Innovative way of enabling gas transfer in/out of liquid with extremely high efficiency US Patent No. US 8,292,271 B2 and US 7,494,534 B2

I recently travelled to Japan, where I met the original inventor of our technology. His name is Mr. Tetsuhiko Fujisato, a professional focused on water treatment, public health, and environmental protection.

He is the gentleman on the far left

No matter how small they are, micro nanobubbles are still air bubbles and are not dissolved in water. According to Mr. Tetsuhiko micro-nanobubble generators are not good at dissolving gases.
The device we will introduce to you today is highly efficient, dissolving gas components in water to saturation. It is also possible to incorporate a micro-nanobubble or ozone generator into the device, allowing micro- nanobubbles to be added to the treated water. This will make everything more efficient. We feel this will allow for the best of both technologies to work better for your application.
Instead of making small bubbles in the liquid, it turns the entire liquid into bubbles. This technology is a new concept of gas transfer in and out of liquid
All liquids to be processed will form several soap-like bubbles, with the surrounding gas forming a thin liquid film, enabling extremely efficient gas transfer.
Very low power operation. Small footprint with scale-up capability.

Conventional Aeration: Increase the liquid/gas boundary area by making bubbles small.

Fujisato Bubble Tank Technology: Makes liquid into a thinner film form around the gas to increase the boundary area, thus creating an immediate impact that allows for a much better process.

The technology of the saturated water generator instantly transforms the water to be treated into a film, generating saturated water.

The device also generates water with a saturation level that corresponds to the air pressure at the location where it is placed.

Based on the oxygen saturation concentration table for seawater and freshwater above, a DO concentration of 6.35 mg/L at a water temperature of 31.7°C is wastewater that contains a lot of organic matter and minerals, and is therefore thought to have properties similar to seawater.

The graph above also shows a saturation value table based on air composition.
When the water temperature is 30°C and the dissolved oxygen level is 0 mg/L, the N2 concentration is dissolved up to the S.N2 level.
To increase O2 to saturation, the S.N2 dissolved concentration must be reduced to the N2 level indicated by the graph line.
O2 will never be dissolved.
The quickest way to do this is to turn the water into a film.

By treating the treated water in a film form, even if there is an excess of N2, it will return to the blue N2 saturation line, and even if the O2 content is 0 mg/L, it will automatically return to the yellow O2 saturation line.

It can also be easily operated in deep water.

Existing Fine Bubble Aeration Method in Westwater Treatment

Fine bubble aeration works well to dissolve air into water. We often talk about just OTE (Oxygen Transfer Efficiency) and assume higher OTE is desirable. Have you thought about N2 gas transfer efficiency, CO2 gas transfer efficiency etc.? They are in the air as well and will also get dissolved into water.
The dissolved oxygen will be consumed by aerobic bacteria but dissolved N2 gas or CO2 gas will remain in the water.
Continuous air injection at deep water will cause the water to be super saturated with N2 gas and CO2 gas etc. Once such condition is created, it is very hard for new air to be dissolved as water is “too full”.

Measured by head-space-method, using Gas Chromatography

Super saturated N2 gas and CO2 gas are measured. You must remove those gases to make a room for new air to come in.

	Dissolved concentration of gases (mg/L)
	Measured in ML (a)	Saturation level (b)	a/b
N₂	48.6	17.8	2.7
CO₂	79.5	0.58	132
O₂	0.71	9.56	0.07

Fujisato's “gas exchange” is not gas injection.

For such water conditions on the previous page, you need to remove excess dissolved gases (nitrogen gas and carbon dioxide), then replace them with new air.
Fujisato balances the gas ratio of new air and dissolved gases via equilibrium and maintains dissolved gas in the water at the saturation level (without creating a saturation condition from small bubble injection).
Please see a video from the link below of Mr. Tetsuhiko Fujisato. The DO of water measures approximately. 0.6ppm. By capturing air from existing diffusers with the Fujisato device, DO increased to 2.8 ppm. This tells you that the air injected with fine-bubble diffusers still contains a lot of oxygen but is mostly unused.

The same air volume for both methods with different ML SS concentrations.

The advantage of Fujisato Bubble Tank is evident.

The DO increases by just placing the Fujisato units at the surface of aeration basins. Doing this increased the DO level from 0.3ppm to 3.6ppm. No other change is made, no chemicals, nothing.

Fujisato enables shallow depth aeration. Unlike fine bubble diffusers, Fujisato devices DO NOT require aeration the aeration point to be 14ft (4m) or deeper. 3-4ft (1m) deep water is enough to achieve higher DO and it uses less power.

