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Unformatted text preview: 1 Arsenic, MFB, and Residence Time ¡ Lecture#9 ¡ review steady state assumption (ICP#7) ¡ residence/retention time ¡ multiple inflows/outflows ¡ evaporation (ICP#8) ¡ Reading V: Ch. 3 pg. 56-61 (Ex 3.5); Handout on Arsenic Contamination in Bangladesh Overview ¡ What type of contaminant is arsenic and what is its MCL? ¡ Where does the arsenic contamination come from that is causing sickness in Bangladesh ¡ What is residence or hydraulic retention time? ¡ How does evaporation impact residence time or concentration of pollutants? ¡ How does evaporation effect pollutant concentrations under steady-state conditions? Mass Balance Problems ¡ 1. Draw a system diagram ¡ 2. Add information (knowns and unknowns) ¡ 3. Circle control volume to be balanced ¡ 4. Decide what materials are to be balanced ¡ 5. Write the mass balance equation (MBE) ¡ 6. If only one unknown, then solve MBE ¡ 7. If more than one unknown repeat procedure for each unknown Mass balance equation ¡ accumulation rate = inflow rate – outflow rate + net transformation rate ¡ conservative compound: no generation or decay, m ● rxn = 0 ) ¡ steady state: amount of mass in control volume stays constant ( dm/dt = 0 ) ¡ m ● in = m ● out dm/dt = m ● in- m ● out + m ● rxn Mass balance equation m ● in = m ● out ¡ mass flow rate balance on water : Q in ρ in = Q out ρ out ¡ mass flow rate on conservative compound: Q in C in = Q out C out ¡ last time ICP#7 illustrated an example of MBE approach for steady state, multiple conservative compounds with two inputs and a single output Mass Balance Equations ¡ ICP#7 ¡...
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This note was uploaded on 04/17/2008 for the course CEE 260 taught by Professor Kimf.hayes during the Fall '06 term at University of Michigan.
- Fall '06