Question

reply ma as soon as possible

120 points total Due: October 23, 2019 Budget your time carefully TRUE OR FALSE (45 points - 3 points cach): Mark whether the statements as written are "true" or "false". If the statement is false, make minor changes to the statement so that the statement is true. The primary adverse health effect resulting from the disposal of mercury wastes into Minamata Bay was dysentery The flow regime in horizontal velocity grit chambers approaches continuous mixed flow Screening and comminution are preliminary treatment processes. A bar rack is a device consisting of parallel bars evenly spaced that is placed in a waterway to remove debris, suspended solids, and floating solids from a wastewater In pretreatment operations, aeration is usually accomplished by cascades, multiple tray aerators, spray nozzles, or diffused compressed air tanks. Total solids (TS) refers to the residue left behind in a drying dish after igniting at 450+50°C Flow equalization dampens the daily variation in flow rate, along with variations in BOD suspended solids, etc. Oftentimes, grit from horizontal velocity grit chambers is washed to free it from any organic particles that may have been collected on it. The reason grit is removed as much as possible is to prevent wear on pumps, accumulations in acration tanks, clarifiers, and digesters; and clogging of sludge piping A mass balance performed on a steady state process involving a first-order chemical reaction for component using a continuous stirred tank reactor and a plug-flow reactor system, results in a differential equation and an algebraic equation, respectively. The residence time for a particular unit operation is defined as the average time that a fluid clement remains within that unit operation, and can be described mathematically as t-QIV. For a given level of conversion, the continuous stirred tank reactor (CSTR) will provide a smaller reactor volume and smaller detention time than a plug flow reactor. The performance equation describing dispersed plug-flow is given by: CN- 41 cxp [12. (LDL CA (1 + i)exp(1/2 (LID)) - (1-1) exp(1/2 (LID)) where: 1 = [1 + 4% (Divz)). (dimensionless) V = velocity in the radial direction, (length time) L = reactor length, (length) D-longitudinal or axial dispersion coefficient, (length time) rate constant, (time) In dispersed plug-flow reactors, the flow regime is between plug-flow and completely mixed flow. Primary treatment of a wastewater utilizes sedimentation to remove a substantial amount of the suspended solids. 15. MULTIPLE CHOICE: (5 points cach, 35 points total) Choose the most

Answer 1

1) True

2) True

3) True

4) True

5) True

6) False

(24) Volume of tank = Area x deep = 5887.5 feet = 36682.2 gallons

7) True

8) False

9) True

10)

11)True

12) False ( CSTR need larger reaction volume achieve the same reaction rate )

13) True

14) True

15) True

16) a(Grit)

17) d(Grit)

18) d(finely divided suspended material)

19) c

20) c

(20) Assume , V. = Approach velocity before the bar seren = Velocity through the bar. V, A, = V₂ A₂ Az Wspace 3/4 A = Whart Wspace V = 5 3 x 3 = 13 = 2.14 ft /sec option (c) 2.14 ft/sec As 29 x 0.7 - 137–12.14) 2x9.81 289-81*07 = 9-4,58 = 0:32. A 2 x 9.81 option (g) None of the above Au

21) g