反渗透基本原理

水中的杂质 Impurities in Water
• 离子类的 Ionic
水中的杂质 Impurities in Water
阳离子 Ca+2 Mg+2 Na+ K+ Fe+3 Mn+2 Al3+ NH4+ 阴离子 ClNO3SO42HCO3CO32SiO2 PO43-
• 离子的 Ionic
水中的杂质 Impurities in Water
• 离子的 Ionic
•非离子的 Non Ionic
Impurities in Water
• 有机物Organics
• 离子的Ionic • 非离子的Non Ionic


酒精 Alcohols
酮 Ketones 醛 Aldehydes 苯酚 Phenols
Impurities in Water
聚酰胺超薄 屏障层
Polyamide Ultra-thin Barrier Layer
0.2 micron 40 micron
多微孔聚砜
Microporous Polysulfone
120 微米 micron
Compaction is not an issue
强化纤维 Reinforcing Fabric
• • • • 反渗透 Reverse Osmosis 纳滤 Nanofiltroation 超滤 Ultra Filtration 微滤 Micro Filtration
进水 Feed Water
垂直过滤
Direct Filtration
产品水 Product Water
垂直过滤 Direct Filtration
不均匀/不对称膜 Asymmetric Membrane
醋酸纤维素 Cellulose Acetate
屏障层
Barrier Layer
支持 Support
分级的密度 Graded-density cellulose acetate
薄膜合成物聚酰胺膜
Thin Film Composite Polyamide Membrane
Typical Passage of Ions
Mg/l 68.0 21.0 21.0 80.0 9.3 51.0 132.0 163.0 528.0 % Rejection 99.4 99.4 99.8 99.8 98.9 99.5 99.3 99.8 99.6
离子 Ion 钠 Sodium 钾 Potassium 镁 Magnesium 钙 Calcium 硅酸 Silica 氯离子 Chloride 重碳酸根 Bicarbonate 硫酸根 Sulfate TDS
• 微粒的 Particulate
水中的杂质 Impurities in Water
• Ionic
• Non Ionic
• Particulate
• 气体类 Gases
水中的杂质 Impurities in Water
• Ionic
• Non Ionic
• 二氧化碳Carbon Dioxide
• 氧 Oxygen
反渗透 Reverse Osmosis
基本原理 FUNDAMENTALS
过滤类型 Types of Filtration
• 死端过滤 Direct Filtration
• 沙或多介质 Sand or Multi Media • 滤筒 Cartridge
• 横流过滤 Cross Flow Filtration
• 较高的水回收率（更高的水利用率）意味着较低 的水流速 Higher water recoveries (greater water utilization) means lower water velocity.
过滤型谱 The Filtration Spectrum
横流过滤
Cross Flow Filtration
Cations (Positive Charge - missing electrons)
离子 Ions
• 丢失或得到一个电子的离子= 单价的 Ions missing or having one electron = monovalent
• 丢失或得到二个电子的离子= 二价的
Ions missing or having two electrons = divalent
NDP
净推动压 Net Driving Pressure
• NDP = PF + PO,P - PP - PO,F • Available Pressure to “Drive” the Process • 含盐水 Brackish water PO,P = 0
各类化合物的渗透压
Osmotic Pressure of Various Compounds
Barrier Layer
聚砜 Polysulfone
支持层 Support Layer
Barrier Layer
Polysulfone
TFC 表面 Surface
脱盐率 – 盐透过率
1 Angstrom = 1 * 10 -10 m
Salt Rejection
Membrane
H2 O ClNa+
Na
+
膜孔径 Membrane Pore Channel
反渗透 Reverse Osmosis
膜 Membranes
第一个RO膜
First RO Membrane
ROGA
ห้องสมุดไป่ตู้
Module #1
离子的相关渗透率 Relative Permeation Rates of Ions
• 一价的 Monovalent = 1 x 10-5 cm/sec 快
• 二价的 Divalent
• 三价的 Trivalent
= 1 x 10-6 cm/sec
= 1 x 10-7 cm/sec 慢
典型离子脱出率
• Ionic
• Non Ionic
• 微粒的 Particulate
Impurities in Water
• Ionic
• Non Ionic
•固体悬浮物Suspended Solids
•胶质物 Colloidal Material
•微生物 Microbiological 细菌 Bacteria 滤过性微生物/病毒Virus 热原物质 Pyrogens 藻类 Algae
渗透压 Osmotic Pressure
• 100 ppm Salt 1 PSI Osmotic Pressure
• 1000 ppm NaCl • 1000 ppm NaHCO3 • 1000 ppm Sucrose • 35,000 ppm Seawater = 11.4 psi = 12.8 psi = 1.5 psi = 374 psi
1964年
Semi渗透膜 Semi Permeable Membranes
制造材料 Materials of Construction
• 醋酸纤维素 Cellulose Acetate • TFC膜 Thin Film Composite
聚酰胺 (Polyamide)
• 聚砜 Polysulfone
Strong Solution
H2O H2O
Pure Water
Osmotic Pressure, PO,P
纯水水流 Pure Water Flow
净推动压Net Driving Pressure （NDP）
进水 Feed
Applied Pressure, PF
渗透水
Permeate
Permeate Pressure, PP Osmotic Pressure, PO,F Osmotic Pressure, PO,P
• 进水速度必须能保证固体杂质的移动
Water velocity of the feed must be sufficient to keep the solids moving.
