This document summarizes research on developing a novel impregnated membrane for wastewater treatment using forward osmosis. Impregnated membranes were created by impregnating a hydrophilic polymer within a porous support structure to increase water flux. Experimental results showed that while impregnated membranes had lower water flux than commercial thin film composite membranes, they had higher performance ratios and salt rejection. This research demonstrates the potential of impregnated membranes for more efficient wastewater treatment using forward osmosis.

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Wastewater Treatment Using
Novel Impregnated Membrane
in Forward Osmosis
Ananthan Balachandran
CE 498
Undergraduate Research Report

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Abstract
Billions of people around the world lack access to clean water to meet their daily needs. Forward
osmosis attracted significant attention for wastewater treatment because of its ability to treat wastewater
and produce high quality water.However,the current forwardosmosis membrane hashigh waterresistance
in the membrane porous structure. Therefore, the water flux is low and not economically viable. Develop
novel high flux forward osmosis membrane based on impregnate membrane was the objective of this
research. Thin and mechanically stable impregnated membrane was created with highly porous support
matrix impregnated with a hydrophilic water-conducting polymer. An important understanding of structure
and property relations in the impregnated membranes will be provide by the results. This will create a
guidelines for designing high performance forwardosmosis membrane for wastewatertreatmenttoincrease
clean water sources.
Introduction
Wastewater Treatment and Water Purification: Water is one of the most important aspects of
life on Earth and becoming an increasingly scarce resource.1
Drinking water is produced mainly from safe
water sources, for example from groundwater. According to the World Bank and World Health
Organization, 2 billion people lack access to clean water and 1 billion people do not have enough to even
meet their daily needs.1
Currently, the fresh water sources have reduced by exploitation of aquifers and
declining groundwater levels, due to population growth and economic development. In the 20th
and 21st
centuries, water quality has become very important and severalmethods of water filtration and purification
have been developed.

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Forward Osmosis (FO). Forward osmosis is an osmosis process that uses a semi-permeable
membrane to effect separation of water from dissolved solutes.2
Forward osmosis attracted significant
attention for wastewater treatment because of its ability to treat wastewater and produce high quality water.
The energy for forward osmosis is supplied by osmotic pressure gradient between a solution of high
concentration, often referred to as a “draw” and a solution of lower concentration, referred to as the “feed”
as shown in figure 1.2
The general equation for water flux in a forward osmosis can be described by:
JW = A (π D - π F) (1)
Where JW is waterflux, Ais the hydraulic permeability constantof the membrane, πD is the osmotic pressure
of the draw solution, and πF is the osmotic pressure of the feed solution.3, 6
The FO membrane usually have
high rejection of the organic matter, extremely low inherent fouling, and ease of operation. Therefore, FO
membrane is ideal for wastewater treatment .The desired FO membrane characteristic for use in the
wastewater treatment is a membrane with a high water flux, sustaining long term operation and high
stability to reduce the capital.3, 6
Figure 1: Flow in the forward osmosis process 8

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Current Asymmetric FO membrane: Figure 2 show a schematic of multi-layer thin film
composite membrane which used in the FO wastewater treatment and water purification.9-10
The FO
membrane are made out of non-woven fabric, microporous support, and separating layer. The non-woven
fabric (100 -150 µm) provides mechanical strength for the membrane and transport resistance to water flux
in FO process. Separating layer (0.1 – 2.0 µm) on the membrane will performs molecular separation.
The picture below shows the different type of membranes that will be use in the forward osmosis
system. Figure 3 shows the commercial membrane from HTI. Figure 4 shows the reverse osmosis
membrane. Figure 5 is the impregnated membrane. Two type of impregnated will be used in this research
which are 80%wt PEGDA 20%wt 20 ethanol and 60%wt PEGDA 40%wt ethanol.
Figure 2: Current asymmetric FO membrane used inFO wastewater
treatment. 9-10
Figure 3: TFC membrane Figure 4: SW30 XLE membrane Figure 5: Impregnated
Membrane

