Osmotic Membrane Bioreactor for Energy-neutral Anaerobic
Wastewater Treatment-Wastewater Concentrated by Forward Osmosis
Student No. 2110869 E-mail: [email protected] Supervisor: Dr Xue Jin
Standard Experiment Wastewater Experiment
Conclusion
Reference
Introduction
Forward Osmosis System
Today, energy crisis and resource scarcity have
become a global problem, the potential valuable
resource existing in the waste water successfully
attract the vision of scientific community (Ozgun et
al, 2013). Comparing with aerobic membrane
bioreactors (MBRs), anaerobic membrane bioreactor
(AnMRB) technology has advantages in low energy
consumption and sludge production. Concentrating
feed solution by forward osmosis (FO) before
treatment can decrease abundant volume and
increase low-strength of wastewater.
Ozgun, H., Dereli, R. K., Ersahin, M. E., Kinaci, C., Spanjers, H., & van Lier, J. B.(2013). A review of anaerobic membrane bioreactors for municipal wastewater treatment:integration options, limitations and expectations.Separation and PurificationTechnology, 118, 89-104.Achilli, A., Cath, T. Y., Marchand, E. A., & Childress, A. E. (2009). The forward osmosismembrane bioreactor: a low fouling alternative to MBR processes.Desalination, 239(1), 10-21.
This poster shows the experiment results about two measurements (water flux and salt diffusion) of membrane performance created by different kinds of draw solution. From the
standard experiment, it can be found that ionic salt as draw solution create high water flux and salt diffusion than organic salt because the ICP phenomenon. In the wastewater
experiment, NaCl as draw solution comparing with sea salt can create more water flux, while the salt diffusion is similar between them. However, because of Ca ion can form binds
with carboxylic acid group existing in wastewater, the membrane fouling in sea salt as draw solution is more serious than in NaCl as draw solution.
c
Average water flux curves
created by different draw
solution (DS) in different
osmotic pressure is showed in
Figure 4. It reflects that DS
osmotic pressure increases, the
water flux with rising water
flux. Besides, sea salt and
NaCl DS create more water
flux than dextrose and sucrose
at the same osmotic pressure.
Figure 5 shows that as the
osmotic pressure increases, the
reverse salt diffusion increases.
Sea salt DS created the highest
salt diffusion, while dextrose
DS created the lowest. The
membrane performance
differences for each DS is
related to internal
concentration polarization
(ICP).
In the wastewater experiments, firstly as the standard experiments, the water flux
and conductivity for each draw solution were measured over 24 hours. Secondly,
after 24 hours, empty both feed and draw tanks and do not clean the membrane.
Put DI water in feed tank and standard DS in DS tank, and then weight the DS
change for 40 minutes. Thirdly, use DI water to clean the membrane surface until
the surface looks clean, and put it in a new DI water feed tank. Then measure the
weight change of DS for 40 minutes. Sea salt and NaCl are chosen as draw
solution.Figure 4: Average water flux
created by different DS in
different osmotic pressure
Figure 5: Salt diffusion of
different DS in different
osmotic pressure
Figure 6: The ICP and ECP explanation in
FO membrane (Kim et al, 2012)
The Figure 6 reflect the
concentration polarization of FS
and DS in the inside or outside of
membrane. This phenomenon
influences the water flux and
reverse salt diffusion. ICP is
severer among large molecular
weight salts, so they creates
lower water flux and higher salt
diffusion (McCutcheon and
Elimelech, 2006.
Kim, T. W., Kim, Y., Yun, C., Jang, H., Kim, W., & Park, S. (2012). Systematic approach for draw solute selection and optimal system design for forward osmosis desalination. Desalination, 284, 253-260.McCutcheon, J. R., & Elimelech, M. (2006). Influence of concentrative and dilutive internal concentration polarization on flux behavior in forward osmosis.Journal of Membrane Science, 284(1), 237-247.
A schematic diagram of this experiment is showed
in Figure 1. The Figure 2 and Figure 3 show the
practical experimental equipment.
Figure 1: Schematic diagram of experiment (Achilli et al, 2009)
Figure 2: Practical experimental equipment
Figure 3: Membrane cell
Figure 7: The water flux inwhiskey wastewater created bydifferent draw solution underdifferent membrane condition
Figure 8: The conductivity ofdifferent draw solutions withwhiskey wastewater as feedsolution
Figure 9: The water flux inmunicipal wastewater created bydifferent draw solution underdifferent membrane condition
Figure 10: The conductivity ofdifferent draw solutions withmunicipal wastewater as feedsolution
