Osmotic Membrane Bioreactor for Energy-neutral Anaerobic

Wastewater Treatment-Wastewater Concentrated by Forward Osmosis

Student No. 2110869 E-mail: 2110869h@student.gla.ac.uk 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