Aeration And Mixing

 Aeration

The Aquaerator was originally designed for reservoirs, developed by witnessing the problems with previous aerators. The aim of the Aquaerator is to destratify, mix and aerate water bodies of any size.

Thermal stratification in lakes is caused by a heating of the surface waters shutting off the convection current which mixes the reservoir leaving the surface water warm, well oxygenated with a diverse and abundant ecosystem.. As convection is the major method of heat transfer within a water body, hot air rises and cool air sinks, the water is unable to mix. This leaves a very warm top layer (epilimnion), a cold bottom layer (hypolimnion) and the transition layer (thermocline or metalimnion). As plants require light for photosynthesis, which creates oxygen, this leaves the epilimnion with plentiful oxygen but the hypolimnion cold bottom water with very little or no oxygen and no way to mix the two layers.

The majority of reservoirs or lakes in the UK and indeed Worldwide usually suffer with significant increases in concentration of Mn and Fe in the water column in the summer. Academics believe increases of Mn and Fe are attributed to the anoxic bottom water, caused by the onset of thermal stratification. Together with a lowering of pH and the presence of certain bacteria is thought to contribute to the release of these elements from the bottom sediment. The bottom waters can become rich in heavy metals as the anoxic water reduces the metals into more soluble forms.

Algal blooms are caused by an increased concentration of algae in the surface waters. These blooms are unsightly and can be toxic. The blooms require sunlight and nutrients to survive in large numbers. If the algal blooms become too large they can cut off sunlight to the bottom waters, depriving the plants there of the ability to photosynthesise. The lack of photosynthesis decreases the oxygen levels in the bottom waters, killing the aquatic life living there. This in turn increases the amount of bacteria needed to break down the food, which further decreases the oxygen concentration in the bottom waters. The cycle will continue until there is no marine life left in the lake except algae and bacteria.

The Aquaerator draws the cold bottom waters from the bottom, by making it less dense with the addition of thousands of tiny air bubbles, forcing it to the surface. This cold water on the surface bump starts the convection currents.

This mixing creates a more constant temperature through the water column, increases dissolved oxygen in the bottom waters and reduces the pH change with depth. This in turn creates a more habitable environment, encouraging a better ecosystem. It also can oxidise heavy metals into less soluble forms, enabling them to precipitate out.

All of this reduces the running costs of the treatment plant and reduces chemical dosing of the water. Aquaeration Systems are custom designed for each project, using our modelling software to calculate the minimum number of Aquaerators required to do the job, thus reducing the price further

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