DAD process

Procédés DAD

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DAD process

PRINCIPLE

The DAD, or Destratification / Diffuse Aeration Diffuse, oxygenate and slowly stirs the entire body of water. As a result, it ensures perfect homogenization in temperature and quality of the waterbody throughout the year.

ADVANTAGES OF DESTRATIFICATION AERATION

By ensuring a very slow mixing of the entire water body, and rising up deep waters masses up to the surface into contact with the atmosphere, destratification aeration limits the eutrophication for lakes and reservoirs less than 25 m deep, as well :

It recreates favorable and balance conditions for deep water fishes

It limits undesirable algae development in the long term

It allows the use of entire water reserve

It improves the management of drinking water treatment plants:

By stabilizing the raw water quality to be treated, season after season,
By decreasing Iron, Manganese and Ammonia concentents,
By reducing the frequency of filter washing. Often clogged by algae.

OPERATION

Compressed air is sent through a network of submerged and judiciously perforated pipes distributed on the bottom of the lake.These air diffusion lines, that can reach up to several kilometers, create curtains of bubbles.Rising up, the bubbles are carrying a very large masses of water by air lift effect.

The water body is obviously and naturally aerated in contact with the bubbles during the rise up, but above all by contact with the atmosphere when they rise the surface: cold water layers of bottom are gradually brought back up to the surface where they are aerated before their sinking back to the bottom.

The DAD process is mainly started during the period of thermal stability of water bodies, generally from April to October in northern hemisphere: period during which cold water is stagnant over the bottom, and their oxygen content is falling rapidly. According to the state of the water quality and morphology of the water body, permanent or intermittent operation can be adopted.