presentazione capannelli 21 10 2016.ppt [modalità ... · nella distillazione a membrana il ruolo...
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Membrane Technologies
Membrane
Selective compact support (≈1 µm)
Macroporous support (≈100 µm)
MEMBRANE DEFINITION
A membrane permits passage of certain
components and retains certain other
components of a mixture
A membrane is a barrier that
allows restricted and/or
regulated passage of one or
more species through it
MEMBRANE APPLICATION
Membranes can be used for different purposes:
- separation and/or concentration (RO, NF, UF, MF, ED, D, PV, etc.).
- control and optimization of the mass transfer for a multiphase system
“membrane contactor” (MD, Saturators, Diffuser, etc.).
- control and optimization of a chemical reaction, where the chemical
reaction is a an integrated membrane process (eg. separation and/or
contactor processes) CMR.
Distillazione a membrana
La soluzione concentrata viene posta a contatto con una
membrana porosa e (idrofobica) che consente il passaggio
attraverso pori del vapor d’acqua ma non quello dell’acqua
liquida e delle sostanze in essa disciolte.
Il passaggio del vapore viene velocizzato applicando il
vuoto.
Il vapore viene poi condensato esternamente al modulo
dove è alloggiata la membrana.
Immagine della superficie di una membrana tipo GORE-TEX
usata per le prove di distillazione
Nella distillazione a membrana il ruolo della pressione osmotica non è rilevante
Si possono così trattare soluzioni altamente concentrate dove l’osmosi inversa non può
essere applicata
Membrane classification
composite
dense porous
symmetric
asymmetric
skinned
Separation mechanism
Porous membranes act as a sieve only allowing the passage of particles whose dimension is smaller than the pore dimension.They are used, for example, in MF, UF, D.
Dense membranes (non porous) separate the species according to their different solubility and diffusion through the dense membrane layer. Their application is, for example, in RO and NF.
Membrane Structure
Dense Layer Retentate
(Solute)Macroporous sub-layer
Substrate Layer
Permeate
(Solvent)
Nomenclature
Feed
Retentate
or
Concentrate
Permeate
or
Filtrate
PRESSURE-DRIVEN MEMBRANE PROCESSES
Microfiltration is mainly used as a clarification
technique, separating suspended particles from
dissolved substances, provided the particles meet
the size requirements.
Ultrafiltration is a method to purify, concentrate,
and fraction simultaneously macromolecules or
fine colloidal suspensions.
Reverse osmosis is essentially considered as a
dewatering technique.
Nanofiltration is a relatively new process,
employing charged membranes having larger
pores than RO ones, but too small to allow the
permeation of many organic compounds, such as
sugars.
Osmosis...Reverse Osmosis
Osmosis
WaterSolution
WaterSolution
P
Reverse
Osmosis
Osmotic
Equilibrium
Solution Water
Osmotic
Pressure
PRESSURE-DRIVEN MEMBRANE PROCESSES
Example of
components
separated by
pressure-
driven
membrane
processes
Microfiltration
�Separates on the basis of size
�Characterised on basis of pore diameter
�Polarisation can occur, and reduce cutoff
�Sometimes a smaller pore size gives better
results
Ultrafiltration
� This fractionates on the basis of molecular size
� The resistance to flow through the membrane is
hydraulic
� The membrane is generally considered to be truly
porous
Nanofiltration
� Characterised on passage of given solutes e.g.
Lactose
Sodium chloride
Magnesium Sulphate
� Rejects inorganics on basis of charge
� Rejection a function of:
valency
charge density
ionic mix
� Negative rejections of some ions possible
Reverse Osmosis
�Non-porous membrane
�Characterised by retention of Sodium
Chloride
PRESSURE-DRIVEN MEMBRANE PROCESSES
Since ultrafiltration deals with the
separation of fairly large molecules, the
employed pressures are fairly low (< 5-
10 bar).
In contrast, pressures involved in
reverse osmosis are fairly high (35-100
bar), in order to overcome the high
osmotic pressures of the small solutes.
Nanofiltration needs lower operating
pressures (10-30 bar), compared to RO.
RO
NF
UF
MF
PRESSURE (DRIVING FORCE) POROSITY
35-100 Bar
10-30 Bar
< 5-10 Bar
1-4 Bar
PRESSURE-DRIVEN MEMBRANE PROCESSES
Unlike conventional filtration processes which operate in a "dead-
end" mode, membranes are configured to be operated in the "cross-
flow" mode, where feed is pumped over the membrane surface,
resulting in two product streams (permeate and retentate).
Properties
� Operating Environment
– pressure
– temperature
– pH
– solvents
– oxidants
– foulants
� Surface Chemistry
– hydrophobic/phillic
– chemical interactions
Specifying an Effective
Membrane ProcessFeed
Volume
Physical properties- viscosity
- temperature
- suspended solids
Chemical properties
- analysis
- pH
- dissolved solids
- chemical compatibility
Retentate
- ‘Product’?
- ‘Waste Concentrate’?
- Required specification?
Permeate
- ‘Product’? Pure fluid?
- Recycle water?
- ‘Waste’?
- Required specification?
