4. A 20 mL wastewater sample was mixed with 280 mL deionized (DI) water in a...

ques) Given: Waste water, volume Vs = 20 ml deionized (DI) watesi , V = 280 ml 5- day Bop test (DO) initial = 9 mgle (Do final) = 3.5 mg/l BOD mate constant at 20°C : K20 = 0·22/day. We know that ca]. Dilution Factor , (D.F) = volume of diluted sample volume of undiluted sample Volume of diluted sample = V +Vs = 280+ 20 = 300 ml Volume g undiluted sample - Vs = 20 ml ii D.F = 300 = 15 DiF - 300 20 . = 15 (b) 20'd tia 5 doy BOD at 20°C Bonzorc = Y = [poinitial) = (2-0) final]=(-) Y: 2014- [ 9-3.5) * (15) = 82.5 mg Le We also know that t day BOD at Id Y = L.(!-e***]

Lo = ultimate BOD of waste water K7 = Kzo'c = 0.22/day t = 5 days putting values Yoz* = Lol1- € 50*5) Lo = 82.5 [1- 402225) 7 ultimate BOD , Lo = 123•664 mgle C) BODY of the wastewatex at 15°C As BoD sate constant. * only depends upon K7 = K2010 (1-04737-20) BOD sota upon temperature - At To temperature - at 15°C, K15'c = K20 = 0·22 (10047)** = 0.17485 /day BODy of the waste water at 15*c Yote = b011-e**y) = 123.664 [1 – 85047455x4) 7,150 = 62.217 mogle