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Oshrat Koren
Dr. Meyer L. Rosoff and Rev. Benzion Bauer
Prize for Excellence in Water Research, 2006
Department of Environmental Hydrology and Microbiology
Zuckerberg Institute for Water Research
Jacob Blaustein Institutes for Desert Research
Ben-Gurion University of the Negev
My name is Oshrat Koren, and I am an M.Sc. student at the Zuckerberg Institute
for Water Research, Jacob Blaustein Institutes for Desert Research, Ben-Gurion
University of the Negev. I was born Oshrat Vaknin in 1978 in the southern desert
town of Arad, Israel, where I have lived most of my life. As a child, I was
interested in both art and science.
My high school years were spent at "Ort Arad" school in Arad, during which
time I volunteered for three years in Magen David Adom (ambulance service),
where I met my husband to be Hagai. After leaving high school in 1996 with
matriculation in biology and chemistry, I was called up to the army. I served
for two years in the Air Force. After leaving the army I worked and then traveled
to South America. On my return, I enrolled for a pre-academic course in Engineering
Studies at Ben-Gurion University, where I then went on to do a degree in Geological
Engineering. During my time at university I began to work as a laboratory assistant
in a large local industrial chemical plant situated near Arad. I was married
upon completion of my degree, and was then delighted to be given a job at the
Zuckerberg Institute for Water Research on a project looking at desalination
scenarios in Israel, with a possible view to their use as a model for Australia.
This is a country which has also held a great fascination for me, and which
I visited in 2004 upon completion of the Pratt Project. As a result of my growing
interest in the topic during this time, I decided to take my studies of water
treatment by desalination even further, to Master's level, which is how I came
to be studying in the Department of Desalination and Water Treatment at the
ZIWR. My current research involves investigating two types of fouling: gypsum
precipitation (scaling) and biofouling on reverse osmosis membrane, and how
biofilm affects gypsum precipitation.
Description of research:
The Relationship between Biofouling and Scale Formationon RO Membranes
Supervisors: Prof. Yoram Oren and Dr. Jack Gilron
One of the problems involved in operating reverse osmosis (RO) and nanofiltration (NF) desalination processes on secondary/tertiary effluents is fouling of the membrane by various constituents in the effluent, such as sparingly soluble inorganic salts, colloids, and organic macromolecular compounds, whether already present in the water or produced by bacteria that attach to the membrane surface. As fouling always involves more than a single component, the immediate question is: how do the various fouling factors affect each other on the membrane surface? In this research the synergism between gypsum scaling (calcium sulfate dihydrate precipitation) and biofouling is studied.
The experiments were carried out with a flat ESPA1 RO membrane in a flow cell
with laminar flow regime. Biofilm growth on a clean RO membrane was studied and
characterized by confocal laser scanning microscope (CLSM). A reliable, repeatable
protocol was developed for biofilm growth based on the use of secondary and tertiary
municipal effluents. Furthermore, we monitored gypsum crystal growth from an
undersaturated solution which became supersaturated at the membrane surface by
concentration polarization. The rates of crystal and biofilm growth were recorded.
Gypsum precipitation rate with and without biofouling was measured and characterized
by scanning electron microscopy (SEM) and fluorescence microscopy. There was
a clear influence of the presence of biofilm on the rate and onset of precipitation
as determined by monitoring flux change with time (Figure 1). The distribution
of growth sites is being studied as a function of the presence and absence of
biofilm for similar initial nominal hydrodynamics (recycle flow rate and permeate
flux) (Figure 2).
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