Water and Wastewater FAQs

Depending on the species of fish and the farm characteristics, Air Products water specialists can determine the requirements and the best way to inject and control the dissolved oxygen levels. Each species of fish and farm configuration are different and need a specific study to deliver the optimum solution. Based on many years’ experience in the sector, Air Products can specify the most suitable solution from pure oxygen aerators to dissolved oxygen probes and transmitters. In addition, Air Products can design the oxygen injection panel to optimally manage the entire system depending on the number of aerators.

Oxygen, ozone and carbon dioxide are the main gases supplied by Air Products and commonly used for aquaculture processes. Pure oxygen is commonly applied to maintain a good level of oxygen for livestock. It can increase productivity and decrease mortality. In addition, it ensures that the livestock is always kept in the best condition by reducing the effects of stress. When water is reused, ozone could also be applied to disinfect it and avoid diseases. Carbon dioxide is also used for downstream food product transformation.

To provide enough oxygen to the river to cover the needs of the downstream ecosystem. The objective is to preserve alive the fishes by boosting the water with the oxygen necessary to their life.

For oxygen to form into ozone, oxygen molecules must be cracked and reformed. This takes energy in the form of electrical excitation of oxygen that disassembles the oxygen molecules. This is usually accomplished with high voltage (corona discharge) ozone generators. Once pulled apart, most molecules will revert to the stable form of oxygen. However, some of the oxygen is converted into ozone in this process. That process requires a lot of energy to crack the molecule and obtain a low concentrated flow of ozone. If air is used the generators will consume much more energy than using pure oxygen because of the huge concentration of inert gases such as nitrogen. Pure oxygen processes are more efficient due to the concentration of oxygen. In parallel, the ozone concentration can be increased from 3-4% with air to 12-14% with oxygen using three times less energy. The high ozone concentrated flow if also more effective in term of mass transfer for further uses.

The process of water mineralisation or remineralisation is a method of adjusting the minerality of the drinking water to the level recommended for consumer health. The recommended method is a combination of calcium and carbon dioxide injections to reach the necessary minerality level. That process is used where ground waters do not have a sufficiently concentration of minerals or as post treatment in the desalinisation processes.

In parallel with the gases and equipment that Air Products provide for the water sector, our specialised water engineers also have a wealth of industry experience. We understand your issues and can build a reliable solution based on our segment knowledge and the know-how acquired over many years of service in water processes. Dedicated people are available to discuss and determine how our gases and technical devices could provide reliable solutions and how they could be operated on each particular water plant design.

Air Products supplies liquid oxygen or carbon dioxide to many drinking water plants all over Europe. Through our understanding and expertise in water treatment processes and the challenges faced we can deliver a suitable product or solution to meet any requirements. We can also use our segment knowledge to suggest the best solutions to optimise existing plants.

Due to low humidity and hydrocarbons contents, pure industrial gases are naturally compatible with the ozone generator operation. No treatment other than a simple filtration has to be applied and that parameter is a natural guarantee for the good operation associated with a low maintenance and a longer generator life.

Air Products has developed different dedicated technologies that can be integrated in an existing water treatment plant to upgrade the treatment or increase efficiency. Mainly based on oxygen and carbon dioxide supplies, which are part of the basics gases supplied by Air Products, our technologies can solve any issue linked to plant overloads, lack of efficiency, nuisances problems, hard COD and microcontaminants releases and safety issue of strong acids handlings. Dedicated experts are available to study any case.

Alongside the gases and equipment that we have developed specifically for water treatment Air Products' specialised water engineers have many years of expertise to develop a reliable, efficient and safe solution. Our dedicated water team is available to discuss and determine if pure oxygen could be a reliable solution and how it could be operated on each particular water plant design.

Nitrogen cycle in water plants consists of nitrification periods followed by denitrification ones. This process is managed by supplying enough oxygen during the nitrification phase (oxygenation period) to convert ammonia into nitrates that will be removed into gaseous nitrogen during the denitrification phase (period without oxygen). The balance between nitrification and denitrification phases has to be managed precisely. An effective way to cover the entire cycle of nitrification and denitrification within a limited period of time is to boost the periods of nitrification by accelerating the kinetics of reaction using pure oxygen, which allow more time for the denitrification period to reach the expected nitrogen level. Pure oxygen nitrification boosting is a reliable solution that requires no investment.

