On-Site Oxygen for Industrial and Municipal Wastewater Treatment
Oxygen Generator for Wastewater Treatment
On-site oxygen for aerobic treatment and aeration. Hold dissolved oxygen in the basin through peak loads, add treatment capacity without building new tanks, and make oxygen at 90% to 95% purity from compressed air instead of trucking in liquid oxygen.
Oxygen purity range
Output band, industrial to municipal
Typical payback vs delivered oxygen
Generator service life
Why On-Site Oxygen for Wastewater
More oxygen, more treatment, less energy per pound of BOD
Aeration is where the oxygen and the energy go. In any aerobic biological treatment process, the bacteria that break down organic load need dissolved oxygen, and supplying that oxygen is the single largest energy user at most treatment plants, commonly 50% to 70% of total plant electricity. An on-site oxygen generator for wastewater treatment delivers pure oxygen into the basin or a sidestream, which raises dissolved oxygen far faster than blowing air and lets the same tank carry a heavier organic load.
Pure oxygen transfers far more efficiently than blower air. Air is only about 21% oxygen, so a blower has to push roughly five volumes of air to deliver one volume of oxygen, and most of it bubbles straight back out. Pure oxygen at 90% to 95% dissolves a much larger fraction per unit of gas, which is why high-rate and high-strength systems use oxygen instead of, or alongside, conventional aeration. The result is higher treatment capacity in the same basin volume and steadier dissolved oxygen through load swings.
On-site instead of delivered. Plants that already use oxygen typically truck in liquid oxygen with tank rental, delivery fees, and contract minimums. An on-site PSA oxygen generator makes that oxygen from compressed air, with no delivery schedule and no consumable in the gas path. Gas Generation Solutions sizes on-site oxygen systems for industrial and municipal wastewater treatment across the United States, on the same standard PSA oxygen line that serves aquaculture, ozone feed, and biogas customers.
On-site oxygen, full lineup
PSA oxygen generators from compact skid sizes through several thousand SCFH. The standard 90% to 95% line covers wastewater aeration, aquaculture, ozone feed, and dairy digester dosing.
All oxygen generators →How PSA produces oxygen from air
Pressure swing adsorption uses a zeolite molecular sieve that selectively adsorbs nitrogen, leaving an oxygen-enriched stream. The same technology that delivers nitrogen at 99.9995% delivers oxygen at up to 95% from ambient air, with no consumables in the gas path.
Learn more about PSA →Wastewater applications
Industrial and municipal aerobic treatment
One PSA oxygen system can supply aerobic treatment across high-strength industrial streams, municipal activated sludge, and peak-load events. Every application below runs on oxygen at 90% to 95% purity, exactly what the standard PSA line delivers.
Industrial high-strength
Food, beverage, dairy, pulp and chemical
High-BOD and high-COD process water from food and beverage plants, dairies, breweries, pulp and paper, and chemical operations needs far more oxygen than a conventional blower can comfortably supply. Pure oxygen lets a compact aerobic stage handle the load and keeps the plant inside its discharge permit during production peaks.
Municipal activated sludge
Aeration basins and activated sludge
Municipal plants use supplemental oxygen to hold dissolved oxygen in the aeration basin, stabilize the activated sludge process, and push more flow through the existing tanks. On-site oxygen replaces or supplements blower aeration where the plant is oxygen-limited rather than tank-limited.
High-purity oxygen activated sludge
HPOAS and covered-tank systems
High-purity oxygen activated sludge systems run a covered, oxygen-rich tank to drive very high treatment rates in a small footprint. These systems are built around a steady on-site oxygen supply, and PSA generation feeds them without the standing liquid oxygen contract the design otherwise depends on.
Peak and shock loads
Seasonal peaks and shock loads
A sudden organic load, a seasonal production swing, or a warm-weather demand spike can pull dissolved oxygen down and threaten the discharge permit. On-site oxygen sized with headroom lets the plant add oxygen on demand to ride out the peak instead of falling out of compliance.
Lagoons and SBR
Lagoons, ponds, and SBR basins
Aerated lagoons, treatment ponds, and sequencing batch reactors all benefit from supplemental oxygen when the load outgrows the installed aeration. On-site oxygen raises dissolved oxygen in the water column to keep the aerobic population working through the high-load season.
Ozone feed gas
Oxygen feed for ozone disinfection
Tertiary ozone systems for disinfection and micropollutant removal run far more efficiently on concentrated oxygen than on dry air. The same on-site generator that feeds the aeration stage can supply the ozone generator, so one oxygen source covers both. See our oxygen generator for ozone generation page for the feed-gas detail.
How It Works
From compressed air to dissolved oxygen in the basin
Scope. This page covers supplying oxygen to an aerobic biological process, whether the oxygen replaces blower air or supplements it. The transfer method (fine-bubble diffusers, sidestream dissolution, oxygen cones, or a covered HPOAS tank) depends on the basin and the plant, and we help match it to the application. Anaerobic digestion H2S control is a different oxygen application covered on the dairy digester page.
