Education

Complete Resume

New Sources of Water
The overarching issue in water science and engineering is to meet the demand for water while at the same time maintaining an ecological balance. Through human history access to water was one of the major factors controlling growth and development. While water is an essential element of life, access to it, or really the lack of access, is not only a moral issue. Poor water supply degrades public health, stunts economic development and even affects the level of education. New solutions to growing water demands will usually consist of water management, water conservation and education, financial tools, and technology. A model for such creative involvement of scientists, engineers and policy makers already exists by linking private and public resources.
Read more...

Toward a Definition of Sustainability
funded (in the past) by the UCB Bridging Grant
The main goal of the proposed project is to advance the development of a quantitative measure of sustainability that can be used for rational decision-making process in the water management field. The specific objectives are:
- to evaluate an entropy-based measure applied to unit processes and operations
- to investigate inclusion of information content in such a measure

Water reuse
Water reuse in many part of the world is becoming a vital element water management. Reclaiming and repurifying water for subsequent reuse reduces an overal demand for water, enhances stability of water supply and its local control, and may protect vulnerable ecosystems. One example of our work focuses on institutional, economic and energy aspects of water reuse. A more general presentation (2MB) provides background for the topic.
Also, a working paper on water scarcity and water reuse drivers

Submerged Membrane Bioreactor Performance And Solids Processing
sponsored by Water Environment Research Foundation and Zenon Corporation
We are investigating the phenomena of increasing filtration resistance at both high and low MLSS concentrations. We postulate that at high solids concentrations the increase of filtration resistance is mainly related to high bulk viscosity of the biosolids suspension. At low MLSS (and corresponding low SRT) the increase of filtration resistance is likely to be caused by exocellular macromolecular compounds produced by microorganisms that may or may not significantly change biosolids viscosity. We are also looking into the the reasons why MBR and conventional system activated sludge behave differently with respect to membrane filtration. A second research objective is to examine the behavior of MBR waste biosolids, compared to conventional waste biosolids in solids treatment processes such as thickening by gravity, dissolved air flotation, centrifuge and gravity belt, and dewatering of anaerobically digested waste biosolids + primary sludge mixtures by belt press filtration and centrifuge.
See more papers below

Biodegradation of estrogens in membrane bioreactors.
funded by the Water Resources Center
Kinetics of biodegradation of selected estrogenic compounds can be potentially intensified in a membrane bioreactor. Estrogenic compounds, discharged with treated wastewater have recently raised concerns because of their potential to interfere with endocrine system of various species (including possibly humans). Natural estrogens (mainly 17b-estradiol and estrone) and their synthetic counterparts (chiefly mestranol and 17a-ethinyl estradiol) are primarily excreted with urine. They are partially removed during typical wastewater treatment but the extent of removal varies from plant to plant and among different estrogenic species. From rough estimates, it seems that the removal rate coefficient could increase significantly when estrogens are present in low mg/L concentrations comparing with ng/L values typically found in wastewaters. This increase may be related to strong sorption of estrogens on biosolids present in a treatment reactor with a potential of a hundred-fold increase in process efficiency. Even if a fraction of this potential could be realized, estrogen removal would be greatly enhanced.

Evaluation of biostability of drinking water
A method for evaluating drinking water biostability is being developed which is based on measurements of growth rates of attached bacterial cells. The cells originate from tested water and are allowed to attach and grow on the surface of a test coupon under uniform mass transfer conditions. Current focus is on investigation of bacterial cell detachment due to starvation.

Development of biofilm structure
Recent advances in confocal laser scanning microscopy have made it possible to examine the internal structure of biofilms in a nondestructive way. Apparently biofilms are not homogeneous and contiguous, as previously assumed, but are often full of holes and channels connected to the bulk liquid. The objective of this work was to develop a procedure based on the principles of fractal geometry for quantification of biofilm structure. Two geometric scales with different fractal dimensions were identified in the biofilm. Small scale biomass clusters (< 5 mm) had fractal dimensions close to the topological dimension while the fractal dimensions of larger aggregates were considerably smaller. Anisotropic morphology was also detected by the difference of fractal dimensions and was possibly related to the direction of water flow. Currently, we are continuing to develop a cellular automata model for the biofilm development (see a paper in Mathematical Biosciences or animation -1MB download; make sure that animations are enabled on your browser).

More Publications