This article aims to give a substantial overview about the use of Oxygen generators for waste water treatment. On this purpose we will introduce some tips about waste water treatment facilities, the physical and chemical process and the benefits of on-site Oxygen generation.


Waste water biological treatment process uses microorganisms to collect the suspended solids, to dissolve organic ones and to stabilize the organic matter. In addition waste water biological treatment removes or stabilizes nutrients such as Nitrogen and Phosphorus, which can stimulate growth of aquatic plants. The survival and relative growth of the various species of microorganisms depends on environmental conditions existing in the liquor. The most important ones are the quantity of food and nutrient, pH, temperature and Oxygen availability in the liquor.

Influent into a wastewater treatment plant first passes through a bar screen, where large objects are removed. If influent includes industrial waste or rainwater from an industrial area, the pH of the influent is sometimes monitored. The wastewater then enters a series of aeration and settling tanks or basins.


The solid sludge and water consequently follow separate paths. The sludge is sent to an aerobic digester to reduce its mass, and it is then conveyed to a belt press for polymer addition and dewatering. The dry sludge is trucked to landfills. The water is instead sent through a clarifier and then to a disinfecting process (either UV or chlorine). If chlorine (as a gas, bleach or sodium hypochlorite) is used as a disinfectant, it must be carefully monitored to maintain the appropriate amount (tenths of a part per million) of residual chlorine. The water is then monitored for pH and Dissolved Oxygen before being discharged into local streams.


Some wastewater facilities have developed sophisticated basins as biological reactors that synchronize the Oxic, Anoxi and anaerobic biochemical processes. Throughout the length of this basins, Nitrogen and Phosphorus are eliminated from wastewater. The key to the success of these reactors is the ability to control DISSOLVED OXYGEN (DO) levels at different locations around the reactor.

Oxic phase is the first stage of the process. In this phase, air or Oxygen is injected into the process to oxidise carbonaceous and Nitrogen compounds (such as ammonia), resulting in nitrification and the formation of nitrates. The nitrifying bacteria also absorb phosphorus from the wastewater. Optimum Dissolved Oxygen level is 1 to 2 PPM (mg/l). The premise is to keep the right amount and type of microorganisms alive to break down organic mass. Aeration/Oxygenation serves two purposes: to supply the BIOCHEMICAL OXYGEN DEMAND (BOD) of the biological activity and to mix the contents of the tank. Aeration/Oxygenation helps dissolve Oxygen in the wastewater and transfer it to the microorganisms. Mixing the contents of the tanks ensures that contact is maintained between the microorganisms and the organic waste on which they feed.

The second stage is the Anoxic or denitrification phase where no air nor Oxygen is injected and the bacteria process the Oxygen from nitrate for respiration. The result is the formation of Nitrogen that leaves the process as a gas. During this phase, the Dissolved Oxygen is typically controlled to 0,1 to 0,2 PPM.

The third stage is the anaerobic phase that begins when the nitrate is depleted. The bacteria are stressed due to lack of Oxygen and release their stored phosphorus. The phosphorus is removed with the sludge. The process enables the bacteria to return to the first stage where they absorb more phosphorus. During this phase, the Dissolved Oxygen is typically at 0,1 to 0,2 PPM.


The basic control strategy is to continuously monitor the Dissolved Oxygen concentrations in the aeration tanks or basins and regulate the supply of air/Oxygen to match Oxygen demand via control valves, blowers and/or pumps.

The injection of Oxygen instead of atmospheric air (21% Oxygen) boosts the biological process, allowing the same waste water treatment basin to increase its treatment capability even of several times. As a consequence of an increased influent mass, Oxygen adoption can also easily solve treatment sufferance in existing basin.

Gasgen can meet all your need of Oxygen for waste water treatment applications. OXYGAS®
MODULAR and TWIN TOWER series are ranges of top quality, efficient and reliable OXYGEN PSA GENERATORS, and current state of the art of PSA technology. Optimize your process and save with an OXYGAS® Oxygen PSA generators at your site.

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