Blocking Mechanism

Blocking mechanisms describe the various physical processes by which the pores of a filter medium become clogged during filtration. Classic models include surface blocking, where particles larger than the pore diameter adhere directly to the surface; intermediate blocking, where smaller particles penetrate already covered pores and narrow them; complete blocking; and cake formation. These mechanisms were mathematically described by Hermia and allow predictions of the time-dependent development of pressure drop and flow rate. In practice, they usually occur in combination: surface blocking dominates at the beginning, later a filter cake forms that provides the main separation performance. GKD optimizes its fabrics in terms of surface structure and pore distribution to delay clogging and promote uniform cake formation. Backwashing, air pulses, or chemical cleaning can reopen the pores and extend service life.