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
•
•
•
•
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
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
渗透水
Permeate
进水
Feed
Water
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
需求记住的事项
Things to Remember
• 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.”
• 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
• 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
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
2
Strong
Solution
H2O
纯水 Pure
Water
H2O
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
Strong
Solution
Pure
Water
H2O
H2O
Osmotic Pressure, PO,P
纯水水流 Pure Water Flow
净推动压Net Driving Pressure （NDP）
进水 Feed
渗透水
Permeate
Applied Pressure, PF
Permeate Pressure, PP
Osmotic Pressure, PO,F
Osmotic Pressure, PO,P
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
渗透压 Osmotic Pressure
• 100 ppm Salt  1 PSI Osmotic Pressure
• 1000 ppm NaCl
= 11.4 psi
• 1000 ppm NaHCO3
= 12.8 psi
• 1000 ppm Sucrose
= 1.5 psi
• 35,000 ppm Seawater
= 374 psi
水中的杂质 Impurities in Water
• 离子类的
Ionic
水中的杂质 Impurities in Water
• 离子的
Ionic
阳离子
Ca+2
Mg+2
Na+
K+
Fe+3
Mn+2
Al3+
NH4+
阴离子
ClNO3SO42HCO3CO32SiO2
PO43-
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
• Ionic
• Non Ionic
• 微粒的
Particulate
Impurities in Water
• Ionic
•固体悬浮物Suspended Solids
• Non Ionic
•胶质物 Colloidal Material
• 微粒的
Particulate
•微生物 Microbiological
 细菌 Bacteria
 滤过性微生物/病毒Virus
 热原物质 Pyrogens
 藻类 Algae
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
• Particulate
• 氧 Oxygen
• 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 !
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）
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
•
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-
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
= 1 x 10-6 cm/sec
• 三价的 Trivalent
= 1 x 10-7 cm/sec 慢
典型离子脱出率
Typical Passage of Ions
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
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
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
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
1 Angstrom = 1 * 10 -10 m
Micrometer
1,000,000
100,000
10,000
1,000
100
10
1
.1
.005 UF
.000,4 RO
Membrane
Salt Rejection
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
Module #1
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
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
聚酰胺超薄
屏障层
Polyamide Ultra-thin
Barrier Layer
0.2 micron
多微孔聚砜
40 micron
Microporous
Polysulfone
强化纤维
Reinforcing
Fabric
120 微米
micron
Compaction is not an issue
Barrier Layer
聚砜 Polysulfone
支持层 Support Layer
Barrier Layer
Polysulfone
TFC 表面 Surface
脱盐率 – 盐透过率
Salt Rejection - Salt Passage
% Rejection = (TDSfeed - TDSProduct) x 100
TDSfeed
% Salt Passage = TDSProduct x 100
TDSfeed
盐通量 Salt Flux
Js = K2(Cm - Cp)
Js
= 盐通量 Salt Flux
K2
= 传质系数 Mass Transfer Coefficient
Cm
= 膜上的浓度 Concentration at the membrane
Cp
= 渗透水的浓度 Concentration in the permeate
水流量 Permeate Flux
Jw = K1( D P - D P)
Jw
= 水流量 Water Flux
K1
= 系统常数/恒量System Constant
P
= 模跨膜压力 Transmembrane Pressure
P
= 渗透压 Osmotic Pressure
渗透水流量
Permeate Flux
通过一平方英尺膜面积的渗
透水流速
The rate of permeate flow through one
square foot of membrane.
• 10 - 25 GFD
• 温度 Temperature
• 压力 Pressure
膜参数对比
Membrane Comparison
特点Characteristic
Opr. pH
Feed Pressure
Salt Rejection
Water Flux
Bacteria Stability
Cl2 Stability
Physical Stability
o
Max T ( F)
Element Cost *
System Cost *
* 有关费用 Relative Cost
CA
5 - 6.5
> 400 PSI
OK
Good
Low
Excellent
Good
104
$1.00
$1.00
TFC
2 - 11
< 200 PSI
优 Excellent
优 Excellent
高 High
差 Poor
较好 Better
113
$1.50
$1.16
膜特点和运行条件 Membrane Characteristics and
Typical Operating Conditions
CA
Salt Rejection
90-96%
Silica Rejection
85%
Nitrate Rejection
85%
Cl2 Tolerance
0.2 - 1.0
SDI Max
5
Temp Range oF)
32 - 95
Op. Pressure
400
pH Range
5-6.5
Flux Rate (GPD/Ft2) 12 - 16
Bio Resistance
差 Poor
3 rd Year Compaction 20%
2X
水解 Hydrolysis
TFC
> 99%
98%
94%
0
3-5
32 - 113
< 200
2 - 11
15 -20
Excellent
0
None
膜生产商
Membrane Manufacturers
•
•
•
•
•
•
•
•
Dow Filmtec
Fluid Systems - Koch
Hydranautics - Nitto Denko
Osmonics - Desal
Dupont - Out of membrane business
Torray
Toyobo
Trisep
反渗透 Reverse Osmosis
膜构造
Membrane Configurations
膜构造
Membrane Configurations
•
•
•
•
卷式 (R/O > 99% USA) Spiral Wound
中空纤维 Hollow Fiber
管状 Tubular
板式 Plate and Frame
卷式膜
Spiral Wound Membranes
• 醋酸纤维素 Cellulose Acetate
• 薄膜合成物 Thin Film Composite
 聚酰胺 (Polyamide)
• 聚砜 Polysulfone
卷式膜构造
Spiral Wound Membrane Elements
卷式膜水流状态
Flow Pattern for a
Spiral Wound
Element
回收率 Permeate Recovery
进水 Feedwater
渗透水
Permeate
浓水 Concentrate
通过压力容器的水流
Flow Through a Pressure Vessel
盐水更加浓 Brine becomes more concentrated
产品水
Product
进水
Feed
浓水
Concentrate
Minimum Element Flow
通过压力容器最后一个膜元件时流速最低
The minimum flow rate
through the last element of
a pressure vessel
反渗透 Reverse Osmosis
系统设计和运行
System Design & Operation
RO系统变量
RO System Variables
• 回收率 Permeate Recovery
• 水通量Permeate Flux
• 最低(通过元件的)浓水流量
Min. Element Concentrate Flow
浓缩倍数和 回收率
Concentration Factor vs. Recovery
蒸发 Evaporation
补水 Make UP
Blow Down
浓缩倍数和回收率
Concentration Factor vs. Recovery
Conc. Factor (x) = Flowfeed
Flowbrine
Conc. Factor =
1
(1 - Recovery)
回收率与浓缩倍数
Recovery vs. Concentration Factor
Recovery
Concentration Factor
50%
2
75%
4
80%
5
90%
10
95%
20
97.5%
40
98%
50
影响回收率的因素
Factors Influencing Recovery
• 成垢离子的浓度
Concentration of scale forming salts
• 渗透压力 Osmotic pressure
• 产品水质量 Permeate quality
影响水通量的因素
Factors Influencing Flux
• 依据给水的污垢特点
Dependent on fouling
characteristics of the feed water
 Wastewater (SDI < 5)
 Surface Water (SDI <5)
 Well Water (SDI <3)
 RO Permeate
8 - 12 GFD
10 - 14 GFD
14 - 18 GFD
18 - 30 GFD
RO 系统

