A Guide to Membrane Filtration of 2021 (PDF)
A membrane is a thin layer of semi-permeable material. It helps to separates substances when a driving force is applied across the membrane. Membrane filtration is a pressure-driven segregation process that employs a membrane for both mechanical and chemical sieving of particles and macromolecules. Membrane filtration helps in the removal of microorganisms, bacteria, natural organic material, and particulates. Which can impart tastes, color, and odors to the water and react with disinfectants to form disinfection by-products.
Innovations in the ceramic membranes to optimize the production efficiency in food processing is also anticipated to have a robust impact in the membrane filtration. Increasing Instances of waterborne diseases is also expected to generate untapped opportunity for the market participants.
The mechanism of membrane filtration technology in detaining microorganisms is a combination of two phenomena: firstly, the effect of physiochemical interactions between the membrane and microorganisms; and secondly, the sieving effect.102,103 The microorganisms that are larger than the pore size of the membrane are retained, and in a similar way the membrane that is negatively charged retains the microorganisms through the repelling force.
The filtration and membrane pretreatment system mainly reduces the formation of biofouling by removing the available nutrients for microorganisms in the feed stream of the RO system. When installing filtration techniques ahead of an RO system, the filter can form a barrier that retains the available nutrients in the passing water, leaving the microorganisms in the RO feed water in a starvation condition.15 Starvation can compromise the reproducibility of microorganisms and their ability to produce dense and widespread biofilm.
Membrane technology can be categorized into three groups, namely:
Innovations in the ceramic membranes to optimize the production efficiency in food processing is also anticipated to have a robust impact in the membrane filtration. Increasing Instances of waterborne diseases is also expected to generate untapped opportunity for the market participants.
The filtration and membrane pretreatment system mainly reduces the formation of biofouling by removing the available nutrients for microorganisms in the feed stream of the RO system. When installing filtration techniques ahead of an RO system, the filter can form a barrier that retains the available nutrients in the passing water, leaving the microorganisms in the RO feed water in a starvation condition.15 Starvation can compromise the reproducibility of microorganisms and their ability to produce dense and widespread biofilm.
Membrane technology can be categorized into three groups, namely:
1) filtration
2) supported liquid membranes (SLM)
3) emulsion liquid membranes (ELM).
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. Pressure-driven membrane processes are generally further classified into four categories based on the mean pore size of membranes:
- Hyperfiltration (HF) or reverse osmosis (RO), which typically separates materials less than 0.001 μm in size such as the separation of monovalent salts from water, as practiced in the desalination of seawater and brackish water.
- Nanofiltration (NF), which separates larger size molecules such as sugars and divalent salts while allowing passage of monovalent salts.
- Ultrafiltration (UF), which is used to separate materials in the 0.001 to 0.1 μm range, such as proteins or colloids and finally microfiltration (MF), which is used for sterilization by removing insoluble particulate materials (microbes) ranging in size from 0.1 to 10.0 μm.
RO units (8) have been used to treat:
- acid mine drainage (AMD)
- flotation water
- copper smelting and refining wastewater
- mill waste waters
- uranium waste waters
- dilute gold cyanide solutions
- ammonium and nitrate bearing effluents.
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