Step 01
PSA generator makes oxygen from compressed air
The on-site generator pulls in compressed air and passes it through a zeolite molecular sieve that adsorbs nitrogen, leaving an oxygen stream at 90% to 95% purity. Oxygen collects in a buffer tank, and a built-in oxygen analyzer reads the tank purity continuously. No deliveries, no liquid oxygen tank, no contract minimum.
Step 02
Oxygen is metered into the basin or a sidestream
A flow controller feeds oxygen from the buffer tank into the aeration basin through fine-bubble diffusers, or into a sidestream dissolution system or oxygen cone that returns oxygen-rich water to the basin. The dose tracks the organic load entering the plant.
Step 03
Aerobic bacteria oxidize the organic load faster
Because the feed gas is pure oxygen rather than 21% air, a far larger fraction dissolves and dissolved oxygen climbs quickly. The aerobic biomass uses that oxygen to break down BOD and COD, so the same basin volume can process a heavier load, or the existing load can be treated with steadier dissolved oxygen and less risk of going anaerobic.
Step 04
DO monitoring holds the setpoint through load swings
Dissolved oxygen probes in the basin signal the control system, which trims the oxygen feed to hold the DO setpoint as influent load, flow, and temperature change through the day and the season. Oxygen demand climbs with the organic load, and metered injection follows that curve instead of running flat out.
Purity and Technology
90% to 95% oxygen is the sweet spot for aeration
Aerobic bacteria respond to dissolved oxygen in the water, not to the purity of the feed gas. The standard PSA line at 90% to 95% drives dissolved oxygen to setpoint just as well as ultra-high-purity oxygen. Going past 95% costs more compressed air per SCF of oxygen and a larger compressor, with no treatment benefit, which is why wastewater systems sit on the standard line.
Three working purity tiers
Lower-cost dose, smallest compressor
Fully sufficient for basin aeration and most lagoon and SBR oxygenation. Lowest compressed-air consumption per SCF of oxygen. Use when operating cost and compressor size matter most.
Headroom for swinging loads
A modest step up from 90% with a bit more delivery margin for plants whose influent load swings with production or season. A practical middle setting for industrial streams.
Standard PSA ceiling, most headroom
The standard line tops out here, and it is the same level used for aquaculture, ozone feed, and biogas dosing. The most delivery headroom on the standard line, with no reason to pay for the 99% high-purity line in a wastewater application.
Why PSA from air, and not delivered oxygen
PSA delivers continuous oxygen on site
Pressure swing adsorption produces oxygen on-site from ambient air using a zeolite molecular sieve that selectively adsorbs nitrogen. There is no delivery schedule, no liquid oxygen tank to rent, no contract minimum, and no driver visit. The system runs on compressed air and a power connection, which a treatment plant already has.
Air consumption rises with purity
Producing 90% oxygen from ambient air takes roughly 11 SCFM of compressed air per SCFM of oxygen. At 95% the ratio rises to about 14. At 99% it is closer to 19. For an application where 90% to 95% works perfectly well, paying for the larger compressor and sieve bed to chase 99% is wasted capital and ongoing kilowatt-hours.
Sizing and ROI
Three numbers size the system
A wastewater oxygen system is sized off the organic load, the dissolved oxygen target, and how the oxygen gets into the water. Each is something the plant already tracks, and the generator is matched to peak demand so dissolved oxygen holds on the highest-load day.
Sizing inputs
Input 01
Organic load and flow
Influent BOD or COD load and flow set the oxygen the aerobic process has to supply, since the biomass consumes oxygen in proportion to the organic load it breaks down. Peak load, not the daily average, sizes the system. Existing influent records are the best starting point.
Input 02
Target dissolved oxygen
The dissolved oxygen setpoint the process requires in the basin, typically held in a band that keeps the biomass aerobic without wasting oxygen. This sets how much oxygen has to be dissolved per minute to hold DO across the basin under load.
Input 03
Transfer method and efficiency
Fine-bubble diffusers, sidestream dissolution, oxygen cones, and covered HPOAS tanks each dissolve a different fraction of the oxygen fed to them. The transfer efficiency sets how much oxygen the generator has to supply to deliver the dissolved oxygen the basin needs.
Payback drivers
Driver 01
Ends liquid oxygen rental and delivery
For a plant already on delivered oxygen, on-site generation removes tank rental, delivery fees, and contract minimums. The generator runs on compressed air with no consumable in the gas path and stays in service for 20 years or more, with a typical 12 to 14 month payback against delivered gas.
Driver 02
Adds capacity without new tanks
When a plant is oxygen-limited rather than tank-limited, adding oxygen lets the existing basins treat more load. That can defer or avoid the capital cost of building new aeration tanks, which is often the largest single number in a plant expansion.