Operating constraints ?e.g.. processing temperature
residence time
cleaning chemical disposal
Operating conditions
Low energy consumption
High accumulation velocity
Quick flux decrease
Lower accumulation
Slower flux decrease
High energy consumption for
recirculation
Qfeed= Qpermeate + Qretentate
Qfeed= Qpermeate + Qdischarge
Dead-end
Cross-flow
Pilot Plant Trials
– Pilot Trial WorkTrial Information
� Flux as a function of concentration
� Retention as a function of concentration
� Degree of fouling
� Effectiveness of cleaning
� Membrane Life
� Pressure drop as a function of concentration
� Quality of product
� Power consumption
Pilot plant >>>
Full Scale Operation
�Factors Influencing the Design of a Full
Scale Plant
�Membrane Configuration
�Pretreatment
�Feed Composition
�Recovery Required for Feasibility
�Concentrate Treatment/Disposal
Once-Through
Permeate
RetentateFeed
Time Time
Permeate FluxSolute Concentration
P
F
R
Advantages
* Simple
* High Flux
* Low Solute Passage
* Short Residence Time
Disadvantages
* Concentration factor limited
No fouling
Fouling
Batch Recycle
Time
Advantages
• High Flux
• Low Solute Passage
• High Concentration
Factor
Disadvantages
• Long Residence Time
• Variation in retentate conc.
= non steady-state process
• High Energy Consumption
Permeate
Retentate
Feed
Time
Permeate FluxSolute Concentration
P
R/F No fouling
Fouling
PRESSURE-DRIVEN MEMBRANE PROCESSES
Feed-bleed operation
It is the most common method that
merges batch and single pass
operations.
The feed pump provides pressure,
while the recirculation pump
provides the tangential flow.
At the start-up, the feed pump is used to fill the recirculation loop,
after the recirculation pump is started.
When the desired concentration is reached in the recirculation loop,
the valve is opened and the feed flows into the loop at the same rate
as the permeate flow plus concentrate flow rate : FF = FR + FP
Permeate
Feed
Advantages
• Continuous operation
• Low residence time
• Low energy consumption
Disadvantages
• Complex
• Flux lower
• Higher solute passage
St 1Retentate
Time Time
Permeate FluxSolute Concentration
P1
F
R2R1
P2
No fouling
Fouling
St 2
Multi-Stage Recycle
PRESSURE-DRIVEN MEMBRANE PROCESSES
Standard
Pressure
RO
High
Pressure
RO
Permeate
Polishing
RO
Concentrate to further treatment
Permeate
Feed
High Recovery Membrane System
PRESSURE-DRIVEN MEMBRANE PROCESSES
MEMBRANE MATERIALS
A survey on scientific
and patent literature
indicates that over 160
materials have been used
for membrane
manufacturing.
However, only a limited
number of polymeric and
ceramic materials have
reached commercial
status.
CHEMICAL RESISTANCE OF POLYMERIC
AND CERAMIC MEMBRANES
Comparison
between the
chemical
resistance of
polymeric and
ceramic
materials used
for membrane
production
Polymeric or Ceramic ?
� Polymeric
– Advantages
� wide range of polymers
� wide range of
modules/configurations
� widespread use
� low investment cost
– Disadvantages
� limited resistance to solvents,
oxidants, high temperature,
pH
� limited life
� Ceramic
– Advantages
� resistance to solvents,
oxidants, high temperature,
pH
� long life
– Disadvantages
� RO/NF not currently available
� high investment cost
MEMBRANE MODULES AND CONFIGURATIONS
Ceramic membranes :
- plate
- single tube
- multichannel monolith
- hollow-fibre (not well developed)
Polymeric membrane
- flat sheet
- single tube
- spiral-wound
- hollow-fibre
POLYMERIC MEMBRANE
(flat sheet)
Industrial-scale, flat-sheet
membrane module
POLYMERIC MEMBRANE
(tubular)
Scheme of a traditional tubular membrane module
POLYMERIC MEMBRANE
(spiral-wound)
POLYMERIC MEMBRANE
(spiral-wound)
CERAMIC MEMBRANE
(single tube and multichannel monolith)
SCHUMACHER (US)
ATECH (GER)
TAMI (FR)
EXEKIA-PALL (US)
FAIREY (UK)
Lenght: about 1200 mm
Outer diameter:
- single tube (up to about 25 mm)
- multichannel monolith (up to about 40
mm)
CERAMIC MEMBRANE
(multichannel monolith)
TAMI (FR)
122mm x 864 mm - 10,7 m 2
up to 99 elements – ca. 35 m 2
CERAMEM (US)
CERAMIC MEMBRANE
(hollow-fibre)
CEPAration – TNO (NL)
Material: Al2O3
Outer diameter: > 0,5 mm
Thickness: > 0,5 µm
Pore size: 0,1-1 µm
Porosity: 30-50 %
Membrane surface:
from 0,05 to 1 m2
�Tubular
�Spiral-wound
Surface area/Volume ≈ 101-102 (m2/m3)
Surface area/Volume ≈ 102-103 (m2/m3)
�Hollow-fibre
Surface area/Volume ≈ 103-105 (m2/m3)
Surface area/Volume ≈ 102-103 (m2/m3)
30 µm30 µm
�Flat
Surface area/volume ratio of
different membrane modules
MEMBRANE MODULE CONFIGURATION
MEMBRANE MODULE CONFIGURATION
Membrane
geometry
Suspended
solids
tolerance
Control of
fouling
Cleaning
easiness
Packing
density
Cost per
volume
unit
Tubular Good Excellent Excellent Low -
Medium
Medium -
High
Spiral-
wound
Low Limited Medium High Low
Hollow-
fibre
(external
feed)
Scant
(Good)
Scant
(Good)
Scant
(Good)
Excellent High
(Low)
Flat Medium Good Medium Medium Medium -
Low
Advantages/disadvantages of different membrane modules
Geometries
GEOMETRIES
Tubular
Spirals
Hollow Fibre
Ceramics
RO NF UF MF
�Permeate Flux [L m-2 h-1]
Depends on driving force (ΔP - Δπ) T, Vr, µ,…
�Retention
FPM
t
RRR
ΔπPJ
++
−=
100C
CCR%
f
pf×
−=
MEMBRANE PERFORMANCE (flux-retention)
CF = feed solute concentration
CP = permeate solute concentration
�Permeate Flux [L m-2 h-1]
Parameters affect drivingforce (ΔP - Δπ) T, Vr, µ,…
FPM
t
RRR
ΔπPF
++
−=
RP = polarization layer resistanceRF = fouling resistance (pectine)
F = permeate flux
RM = intrinsic membrane resistance
∆P = transmembrane pressure differential (feed –
permeate)
∆π = osmotic pressure differential (feed –
permeate)
RESISTANCE MODEL FOR PREDICTING PERMEATE FLUX
A major limit in membrane
technology is represented by
“fouling”.