Nitrogen cycle in water plants consists of nitrification periods followed by denitrification ones. This process is managed by supplying enough oxygen during the nitrification phase (oxygenation period) to convert ammonia into nitrates that will be removed into gaseous nitrogen during the denitrification phase (period without oxygen). The balance between nitrification and denitrification phases has to be managed precisely. An effective way to cover the entire cycle of nitrification and denitrification within a limited period of time is to boost the periods of nitrification by accelerating the kinetics of reaction using pure oxygen, which allow more time for the denitrification period to reach the expected nitrogen level. Pure oxygen nitrification boosting is a reliable solution that requires no investment.

Air based aerators are obviously the main source of oxygen in a conventional treatment system. Although air is free, it limits the transfer efficiencies because of the huge quantity of energy required to handle the gas dissolution to make the dissolved oxygen. In the pure oxygen configuration, the gas concentration and the available pressure make the mass transfer more efficient, which results in pure oxygen devices reducing energy use fivefold compared to air-based systems. This energy savings closes the cost between the two technologies, with the pure oxygen solution similar to the air-based costs allowing you to benefit from the technical advantages offered to improve operational efficiency.

As pure oxygen can be dosed as much as required, the limitations are not linked to the pollution loads in terms of quantities, but more to the hydraulic capacities of the plant. Experts are available to determine the limits case by case.

Hundreds of water treatment plants, both industrial and municipal and of varied sizes, are currently boosted with pure oxygen. This solution has been implemented on a case by case basis, each on solving a particular issue with a flexible and reliable solution. Using pure oxygen can help the overall operation of the water plant including better settling, less filaments, faster treatments and an increase in efficiency. The results is a plant that is less susceptible to the variabilities of influents and delivers a real improvement in the overall reliability of the process. It reduces maintenance and operating cycle times and converts a sensitive system into a robust one while reducing operational expenses by reducing energy consumption needed for aeration to 20% of the original cost.

Oxygen: this component brings process efficiency in every biological and aerobic based water treatment process. It is supplied in accordance with the process requirements to guarantee the stability and reliability of the entire treatment.

Ozone: this component is used where conventional biological treatments have reached their limits because of hard COD or low biodegradability. As a chemical precursor, ozone is one of the strongest oxidant easy to produce and apply.

Carbon dioxide: this product is well adapted for pH neutralization when the process requires a soft acid or when using strong acids is a safety issue.

As a main component of the aerobic biological process, oxygen must be delivered in quantities suited to biomass at any time and in any circumstances, proportional to the needs of the process. Any shortfall is critical for biomass and treatment quality. Pure oxygen boosting is a reliable solution for problems caused by lack of oxygen or a low flexibility of the air aeration system in place. In general, pure oxygen can solve effluent non conformities (COD, BOD, TSS, NTK …), filamentous bulking in biological basins, foam, aerosols, odours nuisances, pollution increase, pollution variability and peaks. In addition to air, pure oxygen provides the flexibility that a water plant needs to manage critical processes and achieve treatment efficiency.

In an aerobic biological process, the pollution load is treated by a bacteria that needs oxygen to live and grow. The key parameter for making this process efficient is to supply the exact level of oxygen required for the pollution load. Any lack of oxygen effects the balance of the process and can reduce the efficiency and cause filament bulking. There are other chemical products that can be used to overcome the issues caused by the lack of oxygen (odour control, filamentous bulking and foam...) but good practice is to avoid the problems in the first instance by supplying the biomass with the correct dosages of basic elements it needs to live and work in optimal conditions. Solving the issue at its source will make the solution more reliable than working on the consequences of the problem.

Pure oxygen uses higher ozone concentrations giving higher solubility and faster reactions. Pure oxygen ozonizers produce ozone concentrations in the range of 10-14% w/w.

Higher ozone concentrations equal higher treatments efficiency.