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HOME > Technical data > The evaluation index of ultrafiltration system

The evaluation index of ultrafiltration system
Source:water treatment technology center   Author:Zhonglan  Release time:2015-09-01

  Against an ultrafiltration system, how to evaluate it, and that we should concern.There are a lot of technical indicators from different angles to measure and evaluate an ultrafiltration system, we selected are defined as follows.
  1.Bubble point tests mercifully point test (BP) membrane for monitoring point is used to test the performance and the integrity of the membrane module a commonly used method and Bubble point refers to the film fully infiltrates and soaked in the liquid, gas from one side of the membrane to a certain pressure, continuous began from the other side of the membrane in the lowest pressure of air bubbles.Bubble point test is often used to detect membrane by the largest aperture.
    2.Cross-flow filtration cross - flow filtration feed water flow parallel to the membrane surface, porous vertical Yu Jinshui flow through the membrane, trapped material enrichment in the remaining water, along the direction of water flow discharge components, back into the water tank, a merger with raw water circulation return ultrafiltration system.Circulating water, the greater the cross-flow cutting speed is higher, the membrane surface intercept the thinner material layer, the lighter in membrane fouling.
    3.Dead end (the flow) filtering Dead - end filtration of refers to the raw material in the form of vertical membrane surface flow through the membrane, and all through the membrane water production, the pollutants in the water by membrane intercept and deposited on the membrane surface.
    4.Raw water of liquid feed into the ultrafiltration system, has not been through the ultrafiltration membrane.
    5.Ultrafiltration Ultra - filtration liquid by ultrafiltration (UF) membrane of solid particles and the material of different particle size of intercept separation process.
    6.Through quantity/Flux generally used to represent the liquid such as water through the membrane Flux rate, usually expressed as per square meter membrane filtration area through the liquid such as water volume per hour (such as 3 m/m 2 h).
    7.Pollution Fouling capsule intercept and deposition on the membrane surface of solid matter.Pollution often cause membrane penetration amount of attenuation.Usually need to adopt the chemical cleaning method to remove contaminants on the surface of the membrane, the restoration of membrane through quantity.
    8.Hydrophobic (Hydrophobic) Hydrophobic membrane materials for water rejection characteristics of Hydrophobic membrane material has low water absorption performance, therefore in the surface water run into granule.
    9.Hydrophilic Hydrophilic Hydrophilic membrane material has strong attraction to water, their surface naturally with wet chemical properties.
    10.Across (transparent) Trans - membrane Pressure difference be Pressure (TMP) said the water through the membrane of the actual need of driving Pressure, the calculation for the raw water side of average Pressure and water production side of average Pressure difference, namely: the transmembrane Pressure difference = (P + P into thick) / 2 - P
    11.Trans - membrane flow be flow (TMF) membrane flow characteristic of the unit.Is defined as the initial volume of liquid in a certain period of time through the membrane, and the membrane filter area and is related to transmembrane pressure difference, general expression for units: ml/min cm2 bar
    12.Cutting Molecular Weight Molecular Weight Cut Off of ultrafiltration membrane pore size is usually use it to intercept size to define the Molecular Weight of the material, will be able to intercept Molecular Weight of the 90% of the material for the membrane Molecular Weight Cut.Usually use typical known molecular weight of the spherical molecules such as glucose, sucrose, bacitracin, myoglobin, pepsin, globulin and other things as a benchmark to determine this.
    13.Backwashing Back flush from membrane ultrafiltration through liquids wire lateral (water production side) under certain pressure flow membrane wire inside (raw water)
    14.Recovery time ultrafiltration Recovery unit net water rate (for backwashing water needed) and the percentage of the total original water R % = net water rate/total water amount by 100
    15.Concentration Polarization Concentration Polarization caused by trapped suspended solids on the membrane surface gathered phenomenon.Usually improve liquid tangential velocity on the membrane surface can effectively reduce the phenomenon of concentration polarization
    How to determine a ultrafiltration system performance parameters needed for your organization
