Vacuum filtration is a fast filtration technique used to separate solids from liquids .
37-420: Filtration is a physical process that separates solid matter and fluid from a mixture. Filter , filtering , filters or filtration may also refer to: Filtration Filtration is a physical separation process that separates solid matter and fluid from a mixture using a filter medium that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through
74-447: A centrifugal force several times stronger than gravity replaces gravitational force. A partial vacuum is typically provided to the container below the filter media when laboratory filtration is challenging to speed up the filtering process. Depending on the type of filter being used, the majority of industrial filtration operations employ pressure or vacuum to speed up filtering and reduce the amount of equipment needed. Filter media are
111-413: A filter due to a pressure difference—fluid flows from the high-pressure side to the low-pressure side of the filter. The simplest method to achieve this is by gravity which can be seen in the coffeemaker example. In the laboratory, pressure in the form of compressed air on the feed side (or vacuum on the filtrate side) may be applied to make the filtration process faster, though this may lead to clogging or
148-475: A similar function. Biofilms are often complex communities of bacteria, phages, yeasts and often more complex organisms including protozoa , rotifers and annelids which form dynamic and complex, frequently gelatinous films on wet substrates. Such biofilms coat the rocks of most rivers and the sea and they provide the key filtration capability of the Schmutzdecke on the surface of slow sand filters and
185-415: A stage of purification: the soluble impurities in the solvent are eliminated in the filtrate (liquid). This apparatus is often used to purify a liquid. When a synthesised product is filtered, the insolubles (catalysers, impurities, sub-products of the reaction, salts, ...) remain in the filter. In this case, vacuum filtration is also more efficient that a simple filtration: there is more liquid recovered, and
222-413: A vacuum source. Centrifugal filtration is carried out by rapidly rotating the substance to be filtered. The more dense material is separated from the less dense matter by the horizontal rotation. Gravity filtration is the process of pouring the mixture from a higher location to a lower one. It is frequently accomplished via simple filtration, which involves placing filter paper in a glass funnel with
259-434: A water current to the mouth whilst the hairs on the legs trap any particle. Others such as some caddis flies spin fine webs in the water flow to trap particles. Many filtration processes include more than one filtration mechanism, and particulates are often removed from the fluid first to prevent clogging of downstream elements. Particulate filtration includes: Adsorption filtration removes contaminants by adsorption of
296-405: Is a unit operation that is commonly used both in laboratory and production conditions. This apparatus, adapted for laboratory work, is often used to isolate the product of synthesis of a reaction when the product is a solid in suspension. The product of synthesis is then recovered faster, and the solid is drier than in the case of a simple filtration. Other than isolating a solid, filtration is also
333-457: Is also used to describe biological and physical systems that not only separate solids from a fluid stream but also remove chemical species and biological organisms by entrainment , phagocytosis , adsorption and absorption . Examples include slow sand filters and trickling filters . It is also used as a general term for macrophage in which organisms use a variety of means to filter small food particles from their environment. Examples range from
370-440: Is imperfect; solids will be contaminated with some fluid and filtrate will contain fine particles (depending on the pore size, filter thickness and biological activity). Filtration occurs both in nature and in engineered systems; there are biological , geological , and industrial forms. In everyday usage the verb "strain" is more often used; for example, using a colander to drain cooking water from cooked pasta . Filtration
407-535: The aspirator , water will suck out the air contained in the vacuum flask and the Büchner flask . There is therefore a difference in pressure between the exterior and the interior of the flasks : the contents of the Büchner funnel are sucked towards the vacuum flask. The filter , which is placed at the bottom of the Büchner funnel, separates the solids from the liquids. The solid residue , which remains at
SECTION 10
#1732773369563444-422: The kidneys function by renal filtration whereby the glomerulus selectively removes undesirable constituents such as urea , followed by selective reabsorption of many substances essential for the body to maintain homeostasis. The complete process is termed excretion by urination . Similar but often less complex solutions are deployed in all animals, even the protozoa , where the contractile vacuole provides
481-457: The separation of substances. Separation is achieved by some form of interaction between the substance or objects to be removed and the filter. The substance that is to pass through the filter must be a fluid , i.e. a liquid or gas . Methods of filtration vary depending on the location of the targeted material, i.e. whether it is dissolved in the fluid phase or suspended as a solid. There are several laboratory filtration techniques depending on
