Odor Control and Disinfections

Odor Control and Disinfections
Geomembrane cover used to end odor issues at paper mill wastewater impoundment

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Liquid permanganate allows plant to treat unanticipated odors

Problem: After a summer drought, winter rains flushed accumulated solids out of the collections system and into a Massachusetts wastewater treatment plant. In addition, septic sewage was received at a station 2 miles from the plant, and a mechanical failure of a centrifuge cut the plant’s biosolids dewatering capability in half. The treatment plant became a large odor source, mainly at the primary clarifiers and aeration basins.

Solution: The plant staff fed CARUSOL liquid permanganate from Carus Corporation at the bar screens, the primary clarifier inlet, the primary effluent outlet, the gravity thickener effluent, and the gravity thickener center well. Eventually, the primary influent and effluent became the main feed locations. The plant also began removing biosolids for processing at a neighboring plant.

Result: The permanganate eliminated the odor. After one week, the dissolved oxygen levels in the aeration basins rose, eventually reaching 3 mg/L as the permanganate destroyed the dissolved sulfides. By week two, the gravity thickeners returned to normal and the plant’s biosolids volume stabilized. In addition, the FOG that had collected in the primary clarifiers dissolved and was treated. 800/435-6856; www.caruscorporation.com.

Washing system helps eliminate FOG problem

Problem: A large north Florida regional wastewater system was battling FOG buildup up to 4 feet thick blanketing lift station walls and equipment. Dry-weather spills exacerbated the problem and drove a search for solutions.

Solution: The agency selected the EP-1100 well-washing and pretreatment system from Anue Water Technologies.

Result: The system eliminated the FOG in two hours. Spills were nonexistent, and confined-space entry for cleaning was no longer necessary. Expenses for a boom truck and two operators for two hours on each occasion were also eliminated, reducing maintenance costs by up to 20 percent annually. The agency now operates 15 EP-1300s and plans to add more. 760/727-2683; www.anuewater.com.

Sodium hypochlorite generation system eliminates safety concerns

Problem: The Anchorage (Alaska) Water and Wastewater Utility’s 28 mgd John M. Asplund Wastewater Treatment Facility wished to eliminate storage of gaseous chlorine and deploy safer and equally effective disinfection.

Solution: Electrolytic Technologies installed a Klorigen sodium hypochlorite generation system including ozone and UV disinfection, 0.8 and 12.5 percent on-site sodium hypochlorite generators, and bulk-delivered commercial sodium hypochlorite. Fully automated systems safely generate chlorine and sodium hydroxide from brine, eliminating chlorine storage and transportation. The products can be combined in the process to produce high-strength 15 percent sodium hypochlorite.

Result: The system can produce up to 5,000 gpd of 12.5 percent disinfectant solution for long-term storage and direct injection. The plant has been designed to enable expansion that would double the system’s capacity if required. 305/655-2755; www.electrolytictech.com.

Water treatment plant expands output capacity

Problem: Expanding population required a 30 mgd water treatment plant in south Florida to increase processed water output while ensuring compliance with sulfurous odor limits on the stripping process. The facility met building codes requiring a 180 mph wind rating. The plant uses membrane softening filters. After filtration, the water is degasified and disinfected. The water is then blended with filtered raw water before distribution.

Solution: Indusco Environmental Services provided a complete degasifier solution meeting NSF-61 material requirements, using one-piece vessel construction fabrication with no body flanges and employing an efficient wet chemical off-gas scrubber design.

Result: The system is operating with more than 99 percent removal efficiency. 251/621-2339; www.induscoenviro.com.

Oxygenation system prevents odor and corrosion in force main

Problem: The City of Raymore, Missouri, has a history of odor and corrosion in its gravity collections system, to which a force main discharged. Low velocities in the oversized, 17,000-foot force main led to long retention times and anaerobic conditions, leading to hydrogen sulfide formation. With no chemical feed, the hydrogen sulfide concentrations peaked at 600 to 900 ppm daily, causing corrosion, odor issues and worker safety concerns.

Solution: The city installed an ECO2 SuperOxygenation System from ECO Oxygen Technologies. The system dissolves high levels of oxygen in a wastewater sidestream that is then blended back into the force main. Automated controls pace the oxygen feed to ensure sufficient dissolved oxygen in the line to maintain aerobic conditions. Hydrogen sulfide is effectively eliminated. The system consists of a stainless steel cone, automated system controls and a sidestream pump that is the only moving part requiring standard maintenance.

Result: The day the system was turned on, hydrogen sulfide concentrations rapidly decreased from over 600 ppm to an average of 2 ppm. 317/706-6484; www.eco2tech.com.

Covers provide over 99 percent odor capture at plant

Problem: The Cronulla Wastewater Treatment Plant owned by Sydney Water in Australia had concerns about odors affecting a new residential development near the plant. The utility developed an Odor Management Program Alliance to reduce the impacts. The plant planned to cover tanks but needed a solution that allowed for easy access.

