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Unformatted text preview: EVEG 31 10
BOD Calculations Assumptions: Lt=Loe'kt Yt= Lo(l e'kt) Where k=ﬁrst ordr decay constant decay constant (0.2 days'l)
Lt: BOD remaining at time tin mgOsz (Organic material remaining)
LO=BOD remaining at time t=0 in mgOZ/L (Organic material at start)
t = time (days)
Yt= BOD exerted in mgOzlL (Organic matter already decayed)
C5: Oxygen saturation level mgOz/L
Ct= Oxygen level at time t Problem I: A 0.5 mgd waste ﬂow with a £40ng of 100 and an oxygen concentration of 4.5 (C) is mixed with a 3.5 mgd river ﬂow with a background BOD20 of 5 and DO level
of 8.0. What is the BODZO and the dissolved oxygen at the point of mixing. ,4, #ﬂrwreitrs) a t W— 449
[L 1‘ ZM7/L Problem 2: What is the BODgo one (1) mile down stream if the stream velocity is l ft/sec?
V c / ff/ﬂé
{f f 49% KW?
Was/:2 7
2 /3
Problem 3: You are asked to estimate the BOD20 in a stream seven miles downstream of
a point of mixing. You are told the BOD5 in the river after mixing is 37 mg/L. What is the BODZO at the point of mixing. What is common between the two numbers? Why are
the numbers different? XL: 1» ( / '6'“) :7? Z" ﬂﬂéA/ufé ﬂag274’ ﬂaw My L. W _ x t .’
pkg/5653A}? ﬂW/wyg (3F EKPKETS/Oﬂf Let f 4r: Zﬂ 6522;” w: ﬂew—if Problem 4: A 500 ml BOD bottle is dosed with 50 of sewage and aerated until the
bottle’s oxygen is at 85% of saturation. The bottle is sealed. The oxygen level in the
bottle is 2.5 mg/l after ﬁve days. What was the BOD20 of the undiluted wastewater
sample? 65 “Wig5M :y‘g'i i X ,zx) r f. ZZZ
8a : <9~Z)(0,M): xvii? ’02: 5’9,”
3: L f er“? .— j:
Aﬁbo) 925352;) ‘" ll
,. [a ﬂ/éas [07
3/3 Problem 5: After you ﬁnish measuring the dissolved oxygen in the BOD bottle described
in Problem 4, you reaerate it and ciose it up again. How much dissolved oxygen will be
left in the bottle aﬁer ﬁve days? ...
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 Spring '10
 Malone
 Organic chemistry, Oxygen saturation, oxygen saturation level, mL BOD bottle, Ct= Oxygen level

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