518-421: The yield is therefore better. It is often necessary to maintain the Büchner flask and, incidentally, the vacuum flask. The rigidity of the vacuum pipes and the difference in height between the different parts of the apparatus (as visible in the diagram) make such an apparatus relatively unstable. Therefore, a three-pronged clamp should be used to maintain the Büchner flask. This clamp should be placed such that
555-400: The absence of a stem in the filter funnel, there is a decrease in the surface area of contact between the solution and the stem of the filter funnel, hence preventing re-crystallization of solid in the funnel, and adversely affecting the filtration process. Cold filtration method is the use of an ice bath to rapidly cool the solution to be crystallized rather than leaving it to cool slowly in
592-460: The attachment of desirable biomass and critical nutrients to immobilized support. So that water may be reused for various processes, advances in biofiltration methods assist in removing significant volumes of effluents from wastewater . Systems for biologically treating wastewater are crucial for enhancing both human health and water quality . Biofilm technology, the formation of biofilms on various filter media, and other factors have an impact on
629-562: The bottom, where it often forms a firm cake . The liquid above can then be decanted. This method is especially useful for separating solids that do not filter well, such as gelatinous or fine particles. These solids can clog or pass through the filter, respectively. Biological filtration may take place inside an organism, or the biological component may be grown on a medium in the material being filtered. Removal of solids, emulsified components, organic chemicals and ions may be achieved by ingestion and digestion, adsorption or absorption. Because of
666-428: The cheaper and safer perlite . Activated carbon is often used in industrial applications that require changes in the filtrate's properties, such as altering colour or odour. These filter aids can be used in two different ways. They can be used as a precoat before the slurry is filtered. This will prevent gelatinous-type solids from plugging the filter medium and also give a clearer filtrate. They can also be added to
703-569: The complexity of biological interactions, especially in multi-organism communities, it is often not possible to determine which processes are achieving the filtration result. At the molecular level, it may often be by individual catalytic enzyme actions within an individual organism. The waste products of some organisms may subsequently broken down by other organisms to extract as much energy as possible and in so doing reduce complex organic molecules to very simple inorganic species such as water, carbon dioxide and nitrogen. In mammals, reptiles, and birds,
740-423: The contaminant by the filter medium. This requires intimate contact between the filter medium and the filtrate, and takes time for diffusion to bring the contaminant into direct contact with the medium while passing through it, referred to as dwell time . Slower flow also reduces pressure drop across the filter. Applications include: Combined applications include: Suction filtration By flowing through
777-415: The contaminated granules than to clean the solid sieve. Filter media can be cleaned by rinsing with solvents or detergents or backwashing. Alternatively, in engineering applications, such as swimming pool water treatment plants, they may be cleaned by backwashing . Self-cleaning screen filters utilize point-of-suction backwashing to clean the screen without interrupting system flow. Fluids flow through
SECTION 20
#1732773369563814-410: The desired outcome namely, hot, cold and vacuum filtration . Some of the major purposes of obtaining the desired outcome are, for the removal of impurities from a mixture or, for the isolation of solids from a mixture. Hot filtration method is mainly used to separate solids from a hot solution. This is done to prevent crystal formation in the filter funnel and other apparatus that come in contact with
851-403: The film on the filter media of trickling filters which are used to create potable water and treat sewage respectively. An example of a biofilm is a biological slime, which may be found in lakes, rivers, rocks, etc. The utilization of single- or dual-species biofilms is a novel technology since natural biofilms are sluggishly developing. The use of biofilms in the biofiltration process allows for
888-448: The filter medium are described as oversize and the fluid that passes through is called the filtrate . Oversize particles may form a filter cake on top of the filter and may also block the filter lattice, preventing the fluid phase from crossing the filter, known as blinding . The size of the largest particles that can successfully pass through a filter is called the effective pore size of that filter. The separation of solid and fluid
925-426: The filter. Filtration is a more efficient method for the separation of mixtures than decantation but is much more time-consuming. If very small amounts of solution are involved, most of the solution may be soaked up by the filter medium. An alternative to filtration is centrifugation . Instead of filtering the mixture of solid and liquid particles, the mixture is centrifuged to force the (usually) denser solid to