Solution: The utility chose retractable cover systems from Geomembrane Technologies to capture foul air while allowing workers quick and easy access to tank internals. The system consists of fabric covers tensioned over aluminum arches. The design includes inspection hatches and clear-span guardrails that allow the covers to be safely opened and closed without interference from standard guardrail supports.

Result: The covers control odors, while protecting plant infrastructure and allowing operations and maintenance teams to perform their work. The ventilation system allows the covers to maintain a negative pressure of around -20 Pascal and achieve more than 99 percent odor capture. 506/449-0993; www.gticovers.com.

Replacement vacuum feeders boost disinfection reliability

Problem: The liquid vacuum feed system for sodium hypochlorite and bisulfite at the 15 mgd wastewater treatment plant in Appleton, Wisconsin, was plagued by plugged injector tube orifices and leaking of the vacuum relief diaphragm, causing feed outages that hindered disinfection reliability. The faulty equipment also distracted the plant’s instrumentation technician and operators. While operators became adept at manual changeout of injectors, new operators lacked that training. When management could not find a replacement for the vacuum relief diaphragm, the problem became critical.

Solution: The facility turned to JCS Industries for a next-generation vacuum feeder without the troublesome diaphragm. Before making the switch to the replacement liquid vacuum feeders, the operations supervisor had his engineering firm consider peristaltic and diaphragm pumping options. They found the replacement vacuum feed to be the most cost-effective.

Result: The replacement feed system ended outages due to plugging and leaks, while providing a 30 percent reduction in bisulfite due to greater feeding accuracy. The instrumentation technician can now focus on his SCADA responsibilities, and plant operators can now focus on other plant operations. 281/353-2100; www.jcsindustries.us.com.

Floating covers help improve chlorine disinfection

Problem: Algae and UV rays were adversely affecting chlorination in an upstate New York reservoir and southern Florida wastewater treatment facility. Algae was shielding embedded bacteria from chlorine, making the bactericide ineffective and requiring increased chlorine dosage. In addition, UV light was dissipating unstabilized chlorine. Calibrating the proper chlorine dosage was challenging.

Solution: Both facilities installed floating covers manufactured by Industrial & Environmental Concepts. New York installed a floating cover on its pond, and Florida installed a cover on its chlorine contact chamber.

Result: Covering the water surface eliminated penetrating UV and sunlight from the water column. Algae disappeared, chlorine demand decreased and residuals stabilized. Dosing expenses went down and disinfection improved with process predictability. 952/829-0731; www.ieccovers.com.

Dryer helps eliminate biosolids odor complaints

Problem: During certain times of year, the Tri-Lakes Biosolids Coalition in southwestern Missouri dealt with wet or frozen ground application restrictions and odor complaints with application of Class B biosolids. There was a need to receive and process biosolids from seven wastewater treatment plants to produce a Class A product. The coalition secured a grant from Missouri Department of Natural Resources that covered half of the project cost; the remaining half was covered by the Taney County Sewer Sales Tax.

Solution: The coalition chose the Therma-Flite BIO-SCRU 3600 dryer for its small footprint, ability to handle material at 20 to 94 percent solids, and continuous operation. Biosolids are dewatered and placed in an inground hopper before feeding to the dryer, which heats the product at 240 degrees F, killing pathogens, removing moisture and producing a 93 to 94 percent solids Class A material. The product is sold to farms.

Result: Running since spring 2015, the unit has helped keep biosolids storage levels low throughout all seasons, with no odor complaints. 707/747-5949; www.therma-flite.com.

Screening plant uses dry scrubbing to control odors

Problem: The Drainage Services Department of the Hong Kong government operates the Wanchai West Preliminary Screening Plant. Several buildings were affected by odors from the plant, and complaints came from several sources. Odor control using a wet scrubber failed.

Solution: Based on hydrogen sulfide design specifications of 15 ppm, Purafil recommended a DS-100 drum scrubber for a wet well upstream of the plant and a customized VS12 vessel scrubber on site. Both scrubbers use a Puracarb dry-scrubbing medium that removes odor compounds via irreversible chemical reactions and conversion to harmless salts that remain in the media. Spent media is treated as ordinary commercial waste and taken to a landfill.

Result: After 60 days, independent lab testing indicated that the scrubbers removed more than 99.97 percent of the hydrogen sulfide, exceeding the specification of 99.5 percent. 800/222-6367; www.purafil.com.

Geomembrane cover used to end odor issues at paper mill wastewater impoundment

Problem: Gases in the wastewater impoundment at ITT Rayonier’s paper mill in Port Angeles, Washington, were causing an odor problem.

Solution: A floating cover using 110,000 square feet of Seaman Corporation’s 8130 XR-5 Geomembrane was installed over the mill’s wastewater impoundment. The flexible material rises and falls with the wastewater levels. The cover can withstand conditions including rain, UV rays, wind, and temperature variations, while retaining its tensile strength.

Result: The cover contained the odorous gases. The low thermal expansion and contraction, chemical resistance and ease of installation made it the right choice for odor control. 800/927-8578; www.seamancorp.com.

