Treatment Design Calculations Group 1 Scheme Design 2014
Department of Civil, Construction & Mineral Engineering
Project
Course & Year
Wastewater Treatment Plant Design
Civil Engineering Year 5
Part of Structure
Calculation Sheet No.
Horizontal Flow Tank (Primary Settlement)
1
Drawing Ref:
Scheme Design Reference
of
Calculations By:
Checked By:
Date:
Maurice Healy
Jason Shields
22/03/2014
Calculations
2
Output
Minimum side wall depth = 2m Q = 59.4m3/day 60% reduction of TSS Peak flow factor = 2.5 Surface Overflow Rate = SOR = 185 - (2.5xTSS removal) = 185 - (2.5x60) = 35 m3/m2/day Step 1 - Calculate surface area (A) of tank required:
Surface Area=1.697m2 Step 2 – Calculate tank dimensions: Assume width/length ratio of 3:1 Hence: Length=2.256m
Width=0.752m
Step 3 - Calculate tank volume: Assume minimum tank depth of 2m. Volume = V = 2mx2.256mx0.752m = 3.393m3
Volume=3.393m3
Department of Civil, Construction & Mineral Engineering
Project
Course & Year
Wastewater Treatment Plant Design
Civil Engineering Year 5
Part of Structure
Calculation Sheet No.
Horizontal Flow Tank (Primary Settlement)
2
Drawing Ref:
Scheme Design Reference
of
Calculations By:
Checked By:
Date:
Maurice Healy
Jason Shields
22/03/2014
Calculations
Step 4 – Hydraulic Retention Time (HRT)
Step 5 – Peak flow SOR
2
Output
HRT=1.37hours
Peak flow SOR=87.5m3/m2/day
Step 6 - Primary Sludge Production Weight of Dry solids = Wds = Q x TSS x F Assume F = 0.6 Q = 59.4m3/day Assume TSS = 300mg/l Wds = 59.4m3/d x 300mg/l x 0.6 x (103/106) Wds = 10.6922 kg/day Wds = 320 kg/day
Wds=320kg/day
Note: External Dimensions of tank are as follows: Length = 2.856m
Length=2.856m
Width = 1.352m
Width=1.352m
Depth = 2.1m
Depth=2.1m
Department of Civil, Construction & Mineral Engineering
Project
Course & Year
Wastewater Treatment Plant Design
Civil Engineering Year 5
Part of Structure
Calculation Sheet No.
Horizontal Flow Tank (Secondary Settlement)
1
Drawing Ref:
Scheme Design Reference
of
Calculations By:
Checked By:
Date:
Maurice Healy
Jason Shields
22/03/2014
Calculations
2
Output
Minimum side wall depth = 2m Q = 59.4m3/day 60% reduction of TSS Peak flow factor = 2.5 Surface Overflow Rate = SOR = 185 - (2.5xTSS removal) = 185 - (2.5x60) = 35 m3/m2/day
SOR=35m3/m2/day
Step 1 - Calculate surface area (A) of tank required:
Surface Area=1.697m2 Step 2 – Calculate tank dimensions: Assume width/length ratio of 3:1 Hence: Length=2.256m
Width=0.752m Step 3 - Calculate tank volume: Assume minimum tank depth of 2m. Volume = V = 2mx2.256mx0.752m = 3.393m3
Volume=3.393m3
Department of Civil, Construction & Mineral Engineering
Project
Course & Year
Wastewater Treatment Plant Design
Civil Engineering Year 5
Part of Structure
Calculation Sheet No.
Horizontal Flow Tank (Secondary Settlement)
2
Drawing Ref:
Scheme Design Reference
of
Calculations By:
Checked By:
Date:
Maurice Healy
Jason Shields
22/03/2014
Calculations
2
Output
Step 4 – Hydraulic Retention Time (HRT) HRT=1.37 hours
Step 5 – Peak flow SOR
Peak flow SOR=87.5m3/m2/day
Step 6 - Primary Sludge Production Weight of Dry solids = Wds = Q x TSS x F Assume F = 0.6 Q = 59.4m3/day Assume TSS = 300mg/l Wds = 59.4m3/d x 300mg/l x 0.6 x (103/106) Wds = 10.6922 kg/day Wds = 320 kg/day
Wds=320kg/day
Note: External Dimensions of tank are as follows: Length = 2.856m
Length=2.856m
Width = 1.352m
Width=1.352m
Depth = 2.1m
Depth=2.1m
Department of Civil, Construction & Mineral Engineering
Project
Course & Year
Wastewater Treatment Plant Design
Civil Engineering Year 5
Part of Structure
Calculation Sheet No.
Extended Aeration (Secondary Treatment)
1
Drawing Ref:
Scheme Design Reference
of
Calculations By:
Checked By:
Date:
Maurice Healy
Jason Shields
22/03/2014
Calculations
3
Output
Population Equivalent = 220x1.5=330 Water use = 180l/day Influent Flow (Qo) = 330 p.e x 180l/day = 59.4m3/day Influent BOD (So) = 300mg/l Effluent BOD (S) = 20mg/l Assume Yield coefficient (Y) = 0.6 Assume decay rate (kd) = 0.06day-1 Assume MLSS (X) = 3500mg/l Assume WAS MLSS (Xw) = 14000mg/l Assume MCRT (ɸc) = 10day-1 Step 1 – Calculate the aeration tank volume (V):
V= 17.82m
3
Volume=17.82m3
Assume 2m depth. Hence: Area = 17.82m3/2m2 = 8.91m2
Area=8.91m2
Width = 2.985m
Width=2.985m
Length = 2.985m
Length=2.985m
Department of Civil, Construction & Mineral Engineering
Project
Course & Year
Wastewater Treatment Plant Design
Civil Engineering Year 5
Part of Structure
Calculation Sheet No.
Extended Aeration (Secondary Treatment)
2
Drawing Ref:
Scheme Design Reference
of
Calculations By:
Checked By:
Date:
Maurice Healy
Jason Shields
22/03/2014
Calculations
3
Output
Step 2 – Calculate the Hydraulic Retention Time (HRT)
Step 3 – Volume of wasted sludge per day (Qw):
Qw=0.4455m3/day
Step 4 – Mass of sludge wasted each day (QwXw): QwXw = 0.4455 x 14 = 6.237kg/day
QwXw=6.237kg/day
Step 5 – Fraction of sludge recycled (Qr/Q0)
Qr/Qo=32.3%
Department of Civil, Construction & Mineral Engineering
Project
Course & Year
Wastewater Treatment Plant Design
Civil Engineering Year 5
Part of Structure
Calculation Sheet No.
Extended Aeration (Secondary Treatment)
3
Drawing Ref:
Scheme Design Reference
of
Calculations By:
Checked By:
Date:
Maurice Healy
Jason Shields
22/03/2014
Calculations
3
Output
Step 6 – Calculate f/m ratio f/m=0.29
Note: External Dimensions of tank are as follows: Length = 3.585m Width = 3.585m Depth = 2.1m
Length=3.585m Width=3.585m Depth=2.1m