Fouling is a result of specific
interactions between the membrane
and various solutes that may cause:
A) pore narrowing/constriction
B) pore plugging
C) gel/cake layer formation
D) selective plugging of larger
pores
MEMBRANE FOULING
Time
Flux
w,0
w,f
wF
FFRR =
The amount of the membrane fouling can be obtained by
measuring pure water Flux before (F0,w) and after (Ff,w)
application
Fouling
�Types
– surface/macroscopic
– absorbed
– in-pore
�Effect
– flux decline (reversible/irreversible)
– separation change
Effect of Fouling
� Flux � Separation
Time Time
Retention
species < 0.1 µmFlux
100
0
- protein are strongly adsorbed on the surface of hydrophobic
membrane (e,g. polysulfone, polyethersulfone, polyvinilidene
fluoride)
- macromolecule-membrane
interactions tend to plug the
pores and form a layer on the
membrane surface that greatly
lowers the permeate flux
MEMBRANE FOULING
Surface of a fouled membrane
Control of Fouling� Crossflow - increase crossflow rate / Re
� decrease fouling
� increase energy consumption
� Pressure - increase pressure
� short term flux increase
� fouling increase?
� Pre-treatment - filter/pH alteration/chemical addition
� decrease fouling
� cost of pre-treatment
� Membrane Selection
� protein solutions >> hydrophilic
� non-aqueous >> hydrophobic
� Cleaning - periodic removal of foulant
Cleaning� Physical
– limitations
– methods
� Chemical
– aqueous
� water flush
� caustic/caustic
detergent
� enzyme detergent
� acid
� oxidants
– non-aqueous
� specific solvents
• Limitations
– pH tolerance
– temperature
– chemical attack
– solvent resistance
MEMBRANE CLEANING
Cleaning is the removal of foreign materials (foulants) from
the surface and body of the membrane, in order to restore
membrane performance.
Physical cleaning
- backwash
- foam balls
Chemical cleaning
- oxidants
- acid / caustic
- detergents
� Reverse Osmosis - Nanofiltration
� Demineralisation
� Industrial wastewater treatment (textile, fermentation,
pharmaceutical, etc.)
� Pharmaceutical industry
� Wine sector
� Whey from dairy farming
� Other sectors in the agro-industrial field
� Treatment of sugar solutions
� Concentration of organic solutions
� Treatment of well, surface and seawater
� Selective removal of metals from well and surface water
� Removal of soluble organic substances
� Removal of radioactive species from well and surface water
� Dumps percolates
Main applicationsWater
treatment
Biochemical
processes
Food
industry
Chemical,
pharmaceutical
industry
� Microfiltration/Ultrafiltration
� Fermentation broths
� Clarification of food liquids
� Electronic industry
� Wine sector
� Pharmaceutical industry
� Agro-industry
� Mechanical industry
� Chemical industry
� Clarification treatments
� Membrane bioreactors
Membrane Processes used in the various
sectors of the Food Industry
Production of fruit juices
and/or syrups
Cheese industry
Production of beer
Production of wine
and vinegar
Production of
proteins: from
albumen, eggs,
potatoes
Sugar industry
Vegetable oils
Biological processes
Starch industry and
its derivates
Jelly industry
MEMBRANE APPLICATION – DAIRY INDUSTRY
(milk micro and ultrafiltration)
MEMBRANE APPLICATION – DAIRY INDUSTRY
(milk ultrafiltration)
The main benefits of
ultrafiltration are:
- increase (10-30%) in
yield of cheese
- decrease of the amount
of enzyme (rennet)
- volume reduction of
milk to handle
- little or no whey is
produced
MEMBRANE APPLICATION – DAIRY INDUSTRY
(whey ultrafiltration)
Whey is a by-product of the cheese industry.
Whey is the liquid fraction that is drained from the curd during
cheese preparation.
