Table of Contents
What is dead-end filtration used for?
Dead-end filtration has been used most commonly for laboratory and medical filtration. The advantage of dead-end filtration is high product recovery and simple operation. The filter cartridges (depth filters), however, cannot be backwashed or cleaned because of internal pore blockage; instead, they are discarded.
Is depth filtration dead-end filtration?
Depth Filtration By contrast with dead-end filtration, in which material is retained on the filter surface, depth filters do not form a filter cake. Additionally, depth filtration can retain particles that are smaller than its pores through a pore-size gradient that separates a broad range of particle sizes (8).
What are the characteristics of a dead-end filtration system?
The characteristics of dead-end filtration include, therefore, recurring production interruptions and product losses by backwashing or replacement of the filter elements.
Is reverse osmosis is a type of dead-end filtration system?
Applied in drinking water production, effluent polishing, and as pretreatment for reverse osmosis (RO) in seawater desalination, dead-end filtration has brought membrane technology to the forefront of water treatment everywhere.
What is filtration membrane?
Filtration membranes are essentially microporous barriers of polymeric, ceramic or metallic materials which are used to separate dissolved materials (solutes), colloids, or fine particulate from solutions.
What is the advantage of crossflow filtration?
Crossflow filtration has the ability to reduce the fouling buildup at the membrane surface. The retentate stream can be easily recirculated allowing the processing of large volumes of feed material.
What is the difference between depth filtration and membrane filtration?
A Depth Filter is a filter consisting of either multiple layers or a single layer of a medium having depth, which captures contaminants within its structure, as opposed to on the surface. A Membrane Filter typically traps contaminants larger than the pore size on the addressed surface of the membrane.
Why are depth filters used?
Depth filtration is used to remove a broad range of particles, such as dirt, grit, sand, organic solids and rust particles. Made of carefully selected materials such as polypropylene, cotton and glass fibre, the cartridges physically intercept particles and prevent them from ending up in the final filtered liquid.
What is the difference between normal flow filtration and tangential flow filtration?
2.4. 1 Normal and Tangential Flow Filtration. In normal flow filtration mode, the feed passes through the membrane and the non-permeating particles are retained by the membrane. In TFF mode, the feed flows along (parallel to) the feed-side membrane surface rather than passing through the membrane.
What is the difference between osmosis and reverse osmosis?
In natural osmosis, the freshwater will cross the semipermeable membrane and dilutes the concentrated solution. In reverse osmosis, the pressure is applied towards the concentrated aqueous solution and the water molecules are forced to cross the membrane towards the freshwater.
What is TMP in membrane?
The pressure that is needed to press water through a membrane is called Trans Membrane Pressure (TMP). The TMP is defined as the pressure gradient of the membrane, or the average feed pressure minus the permeate pressure. The feed pressure is often measured at the initial point of a membrane module.
How does crossflow filtration work?
Cross-flow filtration, also known as tangential flow filtration, separates particles in solution by passing the solution along the surface of a membrane. Liquid passes through the membrane because of the pressure differential across the membrane.
What are the two types of filtration?
Filtration is a technique used either to remove solid impurities from an organic solution or to isolate an organic solid. The two types of filtration commonly used in organic chemistry laboratories are gravity filtration and vacuum or suction filtration.
Why is TFF used?
The primary applications for TFF are concentration, diafiltration (desalting and buffer exchange), and fractionation of large from small biomolecules. In addition, it can be used for clarification and removal of cells as well as cellular debris from fermentation or cell culture broths.
What is TFF and how is it different from NFF?
Normal Flow Filtration (NFF, dead-ended) allows filter cake to accumulate on the surface of the filter which can cause fouling of the membrane. TFF (tangential/cross-flow filtration) inhibits the fouling process by continually sweeping the membrane surface, keeping the membrane clear to perform its separating function.
What is a dead end filtration system?
Dead-End Filtration. The dead-end filtration is the one where the flow of water is perpendicular to the membrane surface (Fig. 1a). And the water is pushed through the membrane by pressure. All the water that is introduced in the dead-end cell passes through the membrane.
How does dead-end filtration affect the flow rate?
In dead-end filtration, the feed stream flows perpendicular to the membrane and is forced through the membrane. In consequence, the retained components accumulate on the membrane surface forming a cake layer, resulting in a decrease of the filtration rate due to the additional resistance to filtration of this cake layer.
How do charged dead-end microfilters work?
In the case of charged dead-end microfilter cartridges, the separation is based on two mechanisms: pore blockage/surface retention due to size, and surface/pore adsorption due to electrostatic interaction.
How does membrane filtration work?
The filtration is performed from the outside to the inside of the membrane (filtering layer is on the outer side of the tube or plate). Sheer forces along the membrane surface are created by a flow of air bubbles along the surface. In some cases the airflow also results in a liquid flow created by the airlift principle.