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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88

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…

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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)

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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

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Other interesting development

in membrane technology

• MBR

• Forward Osmosis

• Improvement through

nanotechnology

Membrane Bioreactor (MBR)

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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

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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)

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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?

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