The By‑Jas system provides a range of aerators for sewage treatment plants matched to individual drive units to provide superlative surface aeration and mixing characteristics with a minimum expenditure of power. Surface aeration is a process which promotes oxygenation of large fluid volumes.
Oxygenation is most often necessary because impurities and bacteria present within the fluid (e.g. polluted water or sewage) demand and consume large quantities of oxygen. Consequently, there arises a need to re‑establish the dissolved oxygen content of the liquid either in order to sustain fish and plant life in a river or lake, or to accelerate treatment within a sewage processing system.
Surface aerators have, over the years, been the subject of intensive development, their chief application having been in the activated sludge process of sewage treatment. The prime factor affecting their design is naturally the efficiency of the transfer of oxygen to water. Surface aerators attempt to develop the largest possible interfacial area between air and liquid so that oxygen can diffuse from the air into the liquid.
In achieving this, it is necessary to prevent local build up of oxygen concentrations by promoting good mixing with the water. By‑Jas' cone aerator satisfies both of these criteria in that it draws liquid from below water level and discharges it in a heavy torrent over the lip of the cone to create high turbulence when it strikes the water surface with great force. The character of the aerator is an important factor influencing the rate of oxygen transfer. The shape of the blades, depth of immersion and speed of revolution are some of the parameters which determine oxygen transfer. In a mathematical approach to the problem, these are defined by a constant ‑ KLa.
The aerators are designed for reliability and long life and are available for conventional bridge mounting, with tripods and light access bridges or as floating units. For activated sludge treatment they are normally installed in simple, inexpensive rectangular tanks or channels which in size and arrangement give infinite scope to the plant designer. The system lends itself readily to any of the accepted methods of plant operation. Manual or any required degree of automatic control can be provided, including adjustment of aeration intensity by dissolved oxygen monitoring.