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Hydrogen Sulfide Control in Bio-Solids Processing with
Hydrogen Peroxide – The Cedar Rapids Experience
By
Michael Fagan, Chester Szczucki – US Peroxide, Inc.
John Haase, Sam Kamhawy – Cedar Rapids Water Pollution Control Facility
The City of Cedar Rapids Water Pollution Control Facility (WPCF) treats an average of 42 MGD of mixed industrial and domestic wastewater. Due to the large percentage of industrial wastewater contribution (e.g. paper mills, corn processors, agricultural products), influent to the Cedar Rapids WPCF is “higher strength” than most municipal sewage, particularly with respect to BOD, sulfate, and nutrients. These conditions result in efficient production of hydrogen sulfide (H2S) in both solid and liquid treatment processes, and thus create significant safety and operational challenges for the Cedar Rapids staff.
One of the highest priority areas for improved H2S control was the bio-solids gravity belt thickener (GBT) building. During normal operations, H2S levels in the GBT building routinely exceeded the Cedar Rapids WPCF mandated levels for worker exposure (10 ppm). Significantly, H2S spikes in the 100-200 ppm range have been measured directly above the gravity belt thickener table. Due to these unsafe levels of H2S, shut down of the GBT’s and ventilation of the building was required before equipment maintenance or other work could be started. This procedure negatively impacts the efficiency of the bio-solids processing operation. High H2S levels in the GBT building over time has also caused severe corrosion of electrical components and equipment, and contributed to odors in and around the GBT building.
Due to the safety and operational issues noted above, a program was undertaken to evaluate hydrogen peroxide (H2O2) oxidation of bio-solids sulfide prior to gravity belt thickening. The objectives of this program were to: 1) Improve worker safety by maintaining GBT building H2S levels in the 0-2 ppm range 2) Reduce bio-solids processing “down time”, 3) Reduce corrosion and odors in the GBT building.
This paper will present results from this ongoing program, which employs injection of hydrogen peroxide into the waste activated sludge line, several minutes ahead of the GBT’s. Results from initial laboratory testing, through full scale implementation of this program will be reported.
To date, the use of hydrogen peroxide has reduced H2S levels at the GBT’s by an average of >90% which has maintained H2S in the GBT building to the target level of 0-2 ppm 95% of the time. These significant reductions in H2S have accomplished the program objectives, e.g.:
- H2S levels in the GBT building are regularly maintained below Cedar Rapids 10 ppm exposure limits, resulting in safer working conditions in the GBT building.
- Routine equipment maintenance and other work in the GBT building can now be done without shutting down the bio-solids processing operation, improving efficiency.
- The environment in the GBT building is less corrosive. It is expected that this will extend the life of electronics and other equipment.
- Odors in and around the GBT building have been reduced
Further optimization of this H2S control program are underway, and include (bio-solids) flow pacing of the hydrogen peroxide metering pumps, and/or automated H2O2 dosing control based on gaseous H2S monitors in the GBT building.
Download Cedar Rapids – IWPCA Abstract (doc)
Download Cedar Rapids – IWPCA Presentation (ppt)[/vc_column_text][/vc_column][/vc_row]
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Introduction
USP-OC31 is a chlorite-based oxidant blend that is designed to efficiently and rapidly oxidize hydrogen sulfide and organic odors in wastewater collection systems, treatment plants (headworks, thickeners, dewatering operations) and industrial wastewaters. USP-OC31 is environmentally friendly and does not form chlorinated by-products, with the end-product being table salt (sodium chloride).
USP-OC31 Properties & Dosing
USP-OC31’s main active ingredient, sodium chlorite (NaClO2), is a fast-reacting oxidant (seconds) that provides immediate control of hydrogen sulfide and many other organic odors in collection systems, treatment plants and industrial wastewaters, particularly in solids processing operations. Unlike hypochlorite, USP-OC31 does not react with ammonia and does not form chlorinated organics. USP- OC31 oxidizes hydrogen sulfide according to the following equation…
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Download USP-OC31-Municipal-Tech-Bulletin-17-LR (pdf)[/vc_column_text][/vc_column][/vc_row]
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Introduction
Sulfide odor control within sanitary sewers has been practiced for over 50 years, yet only recently have substantive advances been made. Where once the choice of chemical treatment was either chlorine or iron salts, safer and more environmentally benign technologies based on hydrogen peroxide, nitrates and/or magnesium hydroxide have gained acceptance. These new alternatives, however, can increase treatment costs substantially and present limitations in themselves. USP Technologies identified and addressed this issue by lessening the adverse impacts of the older, cheaper mainstays, particularly iron salts such as ferrous/ferric chloride or sulfate that provide other benefits to wastewater treatment operations.
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Introduction
Peracetic Acid (PAA) is an organic peroxide compound with the formula CH3CO3H. It is environmentally friendly as it hydrolyzes to acetic acid and hydrogen peroxide in water. It is a broad-spectrum biocide with a fast reaction time in minutes and leaves no harmful by-products.