Typically, every 100 kg of milk will
give about 10-20 kg of cheese and 80-
90 kg of liquid whey
Whey disposal is a major problem for
the dairy industry because of the very
high BOD (Biological Oxygen
Demand)
Component %
Total solids 6,3
Protein 0,6
Fat 0,1
Lactose 5,0
Ash 0,6
Water 93,7
Ultrafiltration of cheese whey to recover protein
The ultrafiltration
membrane separates
protein (retentate)
from salts and lactose
(permeate).
A whey protein
concentrate (WPC) is
the final product.
MEMBRANE APPLICATION – DAIRY INDUSTRY
(whey ultrafiltration)
MEMBRANE APPLICATION – BEVERAGE INDUSTRY
(apple juice production)
Conventional
methodMembrane
process
MEMBRANE APPLICATION –BEVERAGE INDUSTRY
(fruit juice production)
Fruit juice is concentrated without
altering product quality
Tradizional process
Efficiency
80-94%
Process duration
12-36 hours
UF process
Efficiency
95-99%
Process duration
2-4 hours
ADVANTAGES
� A better retention of flavouring
compounds
�Lower contamination
�Lower thermal damnages to the
products
�Lower energy consumption
MEMBRANE APPLICATION – BEVERAGE INDUSTRY
(wine production)
The first UF step removes microorganisms and colloids
The MF step removes yeast
The second UF step is a final filter: it could also be a sterilizing microfilter
Advantages
•Product quality improvement (lycopene, colour, vitamin C, etc.)
•New products’ development
Juice concentration: 7-8 Bx
Discharge water
Tomato
juice RO
Forward osmosis
Reformulation
MF serum
Concentrate tomato juice
Tomato juice
MFDischarge water
RO
Concentrate
pulp
Concentrate
Integrated process
Application: fruit juice industryTomato juice production
SUGAR BEET
SLICES
DIFFUSION
WATER
PRESSED
WATERS
PRESSINGHUMID
PULP
RAW
JUICE
PRESSED
PULP
DEFECATION
FILTRATION
2° CARBONATATION
FILTRATION
1ST CARBONATATION ULTRAFILTRATION OR
MICROFILTRATION
LIGHT
JUICE
SWEETENING WITH
ION-EXCHANGE
RESINSEVAPORATION
JUICE
THICKCRISTALLIZATION
SUGAR
MOLASSES
CaO
CO2
CO2
Sugar industry
Substitution of clarification processes with membrane processes
Advantages:
�Reduction of employed raw materials and
instrumentation.
�Energy consumption reduction.
�Environmental impact reduction.
�Sugar quality improvement.
Activities to develop in close cooperation with productive structures:
� Line 1) Filtration and clarification of extra-virgin oil, direclty at the mill or before the bottling process.
� Line 2) Treatment of vegetation waters, aimed at the recovery and valorisation of noble products (poliphenols and others) to obtain a purified water that can be recycled both for agricultural purposes and for olive washing before pression, or can be discharged.
� Line 3) High-quality de-hydrated aromatic herbs production for human consumption, obtained through forward osmosis. The process is being applied to basil leaves.
� Line 4) Study for the set-up of an integrated ecosustainable process for the production of pickled olives. The process is being applied to the production of Taggia olives (salt solution management).
Results from a project with “Consorzio Ligure dei
Prodotti Tipici Fiori e Frutta di Imperia”, concerning
four different lines:
Schema del processo di produzione dell’olio vergine di oliva con le indicazioni dei punti in cui s’intende svolgere le attività di ricerca oggetto del presente progetto.
Olives
Olive paste
Vegetationwater
Oil
Residues
Washing
Crushing
Kneading
Settling
Membrane filtration(clarification and stabilization)
Water recovery and recycle
Line 1
Line 2
Storage
Water
Recovered
water
Introduction of membrane processes in oil
production
Clarification of extra-virgin oil
Approach: physical innovative process aimed at product quality improvement and
quality level preservation in time.
INTRODUCTION OF MEMBRANE FILTRATION PROCESSES
Membrane filtration processes can be applied to oil production. The
resulting oil will be:
� purified
� brilliant
� with better organoleptic qualities
Extra-virgin oil as it is Filtered extra-virgin oil
Results of microfiltration tests performed on extra-virgin
oil at Isnardi manufacturing plant.
Clarification of extra-virgin oil
OlivesWashing
Olive paste
Pressing
KneadingCrushing
OilVegetation waters
Membrane processes
residue
Olive oil production cycle
Treatment of vegetation water
Vegetation waters
Olive washing water
Vegetation water
Added centrifugation water
Filter disc washing water
Instrumentation washing water
Elements Amount (%)
83,2
1,8
Water
Inorganic elements
Organic elements
1,0
2,0
7,5
1,5
1,5
1,5
Lipids
Nitrogenous compounds
Sugars
Inorganic acids
Polyalcohol
Pentoses, Tannins
Glycosides traces
5,5
15000 - 110000 (mg/l)
pH
BOD5
COD 20000 - 150000 (mg/l)
Surface waters Public sewage
CODMax 40 500
BOD5 Max 160 250
Legal restrictions for industrial
discharges (d.lgs.11 maggio 1999, n°152)
Treatment of vegetation waters
Present disposal processes for vegetation waters
�Lagooning processes
�Methanogenic microrganisms
�Drying processes
�Fertilization (Spreading)
�Discharge
�Incineration
�Dilution
Practical and environmental problems
Impossibility to use metabolic products
Lack of stability, hygroscopicity
Possibility of euthophication
Ground water pollution
Costly process
Treatment of vegetation waters
Identified processes
Vegetation
waters
Microfiltrazione
• Irrigation Water
•
Microfiltrazione
•
• Reuse for olive washing
Recovery of concentrate
to be valorised
Integrated process optimized on lab-scale at the Department
of Chemistry and Industrial Chemistry, aimed at the
valorisation and treatment of vegetation waters.
