What is dead-end filtering?

Dead-end filtration refers to the filtration principle of industrial membranes. Generally, dead-end filtration corresponds to cross-flow filtration.
The filtration process that people generally understand is that the incoming water passes through the filter membrane vertically, leaving particles and suspended substances on the membrane. There is only one incoming water flow and one outgoing water flow for the entire filtration system. This is what we call dead-end filtration.
Dead-end filtration means that all retained substances will continue to accumulate on the surface of the membrane. If it is not regularly removed or cleaned, such a filtration process will stop when all the filtration channels are blocked by the retained substances.
Most of the current ultrafiltration systems use this type of filtration, but after a period of operation, water flushing or chemical cleaning will be performed to restore its filtration capacity.
The reverse osmosis process is another filtration method used, namely: cross-flow filtration.
In cross-flow filtration, the feed water flows tangentially (parallel) rather than vertically across the membrane surface as in dead-end filtration; water and a very small fraction of solutes pass through the membrane as product water, while most of the solutes And part of the water is drained directly.
Cross-flow filtration therefore has one inlet stream and two outlet streams, namely: product stream and concentrate stream. Concentrated water flow is the essential difference between cross-flow filtration and dead-end filtration. Its appearance means that most of the particles and suspended solids will be discharged instead of all being left on the membrane surface.
In addition, since the flow direction of the main aqueous solution of cross-flow filtration is a tangential direction parallel to the membrane surface, it can play a role in scouring the membrane surface, so cross-flow filtration can effectively reduce the concentration polarization, pollution and scaling of the membrane surface occurrence of the phenomenon.
Of course, the flushing effect is related to the flushing water flow, which is why there is a minimum concentration water flow requirement for membrane elements in the reverse osmosis design guidelines. In theory, cross-flow filtration is a continuous filtration process, but in fact it cannot completely prevent the fouling and fouling of the membrane surface, so the filter membrane still needs to be cleaned regularly off-line to restore its flux.