Driver 03
Protects the discharge permit
Holding dissolved oxygen through peak and shock loads keeps the aerobic process stable and the effluent inside permit. Avoiding a single permit exceedance and the penalties and remediation that follow can justify the system on its own.
Worked example
Mid-size industrial plant. A food or beverage plant supplementing its aerobic stage through production peaks sizes to roughly 1,000 SCFH of oxygen at 95% purity, a standard on-site PSA generator in the O-100 class with a packaged compressor matched to its air demand.
Smaller and larger. A small high-strength stream or a lagoon top-up may need only 150 to 400 SCFH. A large municipal basin or HPOAS system can run into the 2,500 to 3,000 SCFH range at the top of the standard PSA line, with multiple units for larger duties.
Each build is matched to peak load so dissolved oxygen holds on the highest-load day of the year.
Not sure of your oxygen demand?
Give us a call and we can go over your influent load, flow, and current oxygen source to help determine a baseline before we size the system.
Frequently Asked Questions
Oxygen for wastewater treatment
How much oxygen does a wastewater plant need?
Oxygen demand is driven by the influent organic load (BOD or COD) and flow, since the aerobic biomass consumes oxygen in proportion to the load it breaks down. A small high-strength stream or lagoon top-up may need only 150 to 400 SCFH, a mid-size industrial plant often lands around 1,000 SCFH, and a large municipal basin or HPOAS system can run into the 2,500 to 3,000 SCFH range. The right way to size is off peak load, ideally from existing influent records.
Why use pure oxygen instead of blower aeration?
Air is only about 21% oxygen, so a blower has to push roughly five volumes of air to deliver one volume of oxygen, and most of it bubbles back out. Aeration is also the single largest energy user at most plants, commonly 50% to 70% of total electricity. Pure oxygen at 90% to 95% dissolves a much larger fraction per unit of gas, which raises dissolved oxygen faster, lets the same basin carry a heavier load, and is the basis of high-rate systems. Many plants use oxygen to supplement blowers rather than replace them.
What is high-purity oxygen activated sludge (HPOAS)?
HPOAS is an activated sludge process that runs a covered, oxygen-rich tank instead of an open air-aerated basin. The high oxygen concentration drives very high treatment rates in a small footprint, which suits high-strength industrial streams and space-limited sites. These systems are designed around a steady on-site oxygen supply, and PSA generation feeds them without the standing liquid oxygen contract the design otherwise requires.
What oxygen purity do I need? Is 99% better?
No. Aerobic bacteria respond to dissolved oxygen in the water, not to the purity of the feed gas, and the standard PSA line at 90% to 95% drives dissolved oxygen to setpoint just as well as ultra-high-purity oxygen. Going to the 99% high-purity line costs significantly more compressed air per SCF of oxygen, a larger compressor, and higher capital cost, with no treatment benefit. Wastewater systems sit on the standard line.
How does on-site oxygen compare to delivered liquid oxygen?
Delivered liquid oxygen carries tank rental, delivery fees, telemetry charges, and contract minimums on top of the gas. An on-site generator produces oxygen from compressed air with no delivery schedule and no consumable in the gas path, cutting oxygen cost by up to 90% versus delivered gas with a typical payback of 12 to 14 months and a service life of 20 years or more.
Can on-site oxygen increase treatment capacity without new tanks?
Often, yes. When a plant is oxygen-limited rather than tank-limited, adding oxygen lets the existing basins treat more organic load, because the biomass can process more when more oxygen is available. That can defer or avoid building new aeration tanks, which is usually the largest single cost in a plant expansion. A load and capacity review confirms whether a given plant is oxygen-limited.
Does on-site oxygen help with peak or shock loads?
Yes. A sudden organic load, a seasonal production swing, or a warm-weather demand spike can pull dissolved oxygen down and threaten the discharge permit. An on-site generator sized with headroom and paired with a buffer tank lets the plant add oxygen on demand to ride out the peak instead of falling out of compliance.
Can the same oxygen feed an ozone system for disinfection?
Yes. Tertiary ozone systems for disinfection and micropollutant removal run far more efficiently on concentrated oxygen than on dry air, and the same on-site generator that supplies the aeration stage can feed the ozone generator. Sizing accounts for both demands so one oxygen source covers the plant. Our oxygen generator for ozone generation page covers the feed-gas detail.
Give us a call and we will size the system
We can go over your influent load (BOD or COD), flow, target dissolved oxygen, the transfer method on your basin, and your current oxygen source to help determine a baseline. From there we recommend the on-site oxygen generator size and the transfer setup to hold dissolved oxygen on your highest-load day.
Request a quote →Gas Generation Solutions sizes on-site oxygen systems for industrial and municipal wastewater treatment across the United States, on the same standard PSA oxygen line that serves aquaculture, ozone, and biogas customers.