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11.5) Determine the methane gas production rate (m3/d) for the reactor from prob

ID: 1732523 • Letter: 1

Question

11.5) Determine the methane gas production rate (m3/d) for the reactor from problem 11.4. Assume COD equivalent of VSS equals 1.42 kg COD/kg VSS.

PLEASE ANSWER 11.5 thank you!

11.4) Design a UASB reactor to treat wastewater at 30°C from a food pro- cessing plant. The wastewater flow rate is 500 m3/d with a soluble COD concentration of 6000 mg/L. The design parameters are as follows:

Reactor effectiveness factor (E) 0.85 Upflow velocity -1.2 m/h Organic loading rate 12 kg sCOD/m3 d Y 0.08 kg VSS/kg COD kd 0.03 d-1 ?max = 0.25 d-l K. = 360 mg/L Height for gas collection 3 Using the given information, determine the following: a. The reactor area and diameter The reactor liquid volume c. Liquid depth and total height of the reactor d. The average SRT (assuming 97% degradation of sCOD)

Explanation / Answer

Given data:

Q=500m3/day

soluble matter=6000 g/m3

efficiency=97%

Step 1:

Prepare a steady state mass balance for COD, to determine the amount of influent COD converted to methane

CODin=CODeff+CODVSS+CODmethane

Step 2:

CODin=COD concentration in influent x waste water inflow=500x6000=3000 Kg/day

CODeff=COD concentration in effluent x waste water inflow=500x6000x0.3=90 Kg/day

COD used=3000x0.97=2910 kg/day

Bio sythesis yeild=0.08 x2910x1.42=330.576 kg

CODmethane=?

step 3:

CODmethane=3000-(330.576+90)

CODmethane=2579.424 kg

Step 4:

As 64 gm comes from 1 mole, then

(1 mole/64)x2579.424=40.3 mole Methane gas/day

step 5:

From the STP conditions

V/T= constant

22.4/273=V2/(273+30)

V2=24.86Liters/mole

Step 6:

Amount of methane=24.86x40.3=1001.858 liters/day or 1.001858m3/day