1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Pavel [41]
3 years ago
11

A waste stabilization pond is used to treat a dilute municipal wastewater before the liquid is discharged into a river. The infl

ow to the pond has a flow rate of Q=4,000 m3 /day and a BOD concentration of Cin = 25 mg/L. The volume of the pond is 20,000 m3 . The purpose of the pond is to allow time for the decay of BOD to occur before discharge into the environment. BOD decays in the pond with a first-order rate constant equal to 0.25/day. What is the BOD concentration at the outflow, Cout of the pond, in units of mg/L?
Engineering
1 answer:
lyudmila [28]3 years ago
4 0

Answer:

<em>Cout = 11mg/L</em>

Explanation:

Assume Steady State and CSTR, this means Qin = Qout

Given: Qin = 4 000m3/day

Cin = 25mg/L

V = 20 000m3

k = 0.25/day

Find: Cout = ?

outStarting from the mass balance equation for steady state 0 = QCin - QCout - kCoutV

manipulate the equation to get:

\(Cout=Cin(Q/Q+kV)\)  

<em>Then simple plug in your givens: </em>

<em>Cout = (25mg/L)((4000m3/day)/(4000m3/day + 0.25/day(20000m3)) </em>

<em>Cout = 11mg/L</em>

You might be interested in
What are the horizontal structures beneath a slab that help transfer the load from the slab to the columns?
Delicious77 [7]

Answer: D) Beams

Explanation:

3 0
2 years ago
Read 2 more answers
simple Brayton cycle using air as the working fluid has a pressure ratio of 10. The minimum and maximum temperatures in the cycl
Irina18 [472]

Answer:

a) 764.45K

b) 210.48 kJ/kg

c) 30.14%

Explanation:

pressure ratio = 10

minimum temperature = 295 k

maximum temperature = 1240 k

isentropic efficiency for compressor = 83%

Isentropic efficiency for turbine = 87%

<u>a) Air temperature at turbine exit </u>

we can achieve this by interpolating for enthalpy

h4 = 783.05 kJ/kg ( calculated in the background ) at state 4 using Table A-17  for  Ideal gas properties of air

T4 ( temperature at Turbine exit ) = 760 + ( 780 - 760 ) (\frac{783.05-778.18}{800.13-778.18} ) = 764.45K

<u>b) The net work output </u>

first we determine the actual work input to compressor

Wc = h2 - h1  ( calculated values )

     = 626.57 - 295.17 =  331.4 kJ/kg

next determine the actual work done by Turbine

Wt = h3 - h4  ( calculated values )

     = 1324.93 - 783.05 = 541.88 kJ/kg

finally determine the network output of the cycle

Wnet = Wt - Wc

         = 541.88 - 331.4  = 210.48 kJ/kg

<u>c) determine thermal efficiency </u>

лth = Wnet / qin  ------ ( 1 )

where ; qin = h3 - h2

<em>equation 1 becomes </em>

лth = Wnet / ( h3 - h2 )

      = 210.48 / ( 1324.93 - 626.57 )

      = 0.3014  =  30.14%

6 0
3 years ago
A mass weighing 22 lb stretches a spring 4.5 in. The mass is also attached to a damper with Y coefficient . Determine the value
Dominik [7]

Answer:

Cc= 12.7 lb.sec/ft

Explanation:

Given that

m = 22 lb

g= 32 ft/s²

m = \dfrac{22}{32}=0.6875\ s^2/ft

x= 4.5 in

1 in = 0.083 ft

x= 0.375 ft

Spring constant ,K

K=\dfrac{m}{x}=\dfrac{22}{0.375}

K= 58.66  lb/ft

The damper coefficient for critically damped system

C_c=2\sqrt{mK}

C_c=2\sqrt{0.6875\times 58.66}

Cc= 12.7 lb.sec/ft

5 0
3 years ago
Which statement most accurately describes Pascal's law?
marin [14]

Answer:

La  C

Explanation:

7 0
3 years ago
Read 2 more answers
An air standard cycle with constant specific heats is executed in a closed system with 0.003 kg of air and consists of the follo
Vsevolod [243]

Answer:

a) Please see attached copy below

b) 0.39KJ

c)  20.9‰

Explanation:

The three process of an air-standard cycle are described.

Assumptions

1. The air-standard assumptions are applicable.

2. Kinetic and potential energy negligible.

3. Air in an ideal gas with a constant specific heats.

Properties:

The properties of air are gotten from the steam table.

b) T₁=290K ⇒ u₁=206.91 kj/kg, h₁=290.16 kj/kg.

P₂V₂/T₂=P₁V₁/T₁⇒ T₂=P₂T₁/P₁ = 380/95(290K)= 1160K

T₃=T₂(P₃/P₂)⁽k₋1⁾/k =(1160K)(95/380)⁽⁰°⁴/₁.₄⁾ =780.6K

Qin=m(u₂₋u₁)=mCv(T₂-T₁)

=0.003kg×(0.718kj/kg.k)(1160-290)K= 1.87KJ

Qout=m(h₃₋h₁)=mCp(T₃₋T₁)

=0.003KG×(1.005kj/kg.k(780.6-290)K= 1.48KJ

Wnet, out= Qin-Qout = (1.87-1.48)KJ =0.39KJ

c)ηth= Wnet/W₍in₎ =0.39KJ/1.87KJ = 20.9‰

7 0
3 years ago
Other questions:
  • If a ball is dropped from a height​ (H) its velocity will increase until it hits the ground​ (assuming that aerodynamic drag due
    5·1 answer
  • B1) 20 pts. The thickness of each of the two sheets to be resistance spot welded is 3.5 mm. It is desired to form a weld nugget
    12·1 answer
  • You are considering building a residential wind power system to produce 6,000 kWh of electricity each year. The installed cost o
    15·1 answer
  • 2 Consider airflow over a plate surface maintained at a temperature of 220°C. The temperature profile of the airflow is given as
    13·1 answer
  • Oil (SAE 30) at 15.6 oC flows steadily between fixed, horizontal, parallel plates. The pressure drop per unit length along the c
    6·1 answer
  • What are the initial questions that a systems analyst must answer to build an initial prototype of the system output.
    14·1 answer
  • Defination of rolling
    13·1 answer
  • A 240-ton tugboat is moving at 6 ft/s with a slack towing cable attached to a 100-ton barge that is at rest. The cable is being
    14·1 answer
  • The pressure at the bottom of an 18 ft deep storage tank for gasoline is how much greater than at the top? Express your answer i
    15·1 answer
  • Label each of the line types in the drawing below. ( will not mark you brainlest or whatever if you don't at least try to help)
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!