Treatment of vegetation waters
Pilot plants employed for test at Frantoio Isnardi
Pilot plants (Microfiltration and Reverse Osmosis) set up at the
Isnardi oil mill for for tests
Treatment of vegetation waters
30 litri concentrato MF 25 litri concentrato OI 945 litri permeato OI Qualitative and quantitative assessment
Integrated process: resultsTreatment of Vegetation Waters
30 l of MF concentrate 25 l of OI concentrate 945 l of OI concentrate
Example of innovative process of treatment and recycling of vegetation water
Project carried out on behalf of the Consorzio Ligure dei Prodotti Tipici Fiori e Frutta - Imperia –
Vegetation water
Microfiltration
Reverse Osmosis
•Irrigation Water •Reuse for olive washing
Recovery of concentrate to be treated
Membranes
�Act as a total barrier against unwanted substances
�Carry out separations at molecular level
�Allow purification and recycling of polluted water
�Allow to water destined to human consumption from
any kind of raw water
�Allow obtaining water with the desired quality
• Membrane processes are a very innovativenanotechnology, used to obtain high-quality water.
• Because of their characteristics and for the high
technological levels reached, they have become the keyto sustainable development.
MEMBRANE PROCESSES: INNOVATIVE TECHNOLOGIES
FOR THE RECOVER OF WASTEWATER.
Water, despite being a renewable resource, is today a limited resource
- The consumption rate is faster than the recovery rate (rain) - The quantity of polluted water is higher than primary water
Depurazione o
Usi industriali
Depurazione
Agricultural useEnvironment
Drinking water treatment
Municipal useIndustrial use
Usi industriali
Wastewater treatment
Water treatment
Current cycle of water usage
� Worldwide � High income
countries
8%
82%
10%
Municipal AgriculturalIndustrial
� Low income
countries
Worldwide use distributionSource: World Bank
8%
70%
22%
Municipal uses Agricultural usesIndustrial uses
30%59%
Municipal Agricultural
Industrial
Access to drinking water:
Access in less than 15 minutes walk to at least 20 l/day of usable water
Worldwide population: about 6 billion
Population with no access to drinking water: about 1.5 billion
General Observations
The problem of having access to water quantities sufficient for all uses – drinking, industrial, agricultural – is a worldwide problem.
Generally speaking water is not lacking, what is missing is its equal distribution in places, times and in the quality needed.
About 80% of water resources is destined for agriculturalirrigation, while water demand is constantly increasing,particularly in urban areas. Since, according to FAO, there are nonew water sources, it is crucial to spare the existing ones and usealternative sources like brackish water-bearing strata, drainagewater and seawater, as well as treated wastewater.
This problem can be solved with various approaches:desalination, transportation, reuse.
Desalination processes can be divided in two typologies:
Thermal treatments
- Flash multistadium distillation
- Multiple effect distillation
- Evaporation with steam compression
Membrane treatments
- elettrodialysis (ED)
- Reverse osmosis (OR)
DESALINATION PROCESSES
The selection of the desalination technology depends
on the feeding water quality.
REVERSE OSMOSIS
Applying a pressure difference on the membrane sides, a
concentrate (pickle) is obtained and a permeate (desalinated pure
water)
Ghalilah
Operative Pressure: 50-80
bar.
Main advantages
- simple construction
- possibility to implement the capacity of the system
- energy saving is higher then thermic processes
Drawbacks:
- product with higher salinity
- Membrane fouling.
KEY FACTOR
good quality of the feeding seawater
REVERSE OSMOSIS
PRE-TRETMENTS REVERSE OSMOSIS
In reverse osmosis systems, the main problem is the membrane
fouling.
Conventional pre-treatments are: clorination, coagulation, flotation,
filtering, antiscalants dosage, declorination and filtering on cartridge
PROBLEM:
They do not always allow to
obtain a good quality of
feeding water.
All desalination processes require pre-treatments. Each type of
desalination process require a different feeding seawater quality.
ULTRAFILTRATION as pre-treatment for the reverse osmosis
Main objectives:
�Optimising of the ultrafiltration process to have a constant
quality for the feeding water in reverse osmosis plant
� Reducing of solfate concentration in the seawater, allowing
higher temperatures in nanofiltration.
Study of membrane processes as pre-treatments indesalination processes
Hollow fiber
DEAD-END filtering
IN-OUT mode
PILOT PLANT (harbour of Genoa)
The plant is composed by two sections:
UF SECTION NF/RO SECTION
NANOFILTRATION
UF: OBTAINED RESULTS
The permeate quality is strictly influenced by the surface
characteristics membrane.
It is important to optimise the preparation process and the
selection of the material.
The A membrane, made of PESM, showed better
performances
The treated seawater reached a goos quality in terms of
fouling.