• 低流速会引起膜表面淤塞
Low water velocity will allow the membrane surface to “foul.”
溶液中的离子 Ions in Solution
•
• •
化合物在水中电离
Compounds dissolve in water to form charged ions 阴离子 （负电 荷– 得到电子） Anions (Negative Charge - extra electrons) 阳离子 （正电 – 丢失电子）
• 反渗透 Reverse Osmosis 溶解的固体杂质 Dissolved Solids • 纳滤 Nanofiltration 二价离子 Divalent Ions (Ca & Mg) • 超滤 Ultrafiltration 有机物和胶体 Organics & Colloids • 微滤 Microfiltration 固体悬浮物 Suspended Solids
• 丢失或得到三个电子的离子= 三价的
Ions missing or having three electrons = trivalent
离子 Ions
• 单价的 Monovalent: NaCl Na+ + Cl• 二价的 Divalent : CaSO4 Ca2+ + SO42• 三价的 Trivalent : Na3PO4 3Na+ + PO43-
• Particulate
• 气体类 Gases
• 氯 Chlorine
• 氮 Nitrogen • 硫化氢 Hydrogen Sulfide
反渗透可去除：Reverse Osmosis Removes
• 离子类Ionic
• 非离子类Non 不去除 Ionic
• 微粒的 Particulate
气体类 Not Gases !
Determined at 200 psi, 25% recovery, pH 7.8 on de-chlorinated city feed water with TFC membrane
Things to Remember 应记住的事项 Rejection Increases with Increasing
渗透 Osmosis
Osmotic Head
H2O
浓溶液 Strong Solution
H2O 纯水Pure
Water
H2O
纯水水流 Pure Water Flow
平衡 Equilibrium
应用的压力 Applied Pressure, PF
渗透压力Osmotic Pressure, PO,F H O
浓水 Concentrate
横流过滤 Cross Flow Filtration
膜表面 Membrane Surface
渗透水Permeate
浓差极化
Concentration Polarization
横流过滤
Cross Flow Filtration
Things to Remember
需求记住的事项
脱盐率随下列变化
• • • •
Degree of dissociation电离程度 Ionic charge离子电荷 Molecular weight分子量 Degree of molecular branching分子结
构
How small is small?
Inches 39.37 3.94 .39 .04 .004 .000,4 .000,04 .000,008 Meter 1 .1 .01 .001 .000,1 .000,01 .000,001 .000,000,2 5 x 10 -9 4 x 10 -10 Micrometer 1,000,000 100,000 10,000 1,000 100 10 1 .1 .005 UF .000,4 RO
Product
固体表面迅速形成过滤薄膜
Solids on surface quickly foul the membrane
反洗水排放 Back Wash to Sewer
垂直过滤
反洗 Back Wash
横流过滤
Cross Flow Filtration
进水 Feed Water 渗透水 Permeate
2
Strong Solution
H2O H2O
纯水 Pure Water
Osmotic Pressure, PO,P
平衡 Equilibrium
反渗透 Reverse Osmosis
Applied Pressure, PF 渗透水压力 Permeate Pressure, PP
Osmotic HO Pressure, PO,F 2