advances in membrane technology for wastewater recycling 1410-1430 prof ir dr abdul … · advances...
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Advances in Membrane Technology for
Wastewater Recycling
Abdul Wahab Mohammad
Centre for Sustainable
Process Technology (CESPRO)
Universiti Kebangsaan Malaysia
43600 UKM Bangi, Selangor, MALAYSIA1
Water Malaysia 2015
Kuala Lumpur 22-23 April 2015
Outline of talk
2
� Introduction
� Membranes: cost effective and proven technology
for water reuse and recycling
� Our own experience on pilot scale study with
IWK
� Other interesting developments in membrane
technology – Membrane Bioreactor (MBR) and
Forward Osmosis, Nanotechnology in membrane
developments
Current challenging issues on water
3
� Dwindling water resources
� Emerging pollutants
� Endocrine disrupting compounds (EDCs),
Pharmaceuticals, Veterinary medicines, Personal
care products, nanomaterials
� Sustainable water management
� Water resources
� Energy requirement
4
Alternative
Water Resources
Desalination
Water Recyling and Reuse
5
Source: BCC Research
In Malaysia, The estimated volume of wastewater generated by
municipal and industrial sectors is 2.97 billion cubic meters
per year
Target Opportunities for Water Reuse
6
� Key target areas:
� For basic treatment
� Agricultural and golf course irrigation
� Landscape watering
� Recreational use
� Toilet flushing
� Fire suppresion
� For advanced treatment
� Potable supplies
� Reservoir augmentation
� Groundwater recharge
� Industrial process
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Cost of water (in USD)
Location $/m3
Adelaide, Australia 3.02
Bangalore India 0.17
Beijing, China 0.54
Jeddah, Saudi Arabia 0.05
London 3.46
New York 2.11
Singapore 3.56
Tolyo 1.96
Manila 0.42
Seoul 2.35
Kuala Lumpur 0.70
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How much we are paying for this?
On average RM 1 per 500 ml
Or RM 2 per litre
Or RM 2000 per m3
When the cost from tap water is
about RM2.5 per m3
….
This is a good business…
10
D. Dale, Siemens Water Technology
Presentation
Pressure-driven membranes
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Water Molecule
Divalent Ions
Monovalent Ions
Protein/ Viruses
Suspended Solids
Bacteria
Microfiltration0.2 – 2 µm
Pressure < 2 bar
Ultrafiltration 5 – 20 nmPressure 1-10 bar
Nanofiltration0.5 – 5 nm
Pressure 5-20 bar
Reverse OSmosis NonporousPressure 50-1000 bar
NF vs RO
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NAnofiltration0.5 – 5 nm
Pressure 5-20 bar
Reverse Osmosis NonporousPressure 50-1000 bar
Nanofiltration
• Porous Membranes, steric and donnan effect
• Selectivity between ions and small molecules
• More flexibility in applications
• Low applied pressure required
Reverse Osmosis
• Non porous, solution diffusion mechanism
• High rejections for all ions and small molecules
• High applied pressure required
Microfiltration, pore sizes 1-2
µm
Ultrafiltration, pore sizes 5-20 nm
Nanofiltration, pore sizes 1-3 nm
Surface imaging using Atomic Force
Microscope (AFM)
13
INTEGRATED/HYBRID MEMBRANE SYSTEM
Integrated/Hybrid Membrane System :
Processes where one or more membrane process is
coupled with other treatment processes such as
coagulation, adsorption, ion exchange and all these
processes will be integrated into one system to
carry out a specific task*.
Common benefits aim to achieve:
-Overcome limits of single units
-Enhanced quality (safety) of water produced from
deleterious water sources (better performance)
-Energy savings and environmental benefits
-Reduction in capital and operating costs
*Fane 1996, Celine et. al
2012
CONVENTIONAL WATER TREATMENT PLANT
Coagulatio
n
Sand/Cartridge
Filtrations
Weaknesses of conventional process:
-Unable to treat polluted water resources (pesticides, herbicides,
toxins etc.)
-Vulnerable towards microorganisms attack
-Requires softening process
-Unable to remove disinfection by-products (carcinogenic
substances)
BENEFITS OF INTEGRATED/HYBRID MEMBRANE PROCESS
� Consistent performance and resistant to
fluctuation of raw water quality
� Able to treat polluted water resources and
produce better quality of filtrate
� Lesser chemical consumption and sludge
production
� Competitive capital and operating costs
� Reduction in membrane fouling
� Longer membrane lifespan
NEWater – The Singapore recycling
project
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Microfiltration/
Ultrafiltration
Reverse Osmosis UV Disinfection
• A source of revenue:
•High quality ultrapure water for semiconductor manufacturing
• make-up water for industrial cooling and steam generation
• Reallocating other water resources for potable consumption
Findings
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The report from SINGAPORE WATER RECLAMATION STUDY EXPERT
PANEL REVIEW AND FINDINGS (2002) showed that :
• The physical, chemical and microbiological data for
NEWater are well within the latest requirements of the
USEPA National Primary and Secondary Drinking Water
Standards and WHO Drinking Water Quality Guidelines.
