ct4471 drinking water i dr.ir. s.g.j. heijman ... · pdf filect4471 drinking water i dr.ir....

CT4471 Drinking water I

Dr.ir. S.G.J. Heijmannanofiltration and reverse osmosis

Nan

ofilt

ratio

n an

d re

vers

e os

mos

is

1. Introduction2. Theory3. Membrane modules4. Applications5. Design 6. Fouling control

Contents

Approximatemolecularweight

Relativesize of materials in water

Treatmentprocess

Size, µm0.001 0.01 0.1 1.0 10 100 1000

100 200 1000 10000 20000 100000 500000

Viruses Bacteria

Dissolved salts Algae

Metal ions Humus acids Cystes Sand

Clay

ED and EDR

Reverse osmosis

Nanofiltration

Ultra filtration

Micro filtrationConventional filtration processes

Metal ionsArsenicNitrateNitriteCyanide

Dissolved saltsCalcium saltsSulfate saltsMagnesium saltsAluminum salts

VirusesContagiousHepatitis

Bacteria

SalmonellaShigellosis

Vibrio cholera CystesProtozoa

GiardiaCryptosporidium

SiltΔP [bar]

0.01

0.05

0.1

5

30

Introduction

October 16, 2007 4

Introduction

+

+

+

-

•Virusses

+

+

-

-

•Multivalentsalts

++Reversed OsmosisRO

-+NanofiltrationNF

-+UltrafiltrationUF

-+Microfiltration MF

•Monovalentsalts

•Bacteria

Introduction

• Spiral wound membrane

Introduction

• Spiral wound membranes

Modules

October 16, 2007 8

v = 0.10 m/hd = 0.15 – 0.35 mm

Introduction

• Principle slow sand filtration

October 16, 2007 9

slow sand filtration

• Slow sand filtration

Introduction

October 16, 2007 10

• Parallel MF/SSF

Problems: 1. Fouling2. Packing

flux = 0.01 m/h

Introduction

October 16, 2007 11

• Traditional RO/NF - fouling

Turbulent flow across membranes

spacers

Concentrate channel

Permeate channel

Introduction

• Filtration process and particle size

Micro filtrationUltra filtrationNano filtrationReverse osmosis

Particle size[nm]> 100

10 - 1001 - 2

0.2 - 1

pressure [bar]< 1< 2

5 - 1015 - 60

MWCO

1000 - 10000200 - 500

100

MWCO = Molecular Weight Cut Off = 90% of organic molecules is

removed

flux[m3/m2·h]0.04 - 0.20.08 - 0.20.02 - 0.080.01 - 0.04

Introduction


Contents

• Principle NF/RO

flow acrossmembrane wat

erdi

ssol

ved

ions

mac

ro m

olec

ules

collo

ids

product = 80% of supply water

membraneconcentrate = 20% of

supply water

water

concentrate is 5 times more concentrated compared to the feed water

Theory

• Reverse Osmosis ??

purewater

saltwater

semi-permeable membrane

Theory

• Osmotic balance

purewater

saltwater


osmotic pressureΔΠ

Theory

• Reverse osmosis

purewater

saltwater


PressureΔP−ΔΠ

Theory

Qf, Pf, cf

Qp, Pp, cp

Qc, Pc, cc

Mass balance water: Qf = Qc + Qp

Recovery γ =QQ

p

f

Mass balance salt: Qf·cf = Qc·cc + Qp·cp

c c 11

, c 0c f p= ⋅−

≈γ

Ret 1ccp

f= −Retention

Theory

Sea water25

350000.355

0.9950.70.730 36 19

0.9942107.22.5

parameterT [°C]cf [g/m3]γ [−]ΔP [bar]Ro [-]η [−]ηrec [−]πf [bar]Δπ [bar]ΔP-Δπ [bar]R [-]cp [g/m3]E [kWh/m3]Erec [kWh/m3]