分段 Reject Staging
 AKA: multi-stage多段
 提高水回收 Improves water recovery

Multi - Pass
 AKA: product staging
 提高水质 Improves water quality
Single-Stage RO System
TRAIN #1
进水FEED
渗透水 PERMEATE
高压泵
HIGH
PRESSURE
PUMP
TRAIN #2
容器 VESSEL
元件 ELEMENTS
盐水 BRINE
Two Stage RO System
2:1 Array
渗透水
PERMEATE
50 GPM
100 PPM
进水 FEED
100 GPM
1000 PPM
PERMEATE
75 GPM
130 PPM
1st STAGE
CONCENTRATE
2nd STAGE FEED
50 GPM
1900PPM
回收 Recovery = 75%
Salt Rejection = 87%
PERMEATE
25 GPM
190 PPM
CONCENTRATE
25 GPM
3920 PPM
二段RO系统的操作数据
Typical Operating Data for Two Stage RO System
Item
1st Stage
2nd Stage
Total System
进水流量 Feed flow
渗透水流量 Permeate flow
浓水流量 Concentrate flow
100 GPM
50 GPM
50 GPM
50 GPM
25 GPM
25 GPM
100 GPM
75 GPM
25 GPM
回收率 Recovery
50%
50%
75%
Feed TDS
Permeate TDS
Concentrate TDS
1000 ppm
40 ppm
1960 ppm
1960 ppm
70 ppm
3850 ppm
1000 ppm
50 ppm
3850 ppm
Feed Conductivity
Permeate Conductivity
Concentrate Conductivity
1414 mmho
60 mmho
2700 mmho
2700 mmho
104 mmho
5030 mmho
1414 mmho
75 mmho
5030 mmho
Percent Salt Rejection
96%
96.4%
95%
进水压力 Feed Pressure
250 psi
渗透水压力 Permeate Pressure 10 psi
浓水压力 Concentrate Pressure230 psi
230 psi
10 psi
210 psi
250 psi
10 psi
210 psi
Feed/Concentrate D P
跨膜压力TransmembraneDP
20 psid
240 psid
20 psid
220 psid
40 psid
240 psid
Membrane area / vessel
Flux 容器流量(avg.)
3720 ft2
19.4 gsfd
1860 ft2
19.4 gsfd
5580 ft2
19.4 gsfd
Reject Staging
• 提高水的利用率
Increased Utilization of Water
投资增加
Incremental Increase in Investment
最大限度提高产品水水质
Minimal Degradation in Water
Quality
Average Rejection 平均脱盐率
• 平均膜进水TDS
Average Membrane Feed TDS
= 进水Feed TDS + 浓水Concentrate TDS
2
• % Membrane Rejection
= Average Feed TDS - Permeate TDS x100
Average Feed TDS
平均浓度 Average Concentration
• …对数计算 Log Mean Calculation:
CAVG = CF ln (CF/CC)
1 - (CF/CC)
CAVG
CC
CF
= 系统中平均浓度 Average Concentration in System
= 浓水浓度 Concentration of Concentrate
= 进水浓度 Concentration of Feedwater
二级RO系统 Double Pass RO System
2:1 Array
PERMEATE
50 GPM
100 PPM
进水FEED
100 GPM
1000 PPM
渗透水
PERMEATE
35 GPM
2 PPM
2nd Stage Reject
15 GPM
328 PPM
Reject Recycle
Double Pass
Product Staging
• 应用 Applications:


海水 Seawater (High TDS)
超高纯度使用 Ultra-high purity applications
• 级间pH值的调节 Interstage pH adjustment w/ NaOH



Improved Alkalinity Rejection
Improved Silica Rejection
Improved TOC Rejection