In membrane ceramic elements the principle of tangential (cross, dynamic) filtration is used, in which the flow of the treated liquid moves parallel to the filter surface, and the movement through the membrane itself occurs not so much due to the pressure drop on the membrane, but due to the Brownian motion of particles and the turbulent flow movement.
Figure 1. illustrates the principle of tangential (cross, dynamic) filtering.
Figure 1. Tangential (cross or dynamic) filtration through a ceramic membrane
During the filtration process, the liquid flows through the channels of the ceramic membrane, particles with sizes smaller than the pore size of the membrane penetrate through the membrane due to Brownian motion and turbulence of the flow, forming a purified liquid – permeate.
Particles larger than the pore size are carried away from the membrane surface by the liquid flow, forming a concentrate.
To implement tangential (cross, dynamic) filtration, it is important to maintain a stable flow, therefore, at the next filtration cycle, an additional amount of the treated liquid is introduced into the flow, equal to the amount of permeate withdrawn.
Tangential (cross, dynamic) filtration is characterized by high filtration rates and filtration plant capacities, but it requires multiple circulation of the treated liquid through the MFE.
Another feature of tangential (cross, dynamic) filtration is a gradual decrease in the performance of the MFE caused by contamination of the pores with particles from the concentrate. To restore the filtering ability of the MFE, flushing is used. Washing of the MFE is performed at increased speeds of movement of the washing liquid through the MFE channels, which ensures the " washing out "of concentrate particles from the pores and their" removal "from the MFE channel, it is possible to use" reverse " washing, if necessary, chemical or CP-washing is used.