Tricking filters imitate what happens in nature along a river’s course.
In wastewater purification, trickling filters have always stood in a significant place. Their application comes from the end of the 19th century, but their efficiency reached no more than about 50% because of the utilization of mineral fillings: gravel, volcanic stone, etc. This changed when plastic fillings were introduced, since they increase the contact surface between water and microorganisms’ colonies, as well as the air flow necessary for organic matter oxidation and the bacteria endogenic respiration. With this innovation, introduced in the 60s and 70s, the performance in BOD elimination reaches about 98% .
A trickling filter is a biologic purification system with a fix biomass bed, operating in anaerobic conditions. The wastewater which is to purify is splashed over the filling of the filter, using a rotation mechanic system which is in general pulled by hydraulic force without need of an electric supply. Only when the trickling filters have a really huge diameter, a low-power motoreductor shall be installed in order to guarantee that the system keeps on moving over its weight inertia.
Bacteria colonies grow in the filling pieces surface. When water passes through the filling takes contact with the bacteria colonies that have grown, these degrade the organic matter and transform the carbon compounds into CO2, water and others.
Aeration is produced by natural convection of air: the tank has ventilation windows through which the ascendant air enters, colliding with the descendent water coming in the opposite direction.
The design of the trickling filter is basic in order to achieve the desired performance. The mass and hydraulic charge of design will depend upon many factors, like the average temperature of the water and kinetics constant of the installed filling. BIOLOGÍA Y FILTRACIÓN S.L. can help you with the design.
Wastewater has to go first through a decanter, in order to prevent that a large quantity of suspended matter is deposited in the filling’s surface and blocks it. Furthermore, charge in excess can eventually saturate it with sediments.
A correctly designed trickling filter is the cheapest operating system, because it can work even without electric supply.