Peracetic acid is a strong oxidant and disinfectant with oxidation potential higher than that of chlorine or chlorine dioxide. PAA is available in the form of equilibrium mixture which also contains hydrogen peroxide, acetic acid (vinegar) and water as shown by the following equation…
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Download Peracetic Acid-Municipal-Tech-Bulletin-17-LR (pdf)[/vc_column_text][/vc_column][/vc_row]
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Introduction
The use of hydrogen peroxide (H2O2) as a pre-oxidant in municipal water treatment is well documented and has been practiced for over 15 years. Historical applications of H2O2 in drinking water have been for taste and odor control, hydrogen sulfide removal, iron removal and ozone enhancement/destruction. With the EPA Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 DBPR) coming into effect, more recent emphasis has been on the reduction of the formation of total trihalomethanes (TTHM) and haloacetic acids (HAA5).
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Download DrinkingWater-Municipal-Tech-Bulletin-17-LR (pdf)[/vc_column_text][/vc_column][/vc_row]
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Cloevis Biofilm Removal Service (Cloevis BRS) is an innovative technology offering that removes the biofilms that adhere to the inner surfaces of wastewater forcemain walls, including the underlying Sulfate Reducing Bacteria (SRB) that produce hydrogen sulfide. As a result, gaseous hydrogen sulfide (H2 S) production is eliminated. The treatment requires an initial conditioning period when the biofilm that harbors the SRB’s is removed, followed by maintenance treatments that are repeated as monitored lines show signs of SRB reformation.
The Cloevis technology, delivered as a turn-key, fixed-cost, full-service program, provides the following benefits relative to conventional sulfide control treatments:
- Avoidance or minimization of onsite chemical storage
- Independence from sulfide loading, retention time or oxygen uptake
- No labor/maintenance requirement
- Removal of sulfide odors for up to three weeks after treatment cycle
- Elimination of methane production within the treated segment
- No downstream adverse impacts due to residual treatment chemicals
- Effective cost similar to caustic shocking and less than nitrate or iron salts
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Download Cloevis-BRS-Municipal-Tech-Bulletin-17-LR (pdf)[/vc_column_text][/vc_column][/vc_row]
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Introduction
USP-OC31 is a chlorite-based oxidant blend that is designed to efficiently and rapidly oxidize hydrogen sulfide and organic odors in wastewater collection systems, treatment plants (headworks, thickeners, dewatering operations) and industrial wastewaters. USP-OC31 is environmentallyfriendly and does not form chlorinated by-products, with the end-product being table salt (sodium chloride).
USP-OC31 Properties & Dosing
USP-OC31’s main active ingredient, sodium chlorite (NaClO2), is a fast-reacting oxidant (seconds) that provides immediate control of hydrogen sulfide and many other organic odors in collection systems, treatment plants and industrial wastewaters, particularly in solids processing operations. Unlike hypochlorite, USP-OC31 does not react with ammonia and does not form chlorinated organics. USP- OC31 oxidizes hydrogen sulfide according to the following equation…
Read More
Download USP-OC31-Industrial-Tech-Bulletin-17-LR (pdf)[/vc_column_text][/vc_column][/vc_row]
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Introduction
Wastewater streams and process baths at metal surface finishing operations can be very challenging to effectively treat. USP Technologies (USP) can help metal finishers and processors by characterizing each unique situation and matching it to our technically sound and proven options for NOx emissions control in stainless steel and titanium pickling operations, as well as for treatment of organic compounds, cyanide and a range of wastewater contaminants…
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Download Surface Finishing-Tech-Bulletin-17-LR (pdf)[/vc_column_text][/vc_column][/vc_row]
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Introduction
Peracetic Acid (PAA) is an organic peroxide compound with the formula CH3CO3H. It is environmentally friendly as it hydrolyzes to acetic acid and hydrogen peroxide in water. It is a broad-spectrum biocide with a fast reaction time in minutes and leaves no harmful by-products.
Peracetic acid is a strong oxidant and disinfectant with oxidation potential higher than that of chlorine or chlorine dioxide. PAA is available in the form of equilibrium mixture which also contains hydrogen peroxide, acetic acid (vinegar) and water as shown by the following equation…
Read More
Download Peracetic Acid-Industrial-Tech-Bulletin-17-LR (pdf)[/vc_column_text][/vc_column][/vc_row]
Introduction
Nitrogen oxides are major pollutants in the atmosphere and are a precursor to acid rain, photochemical smog, and ozone accumulation. The oxides are mainly nitric oxide (NO) and nitrogen dioxide (NO 2 ), both of which are corrosive and hazardous to health.
Stationary Source Focus
With the use of catalytic converters on automobiles, the initial regulatory focus of controlling mobile NOx emissions has reached the point where further restriction has become economically impractical. Consequently, the stationary sources of NOx emissions are now being subjected to more stringent standards in many areas of the U.S . These stationary sources include nitric acid manufacturing plants, manufacturers of nitrated materials such as fertilizer and explosives, and industrial manufacturers such as metallurgical processors, glass manufacturers, cement kilns and power generators where high processing temperatures are used. Because of the environmental concerns posed by air pollution, a great deal of research and money has been expended to develop methods for controlling NOx emissions…
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Download NOx-Tech-Bulletin-17-LR (pdf)