    When you want to choose a suitable ultrafiltration system, for a thorough understanding of the technical parameters of other industry experts, is a clear need for the support equipment manufacturers have more experience.Company cooperate with the Chinese academy of sciences, common research and development, manufacturing ultrafiltration membrane, its products have reached the international leading level.This is more of many traditional equipment manufacturers and engineering companies.
    A technical advantage, ultrafiltration system
    Relative to the reverse osmosis membrane and membrane separation technology such as gas separation membrane, ultrafiltration separation process has the following distinctive features:
    1.At room temperature and low pressure, and low energy consumption, so that the equipment operation cost is low.
    2.Equipment, small volume, simple structure, low investment costs.
    3.Ultrafiltration separation process is simply pressure conveying liquid, simple process, easy operation management.
    4.Ultrafiltration membrane is made of polymer materials of homogeneous continuum, pure physical methods to filter, material no qualitative change in the separation process.Fall off and will not have any impurity in use process, ensure the ultrafiltrate of purity.
    Ultrafiltration system in use process also has significant advantages, summarized as follows:
    (1).Multiple sets of alternating operation, continuous recoil
    (2).Large flow cross-flow, homogenization of pollution
    (3).Recoil dosing, curb pollution
    (4).Chemical medicine, recover in time
    (5).Recoil water recycling, water conservation
    (6).And easy to control automatically, intuitive and efficient
    Above characteristics determine the ultrafiltration membrane has a very wide range of applications, from ordinary household drinking water purification to high and new technology has widespread application, thus ultrafiltration membrane separation technology is a kind of has a broad prospect of membrane separation technology.
    Ultrafiltration system process
    The micro pore size of membrane in membrane separation technology in 20 x 10-10 x 10 m to 1000-10 m between called ultrafiltration membrane filtration membrane, namely between 0.002 0.1 um, which generally colloid volume are acuity 0.1 um, latex acuity 0.5 um, coliforms, staphylococcus aureus and other bacterial volume acuity 0.2 um, suspended solids, such as micro particle size or greater 5 um, ultrafiltration membrane can filter out the bacteria in the solution, colloid, macromolecular substances such as suspended solids, protein.
    Ultrafiltration system selection guide
    1. The basic form of ultrafiltration and application scope
    From the structure to be divided into: plate and frame type, tube type, volume and hollow fiber four;Of the density of membrane layer (layer separation) is on the inner surface of the hollow fiber or the exterior surface to be divided into: internal pressure, external pressure type and three kinds of inside and outside pressure from the operating way is divided into: the dead end, wrong stream and part of cross-flow three categories;From the operation mode is divided into: constant voltage and constant current and variable pressure flow three ways.
    In the form of application areas
    Plate and frame type wastewater reuse, food, chemical industry and medicine concentration or purification, etc
    Tube type of food, chemical industry and medicine concentration or purification, etc
    Roll type electrophoresis paint recycling, etc
    Hollow fiber wastewater reuse, surface water treatment, reverse osmosis pretreatment, etc
    2. The internal pressure and external pressure type hollow fiber ultrafiltration membrane
    A. internal pressure type: concentrate to enter inside the hollow yarn, the first by pressure differential drive, and by the radial penetration through hollow fiber become through the liquid outside introversion, concentrate stayed in the interior of the hollow yarn, from the other end.
    Including the effect of epoxy resin side is at the end of the hollow fiber membrane silk seal up the gap between the membrane silk, so that the concentrate and through liquid separation, prevent concentrate not directly into the wire through the membrane filter through the liquid.
    B. external pressure type hollow fiber ultrafiltration membrane is concentrate by the pressure difference along the radial outside-in infiltrate hollow fiber become through the liquid, and intercept the material collected in the hollow yarn outside.
    C. the filtration and the cross-flow filtration method
    Hollow fiber ultrafiltration membrane filtration method consists of filtration and the cross-flow filtration two full quantity.
    The filter structure refers to the amount of water molecules in the concentrate all permeate ultrafiltration membrane, no concentrate flow out.
    Cross-flow filtration way is in the process of filtering is part of the condensed liquid from the ultrafiltration membrane at the other end of the row.

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