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Water Treatment

Water scarcity and environmental concerns are driving today’s demand for reliable and cost-effective technologies to treat and recycle water. With more than 35 years of experience and references in water treatment, Air Liquide assists private and public companies with industrialised gas solutions to treat water.

Water Treatment at a Glance

Water treatment consists of several mechanical and chemical processes that aim to remove water contaminants or reduce their concentration in order to make water more acceptable for a desired end-use.

The contaminants can be solid or dissolved and include metals and minerals, organic substances, viruses, bacteria, fungi…

Water treatment technologies are used to treat water intended for drinking, recycling or water discharges to be released in the environment. They can also be employed to prevent corrosion, scaling and bacterial development in various industrial processes. Water is a precious resource and water regulations are very stringent.

Our Solutions

Air Liquide has a range of solutions depending on your water treatment  application:

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Water Purification

The Industry Challenge

The ultimate objective of drinking water treatment is to mitigate any sanitary risks due to pathogenic micro-organisms and dissolved pollution. Ozone, one of the most powerful oxidising agents, is particularly efficient at killing germs including protozoan, which are resistive to other treatments. Additionally, ozone acts like a micro-flocculant to remove dissolved pollution.

If you are aiming for a high quality, safe and reliable drinking water production, industrial gases can provide you with a truly effective solution.

Your Solution and Advantages

A comprehensive gas offer designed for and adapted to your specific needs, Our Solutions for Water Purification combine the best of our gases, application technologies and expert support.

Our Solutions for Water Purification consist of water ozonation in substitution for chlorine or other chemicals. Ozone is produced by electrical high voltage corona discharge in an oxygen-fed generator. Ozonated oxygen is dissolved into water inside a reactor. Ozone kills microorganisms by damaging their cell walls. What’s more, ozonation of dissolved pollution creates polymers that enhance coagulation and are easy to filter out.

Our Solutions for Water Purification can optimise ozone production from 3 mg/l up to 20 mg/l with dosage control and compact transfer reactor design.

• Less Investment – Smaller Footprint
Pure-oxygen-fed ozone generators require a reduced footprint without any air compression and air treatment installation. Implementation is easier.

• Less Maintenance – Longer Lifetime
Without any rotating parts (air compressor) and no pollution risk (air treatment) maintenance is easier too, and ozone generator lifetime is increased.

• Higher Efficiency
Pure-oxygen-fed ozone generators reach higher ozone concentrations of typically up to 14%. The water ozonation reactor is more compact, which kills bacteria, germs and parasites in a short contact time of typically 5-15 minutes.

• Energy and Flocculant Cost Savings
Pure-oxygen-fed ozone generators are 40% less power intensive as air-fed generators. Ozonation of raw water is more effective than pre-chlorination to reduce filter effluent turbidities. It improves the water clarity and reduces the need for flocculent by 20% to 50% in some cases.

• Safe and Environmentally Friendly
Ozone is more effective against chlorine resistant microorganisms. And because ozone breaks down into oxygen rapidly, it dramatically reduces chemical consumption and eliminates health hazards associated with chemical by-products.

Remineralisation

The Industry Challenge

The largest use of carbon dioxide (CO₂) for potable water treatment is for remineralisation. This application is used for hardening of either naturally soft waters or waters that have been softened during the treatment process, through nanofiltration or reverse osmosis. Water hardness levels are a requirement of standards for potable water.

Following desalination, water’s mineral level becomes very low. It must therefore be remineralised in order to reincorporate the elements that make it drinkable and non-corrosive.

Adding lime or limestone along with an acid is an essential step in remineralisation. And using CO₂ is an almost mandatory standard in this process.

Your Solution and Advantages

A comprehensive gas offer designed for and adapted to your specific needs, Our Solutions for Remineralisation combine the best of our gases, application technologies and expert support. Our Solutions for Remineralisation include process expertise on system design and equipment for safe and effective carbon dioxide dissolution into the water. The offer encompasses everything from the most suitable liquid CO₂ supply, dosing and control cabinet, and static mixers or injection systems in pipe-in-pipe or bypass modes.

• Compliance with Most Stringent Regulatory Standards
Carbon dioxide product compliance with the latest International Society of Beverage Technologists (ISBT) guidelines, the European standard EN936 and local regulations. Carbon dioxide supply chain compliance with the Air Liquide
Food Safety Management System.

• High Efficiency
Our engineering design coupled with a suitable injection and mixing equipment, achieve high CO₂ solubility above 95%.

