Wastewater Flow Meters

Optimize your Wastewater Treatment Facility with Thermal Mass Flow Meters

Gas flow meters are essential tools for managing aerobic and anaerobic processes at wastewater treatment plants. Thermal mass type flow meters from Fox Thermal are the ideal solution for measuring gas flow rates, reducing costs, and meeting emissions requirements for greenhouse gases.

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Advanced Wastewater Flow Meters

Minimize flow measurement costs and maintenance

Thermal mass flow meters require no additional pressure or temperature compensation instrumentation and unlike PD or turban meters, they have no moving parts that can wear or bind so they require no maintenance.

Make treatment plant downtime a thing of the past

Anaerobic wastewater digesters produce biogas mixtures that can change over time. To reprogram the percentages of component gases in your flow meter and avoid sending it back to the factory for recalibration, you need a more flexible solution.

Accurately measure over a wide range of flow rates!

Compared to DP meters, Fox Thermal mass flow meters provide a large turndown rate, with a repeatability of up to 1,000:1 (typically 100:1) for very high velocity or for very low flow rates, which are common in anaerobic digesters.

Thermal Gas Mass Flow Meters: The Best Choice for Wastewater Treatment Plants

Properly managed, wastewater treatment reduces risks to the environment and public health caused by pathogens, toxic chemicals, antibiotics, and excess nutrients.

Gas flow measurements of compressed air in aerobic wastewater treatment can improve efficiency. For the anaerobic digestion of organic particles in wastewater, flow measurements can help keep track of biogas emissions. When biogas is used for heat or power generation, flow meters ensure accurate measurement of the fuel gas produced.

All of these operations in wastewater treatment plants require accurate measurement of gases flowing through the system.

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An electromagnetic flow meter is not an option for measuring the flow of gases in wastewater applications, due to their low conductivity. Ultrasonic flow meters and Coriolis mass flow meters can be used, but these come at a higher cost than thermal mass flow meters.

The best flow meter technology for wastewater treatment facilities is thermal mass flow meters, which offer a low-cost, high-accuracy option with a wide turndown ratio.

For example, the Fox Thermal model FT4X thermal mass flow meter comes equipped with the state-of-the-art DDC-Sensor™ technology, new expanded Gas-SelectX® gas selection menu, CAL-V™ Calibration Validation, AC input power option, and a standard data logger with date and time stamp, for accurate emissions reporting.

Click below for three easy steps to select the best model for your application.

Help Me Choose A Flow Meter
FT4X Thermal Gas Mass Flow Meter

Wastewater Flow Meter Applications

Fox Thermal Flow Meters for Aeration & Digesters.
Aeration & Digesters in Wastewater Treatment

The process of treating wastewater consists of several stages. Once the larger solids are screened and settled out, the next step is to degrade the biological particles, such as food waste and sewage, in an aeration tank.

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Just as the name implies, the aeration process pumps compressed air or oxygen into the wastewater in the right proportion to support the oxygen-loving bacteria and protozoa added to the tank in the form of activated sludge. These microscopic creatures breathe oxygen and feed on the biological solids in a biodegradation process that removes more than 80% of the waste without using chemicals.

For successful aerobic wastewater treatment, a particular ratio of air or oxygen flowing into the wastewater must be maintained throughout the basin. To accomplish this, the oxygen must be monitored with an oxygen or air flow meter and then compared with water sample data to find oxygen transfer inefficiencies.

Some wastewater treatment facilities may also use anaerobic digesters, which are airtight-covered tanks containing wastewater or other waste products. When organic matter in sewage, manure, or vegetable matter decomposes in the absence of oxygen, biogas is formed.

Biogas can be used as an energy source to power engines or fuel cells, and can even be processed into natural gas for use in vehicles or power plants.

In anaerobic digesters, a flow meter is necessary to measure and monitor gas mixes throughout the treatment process.

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Fox Thermal Flow Meters for Landfill Gas Recovery.
Landfill Gas Recovery

Landfill Gas (LFG) is created when organic waste in a municipal solid waste landfill decomposes, producing biogas containing methane and carbon dioxide. LFG can be captured in large airtight digesters, converted, and used as an energy source. The EPA requires municipal solid waste landfills of a certain size to install and operate an LFG collection and control system.

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The benefits of capturing LFG are numerous. By trapping the gases and isolating them from the atmosphere, greenhouse gas emissions are reduced. More importantly, use of LFG to power landfill facility needs and equipment reduces the amount of fossil fuels required for landfill equipment operations. The biogas allows the facility to operate almost completely self-contained and offsets the need for non-renewable energy resources such as coal and oil.

Furthermore, by containing LFG from the atmosphere, it diminishes the threat of explosions and unpleasant odors for surrounding communities.

To comply with the EPA Clean Air Act, landfill owners can either burn off excess gas by flaring it, or install an LFG energy system. Beneficial use of LFG is the only option that offers communities and landfill owners the opportunity to reduce the cost of regulatory compliance by turning a landfill byproduct into a marketable resource. In fact, local utilities and power providers often opt to purchase the electricity generated from the recovered LFG, thereby adding a renewable energy component to their energy portfolio.

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Fox Thermal Flow Meters for Co-Gen Power Systems.
Co-Gen Power Systems

Cogeneration, or combined heat and power (CHP), is the production of two forms of energy – heat and electricity – from a single fuel source.

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Co-generation plants located near wastewater treatment facilities can provide a supply of standby power for utility outages. At the same time, by producing a form of renewable energy, co-gen plants can qualify for the significant grants and incentives being offered by state and federal governments for green investments.