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Objectives
Currently, the commercial membranes structures are thin film composite membrane which has
larger water transport resistance because of the thickness. The purpose of this research is to study whether
novel impregnated membranes are suitable for wastewater treatment using forward osmosis. In order to
justify the purpose of experiment, the water permeability coefficient, water flux, and salt flux have to be
determined.
Experimental Design
A: Membrane cell holder B: Feed solution C: Draw solution
D: Feed pump flow meter E: Draw pump flow meter
Determining water permeability coefficient. A dead end filtration cell operating with a pure
water feed was used to determine the water permeability coefficient in the impregnated membranes.11
The
water permeability coefficients was calculated by measuring the water flow rate in permeate.
B
DE
A
C
Figure 3: Schematic of forward osmosis membrane test apparatus

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Determining water flux. The water flux across the membrane from the feed solution was calculated by
monitoring the weight change in the draw solution storage tank.11
The draw solution concentration ranges
from 0.05 to 1.5 M(deionized water),and the feedsolution concentration range from 0 to 1.0 M (salt water).
Determining salt flux. The salts (Sodium Chloride in this experiment) diffused from the draw
solution to the feed solution. Salt flux across the membranes was measured by using a conductivity probe
by monitoring the salt concentration in the feed solution.
Results
In this research,three type of membranes were tested using the forward osmosis membrane test
apparatus as shown in figure 3. The commercial membrane, reverse osmosis membrane and impregnated
membrane were the three type of membranes used in this research. From this research,salt rejection, water
flux and salt flux of the membranes were collected.
The experimental water flux of TFC membrane from HTI was 11.1 LMH. The expected water flux
was 75.5 LMH. Expected water flux of TFC membrane was higher compared to experimental water flux.
Performance ratio of this commercial membrane was 0.15. Performance ratios of membrane was calculated
by dividing experimental water flux with expected water flux of the membrane.
Total time (min) Salt Rejection (%) Water Flux (LMH) Salt Flux (gMH)
50 98.6 10.71 7.93
60 98.7 11.57 7.84
95 99.0 11.14 5.85
130 98.9 11.27 5.86
Table 1: Date for TFC Membrane in Forward Osmosis (Commercial Membrane)

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Total time (min) Salt Rejection (%) Water Flux (LMH) Salt Flux (gMH)
15 95.9 1.43 3.39
30 99.3 2.29 0.97
45 99.1 3.14 1.69
60 98.6 2.29 1.79
75 9.5 2.86 0.86
90 99.7 2.57 0.46
105 9.7 2.29 0.32
120 96.9 2.57 4.43
135 99.4 2.29 0.76
Table 2: Data for SW 30 XLE Reverse Osmosis Membrane in Forward Osmosis
The data in table 2 was recorded when the flow rate on both side of the membrane cell was 50%
maximum of the pump. The theoretical flux of SW 30 XLE (Reverse osmosis membrane) was 71.9 LMH
but it has lower experimental flux which was 2.46 LMH. Therefore, the performance ratio of this reverse
osmosis membrane was 0.04.
Data of all the membranes that been tested in forward osmosis system were shown in table 3. From
table 3, TFC membrane from HTI (commercial membrane) has higher water flux and salt flux compared to
Type of
membranes
Water Flux
(LMH/bar)
Expected Water
Flux (LMH/bar)
Salty Water
Flux
(LMH/bar)
Performance
Ratio
Salt Rejection
(%)
TFC 0.23 1.54 N/A 0.15 98.9
SW30 XLE 0.05 1.47 N/A 0.04 99.0
80 PEGDA 20
Ethanol
0.05 0.28 0.23 0.23 95.3
60 PEGDA 40
Ethanol
0.08 0.41 0.31 0.25 96.8
Table 3: Data comparison ofdifferent types ofmembranes in Forward Osmosis

