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Unformatted text preview: CE 3101 Fall 2011 Homework 05 The Monod Growth Model for Biodegradation Kinetics Due Tuesday, 11 October 2011, 11:55 P.M. The study of the growth of bacterial cultures does not constitute a specialized subject or branch of research: it is the basic method of Microbiology. Jacques Lucien Monod (1910- 1976), french biologist and Nobel Prize winner. Abstract In self-selected groups of up to three members, you will write an Excel spreadsheet program to fit the coefficients of the Monod Growth Model. Each group must analyze at least two (2) of the nine (9) available data sets. A full written report is required in addition to the working code. Group Evaluation and the Time Card After completing this assignment you are each required to INDIVIDUALLY complete the Homework 05 Group Evaluation , found on the course Moodle web site. Your evaluation activity must be completed by 6:00 P.M., Friday, 14 October 2011, or you risk the imposition of an egregious penalty. 1 Biodegradation Kinetics The primary objective of biological treatment of wastewater 1 is to facilitate the removal and utilization of organic chemicals (potential pollutants) by microbes. Bacteria and fungi dominate 2 the conversion of soluble organics. Protozoa may be involved in conversion of colloidal materials. The overall conversion can be described by the following conceptual formula: cell mass ( X ) + organic substrate ( S ) cell mass + CO 2 + H 2 O (1) where X represents the active cell mass that exploits organic materials (substrate S ) to form additional cell mass and by-products of growth metabolism. These by-products include carbon dioxide and water, and possibly other minerals. Growth also requires the presence of small concentrations of nutrients (e.g. P and N) as well as trace metals at very low concentrations. Most wastewaters have adequate concentrations of nutrients and trace metals so that growth of cells depends primarily on availability of organics (in laymans terms: food). For aerobic processes, molecular oxygen is also required; for anaerobic 3 growth, oxygen must be excluded. Engineering applications of biological treatment for wastewater purification make use of microbial pro- cesses to convert soluble and colloidal organic pollutants into cell mass (biomass). The biomass (sludge solids) can be separated from the water phase by sedimentation and reused as inoculum for incoming wastes. Engineered applications require quantitative descriptions of rates of growth of cells, rates of utilization of substrate, production of cell mass, rate of oxygen utilization, and the quantities of nutrients required. The better we understand the microbiological processes involved, the more effective and efficient our designs. As is often the case, knowledge is power 4 ....
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- Spring '11