Odor Control and Disinfection

Odor Control and Disinfection

Primary clarifier odor controlled using oxygenation

Biohybrid filters alleviate odor concerns with force main upgrade

Problem:

Odor control often is not incorporated into plant design and is considered only after residents and business owners complain. Managers of the Lake Wildwood Wastewater Treatment Plant in Penn Valley, California, planned a sewer force main upgrade and anticipated the need for odor control and corrosion protection.

Solution:

Working with stakeholders, Anua recommended two Airashell Biohybrid Filters, one at the new lift station and one at the plant headworks. The unit uses recycled seashells as treatment media. The biohybrid filter treatment process provides high performance with virtually hands-off operation.

Result: 

The filters were commissioned in January 2018. Both filters are providing suitable odor treatment and corrosion protection. “It has been working smoothly for us in this first year of operation,” says Brad Rist, operator III. “Being that our district is so spread out and our staffing minimal, the Airashell units fit our needs perfectly.” 800-787-2356; www.anuainternational.com


Primary clarifier odor controlled using oxygenation

Problem:

The Trinity River Authority of Texas serves a population of 3.5 million in the Dallas-Fort Worth area. In 2003, the authority completed a comprehensive evaluation of structural and chemical odor control options as part of a Stage VII Odor Control Improvement Program at the Central Regional Wastewater System. One of the goals was to reduce odorous emissions at the primary clarifiers. With 150 mgd channeling into the system, a comprehensive treatment was needed.

Solution:

Two ECO2 SuperOxygenation Systems from ECO Oxygen Technologies, designed in conjunction with Alan Plummer Associates, were installed to dissolve 13,800 pounds of pure oxygen into a wastewater sidestream, elevate dissolved oxygen in the influent to a minimum of 11 mg/L at the headworks, thus maintaining aerobic conditions to the primaries without compromising solids settling. The systems effectively remove odor and hydrogen sulfide before the wastewater reaches the plant headworks.

Result: 

Since startup of operation in 2006, the system has maintained positive dissolved oxygen levels, effectively eliminating hydrogen sulfide release and reducing the BOD load downstream, meeting all design criteria. 317-706-6484; www.eco2tech.com


System helps eliminate hydrogen sulfide odors at pump station

Problem:

High hydrogen sulfide levels at the Forest Hills Pump Station in Pikeville, Kentucky, were creating a nuisance odor and a possible health risk. The station is at a major intersection and across the street from a high school and football stadium. Operators had tried various chemicals and other odor controls with limited success.

Solution:

The operators tried a Phantom odor control system from Anue Water Technologies that uses sidestream wastewater to draw in concentrated oxygen and ozone. The aerated/ozonated stream is delivered back to the wet well through well washing systems, uniformly transferring the oxygen and ozone for FOG and odor/corrosion control. 

Result: 

The hydrogen sulfide levels dropped to 9 ppm after the first day of operation and to zero during the second day. 760-727-2683; www.anuewater.com


Granular activated carbon system provides solution to combat algal toxins

Problem: 

The town of Owasco, New York, needed an emergency solution to remove algal toxins from Owasco Lake, which provides drinking water to the town and surrounding areas.

Solution: 

The town installed a Calgon Carbon Model 10 system with two 10-foot-diameter pressure vessels containing 40,000 pounds of granular activated carbon. GAC protects against algal toxins while addressing other critical challenges, such as carcinogenic disinfection byproducts, volatile organic compounds, endocrine-disrupting compounds and many others.

Result: 

After the system was installed, the town experienced another less severe algal bloom. This time, because of the Model 10 GAC system, no algal toxins were detected in the drinking water. 800-422-7266; www.calgoncarbon.com


Mixer helps alleviate odor concerns

Problem:

The Seabrook (Texas) Wastewater Treatment Center lies close to many waterfront properties and so needs to limit odors. “Try as we might, moisture had gradually crept into the mixer, leading to a complete burnout, so we needed to find a good, sturdy replacement,” says Rafael Gonzales, site superintendent.

Solution:

A submersible mixer from Landia addressed the problem. “When the air has been turned off in our digester for the dewatering process, we use a Landia gear-driven mixer for several hours to slowly mix everything back up without creating unnecessary odors,” Gonzales says. “This is very important when the digester is thick, and it also depends on how long we’ve been waiting for the dewatering contractor to arrive. Sometimes the sludge has been sitting there longer than we would have liked.” The Landia mixer weighs about 235 pounds, about half the weight of the previous mixer. It uses a 12 hp motor; the old mixer’s motor was 15 hp.