SEZIONE UF: CONCLUSIONS
�Treatments lyne are shorter, so it means a lower surface need
� the chemical agents consumption is lower� Fouling velocity decrease, so less frequent washing operations
� membrane life for RO becomes longer
� The permeate flux for RO membrane can be increased
� a better quality of desalinisated water
� desalination process is more convenient
The hybrid process UF + RO has more advantages in
comparison to the system «traditional pre-treatments»
+RO:
Water reuse by means of innovative and low cost technologies has
become a worldwide need for the management and preservation of
water resources
MEMBRANE APPLICATION
(waste water treatment – water recovery)
Advantages of membrane technology compared with conventional treatments
• Steady quality of permeate independently of raw water quality
• Low SDI of the permeate
• Reliable removal of bacteria and viruses
• Plants are highly automated
• Plants are very flexible in their performance
• High reliability of operation
• Chemicals free operation
Membrane processes as an alternative to traditional technologies for drinking water
Drinking water treatment
Acqua Grezza
Coagulation
e Flottazione
Filtrazione
Clorazione
Raw water
Coagulation
Flotation
Clarification
Filtration
Chlorination
Membrane processes
Drinking water
Lower chlorine consumption
Specific applications in areas of water shortage
� Water reclamation from civil drains:
– For civil use (services, irrigation etc.)
� Water remediation
Wastewater
Waste
Water to the consumer
Treatment(Chemical-physical)
Hygienic stabilization
Activated sludge process
ClarificationMF/UF
N F / O I
Water from the Elbe river, Germany
Aim of the process:To produce 350 000 m³/dof treated water (Elbe).
Process:Combination (UF) and (RO)
Economy:Amortization of UF-RO plant costs in 2.6 yearsTotal cost 0.70 €/m³
Example of innovative process of wastewater recovery and recycling from an industrial laundry
Traditional process
Innovative process
laundry
5 mc/h
A1: 5 mc/h
detergent; hypoclorite 3 mc/h
P1: 3 mc/h
detergent; H2O2 3 mc/h
L1: 3 mc/h
acetic acid; H2O2
R1: 6 mc/h
drinking water11 mc/h
5 mc/h
PR1: 5 mc/hPRESS
SOAK
PRE-WASH
WASH
RINSE
3
PRE-TRE 13 M.F. 10 R.O. 7
3 tap water
water to be treated Y
to the rinse
to the wash
Membrane processes as an alternative to
traditional technologies for drinking and
wastewater treatment
Tertiary treatments
Wastewater
Screening
Primary sedimentation
Biological treatment
Secondary
sedimentation
Membrane bioreactor
Drain or reuse
Wastewater treatment
Development a new of modules with a high surface/volume ratio at ever decreasing costs
Costs reduction in time
10
100
1.000
10.000
100 1000 10000 100000 1000000
Cumulative membrane sale in m2
Co
st
in $
pe
r 1
00
mc/g
1989
1996
1992
1995
1990
1998
Zenon
Memcor-USFilter
KMS
Can treat 1000 m3/day
Permeate
Air
with reversible
backflushing
fouling
Drain
Feed
Concentrate
Deposit formation Removal of the
deposited layer
Filtration and backwashingPermeability
[l/(m2
·h·bar)]
TIME
TMP limit
Mimimum flux
backwashing Filtration
interval
Flux recovery
with backwashing
Chemical wash with frequency from 3 to 6 months
depends on• water initial characteristics
• TMP• backwashing procedures
a
Flux decrease without backwashing
Chemical wash
Acceptable flux line
Developing the technology define the new working modalityto control flux stability in time (Fouling)
Worldwide membrane market
UF
25%
MF
25%
RO
50%
- Desalination
- Ultrapure water
- RO pre-treatment
- Drinking water
- Food industry
- Drinking water
- Water treatment
Sale
s (
MLD
€)
Year
*
0
1
2
3
4
5
6
7
8
9
2004 2005 2006 2007 2010
forecast
Year
Ma
rke
t (M
LD
US
D)
0
50
100
150
200
250
300
350
400
2005 2010
Europe
World
Approx 1000 new MBRs will be built in the next 5 years
Membrane bioreactorsMembrane treatmentsOther advanced treatments
Average annual growing rate
10.9%8-9%5.5%
MBR - Market
T. Melin, Desalination 187 (2006) 271
Area Dimention(m3 /d )
Membranesupplier
Start up year
Rödingen, DE 2.400 Zenon 1999
Ile de Yeu, FR 2.260 Zenon 2000
Markrantstädt, DE 3.600 Zenon 2000
Swanage, UK 12.720 Kubota 2000
Campbeltown, UK 2.678 Zenon 2001
Westbury, UK 3.536 Kubota 2002
Lowestoft, UK 14.160 Zenon 2002
Brescia, IT 42.000 Zenon 2002
Monheim, DE 2.400 Zenon 2003
Schilde, BE 6.520 Zenon 2003
Kaarst, DE 45.144 Zenon 2003
Waldmössingen, De 2.160 Zenon 2004
Guilvinec, FR 2.600 Kubota 2004
La Bisbal, SP 3.240 Zenon 2004
Riells I Viabrea, SP 5.160 Kubota 2004
Uerikon, CH 5.200 Zenon 2004
Cardigan, UK 8.640 Kubota 2004
Buxton, UK 10.627 Zenon 2004
Varsseveld, NL 18.120 Zenon 2004
•Zenon environmental
•Kubota
•Ionics/Mitsubishi Rayon
•USFilter
•Aqua-Aerobics/Pall
•Norit X-flow
MBR – European plants
Innovative processes and technologies for wastewater treatment by MBR = Membrane Biological Reactor
A MBR combines a biological process with a membrane separation
process (generally a MF or UF).