The Fujisato system works for various applications including wastewater, drinking water, dam/pond/storm water, aquaculture, hydroponics, bio-reactors, algae growth, gas dissolution/stripping etc.

It has the following advantages

Low power consumption
Operate by gas inlet with low pressure loss
High gas transfer efficiency
Large aperture - No clogging, low maintenance
No new construction or retrofit
Various device configurations – Design flexibility
Move water and aerate at the same time
Scale-up capability
Small footprint

What is Dissolved Oxygen (DO)?

Dissolved oxygen (DO) refers to the amount of oxygen gas (O₂) mixed into and available within water. While water molecules (H₂O) contain oxygen, aquatic organisms and microbes cannot use that oxygen. They rely on free O₂ molecules dissolved in water for respiration and survival.

Key Roles of DO:

Supports aerobic bacteria, which break down organic matter in water.
Essential for fish, invertebrates, and other aquatic animals to breathe.
Indicates water freshness and quality in drinking water systems.
Enables key chemical reactions, such as oxidation of iron, manganese, and hydrogen sulfide.

How DO is Measured and Assessed

Biochemical Oxygen Demand (BOD): Measures oxygen consumed by microorganisms as they break down organic material over 5 days.
Chemical Oxygen Demand (COD): Measures total oxygen required to oxidize all organic and inorganic matter in water. COD results are generally higher and obtained more quickly than BOD.
Both BOD and COD are used to assess pollution and treatment effectiveness in water and wastewater.

Process / Use	Good DO Level	Purpose
Wastewater aerobic treatment	2–4 mg/L	Supports aerobic bacteria, reduces BOD/COD
Nitrification	2 mg/L	Converts ammonia to nitrate
Drinking water distribution	6–8 mg/L	Maintains taste, reduces corrosion
Rivers/lakes	8–12 mg/L	Healthy aquatic habitat

What DO Does NOT Remove:

Heavy metals (except iron/manganese via oxidation)
PFAS, microplastics, pharmaceuticals
Bacteria/viruses
Hardness (calcium/magnesium), salts, or total dissolved solids (TDS)
These require other treatment processes (filtration, reverse osmosis, carbon, UV, etc.)

Effects of Low DO:

Stresses aquatic life: <5 mg/L can harm fish, <2 mg/L may cause fish kills.
Anaerobic bacteria take over, leading to production of hydrogen sulfide (H₂S), methane, and organic acids.
pH usually drops due to CO₂ and acid formation.
Can cause release of iron and manganese into water.
In aquaculture, low DO stunts growth, increases disease risk, and can lead to fish/shrimp deaths.
In wastewater, low DO slows pollutant breakdown, causes odors, and leads to treatment failures.

Why DO is Important in Drinking Water:

Indicates freshness, prevents stagnation, and discourages unwanted bacteria.
Supports oxidation of iron, manganese, and hydrogen sulfide, improving taste and odor.
High DO leads to clean, crisp water with fewer issues.

Why DO is Important in Aquaculture:

Fish and shrimp require DO for respiration, growth, metabolism, and stress resistance.
Low DO reduces feeding, slows growth, increases mortality, and raises the risk of disease.
DO above 6 mg/L is best; below 4 mg/L is dangerous and can be fatal.

Why DO is Important in Wastewater:

Needed for aerobic bacteria to break down organic waste, lower BOD, and prevent odors.
Nitrifying bacteria (for ammonia removal) need even higher DO.
Proper DO ensures efficient treatment, healthy microbial populations, and regulatory compliance.

DO as a Water Quality Indicator:

High DO signal a healthy, well-aerated system.
Low DO may indicate pollution, organic overload, or stagnation

DO Level	Dominant Processes	Effect on pH
High DO	Aerobic respiration, CO2 removal, photosynthesis	pH stable or slightly higher
Low DO	Anaerobic activity, CO2 build up, organic acid production, reducing conditions	pH typically decreases
Very low / anoxic	Strong anaerobic digestion, H2S formation, acid production	pH drops even further

Bottom Line:

Dissolved oxygen is vital for water quality, treatment effectiveness, aquatic health, and overall ecosystem stability. While not directly regulated in drinking water, it is a key indicator of water system health and operational efficiency. Maintaining proper DO is one of the simplest and most effective ways to ensure safe, high-quality water for people, aquatic life, and the environment.

Best Water Solutions Provider Awards

Puroxi Pure Water Global Inc was shortlisted for the awards category, Water Solutions Provider of the Year! As highlighted, it was some good news. I can confirm you that you have been chosen as the 2023/24 winners. Congratulations Zak! The generic winner’s logo has been attached which you can utilize to promote the recognition and the official press release will be conducted in March (defined date to come

Bubble tank + do technology