Floating Flocs
Annotated Bibliography
Fundamentals of Bubble Formation during Coagulation and Sedimentation Processes
Gas bubbles can form in solution whenever the total dissolved gas pressure (TDG) is greater than the local solution pressure (supersaturation). Rapid mixers can also cause floating floc even in undersaturated water. This article outlines the experiments conducted to investigate the initial formation and then stability of floating floc during conventional coagulation-sedimentation processes. The volume of the bubbles formed and the equilibrium dissolved gas concentration in the water was estimated using a gas bubble equilibrium model based on the assumption of a closed system. This article also looks into the mass transfer rate of the dissolved gas into the gas bubbles. Factors such as water temperature and coagulant type are also discussed.
Scardina, P., and Edwards, M. (2006). "Fundamentals of bubble formation during coagulation and sedimentation processes." Journal of Environmental Engineering. 132(6):575-585. Available from <http://cedb.asce.org>. Accessed 2009 February 21.
An Improved Gas-Stripping Column for Deoxygenating Water
The article discusses gas-stripping columns and an experiment using a gas-stripping column. In the introduction, the article mentions the advantages of using such columns to deoxygenate water due to their simplicity and low cost. These columns generally involve a porous substrate in the column through which water flows downwards and nitrogen gas flows upwards. The methods section describes the setup of the experiment and how nitrogen gas was introduced into the compresses gas cylinder. They found that the amount of dissolved oxygen in the output water was inversely related to the rate of nitrogen gas flow.
Barnhart, M. (1995). "An improved gas-stripping column for deoxygenating water." Journal of the North American Benthological Society. 14(2):347-350. Available from <http://jstor.org/stable/1467786>. Accessed 2009 February 26.
Water Treatment Unit Processes: Physical and Chemical
This is a book describing water treatment processes, but in certain sections it mentions the stripping of dissolved oxygen from solution, which is what the Floating Floc Team is trying to accomplish this semester. The book briefly discusses gas transfer and the transport of gas from aqueous phase to gas phase, which is controlled by rate of interface area created. On page 956, there is the mention of using gas transfer to strip air in order to remove volatile compounds from the solution. On page 979, the book refers to an experiment in which nitrogen was used to strip oxygen from solution.
Hendricks, D.(2006). Water treatment unit processes: physical and chemical. Boca Raton, Florida: CRC Press. Available from <http://books.google.com/books>. Accessed 2009 February 25.