In practice the membrane substitutes the secondary sedimentation and
optimizes the biological purification process.
Air
Sludge drain
PermeatoPermeateWastewater
Air
Sludge drain
Permeate
Wastewater
Retentate recycling
Immerse membrane bioreactor External circulation membrane
bioreactor
Treatment of domestic wastewater with MBR
Wastewater
Pre-treatment Primary sedimentator
Membrane filtration
Final effluent
Sludges drying process / disposal
Active sludges
Agricultural use
Nanofiltration
Reverse Osmosis
Industrial use
Drain (sensitive areas)
Wastewater
Pre-treatmentPrimary sedimentation
tank/settler Active sludges
Biomass
stabilization
Sludges drying process / disposal
Secondary sedimentation
tank
Sand filter
Disinfection
Final
effluent
Drain
TR
AD
ITIO
NA
LM
BR
Active sludges conventional
treatment plants show the
following disadvantages:
•Large bulk
•Low depuration efficiency
•Low quality waste (SS, bacterial
load, high nutrients
concentration, etc.) therefore
can only be used at high costs
•Low flexibility
•High sludge production
Operating conditions of MBR treatment plantsTypical MBR immersed membrane operating conditions
Parameter ValueFlux
- Instant L/(m2h) 25-35- Long term L/(m2h) 15-30
Transmembrane pressure kPa 20
Biomass concentration gMLSS/L5-25
Solids retention time (STR) days>20
Sludges production kgSS/(kgCODday) <0.25Hydraulics retention time (HTR) hours 1-9Feed/microorganism ratio kg COD/(kg MLSSday) <0.2Volume (kgCOD/m3 day) Up to 20Air capacity Nm 3 /h per module 8-12Temperature °C 10-35pH 7-7.5Backwash frequency min 5-16Backwash length s
15-30Filtration energy consumption kWh3/m 0.2-0.4- For membrane aeration % 80-90- For permeate pumping %
10-20
The suggested biomass concentration is 12-15 g/L
T. Melin, Desalination 187 (2006) 271
Treatment of industrial wastewater with MBR
Oil contaminated industrial wastewater has been successfully treated
using a submerged membrane reactor. Removal efficiency is 98%
Lab-scale MBR
Hollow fibre membranes
Hydrocarbon removal
Removal efficiency % (COD - BOD5 - SST)
40,0
60,0
80,0
100,0
24-lug 26-lug 28-lug 30-lug 01-ago 03-ago
Days
%
COD BOD SST
80 %
Days COD
removal
efficiency
%
BOD5
removal
efficiency
%
TSS
removal
efficiency
%
24-lug 98,2 98,3 100
26-lug 93,6 93,9 100
28-lug 88,6 89,2 100
31-lug 94,0 94,4 100
02-ago 96,1 96,3 100
04-ago 96,1 96,3 100
Treatment of civil wastewater using MBRs carried out by the University of Genoa (example 2)
The removal of micro-organism
and TSS is complete
Employed membranes:
hollow fibers produced by
KMS Coreana
Material HD
Poliethylene
Porosity Symmetrical
Thickening 400 µm
Nominal
diameter of
pores
0,4 µm
Filtering
surface
40 m2
MBR pilot plant in Genoa-
Voltri (example 3)
Boro (mg/l)
0,14-0,4
0,15 Cianuro tot.(mg/l)
0,04-0,05
0.02
pH 6,5-7,5
6,5-7,5
Cadmio (mg/l)
Ass. Ass. Solfuri (mg/l)
Ass. Ass.
S. Sospesi T.(mg/l)
440 3-4,5 Cromo Tot (mg/l)
Ass. Ass. Solfiti (mg/l)
0,5-3,75
0.5
BOD5 (mg/l)
300 10-15 Cromo VI (mg/l)
Ass. Ass. Solfati (mg/l)
34-97
50
COD (mg/l)
400 20-30 Ferro (mg/l)
0,05-0,15
0.05 Cloruri (mg/l)
26-130
60
Fosforo Tot. (mg/l)
7 2 Manganese (mg/l)
0,01-0,3
0.02 Floruri (mg/l)
0-0,05
0.02
Azoto Totale (mg/l)
40 15-40 Mercurio (mg/l)
Ass. Ass. Solventi cloruri t.
Ass. Ass.
Azoto Amm. (mg/l)
40 0 Nichel (mg/l)
0-0,03
0.06 Solv. Org. Arom.
Ass. Ass.
Conducibilità (µS/cm)
3000 < 3000
Piombo (mg/l)
Ass. Ass. Mat. Grossolani
Ass. Ass.
Alluminio (mg/l)
0-0.4 0,05 Rame (mg/l)
0-0,05
0,01 Fenoli (mg/l)
Ass.
