Rotational Disc System

A series of circular discs built of poliuretan plastic were used to support the pellicle of bacteria. These are submerged in the solution in the manner that the 35% of the area of the disc is covered. The diameter of a disc is of 1.25 m. with a thickness of 12 mm. with a distance of 18 mm. between each disc. The total area of the disk is of 10 m2. the discs are rotated at 56 rpm., when turning these take to the atmosphere a pellicle of solution where the natural difusion of air subministers the necessary air for the bacteria. The movement of the discs also agitates the solution. A fresh ferrous sollution is pumped in a direct form by one side of the tank of the disc; the overflow which is expelled from an opposite side consists of a ferric solution.

System of Draining Over Plastic Rings
Plastic PVC rings which are packed by chance in a column support the pellicle of bacterias. Eahc ring has a diameter of 7.0 cm. x 3.8 cm. the rings are retained in a column of 0.38 m. in diameter x 2.25 m. of length. The total area of surface provided by the rings is of 48 m2 in a volume of 0.253 m3. the sollution is pumped to the top part of the rings where it is distributed as a pellicle of liquid over the packed rings. The circulation of the fluid is of 4.6 l/min. The aeration is performed by natural difussion through the pellicle of liquid. One fresh sollution is pumped in the sollution of circulation, the volume is conserved constant due to the overflow from the tank.

System of Corrugated Wrapping with Forced Aeration
A hive as a block of plastic of orrugated PVC upholds the pellicle of bacterias, which is completely submerged in the sollution. The distance between the surfaces is of about 5 cm. the area of surface of bale is of 100 m2 in a volume of 1.08 m3. the aeration is effectuated by a aerator, with a capacity of m3/h, which saturates completely the solution with air. The aerator is located in thelower part of the tank.

The fresh ferrous solution is pumped at one side of the tank, the same which overflows by the other border. The flux of the air in the tank is enough for providing agitation of the solution.

The four systems are automatically operated by measurement of the pH when leaving the overflow, it is operated to the valve of entrance of the sollution according to when it increases the pH, the valve automatically opens to increase the flux of ferrous acid sollution and closes when the pH diminishes. A controller (potentiometer) is placed in the system to operate a pH of 1.75.