What Is The Difference Between Dead-End Filtration And Cross-Flow Filtration?

Ceramic membrane manufactured by JIUWU HI-TECH is used for liquids separation in a cross-flow filtration way, which is different from dead-end filtration. There are discussed in the following contents.

1. Dead End Filtration

1.1 Dead End Filtration Definition

Dead end filtration means the fluids flow is vertical to the filter surface, and the retained particles rapidly solidify on the surface of the filter to form a so-called filter cake. The pores of the filter are clogged by the filter cake, and the filtration performance is greatly reduced in a short period of time.

1.2 Dead End Filtration System

In the dead end filtration system, it only needs to overcome the membrane resistance. So, an ordinary laboratory vacuum pump or booster pump can provide enough energy to achieve the required flow rate of the microfiltration. However, with the increase of time, the accumulation of particles on the membrane surface also increases, and the filtration resistance decreases the membrane penetration rate. Therefore, the dead-end filtration is intermittent, and it is necessary to periodically stop and clean the contaminated layer on the membrane surface or replace the membrane.

1.3 Advantages of Dead End Filtration

With its own special advantages, the dead end filtration has been used most commonly for laboratory and medical filtration. 
(1)The dead end filtration operation is simple and suitable for small-scale occasions;
(2)The dead end filtration has an advantage of high product recovery;

In addition, the dead end filtration is usually used for materials with a solid content of less than 0.1%.

2. Cross Flow Membrane Filtration

2.1 Cross Flow Filtration Definition

Cross-flow filtration means turbulence will happen on the surface of the membrane. Therefore, it allows the filtered material to form a filter cake on the filtering surface and keep the flow constant.

2.2 Cross Flow Filtration System

The cross flow filtration is a kind of tangential flow filtration, which has been used widely in industry around the globe. In the cross flow filtration system, the solution to be filtered is pushed through the pores of the filter membrane by pressure. Because the liquid flow rate is very fast, so the filter pores of the filter membrane will not be blocked. The pore size of the filter membrane determines whether the nature of the filter membrane is microfiltration or ultrafiltration.

2.3 Advantages of Cross Flow Membrane Filtration

Compared with the dead end filtration, the cross flow filtration system has its own special advantages as follows:
(1)There is no need to add filter aid;
(2)It has simple and compact system structure;
(3)It is reusable after backwashing;
(4)The hollow fiber mold stack can be replaced to produce different products;
(5)It is easy to operate.

In conclusion, cross flow can remove build up from the surface of the membrane. So, the permeate flux does not drop as fast when compared to dead end filtration. Cross flow technology also provides the benefit of an improved membrane lifespan by helping to prevent irreversible fouling.