Calculate the recycle flow qr required

Assignment Help Other Engineering

Reference no: EM131128552

Environmental engineering

Q1) 10,000 gallons per day of wastewater enters a 1500 gallon activated sludge tank. The raw wastewater has a SS = 200 ppm and a BOD = 230 ppm. The MLSS needs to be 2800 ppm and the effluent SS should be less than 10 ppm. The total wasted sludge has a Q of 5 GPD with a SS concentration of 6000 ppm.

A. Calculate the recycle flow, Q_r, required. (8710 GPD)

B. Calculate the F/M ratio in lbs BOD/lbs SS - day (0.55 lb BOD/lb SS-day)

C. Calculate the BOD Loading in lbs BOD/day - 1000 ft³ (95.6)

D. Based on these calculations, is the activated sludge tank over designed or under designed? What could you do to remedy this situation?

Q2) Colloidal gold has been released into the water supply from an electronics manufacturing plant. These particles are 0.1 mm in size with a specific gravity of 19.3. Your water treatment plant has 3 clarifiers each with a volume of 0.3 million gallons and a height of 6 ft. The total flow going into all 3 clarifiers is 5 MGD.

a. Will these particles settle in this clarifier or will we be drinking gold? Assume that they are not flocculated. Defend your answer quantitatively.

b. What is the minimum detention time needed to settle these gold particles over a height of 6 ft? (214 days)

c. If you cannot remove these gold particles, should you add a sand filter or a reverse osmosis unit? Give two reasons for your answer and state your assumptions.

d. If you decide to flocculate these particles, what is the minimum diameter of a gold particle (with a specific gravity of 19.3) that can be removed in this clarifier? (3.4 mm)

Q3) You are given the following information:

	Conc, mg/L	MW g/mole	EW mg/meq	Conc, meq/L	Conc mg/L as CaCO₃
Ca²⁺	180	40
Mg²⁺		24.3			173
Na⁺	30	23
CO₃²-		60			169
HCO₃^-	8	61
SO₄^2-	11	96
OH^-		17

a. Calculate the hardness in meq/L. (12.5 meq/L)

Q4) An activated sludge tank treats 1 MGD from the primary clarifier and has an [SS], or X of 2200 ppm. The water effluent is 0.9 MGD. 1.0 MGD of the sludge is recycled back into the tank and has an [SS] of 3980 ppm. The concentration of BOD exiting the primary clarifier is 200 ppm.

a. Calculate the minimum volume of the tank that will satisfy the following requirements: (Hint: Calculate the volume for each condition and then determine which volume satisfied all the requirements).

i. BOD loading < 35 lb BOD/1000 ft³ - day

ii. Sludge age > 5 days

iii. Aeration period > 4 hours

Q5) 10,000 gallons per day of wastewater enters a 1500 gallon activated sludge tank. The raw wastewater has a SS = 200 ppm and a BOD = 230 ppm. The MLSS needs to be 2800 ppm and the effluent SS should be less than 10 ppm. The total wasted sludge has a Q of 5 GPD with a SS concentration of 6000 ppm.

A. Calculate the recycle flow, Q_r, required. (8710 GPD)

B. Calculate the F/M ratio in lbs BOD/lbs SS - day (0.55 lb BOD/lb SS-day)

C. Calculate the BOD Loading in lbs BOD/day - 1000 ft³ (95.6)

Based on these calculations, is the activated sludge tank over designed or under designed? What could you do to remedy this situation

Q6) Water flows out of the primary clarifier with a SS = 200 ppm and a BOD = 250 ppm. An activated sludge tank treats 5 MGD from the primary clarifier and has an [SS], or X of 2500 ppm. The water effluent is 95% of the influent and 50% of the sludge is recycled back into the activated sludge tank with an [SS] of 6800 ppm. What is Qe? in MGD

Q7) Water flows out of the primary clarifier with a SS = 200 ppm and a BOD = 250 ppm. An activated sludge tank treats 5 MGD from the primary clarifier and has an [SS], or X of 2500 ppm. The water effluent is 95% of the influent and 50% of the sludge is recycled back into the activated sludge tank with an [SS] of 6800 ppm. What is Qr? in MGD

Q8) Water flows out of the primary clarifier with a SS = 200 ppm and a BOD = 250 ppm. An activated sludge tank treats 5 MGD from the primary clarifier and has an [SS], or X of 2500 ppm. The water effluent is 95% of the influent and 50% of the sludge is recycled back into the activated sludge tank with an [SS] of 6800 ppm. What is Qc (the flow leaving the bottom of the secondary clarifier)? in MGD

Q9) Water flows out of the primary clarifier with a SS = 200 ppm and a BOD = 250 ppm. An activated sludge tank treats 5 MGD from the primary clarifier and has an [SS], or X of 2500 ppm. The water effluent is 95% of the influent and 50% of the sludge is recycled back into the activated sludge tank with an [SS] of 6800 ppm. What is Xw? in ppm

Q10) The BOD loading you calculate is 53 lb BOD/1000 ft³-day. The BOD loading should be between 30 - 50 lb BOD/1000 ft³-day. Is the tank over or under designed?

under designed
over designed
It is just fine

Q11) BOD in wastewater can be represented in all the following ways EXCEPT:

SS
BOD
S
F

Q12) In an activated sludge tank it is best if the microorganisms have:

less food than they need so that all the food is gone.
more food than they need so that the microorganisms continue to reproduce.
no food so they all die.

Reference no: EM131128552

Questions Cloud

Who knows what the future will bring : Cell phones are constantly evolving. There are iPhones, Droids, and Blackberries, and more. Who knows what the future will bring? Using the resources listed and your own research the affects of technology disposal.

Marketing research-disadvantage of online survey method : Which of the following is true of marketing research? Qualitative research is likely to prove most efficient when the research objective is to. Which of the following is a disadvantage of the online survey method?

How high can the person climb based on this energy intake : how high can the person climb based on this energy intake?

How many checkouts did the old system provide in shift : A grocery chain is considering the installation of a set of 4 self-checkout lanes. The new self-checkout lane setup will replace 2 old cashier lanes that were staffed by a cashier and bagger on each lane. One cashier mans all 4 self-checkouts. How ma..

Calculate the recycle flow qr required : Calculate the recycle flow, Qr, required. (8710 GPD). Calculate the F/M ratio in lbs BOD/lbs SS - day (0.55 lb BOD/lb SS-day). Calculate the BOD Loading in lbs BOD/day - 1000 ft3 (95.6).

How job enlargement modifies repetitive motion frequency : What is the recovery/work ratio for a worker who performs a task that lasts one minute 450 times per shift, five days per week? Demonstrate how job enlargement modifies repetitive motion frequency

Write down the components of cash flow statement : Question No: 1 Mr. A, B & C entered into a partnership. At the beginning of the year their capital balances were Rs. 180,000, Rs. 140,000 and Rs. 80,000 respectively. Profit or loss is to be divided as

Website is a software package called neave planetarium : how many and which of the objects you were actually able to find why you think you were unsuccessful, for any you couldn't find

Discuss two or three ways mass media influence you : From the e-Activity titled "Mass Media Influence on Today's Society" discuss two or three ways mass media influence you and others you know. Explain two or three reasons or ways in which mass media impact us. (Cite any sources you referenced.)

User Account

All Pages