility and reliability in performance.
Figure 3. Fecal coliform test results at ferrate doses of 2 ppm and 3 ppm
Disinfection By-Products and Aquatic Toxicity
A critical component of the Ferrator Pilot Test was to look for any disinfection by-products produced by ferrate treatment that could be toxic to freshwater aquatic species. Results of testing by American Aquatic Testing, Inc. showed that 3-ppm ferrate was a “No Observable Effects Concentration” (NOEC) for Ceriodaphnia dubia, the most sensitive species tested. The treated effluent was not diluted in the aquatic tanks, which was the worst-case test condition (i.e., 100% concentration level). The 3-ppm dose was higher than the 2-ppm dose that was shown to be effective for fecal coliform disinfection, thus providing a significant safety margin. This test proved that any trace residuals in the disinfected effluent were non-toxic.
Lancaster Laboratories measured THM concentrations in the effluent after ferrate treatment. Figure 4 shows the plotted THM data. In most samples, THMs were very much the same as background levels in the 0.2- to 0.3-ppb range for doses of 2- and 3-ppm ferrate. Cooler ferrate synthesis temperatures in the reactor caused spikes; however, concentrations at both the 2-ppm and the 3-ppm doses stayed an order of magnitude below the plant permit THM limit of 5.7 ppb. At the 2-ppm ferrate dose, THMs were well below the analytical accuracy limit and were close to the detection limit.
Figure 4. THMs (Trihalomethanes)
Florida Wastewater Treatment Plant
A central Florida facility was under a consent order from the FDEP to reduce disinfection by-products (DBPs), especially chlorodibromomethane (CDBM) and dichlorobromomethane (DCBM), in the effluent of the facility, while continuing to meet high level disinfection.
Ferrate Treatment Technologies, LLC (FTT) conducted a number of bench scale tests. The results of these tests suggested that the treatment with Ferrate, at relatively low doses, would achieve high-level disinfection without the creation of DBPs. The tests further indicated that the concentration of phosphorus was substantially reduced at similar doses. As a result of these tests and additional information that has recently been developed, the County agreed to conduct a Pilot Study to either substantiate or disclaim the validity of the Ferrate Treatment System (FTS).
The primary objectives of the Pilot Study were to:
Determine the Ferrate dose necessary to achieve the high level disinfection without creating DBPs.
Determine the contact time necessary to achieve this level of disinfection.
– Determine the level of phosphorus reduction at the disinfection dosage.
– Determine, if any, the increase in Ferrate application necessary to reduce phosphorus levels to 200 ug/L (0.20 mg/L) in the effluent.
– Determine, if any, the increase in contact time necessary to achieve phosphorus reduction to this level.
– Determine the volume of solids production resulting from the addition of Ferrate.
– Develop an estimated capital and operating cost for the FTS based on mutually accepted treatment conditions, i.e., flow rates, etc.
– Develop, based on the above information, the design criteria necessary to prepare a conceptual design for implementation of the FTS.
The goals of the Pilot Study were to achieve the following on a consistent basis:
– Disinfection to less than 1 CFU/100mL.
– CDBM and DCBM concentrations of less than 34ug/L and 22ug/L respectively.
– Phosphorus concentration reduction to below 200ug/L (0.20 mg/L) at the disinfection dose.
FTT conducted pilot testing three days per week over a thirty (30) day period to accomplished most of the objectives outlined above. The results of pilot testing demonstrated that the FTS met or exceeded the established goals with:
High level disinfection being achieved at a dose of 2.0 mg/L and Phosphorus reduction to less than 0.10 mg/L at the disinfection dose of 2.0 mg/L with CDBM and DCBM (Disinfection By–Products) well below the permit levels.
Florida Drinking Water Treatment Plant
Demonstration Test Results
Odor control was achieved using a Ferrate dose of 3 ppm followed by a 3.6-mg/l dose of chlorine to provide disinfection and a chlorine residual leaving the Plant of 2.2 mg/l.
Raw water total sulfide was reduced from 1.25 mg/l to 0.15 mg/l during bench-tests by a Ferrate dose of 2 ppm, with pH adjustment to 8.0 utilizing CO2 and allowing 45 minutes of settling time.
After a 70-hour Simulated Distribution System Test, Disinfection By-Products were 13.7 μg/l TTHM and 4.88 μg/l HAA5 in water treated with 5-ppm Ferrate compared to 108.2 μg/l TTHM and 11.4 μg/l HAA5 for Plant tap water. Both the Ferrate-treated and the Plant tap water samples had a chlorine residual of approximately 2 mg/l when the test began.