• Exposure to or consumption of NEWater does not have
carcinogenic (cancer causing) effect on the mice and fish,
or estrogenic (reproductive or developmental interference)
effect on the fish.
• NEWater is considered safe for potable use, based on the
comprehensive physical, chemical and microbiological
analysis of NEWater conducted over two years.
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Pilot Plant for Water Recycling,
Cyberjaya STP
Treated
Water
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Parameters Option 1
(PCF-RO)
Percent
reduction
Option 2
(UF-RO)
Percent
reduction
pH 5.66-6.47 - 5.87-6.13 -
BOD5
(mg/L) 1.3-5.3 4.51-74% 1.15-4.15 31-80%
COD (mg/L) 0-3 71-100% 0-9 71-100%
TSS (mg/L) 2.5-7.0 14-55% 1.0-5.6 20-86%
TDS (mg/L) 6.13-38.36 83-97% 5.62-32.73 80-97%
Ammonia
(mg/L)
0.15-1.05 51.61-97% 0.03-1.02 63.70-97.92%
Nitrate
(mg/L)
0.03-1 47-94% 0.02-0.7 12-97%
Nitrite
(mg/L)
0.02-0.3 2.27-98% 0.01-0.13 80-99%
Silica
(mg/L)
0-1.4 87-100% 0-1.9 73-100%
Color 0-13 61-100% 0-6 85-100%
TKN 0-5 50-100% 0-2 71-100%
Conductivity
(µS/cm)
13-63 79-97% 11-59 79-97%
Total
surfactants
(mg/L)
<0.05 - <0.05 -
E.coli 0-86 - 0-204 -
Odor 1-2 - 1 -
Alkalinity 3-22 0-87.5% 3-15 >63%
Turbidity 0.10-0.25 27-98% 0.08-0.21 13-73%
Generally meeting the potable
water standard!
Silt Density Index (SDI)
SDI values Indications
SDI < 1 Reverse osmosis system can run for
several years without colloidal
fouling
SDI < 3 Reverse osmosis system can run
several months between cleaning
SDI 3 - 5 Particulate fouling is likely to
be a problem and frequent, regular
cleaning will be needed
SDI > 5 Unacceptable, additional pre-
treatment is needed
• Silt density index (SDI) is an analytical method to measure the fouling
potential of feed water before entering RO unit.
Points SDI
10-April 17-April 24-April 30-April 8-May 15-May 29-May 5-June
2 5.63 5.27 5.27 4.02 4.43 4.49 4.01 4.52
3 5.51 6.13 4.52 3.74 4.66 3.90 4.49 2.87
Table 1: Silt density index for points before RO in Phase 2
Table 2: Indicators for SDI values • Comparison of SDI values with other
integrated process (Dual-membrane
MF/RO process was used in Singapore):
(i) Suspended solid in raw feed water -
Singapore: 5.8 mg/l
Our Pilot plant: 12.3-33.8 mg/l
(ii) SDI values -
Singapore : 3.1
Our pilot plant: 3.5-6
Membrane Morphology Analysis
� SEM analysis showed that foulant layer of PCF-RO was
generally thicker than that of UF-RO system.
� The thickness of fouling layer:
(i) PCF-RO - 4.29-6.43 µm
(ii) UF-RO - 0.13-0.75 µm
• Sand filtration-UF-RO was more effective in terms of
reducing the foulants as compared to coagulation-
PCF-RO system.
(a) PCF-RO
(b) UF-RO
• Energy Dispersive X-ray Spectroscopy (EDS) analysis
is used for the elemental analysis or chemical
characterization of a sample.
• The percent w/w of foulants composition (Fe):
(i) PCF-RO - 14.81%
(ii) UF-RO - 1.86%
• Use of FeCl3
as coagulant might have some influence
on the RO membrane fouling.