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the impregnated membranes and SW 30 XLE membrane. On the other hand, the performance ratio of
impregnated washigher compared to TFC membrane and SW 30 XLE. Salty waterflux for TFC membrane
and SW 30 XLE membrane not available because no test was performed to find the salty water flux.
Discussion and Conclusion
As shown in table 3, water flux and salt flux in impregnated membrane is lower compared to the
TFC membrane and SW 30 XLE membrane because of concentration polarization. Concentration
polarization of a membrane will decrease the driving force for water to go through the membrane. The
absolute water flux of impregnated membrane is lower than the commercial membrane.
The impregnated membrane has higher performance ratio and acceptable salt rejection although
waterflux is lower. The novel impregnated membrane has higher efficient in forwardosmosis in wastewater
treatment.
Broader Impacts
The success of this research will have few main impact on society. The novel impregnated
membranes in wastewatertreatmentcan transform the contaminated water to drinking water. People around
the world will have easy access to clean water supply no meet their daily needs. In addition, the reclaim
water will provides a reliable source,even in drought years.
There are one main contemporary issues that influence this research area. Increasing pressure on
existing water resources due to population growth and economic development. This research would help to
increase the source of clean water.
Ethics plays an important role in this research field as well as in all research fields. Scientists need
to be completely honest about their research for it to be successful and benefit society. Scientists or any

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other party cannot manipulate the data for their needs, and the work needs to be reproducible. In addition,
researchers need to cite other research and give credit to other researchers where credit is due.
Safety is another agenda that comes into play in this area of research whether it is through a lab
scale or a commercial scale process. Researchersneed to wear personal protective equipment (PPE) when
handling ethanol because ethanol causes severe eye irritation and moderate skin irritation.5
Ethanol may
also cause central nervous system depression.5
Therefore, it is the responsibility of the researchers follow
the safety regulations when carrying out experiments with chemicals.

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References
(1) Arlington Institute. (2005). Global Water Crisis.Retrieved from World's Biggest Problems:
http://www.arlingtoninstitute.org/wbp/portal/global-water-crisis
(2) International Forward Osmosis Asscociation. (2014-2015). What is Forward Osmosis? Retrieved
from International Forward Osmosis Asscociation: http://forwardosmosis.biz/education/what-is-
forward-osmosis/
(3) Keursha Lutchmiah, A. V. (2014). Forward osmosis for application in wastewater treatment:A
review. Water Research,179-197.
(4) Naddeo, V. (2012, July 18). Membrane Technology in WastewaterTreatments. Retrieved from
International Publisher of Science, Technology and Medicine: http://scitechnol.com/membrane-
technology-in-wastewater-treatments-yMkx.php?article_id=137
(5) North American Fire Arts Asscociation (NAFAA). (2001, April 17). Material Safety Data Sheet.
Retrieved from North American Fire Arts Asscociation (NAFAA):
http://www.nafaa.org/ethanol.pdf
(6) Tzahi Y. Cath, A. E. (2006). Forward osmosis: Principles, applications, and recent developments.
Journal of Membrane Science,70-87.
(7) Yuliwati, A. I. (n.d.). MEMBRANE SCIENCE AND TECHNOLOGY FOR WASTEWATER.
Johor Bahru, Johor, Malaysia. Retrieved from http://www.eolss.net/sample-chapters/c07/e6-144-
32-00.pdf
(8) HTI. (2010). Forward Osmosis Solutions. Retrieved from HTI Water Technology:
http://www.htiwater.com/technology/forward_osmosis/
(9) Zhao, S., Zou, L., Tang, C. Y., & and Mulcahy, D. (2012). Recent developments in forward
osmosis: Oppurtunities and challenges. Journal of Membrane Science,396, 1-21.
(10) Baker,R. (2012). Membrane Technology and Applications, 3rd ed. Chichester,UK:John Wiley
and Sons.
(11) McCutcheon, J. a. (2007). Modeling water flux in forward osmosis: Implications for improved
membrane design. AIChe Journal,53,1736-1744.