Municipal Wastewater Treatment Plants (WWTP) have shown interest in building co-gen facilities in the last couple of years with the most co-gen facilities operating in California and Oregon.

Anaerobic digestion is the key factor in CHP potential at WWTPs because the process generates biogas containing approximately 60-70 percent methane. The biogas can be used as fuel for a number of purposes:

  • To fire boilers and hot water heaters needed to maintain optimal digester temperatures and provide space heating.
  • To generate electricity to operate pumps and blowers used throughout the treatment process.
  • To generate electricity using equipment such as microturbines for onsite use and/or to sell back to the grid.

Anaerobic digestion produces biogas on a continuous basis, allowing for constant electricity production.

Internal process heat used for the digestion process represents the most common use of wastewater treatment methane, but great potential exists for facilities to use the generated biogas for CHP applications.

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Fox Thermal Flow Meters for Agricultural Waste Digesters.
Agricultural Waste (Dairy, Swine) Digesters

Methane, a potent greenhouse gas, is produced during the anaerobic decomposition of organic material in agricultural wastes. As more countries move toward net zero emissions, digester gas collection on-site is becoming a popular solution for reducing greenhouse gases given off by organic wastes.

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Liquid manure management systems, such as lagoons and holding tanks, can produce significant amounts of biogas, which consists mainly of methane and carbon dioxide. Many large swine and dairy operations are turning manure into a valuable resource by substituting biogas for natural gas or propane as fuel for boilers and electrical generators.

Farmers are also capturing methane from anaerobic digesters and monetizing the resulting carbon credits through greenhouse gas emissions allowance trading systems. In order to participate in such programs, accurate reports of gas flow must be made. Fox Thermal Mass Flow Meters provide direct measurement of methane in emissions using thermal mass flow rate technology. This type of gas meter measures accurately over a wide range of flow rates and it's no-moving parts design results in minimal maintenance costs.

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Fox Thermal Flow Meters for Fermentation Systems.
Fermentation Systems

The principal by-product of biogas fermentation is a methane/hydrogen/carbon dioxide gas mix. The biological and chemical stages of biogas fermentation take place in airtight digesters.

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Biogas production of farmyard manure has been shown to produce an average of 0.9m³ per animal per unit per day. This gas can later be used in a combustion system or fed to a fuel cell system to generate electricity that can be used on-site or sold to a utility.

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Get the Best Thermal Mass Flow Meter for Your Wastewater Flow Meter Application

Our new app can help you choose a wastewater flow meter model fast

If you’re not sure which meter is right for your application, our Help Me Choose app walks you through a short series of questions to help you choose the ideal meter.

Once you’ve selected a model, fill out the questions in our meter configurator form

Next, enter your process data and flow meter requirements into our automated product configurator. Drop-down menus and Help icons will guide you to answer each question.

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Save and submit your application data to us for a quote – it’s that easy!

Save the data you entered into the configurator to create a PDF with a model code and AppID. When you're ready, submit your application to Fox Thermal for a quote.

Wastewater Flow Meters

FT1 Flow Meter for Biogas Applications.
Biogas Flow Meters

Biogases produced from anaerobic digesters at wastewater treatment plants, landfills, and agricultural or livestock management systems are commonly monitored by thermal mass flow meters.

For gas mixes like biogas that tend to change composition over time, you'll need a more flexible solution with NIST-traceable calibrations and field-programmable settings like the Fox Thermal FX4A to keep your process running.

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Flow Meters
FT2A Flow Meter for Oxygen and Air Applications.
Oxygen and Air Flow Meters

Wastewater treatment plants with aeration tanks require flow meters to maintain the correct oxygen diffusion ratio. Choose an accurate gas measurement device from Fox Thermal.

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FT3 Flow Meter for Methane and Flare Applications.
Methane and Flare Flow Meters

After biogas from anaerobic digesters has been conditioned, methane and carbon dioxide or other by-product gases are separated for use in heat and power systems, with excess gas to be flared. The flow of these gases can best be measured with a Fox Thermal mass flow meter.

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FT1 Flow Meter for Natural Gas Applications.
Natural Gas Flow Meters

Natural gas is a common fuel gas sub-metered to buildings at large wastewater treatment facilities or in the agricultural sector. Choose a rugged, accurate flow meter.

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Thermal Mass Flow Meters for Other Industries


Industrial gas flow meters must be rugged, packed with features and options, and ready to measure out of the box. Plant operators must often keep the process gas flow uninterrupted in order to keep production running.

Industrial gas mass flow meters by Fox Thermal provide easy installation with either insertion or inline style meters. This type of meter operates with no moving parts and offers a wide measurement range (up to 1,000:1, 100:1 typical).

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Oil & Gas

The demand for shale oil has led to horizontal fraction drilling. The flowback from shale oil plays has many different components that must undergo a process to separate the water/chemical solution from the oil and gas components.

Fox Thermal mass flow meters can accurately measure gas components for accounting and allocation purposes and can monitor exhaust and vent gases for environmental impact.

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Pure Gas

Industrial customers of all types rely on specialty gas producers to supply them with the pure or mixed gases that they need for their processes.

Thermal mass gas flow meters from Fox Thermal can help specialty gas producers maintain a leak-free system of storage and transfer of gases such as ammonia, argon, ethane, helium, and oxygen.

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ESG Reporting

Flow meters are increasingly being used to help companies meet their environmental criteria for ESG reporting. Thermal mass flow meters from Fox Thermal can be used to track gas consumption or emissions at facilities.

For example, Fox Thermal customers use our flow meters to proactively monitor their flare gas emissions and log the data to combat a potential negative ESG rating.

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