• Accurate pH Control
Whereas small quantity of strong acids - like sulfuric acid - can change pH dramatically, a weaker acid with natural buffering effect like CO₂ offers very accurate pH control.

• Better Organoleptic Quality of Water
Soft water tastes salty and is not suitable for drinking. Water hardening is necessary to add minerals like calcium and magnesium, which makes water suitable for drinking not only because of health benefits, but also for better flavour and taste.

• Less Corrosion and Scaling
Carbon dioxide reduces corrosion in equipment and piping that is caused by strong acids, generating savings on maintenance. Additionally, CO₂ is safer to handle than strong acids.

• Eco-responsible Operation
Carbon dioxide is a recycled product and unlike sulphate and chlorine, does not produce residual pollution.

• Reliability
We provide peace of mind with a reliable CO₂ supply to prevent critical desalination plant interruption. Furthermore, we offer modular solutions to increase treatment capacity as desalination plants ramp up over the years.

Groundwater

The Industry Challenge

Drinking water is one of the most controlled and protected food products. It must not only be free of pathogens, germs and toxic compounds, but also of colour and smell. Iron and manganese are drained from sediments and dissolved in groundwater. Iron ions create a rust-brown colour of the water, and a high content of manganese adds a bitter taste. Additionally, iron and manganese cause precipitation in piping and sanitation systems. It is therefore essential to remove both metals from drinking water.

Your Solution and Advantages

A comprehensive gas offer designed for and adapted to your specific needs, our Solutions for Groundwater combine oxygen supply, application technologies which comply with the Australian Standard AS/NZS 4020(1), and expert support. Our Solutions for Groundwater consist of injecting oxygen into the water to form iron and manganese oxides that can be easily removed by filtration. The offer encompasses everything from the most suitable oxygen supply, dosing and control cabinet, and injection system such as static mixer.

• Higher Purity
The fewer gas bubbles, the larger the adsorption surface available to oxidise and remove iron and manganese in a sand filter. Using pure oxygen instead of compressed air reduces the required gas volume tenfold, which results in fewer bubbles and higher water purity.

• Lower Power Consumption
The less gas bubbles, the less pressure drop inside a sand filter. As using pure oxygen reduces the formation of bubbles compared with compressed air, the pressure drop is lower – typically 0.45 bar vs. 0.6 bar – which results in a lower power consumption to pump the water from the well to the drinking water system.

• Maximum Run Time
The reliability of our static mixer and its low maintenance, combined with smoother operation, allows for less filter cleaning and risk of blocking.

• No Smell or Corrosion
When using compressed air, which provides a constant flow rate, oxygen dissolution decreases as filtration generates an increasing pressure drop. Using pure oxygen ensures that the dissolved oxygen content is above 85% as recommended by the Australian Drinking Water Guidelines (ADWG), whatever the pressure drop in the filtration process. This avoids bad smell at the tail end of the water system and its corrosion.

(1)AS/NZS 4020: Products for use in contact with drinking water

pH Control

The Industry Challenge

Cleaning–in-Place (CIP) in hygiene critical industries such as Food, Beverage and Pharmaceutical leads many businesses to utilise strong alkali cleaners for process vessels and pipe work systems. There are also many processes which, as a consequence of routine operation, generate highly alkaline i.e. high pH wastewater. Environment agency guidelines state that buffer storage or balancing tanks should normally be provided to cope with the general variability in flow and composition of wastewater, or to provide corrective treatment like pH control.

Your Solution and Advantages

A comprehensive gas offer designed for and adapted to your specific needs, our Solutions for pH Control combine the best of our gases, application technologies and expert support. Our Solutions for pH Control are environmentally friendly options for pH control from Air Liquide which can solve the problems inherent to a process using mineral acids. The offer encompasses everything from gas to dissolution systems of carbon dioxide (CO₂). Our Solutions for pH Control are suitable for municipal and industrial wastewater treatment plants.

Natural safety net
Thanks to a natural buffering effect, CO₂ cannot reduce effluent pH far below 6, even if overdosing occurs.

• Improved process control
pH drop with CO₂ occurs more gradually than with mineral acids, making accurate control inherently easier.

• Environmentally friendly operation
CO₂ is a recycled product and does not produce saline residuals as sulphate and chlorine.

• Cost effective
CO₂ is typically about the same price as sulphuric acid and half that required for an equivalent dose of hydrochloric acid.

