03-08 - Prelim 1:Thursday, March 18 7:00 pm Kimball Hall...

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Prelim 1:Thursday, March 18 7:00 pm Kimball Hall B11 Water quality parameters Categories Units of expression Drinking water standards Primary, secondary Standard vs. criteria Regulation of wastewater Stream standards Effluent standards Riparian doctrine Mass balance Assimiltative capacity Qualitative description of oxygen sag curve Diversity index Biotoxicity Microbial growth and metabolism Energetics Stoichiometry Rates Oxygen demand concepts: COD, BOD, NOD Reaeration Mixed-lake model (CSTR) for BOD and DO
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Mass Balance dVdC = dt [Note: we can write Q dC as Q dC dx] dx Divide through by dV to get: dC = dt but dX = dV QC mass/time input output decay term 12 QdC dX k (L) k (C* C) dX dV 1/A dC can be (+) or (-) Q A Q D.O. = C BOD = L dL is (-) D.O. =C+dC BOD=L+dL [segment volume = dV= ] AdX dX A Q(C dC) 1 k (L)dV 2 k (C* C)dV reaeration term
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so dC = - Q dC - k 1 L + k 2 (C*-C) dt A dX and Q/A= also, at steady state dC = 0 dt u (stream velocity) C) * (C k (L) k dX dC u 0 2 1 @ steady state: dC dt 12 QdC dX k (L) k (C* C) dX dV 1/A but dX = dV
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Recall that the change in oxygen concentration is equal and opposite to the change in the oxygen deficit[D=(C*-C)]. Therefore, we can rewrite the above equation in terms of the oxygen deficit. u dD = k 1 L - k 2 D dX also recall: L = L O e - (k r X/u) integration with the initial deficit = D O @ X = 0 gives: D k e L k 2 (X/u) r k - o 1 (X/u) 2 k - e r k -
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03-08 - Prelim 1:Thursday, March 18 7:00 pm Kimball Hall...

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