Challenges for municipal water reuse in
Malaysia
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Technology is available, however the main issues
are:
� Acceptance by the public/industry
� Minimizing the cost of treated water
� Incentives by the government
Feasible concept:
� Centralized treatment and distribution to
industries for indirect reuse
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0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
80.0%
Pathogen
Toxic
substances
Long term
unknown
health
effect
Doubt with
wastewater
treatment
Cost
Water
Source
Religion
Reason to be suspicious in wastewater
reuse.(You may tick more than one answers)
Malaysian public perspective on water reuse
from sewage
Malaysian industries perspective on water reuse
from sewage
25
Other interesting development
in membrane technology
• MBR
• Forward Osmosis
• Improvement through
nanotechnology
Membrane Bioreactor (MBR)
26
Membrane bioreactor (MBR) is the combination of a membrane
process like microfiltration or ultrafiltration with a suspended
growth bioreactor, and is now widely used for municipal and
industrial wastewater treatment with plant sizes up to 80,000
population equivalent (i.e. 48 million liters per day)
- Simon Judd (The MBR Book, 2011)
Drivers for MBR applications
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� Legislation
� Higher standard for water quality
� Water scarcity leading to water recycling
initiatives
� Financial considerations (ROI)
� Increasingly competitive costs of MBR compared to
conventional STP
� Space constraints
� High population densities and reduced land
availability
Membrane Bioreactors (MBR)
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MBR
OTHER SIGNIFICANT
IMPROVEMENTS
• Improvement in fouling
prevention and control
• New materials rendering
improved membrane
performance and lower
energy requirements
• Lower capital and
operating costs
• Cost competitive due to
market availability
2 Different MBR Configurations: Side-stream (external)
and submerged (internal)
Process Scheme of MBRs
Membrane Fibers
SupportPolymeric membrane
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Simon Judd (The MBR Book, 2011)
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Simon Judd (The MBR Book, 2011)
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Simon Judd (The MBR Book, 2011)
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Forward osmosis (FO), is one of the membrane separation
technologies in which water migrates across a semi-permeable
membrane from a lower osmotic pressure feed solution to a
higher osmotic pressure draw solution
Forward Osmosis Technology
36
Schematic diagram of an integrated
FO-RO process used for treating
anaerobic digester centrate
Schematic diagram of the integrated
FOMBR or OMBR system for the
production of potable water
Benefits of FO
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� Operates at very low hydraulic pressures and ambient
temperature, which significantly reduce capital costs as a
result of the lower energy consumption
� Low membrane fouling propensity compared to pressure-driven
membrane processes, allowing the proper separation and
concentration of difficult feed such as waste streams.
� Water molecules selectively pass through a semi-permeable
membrane via osmotic pressure differences into more
concentrated streams, thus avoiding membrane fouling and
compaction.
� Loose and lower compaction of the foulant layer on the FO
membrane could be easily removed. Studies have shown that the
foulant layer formed on the FO membrane surface is considered
reversible and could be removed by simple physical cleaning,
whereas the densely and higher compaction of the foulant
layer formed on the RO membrane may require chemical cleaning
methods.
� Expected FO membrane lifespan is longer compared to the
membrane process that utilises hydraulic pressure such as RO.
Desirable ENM properties Examples of ENM-enabled technologies
Large surface area to
volume ratio
Superior sorbents with high, irreversible adsorption
capacity (e.g., nano-magnetite to remove arsenic and
other heavy metals) and reactants (NZVI)
Enhanced catalytic
properties
Hypercatalysts for advanced oxidation (TiO2
&
fullerene based photocatalysts) & and other priority
pollutants
Antimicrobial properties Disinfection without harmful byproducts (e.g.,
enhanced solar and UV disinfection by TiO2
&
derivatized fullerenes)
Multi-functionality
(antibiotic,catalytic,
etc.)
Fouling-resistant (self-cleaning) multi-functional
filtration membranes that inactivate virus and destroy
organic contaminants
Self-assembly on surfaces Surface structures that decrease bacterial adhesion,
biofilm formation and corrosion of water distribution
and storage systems
High conductivity Novel electrodes for capacitive deionization (electro-
sorption) and low-cost, energy-efficient desalination
ENGINEERED NANOMATERIALS
Opportunities for ENM in water treatment and reuse(Brame et. al.
(2011)
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Potential Applications in water industry
Membranes
Adsorbent
Nanocatalyst
• Pressure-driven membranes
• novel opportunities to develop more
efficient and cost effective
nanostructured and reactive membranes
for water purification and
desalination.
• Nanoparticles as adsorbent
• Large surface area
• functionalized with various chemical
groups to increase their affinity
towards target compounds
• water-purification catalysts and redox
active media due their large surface
areas
• size and shape dependent optical,
electronic and catalytic properties
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Results and discussion
Average P.S= 20 nm Average
P.S= 20 nm
Graphene oxide (GO) synthesis Via hummers method
�Single atomic layer of sp2 carbon atoms�Large surface area.�Excellent mechanical properties.� Excellent antibacterial activity.
Ag- Graphene oxide (GO)
Average P.S= 20 nm Average
P.S= 20 nm
ZnO- Graphene oxide (GO)
42
Psf membranesPsf membranes with GO-silver
E-coli growth was inhibited almost completely in Psf-silver-GO
membrane
Final words
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� Various challenges for water industry in the
future: resources, emerging pollutants and
sustainability
� Water recycling and reuse is an important
alternative water resources
� Membrane technology, integrated with other
methods, as a tool for water treatment, recycle
and resource recovery has been demonstrated in
many applications
� MBR and FO are among the membrane technologies
with increasing potential applications
� Advances in nanotechnology may also bring
significant improvement in membrane processes.
Thank You For Listening
any questions?
44