TABLE 11-1 Membrane Terminology Term Definition Array,train,or pass Multiple interconnected stages in series by concentrate staging or permeate staging Asymmetric A membrane that varies in density or porosity across its structure,and having a varying consistency throughout Backwash The intermittent residual stream from a MF or UF membrane system Brine Concentrate stream containing a TDS concentration greater than seawater (approximately 35,000 mg/L total dissolved solids) Brackish water Water having a TDS concentration ranging from approximately 1000to15.000mg/L Chemical cleaning or clean in place The periodic application of a chemical solution to a membrane system to remove accumulated foulants in order to maintain productivity and retum the membrane to baseline operation levels Concentrate,reject,retentate, The membrane output stream that contains higher TDS (NF,RO) residual,or blow-down stream or higher TSS (MF,UF)than the feed stream Concentration-polarization A phenomenon that occurs when dissolved and/or colloidal materials concentrate on or near the membrane surface in the boundary layer Conventional MF or UF process A treatment system consisting of a configured group of pressure-or vacuum-driven membranes contained in modules or basins consisting of a pretreatment strainer,air and reverse filtration discharges,filtrate tankage and associated appurtenances,including chemical feed for posttreatment Conventional RO or NF process A treatment system consisting of acid and/or scale inhibitor addition for scaling control,cartridge filtration for pretreatment, the RO or NF membrane treatment process,including the processes of aeration,corrosion control stabilization and pH adjustment,and disinfection for posttreatment (Continued)
Tongji University
TABLE 11-1 Membrane Terminology (Continued) Term Definition Differential pressure A pressure drop across a membrane element or module from the feed inlet to concentrate outlet Feed Input stream to the membrane array Flux The throughput of a membrane process expressed as a mass (mL 2t-)or volume (Lt-)rate of transfer through a membrane surface Fouling Deposition of solid material from the feed stream onto the membrane surface or within a porous membrane structure that restricts the passage of water decreasing productivity High-recovery array Array where the concentrate stream from one array becomes feed to a succeeding array to increase recovery Hollow fiber membrane A geometry in which the membrane material is configured into a very small diameter and mounted in a housing or pressure vessel,or submerged in a basin Instantaneous flux The flux that occurs in a MF or UF membrane when the unit is operating between backwash operations and is generally the highest flux reported for a system,as it does not account for system downtime or filtrate losses during treatment Lumen The center or bore of a hollow fiber membrane Mass transfer coefficient (RO.NF). Mass or volume unit transfer through a membrane based on or specific flux (MF,UF) driving force expressed in volume per unit area per unit time Membrane element A single membrane unit containing a bound group of SW or HFF membranes to provide a nominal surface area Module or cartridge The smallest component of a MF or UF membrane unit where the membranes are placed in a housing device with a filtrate outlet structure
Tongji University
Membrane softening The use of membranes for removing hardness from water most often accomplished using NF membranes Net driving pressure The hydraulic pressure differential across the membrane minus the osmotic pressure differential across the membrane that is available to force water through the membrane Permeate,product(filtrate) The membrane output stream that contains lower TDS (lower TSS)than the feed stream Pressure vessel A single tube with several membrane elements in series Raw Input stream to the membrane process Recovery The ratio of the permeate flow to the feed flow expressed as a percentage Rejection Percentage solute concentration reduction of the permeate stream relative to the feed stream Scaling Precipitation of solids in an element due to solute concentration in the feed stream Solute Dissolved solids in raw,feed,permeate,and concentrate streams Solvent Liquid,usually water,containing dissolved solids Stage or bank Parallel pressure vessels System arrays Several arrays that produce the required plant flow Transmembrane pressure Pressure drop across the membrane barrier Abbreviation key:TDS,total dissolved solids;TSS,total suspended solids;MF,microfiltration;UF,ultrafiltra- tion:NF,nanofiltration;RO,reverse osmosis
Tongji University
同©大号 Tongji University different modules 图1RGE平板膜元件 Flat sheet module
Tongji University Flat sheet module different modules
9 同海大学 Tongji University different modules Tubular module
Tongji University Tubular module different modules