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
Sergeeva-Olga [200]
2 years ago
15

(2 points) A perfectly mixed aeration pond with no recycle serves as the biological reactor for a small community. The pond rece

ives 30 m3 /d of influent with a BOD of 350 mg/L that must be reduced to 20 mg/L before discharge. It has been found that the kinetic constants for this system are: Ks = 100 mg BOD/L, kd = 0.10 day-1 , μm = 1.6 day-1 , Y = 0.60 mg SS/mg BOD. Assume Xo = 0. a. What must the hydraulic retention time (θ = V/Q) be in the aeration pond? b. What mass of microbes will be produced in the pond each day?
Engineering
1 answer:
FromTheMoon [43]2 years ago
3 0

Answer:

a)  t = 165 days

b) 9.9 kg/day

Explanation:

Given data:

final lelvel of BOD is 20 mg/l

Ks = 100 mg BOD/L,

kd = 0.10 day-1 ,

μm = 1.6 day-1 ,

Y = 0.60 mg SS/mg BOD

a) we know that

c_{out} = \frac{c_{in}}{1 + kt}

20 = \frac{350}{1 + 0.1 t}

solving for t

t  =  165 days

b) mass of microbes = Q(mlD) × C(mg/l)

= 30\times 10^{-3} (350-20) = 9.9 kg/day

You might be interested in
The correct statement about the lift and drag on an object is:_______
Lisa [10]

Answer:

(a). the resultant force in the direction of the freestream velocity is termed the drag and the resultant force normal to the freestream velocity is termed the lift

Explanation:

When a fluid flows around the surface of an object, it exerts a force on it. This force has two components, namely lift and drag.

The component of this force that is perpendicular (normal) to the freestream velocity is known as lift, while the component of this force that is parallel or in the direction of the fluid freestream flow is known as drag.

Lift is as a result of pressure differences, while drag results from forces due to pressure distributions over the object surface, and forces due to skin friction or viscous force.

Thus, drag results from the combination of pressure and viscous forces while lift results only from the<em> pressure differences</em> (not pressure forces as was used in option D).

The only correct option left is "A"

(a). the resultant force in the direction of the freestream velocity is termed the drag and the resultant force normal to the freestream velocity is termed the lift

8 0
3 years ago
Read 2 more answers
8. Block A shown in the figure below weighs 2000 N. The chord attached to A passes over a
Kobotan [32]

Answer:

Read the passage. Then, answer the questions about the metaphor in boldface in the text.

Lately, I've been so overwhelmed with school and sports. There was a time when I enjoyed going to classes and going to practice every afternoon. Now, everything is piling up and wearing me down. Thankfully, I get to see you every day. You are truly the sunshine of my life. Thank you for making me laugh when I'm feeling down.

What is the context of the passage?

What is being compared in the metaphor?

What is the meaning of the metaphor?

Explanation:

4 0
2 years ago
Air enters the combustor of a jet engine at p1=10 atm, T1=1000°R, and M1=0.2. Fuel is injected and burned, with a fuel/air mass
snow_lady [41]

Answer:

M2 = 0.06404

P2 = 2.273

T2 = 5806.45°R

Explanation:

Given that p1 = 10atm, T1 = 1000R, M1 = 0.2.

Therefore from Steam Table, Po1 = (1.028)*(10) = 10.28 atm,

To1 = (1.008)*(1000) = 1008 ºR

R = 1716 ft-lb/slug-ºR cp= 6006 ft-lb/slug-ºR fuel-air ratio (by mass)

F/A =???? = FA slugf/slugaq = 4.5 x 108ft-lb/slugfx FA slugf/sluga = (4.5 x 108)FA ft-lb/sluga

For the air q = cp(To2– To1)

(Exit flow – inlet flow) – choked flow is assumed For M1= 0.2

Table A.3 of steam table gives P/P* = 2.273,

T/T* = 0.2066,

To/To* = 0.1736 To* = To2= To/0.1736 = 1008/0.1736 = 5806.45 ºR Gives q = cp(To* - To) = (6006 ft-lb/sluga-ºR)*(5806.45 – 1008)ºR = 28819500 ft-lb/slugaSetting equal to equation 1 above gives 28819500 ft-lb/sluga= FA*(4.5 x 108) ft-lb/slugaFA =

F/A = 0.06404 slugf/slugaor less to prevent choked flow at the exit

5 0
3 years ago
90% of traffic crashes are due to driver error.<br> True<br> False
kumpel [21]

90% of traffic crashes are due to driver error.

True

3 0
2 years ago
Read 2 more answers
What to you do if you have a flat tirer
Vika [28.1K]

Answer: change the tires

Explanation: you can’t drive on a flat tire

6 0
3 years ago
Other questions:
  • : The interior wall of a furnace is maintained at a temperature of 900 0C. The wall is 60 cm thick, 1 m wide, 1.5 m broad of mat
    12·1 answer
  • A heavy ball with a weight of 110 N is hung from the ceiling of a lecture hall on a 4.9-m-long rope. The ball is pulled to one s
    6·1 answer
  • 3. (9 points) A square-thread power screw is used to raise or lower the basketball board in a gym, the weight of which is W = 10
    12·1 answer
  • Yasir is trying to build an energy-efficient wall and deciding what materials to use. How can he calculate the thermal resistanc
    6·1 answer
  • Whats the best used for Arch bridge
    11·1 answer
  • Three possible career opportunities in embedded systems engineering
    11·1 answer
  • The current flow in an NMOS transistor is due to one of the following:
    11·1 answer
  • What are the nominal dimensions for a 1x2 stick of lumber, a 2x4 stick of lumber and a standard sheet of plywood?
    11·1 answer
  • Technician A says when you push the horn button, electromagnetism moves an iron bar inside the horn, which opens and closes cont
    5·2 answers
  • As you get older your muscles grow. True or False
    15·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!