Result: 

“We run the mixer for an hour to two hours per day with no problems at all, and for its performance and reliability, we can see that it’s just right for the application,” Gonzalez says. “The mixing pattern is good, and with an adjustable guide pipe, we can also use it during dewatering to push the solids over in the right direction.” 919-466-0603; www.landiainc.com


Expansion and upgrade of ozone disinfection system leads to cost savings 

Problem:

The Southwest Clean Water Plant in Springfield, Missouri, has used ozone to disinfect secondary wastewater since 1978. By 2008 the annual ozone maintenance cost approached $100,000.

Solution:

The city replaced the high-energy turbine mixers with a lower-energy, more efficient sidestream ozone injection system from Mazzei Injector Co. It uses sidestream Venturi Aeration injectors for primary ozone contact, followed by basin nozzle manifolds for secondary gas contact into the basins’ bulk wastewater flow. The design included a structural modification of the basin inlets to allow the retrofit to contact all of the basin’s wastewater flow. The dual inlet gates at the front of each contactor are enclosed in a concrete structure that funnels wastewater into a narrow tunnel to allow confined-space gas mixing. 

Result: 

Plant data comparing the energy cost of the ozone dissolution system with the turbine mixing design showed that the retrofit reduced the energy cost of ozone contact by an average of 69.2 percent under all plant flow conditions. An ozone transfer efficiency of 92.1 percent was achieved using an applied ozone dosage of 2.5 mg/L of 6 percent weight ozone. 661-363-6500; www.mazzei.net


Aeration tank odor eliminated using pure oxygen injection

Problem:

A Midwest meat-processing plant’s wastewater pretreatment facility produced an odor linked to insufficient dissolved oxygen in the first of three aeration tanks. Hydrogen peroxide had been used to control odor, but there were concerns about the cost and effectiveness. The addition of new aeration equipment was constrained by the structural cover of the aeration tank.  

Solution:

Praxair demonstrated that odor could be eliminated through restoration of aerobic conditions in the first aeration tank. The shortfall in oxygen transfer rate could be met through injection of pure oxygen into the recirculating waterline of the jet aeration system of the first aeration tank. A demonstration showed that dissolved oxygen levels above 0.5 mg/L could be maintained for about half of the day, and the sulfide odor was eliminated.

Result: 

The cost of adding pure oxygen was less than the previous approach to addressing odor. The plant expected operating cost savings of 74 percent. 800-772-9247; www.praxair.com


Ozone boosts performance at water recycling facility 

Problem:

The West Basin Municipal Water District’s Edward C. Little Water Recycling Facility in El Segundo, California, has a plan to supply five different designer effluent streams to meet the needs of five end users. Water uses are to include industrial process water, landscape irrigation and groundwater recharge.

Solution:

The district developed a treatment train using high-rate clarification, microfiltration, reverse osmosis, UV disinfection, advanced oxidation process and BioFOR biological treatment from SUEZ Water Technologies & Solutions. To meet the efficiency and flow rate requirements, ozonation was used to increase membrane flux. SUEZ designed and supplied an ozonia ozone system with a total ozone production capacity of 2,000 pounds per day to membrane pretreatment.

Result: 

The ozone technology allowed the plant to optimize the process train, maximize efficiency and meet customers’ demands. The technology helps reduce organic fouling and increase microfiltration membrane flux. www.suezwatertechnologies.com


Ion exchange system helps deliver quality water

Problem:

The water treatment plant in Pembroke Pines, Florida, was producing water with high levels of total organic carbon and color. It had traditionally used chlorine to oxidize the organic matter. The aggressive chlorination caused the formation of trihalomethane and haloacetic acid.

Solution:

Calvin, Giordano & Associates, a regulatory compliance consulting firm, proposed removal of organic matter using strong base anion exchange. The treatment process consists of four 12-foot-diameter ion-exchange vessels containing 45 inches of strong base anion exchange resin and support gravel. Water is pumped directly from the wells through the Organix ion exchange system from Tonka Water, a U.S. Water Brand, to storage and the distribution system. The ion exchange vessels were designed with a domed plate underdrain that uniformly distributes flow and allows for painting below the underdrain. Uniform flow reduces headloss across the underdrain system and reduces system operating pressure. The ability to paint below the underdrain prevents corrosion and ultimately extends vessel life.

Result: 

The treatment process has been highly efficient in delivering high-quality water, as indicated by 95 percent color removal, 67 percent TOC removal and 67 percent THM reduction. 763-559-2837; www.tonkawater.com  



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