962-458: The fluid to be filtered be able to flow through the filter media. Gravity , centrifugation, applying pressure to the fluid above the filter, applying a vacuum below the filter, or a combination of these factors may all contribute to this force. In both straightforward laboratory filtrations and massive sand-bed filters, gravitational force alone may be utilized. Centrifuges with a bowl holding a porous filter media can be thought of as filters in which
999-449: The growth structure and function of these biofilms. To conduct a thorough investigation of the composition, diversity, and dynamics of biofilms, it also takes on a variety of traditional and contemporary molecular approaches. Filter feeders are organisms that obtain their food by filtering their, generally aquatic, environment. Many of the protozoa are filter feeders using a range of adaptations including rigid spikes of protoplasm held in
1036-413: The liquid passing through by gravity while the insoluble solid particles are caught by the filter paper. Filter cones, fluted filters, or filtering pipets can all be employed, depending on the amount of the substance at hand. Gravity filtration is in widespread everyday use, for example for straining cooking water from food, or removing contaminants from a liquid. Only when a driving force is supplied will
1073-434: The materials used to do the separation of materials. Two main types of filter media are employed in laboratories: Surface filters allow the solid particles, i.e. the residue, to be collected intact; depth filters do not. However, the depth filter is less prone to clogging due to the greater surface area where the particles can be trapped. Also, when the solid particles are very fine, it is often cheaper and easier to discard
1110-402: The microscopic Vorticella up to the basking shark , one of the largest fishes, and the baleen whales , all of which are described as filter feeders . Filters may be used for the purpose of removing unwanted liquid from a solid residue, cleaning unwanted solids from a liquid, or simply to separate the solid from the liquid. There are many different methods of filtration; all aim to attain
1147-486: The passage of fine particles. Alternatively, the liquid may flow through the filter by the force exerted by a pump , a method commonly used in industry when a reduced filtration time is important. In this case, the filter need not be mounted vertically. Certain filter aids may be used to aid filtration. These are often incompressible diatomaceous earth , or kieselguhr, which is composed primarily of silica . Also used are wood cellulose and other inert porous solids such as
Filter - Misplaced Pages Continue
1184-422: The room atmosphere. This technique results in the formation of very small crystals as opposed to getting large crystals by cooling the solution at room temperature. Vacuum filtration technique is mostly preferred for small batches of solution to dry small crystals quickly. This method requires a Büchner funnel , filter paper of a smaller diameter than the funnel, Büchner flask , and rubber tubing to connect to
1221-406: The slurry before filtration. This increases the porosity of the cake and reduces the resistance of the cake during filtration. In a rotary filter, the filter aid may be applied as a precoat; subsequently, thin slices of this layer are sliced off with the cake. The use of filter aids is usually limited to cases where the cake is discarded or where the precipitate can be chemically separated from
1258-399: The solution. As a result, the apparatus and the solution used are heated to prevent the rapid decrease in temperature which in turn, would lead to the crystallisation of the solids in the funnel and hinder the filtration process. One of the most important measures to prevent the formation of crystals in the funnel and to undergo effective hot filtration is the use stemless filter funnel. Due to
1295-401: The top of the Büchner funnel, is therefore recovered more efficiently: it is much drier than it would be with a simple filtration. The rubber conical seal ensures the apparatus is hermetically closed, preventing the passage of air between the Büchner funnel and the vacuum flask. It maintains the vacuum in the apparatus and also avoids physical points of stress (glass against glass.) Filtration
1332-414: The two prongs surround the part of the flask connected to the vacuum tube, the lasting prong resting on the other side. If it is also necessary to maintain the vacuum flask we use either a mandible clamp, or a three-pronged clamp, depending on the apparatus and its stability. The clamp to use is left to the judgement of the operator. Before closing the tap, it is necessary to "break the vacuum" (letting in
1369-555: The water flow as in the suctoria to various arrangements of beating cillia to direct particles to the mouth including organisms such as Vorticella which have a complex ring of cilia which create a vortex in the flow drafting particles into the oral cavity. Similar feeding techniques are used by the Rotifera and the Ectoprocta . Many aquatic arthropods are filter feeders. Some use rhythmical beating of abdominal limbs to create
#562437