Biocatalyst significantly reduces hydrogen sulfide levels in dewatering operation

Problem: A wastewater treatment plant in Saudi Arabia needed to reduce sulfur-related odors generated by its biosolids dewatering belt presses. The plant handles waste for a large industrial complex controlled by a large company in the oil and gas sector.

Solution: Plant operations conducted a 16-day study with two belt presses, drip-feeding an active solution of BiOWiSH Odor biocatalyst from BiOWiSH Technologies at 0.32 gallons per hour into the mixing tanks upstream of one of the presses.

Result: The increased biological action reduced hydrogen sulfide levels by 72 percent on average. 312/572-6700; www.biowishtech.com.

Treatment plant upgrades UV disinfection system for increased population

Problem: Designed to treat wastewater for a population of 165,000, the Swansea Wastewater Treatment Works in the United Kingdom now serves 185,000. To improve treatment performance and ensure capacity to meet future growth up to 225,000, the plant needed an equipment upgrade.

Solution: Dwr Cymru Welsh Water chose to upgrade to the TrojanUV Signa UV disinfection system for its energy efficiency and low lifetime cost. Other key factors included simple installation, TrojanUV Solo Lamp Technology, and the ability to operate and maintain the existing UV disinfection system during the upgrade.

Result: Commissioned in January 2014, the unit has effectively disinfected to regulatory standards. It has a maximum flow rate of 30 mgd and average flow rate of 15 mgd. Three UV banks have a total of 126 lamps for maximum-duty power of 87 kW. 519/457-3400; www.trojanuv.com.

Non-impregnated activated carbon removes malodors from plant

Problem: After investing in an odor-removal system, the City of Grapevine (Texas) Wastewater Treatment Plant still had a hydrogen sulfide odor problem, exhibiting concentrations of 40 to 80 ppm at the headworks.

Solution: Application engineers from Cabot Norit Activated Carbon recommended DARCO H2S activated carbon. The chief plant operator decided to convert based on the product’s high efficiency and the fact that the material is produced without chemical impregnates, preventing bed fires in the odor-control system.

Result: The odor-control system has consistently operated without any nuisance odor. The plant also saw 50 percent cost savings by using half as much activated carbon as before. 800/641-9245; www.cabotcorp.com.

Auto-optimized dosing system used for odor control

Problem: The Town of Palm Beach, Florida, needed an optimized treatment system for fluctuating force main flows and dissolved sulfide levels at one of its lift stations.

Solution: Town leaders selected advanced remote contaminant control and monitoring technology from Kemira. The smart control uses real-time influent dissolved sulfide data to consistently auto-optimize a correct chemical dosage on a weight-for-weight basis, taking into account wastewater flow, temperature and pH.

Result: The remote-operated system lowered the site’s overall chemical usage, shortened response time and maintained a consistent level of less than 5 mg/L total dissolved sulfides leaving the injection site. 704/641-0609; www.kemira.com.

Ozone system helps reduce operating costs

Problem: Years of extreme drought followed by record flooding has caused many utilities to reconsider how they manage water resources. In 2014 the City of Abilene, Texas embarked on a plan to add ozone to its project at the Lake Fort Phantom Hill Water Reuse Project.

Solution: In order to minimize operating cost while maximizing water recovery, the city selected a process where treated MBR effluent is split between reverse osmosis and ozone plus biologically activated carbon for post treatment. The process simultaneously provides disinfection and removal of trace organics while minimizing operating cost, ensuring that trace pharmaceuticals and other organics are removed. The city selected a modular ozone system platform from Pinnacle Ozone Solutions. The integrated controls and compact modular style simplified design and installation to reduce cost.

Result: Since installation the system has been easy for plant staff to learn and operate. Treatment results from the ozone plus biologically activated carbon process have exceeded expectations in terms of water quality and total treatment cost. 321/205-1717; www.pinnacleozonesolutions.com.

Bio-filter replaces carbon adsorption drum in lift station

Problem: Lift Station 103 in the City of Peoria had a carbon adsorption drum that while initially inexpensive to purchase, had total labor, equipment and material costs for carbon media replacement that added up to several thousand dollars per year. The frequency of carbon adsorption media changeouts depends on the concentration of pollutants to be removed (primarily hydrogen sulfide) at the site, as well as the type of carbon media used. Additionally, carbon adsorption systems require shutdown, removal and replacement (manpower and equipment costs), and disposal (transportation and landfill costs) of spent carbon media.

Solution: After analysis and long-term cost considerations, the city installed a Bio-Trickling Filter from EcoVerde that requires no media changeouts or media cleaning, and minimal routine maintenance. The unit maintains more than 99 percent hydrogen sulfide removal. The unit has a higher initial cost than carbon adsorption drums, but lower ongoing operation and maintenance costs. The carbon media will always need replacing over time, while the Bio-Trickling Filter media becomes more robust.

Result: At this site, opting for the higher upfront cost of a Bio-Trickling Filter was cost effective because the system paid for itself within the first three years. 888/330-0772; www.ecoverdetechnologies.com.


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