• Ease of handling
As CO₂ is supplied in a pressurised system (cylinder or bulk storage), it can be stored remotely from the dosage point. Also the product is completely enclosed until it is mixed with the effluent, removing handling issues of corrosive mineral acids.

Biological Treatment

The Industry Challenge

Wastewater treatment has become a major concern. In some regions, water is scarce, and environmental protection is a growing necessity. As a result, the industry needs reliable and cost-effective technologies to comply with today’s strict regulations regarding wastewater discharge. If you’re looking to boost your plant capacity, optimise operating costs, or resolve various foam and odor issues, industrial gases can provide you with a truly effective solution.

Your Solution and Advantages

A comprehensive gas solution designed for and adapted to your specific needs, our Solutions for Biological Treatment combine the best of our gases, application technologies and expert support.

Our Solutions for Biological Treatment consist of introducing pure oxygen into biological basins for the respiration of microorganisms (activated sludge) which consume biodegradable pollution. In combination with sludge ozonation, it also stimulates the whole biological process in a very efficient manner. Advanced application technologies are used to dissolve oxygen in the wastewater, ozonate sludge and re-use oxygen-rich off-gas from a sludge ozonation step.

Our Solutions for Biological Treatment are suitable for municipal or industrial wastewater treatment plants.

• Capacity increase
Pure oxygen dissolves better in water than air. Therefore, using pure oxygen can increase the capacity of a wastewater treatment plant.

• Opex savings
The total power consumption required to transfer pure oxygen in water is reduced compared to air along with operation and maintenance costs.

• Reduced capex
Implementing pure-oxygen technology makes it possible to reduce the size of a new wastewater treatment plant or increase the capacity of an existing one. Additionally, better oxygen dissolution allows for nitrification in an existing aeration tank.

• Reduction of foam formation
Foam is often formed in water treatment plants due to excess growth of filamentous bacteria that high amount of injected air makes float on the water. Using of pure oxygen vs. air reduces the amount of the filamentous bacteria.

• Removal of odors
When there is not enough dissolved oxygen for the respiration of the microorganisms, the bacterial activity consumes the one contained in sulfur compounds of water pollutants. It generates volatile H₂S and bad smell which is avoided by using pure oxygen.

• Effective sludge treatment
Sludge ozonation sustains the microbial activity, increases the settling speed (range of SVI index between 50-100 ml/g) and decreases the production of excess sludge in some cases by up to 60%. Our solution allows re-using the oxygen-rich off gas from the ozonation process, which makes the overall treatment very cost effective.

Tertiary Treatment

The Industry Challenge

Wastewater treatment has become a major concern. In some regions, water is scarce, and environmental protection is a growing necessity. As a result, the industry needs reliable and cost-effective technologies to comply with today’s strict regulations regarding wastewater discharge.

If you’re looking to meet stricter or new regulatory discharge limits, in a cost effective manner, industrial gases can provide you with a truly competitive solution.

Your Solution and Advatages

A comprehensive gas solution designed for and adapted to your specific needs, our Solutions for Tertiary Treatment combine the best of our gases, application technologies and expert support.

Our Solutions for Tertiary Treatment use ozone (O₃) to remove pathogenic organisms or pollutants which are difficult to biodegrade like micro-pollutants (pharmaceutical and personal care product residues), surfactants, inks, etc.

Ozone is one of the most powerful and readily available oxidising agents. The excess oxygen (O₂) to produce ozone is re-used to optimise the overall solution and lower costs.

Our Solutions for Tertiary Treatment are suitable for municipal or industrial wastewater treatment plants.

• Removal of non-readily biodegradable pollution
Degradation of complex chemical molecules to meet effluent discharge limits.

• Removal of micro-pollutants
Compliance with the newest and strongest regulations, particularly targeting micro-pollutants. Ozone breaks down very rapidly, leaving no residual traces. Ozone dosages are precisely adjusted not to produce any toxic transformation products.

• Detoxication
Detoxication of influent is indispensable if wastewater is toxic for microorganisms in biological treatment steps. Ozone converts toxic substances into biologically harmless ones.

• Disinfection
Ozone is a superior disinfectant, acting more rapidly and completely than other common disinfecting agents. Ozone is generated on-site, and thus, there are fewer safety problems associated with shipping and handling of chlorine based chemicals.

• Discoloration
Removal of hard-to-treat dyes and chemicals to meet safe levels of discharge to the environment. Treated water can also be reused in process line for cost reduction.

Water Treatment Process Selector