Brackish water25

20000.825 0.950.70.71.7 5.1 20 0.853001.20.1

Ground water251000.810 0.850.70.70.1 0.5 9.5 0.55450.50.05

Reverse osmosis nanofiltration

Theory

October 16, 2007 20

Theory

• Concentration• polarisation


Contents

Homogenous

Asymmetric

Composite

Liquid

Membranes structure

Tubular membranes 20 - 200 m2/m3

Plate and frame membranes 400 - 600 m2/m3

Spiral wound membranes 900 - 1000 m2/m3

Hollow fiber membranes until 12000 m2/m3

Membrane modules

• Tubular membranes

Modules

• Spiral wound membrane

Modules

• Hollow fiber membranes

Modules

October 16, 2007 27

Modules


Contents

1. Desalinization of sea or brackish water- high costs: ( 1.0 euro /m3 till 3.5 euro /m3 sea water)- examples: Heineken

Greenhouse agriculture2. Split flow membrane filtration

- costs: 50 euro cents/m3 product- example: Na+/Cl- Andijk (PWN)

3. Direct treatment of surface water- removal of micro organisms, organic compounds,

hardness and salts- examples:

Applications RO

IJssel lake

Coagulation

Sedimentation

Rapid filtration

Micro sievesFe3+

Ca(OH)2 Dune infiltration

Drinking water

Rapid filtration

Softening

Aeration

Rapid filtration

ACF

AOP

Ultrafiltration

Reverse osmosis

50%50%

Application RO• Treatment Heemskerk (PWN)

October 16, 2007 31

Application RO

• Treatment Heemskerk (PWN)

October 16, 2007 32

Application RO• Treatment Heemskerk (PWN)

October 16, 2007 33

Application RO

Removal percentage [%] NF RO

Pesticides > 90% > 95%

DOC > 90% > 95%

Hardness (Ca2+, Mg2+) > 90% > 99%

Salts (Na+, Cl-, NO3-) 50 - 70% > 90 %

Disinfection - bacteria, viruses > 99.99% > 99.99%- Giardia, Cryptosporidium > 99.99% > 99.99%

Performance NF/RO

1. Split flow membrane filtration for softening and removal of organic compounds- alternative for softening and activated carbon filtration- examples: colored ground water

bank filtration waterpretreatment for infiltration (IB)

- costs: 35 euro cents/m3 product

2. Direct treatment of surface water- removal of micro organisms, organic compounds

and hardness

Application NF

• Treatment anaerobic groundwater

Application NF

Anaerobic GW

RWK

Candle filter

nanofiltration

Conditioning

Permeate storage

Concentratedischarge

100%

44%56%

45%

45%

11%

45%

89%

Conventional treatment


Contents

HCl/H2SO4/AS

ΔP

Rawwater

Micro filter

TIPIMembrane

unit TI

FIC

Concentrate

Product

Design

• Membrane staging

Christmas tree staging

Circulation

Product

Product

Concentrate

ConcentrateSupply

Supply

PC

PC

Design

• Staging 22-11-5

Design

October 16, 2007 41

Design

• Standard designstandard design:

6 elements/vessel2 stages (staging 2:1)

Design

• Recent research

Design

1 2 3 4 5 6 71:12:13:14:15:16:11 stage

0,510,560,610,660,710,760,810,860,91

Elem

ent p

rodu

ctio

n(m

3/h/

elem

ent)

Elements/vessel

Staging

maximum: 0.918 conventioneel:conventional:0.7230.723

• Production per element

Design

October 16, 2007 45

Design Optiflux®

Addapted pressure vessel with special connector


Contents

October 16, 2007 47

Fouling control

++/-?+

ParticlesScalingBiofoulingOrganic fouling

Optimali-sation

processconditions

-+++/-++

Pre-treatment

++-

+++

cleaning

October 16, 2007 48

Fouling control: scaling

October 16, 2007 49


• Process design:• module design• staging

• operational parameters:• cross flow velocity• flux• recovery• acid or anti-scalant

October 16, 2007 50


• Spiral wound membranes


• Staging: increasing cross-flow velocity in second stage


October 16, 2007 53




October 16, 2007 54


October 16, 2007 55


October 16, 2007 56


Sr BaSO4[-]

Element #

0

2

4

6

8

0 2 6 8 10 12

Concentrate

Permeate Permeate

feed

4

October 16, 2007 57




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