Risultati
Valori in ingresso
Valori in uscita
Riuso
Tutti i valori in uscita sono inferiori ai Limiti di
legge per il riuso D.M.12 giugno 2003, n.185
Impianto pilota MBR
di Genova-Voltri
Average inlet: COD: about 400 mg/lBOD: about 300 mg/l
Results: COD - BOD
The Microorganisms and TSS removal is complete
MBR pilot plant in
Genoa-Voltri
Industrial wastewater containing hydrocarbons
Industrial wastewater contaminated with oil have been successfully
treated using a MBR. The removal efficiency has been 98%.
MBR at laboratory scale
Hollow fibers membrane
Hydrocarbons removal
Collecting gas (400 °C)
Gas cooling (17°C)
Elimination NH3
Elimination H2S
Utilities
Ammoniawater Decantation
Process water
Tar
Stripping
Biologic
NH3
Gas treatment
Design parameters
To design the new structure has been referred tothe plant condition:
• Feed : 36 m3h-1 (864 m3d-1)• Recirculation: 576 m3h-1
• COD= 2600 mg l-1
• Ntot= 270 mg l-1
• N-NH3=110 mg l-1
Study objectiv
Assess the feasibility of revamping of the system that involves the insertion of denitrification and microfiltration with the reuse of existing structures
Objectiv for the parameter of the descharge waterThe new plant have to produce water that respect thelimits for discharge into rivers
1-3
1-tot
-1
l mg 15 NH-N
l mg 20 N
l mg 160 COD
≤
≤
≤
MBR for the treatment of industrial wastewater- They allow the preservation of slow growing microorganisms able to degrade
complex organic matter (soluble and particulate).
- Flexible and optimal STR control (from <1- >30 days) and independent from
HRT, allowing an optimal control in microorganisms populations.
- Compact bioreactor
- No biodegradable compounds tend to remain more in the sludge
- Short start-up
- No need of adjuvants for settling
- Revamping of existing activated sludge treatment plants
- Direct application of inverse osmosis for the reuse.
The colloidal and suspended fraction is responsible for fouling.
Its concentration and composition depends on biological parameters and
membrane cut-off.
Tight correlation between operative parameters and membrane fouling:
-Choice of the most suitable membrane (material and geometry)
-Critical flux determination
-Choice of appropriate operating conditions
-Flux and wash optimization
The success of membrane processes is based on fouling control (MBR)
Membrane bioreactors
ADVANTAGES
� High efficiency (BOD and TOC removal between 96-98%) high nitrification and total denitrification with the denitro stage
� SS absence, absence or little presence of bacterial charge in the permeate
� Direct use of clarification which can be qualified at low cost for any kind of use
� High flexibility with respects to the charge, complete automation and plant control
� Reduction in dimensions and installation costs (without the sedimentation stage)
� Low costs when comparing not only the mc/H treated but also the values obtained of treated water
DISADVANTAGES
� Technologies still fairly unknown (high initial mistrust)
� Need to train technicians with high competence and engineering knowledge as well as experience on membrane and membrane processes (for this purpose the University of Genoa is currently running a second level University Master)
•Present technologies allow a virtually total reclamation.
•Reuse can be complete; Italian law limit water reuse to the fields of agriculture
and industry.
Domestic use
Environment
Industrial use and irrigation
Usi industriali
Purification or Potabilisation
Purification
Present purification technologies
Allow to bring
wastewater back to
the required
characteristics
Water recycling and reuse: general aspects
Primary water
Reuse resource
Wastewater
TREATMENT PLANT
SITUATION AND DEMAND
Plain of Albenga
� The creation of a purification plant in Villanova is a keystone for the integrated management of water in the area of Albenga.
� A significant part of water destined to industrial, agricultural and human consumption is brought back to the natural cycle from the purification plant.
� It is assumed that the purification unit will produce and release re-usable waters for agriculture and industry. In any case, reclaimed water is brought back to itrs original characteristics and can be re-introduced into the environment.
� The area considered for water reuse includes 6 municipalities: Alberga, Ceriale, Garlenda, Ortovero, Villanova d’Albenga, Cisano sul Neva.
� The area in which the purification plant is situated is particularly interesting; for many reasons, it provides also a critical model for situations at the limit of permanent stress.
I fabbisogni
Study results:1) Need to create a purification plant aimed at the reclamation
and recycling of waters for a sustainable development of
agriculture in the plain of Albenga.
2) Need to have a high-quality water as a result of the
purification process (choice of a MBR plant).
3) Need to perform a treatment to reclaim 70 % of waters for
agruicultural use (choice of a NF/RO plant).
4) Importance and necessity for the area to take into account a
treatment plant on behalf of a third party (vegetation waters)
with zero discharge. Integrated membrane plant to treat at
least 20 mc/day.
The reclaimed water can be used for:
AGRICULTURE
RETURN TO HYDROGEOLOGICAL BALANCE
SALT-WEDGE REDUCTION
DESERTIFICATION PROCESS CONTROL
Membrane processes, alone or combined
with MBR, allow the use of water from
non-conventional sources, such as:
Urban wastewater
Primary waters lacking required
parameters
Hard and brackish waters
Present technologies allow to obtain water from non-
conventional sources
Conclusions
The introduction of membrane processes in thewater purification, reclycling and productionfields is widely spreading.
It is expected that, between 2015 and 2030, theoverall growth of water “production” throughthe treatment and reclamation of wastewaterwill be of 43%.
Conclusions
Global water market amounts to 224 MLD €, with an expected growth of 16-20 %.