process calculations

DESIGN PARAMETERS:

Average Flow (Qav) = 1.00 MLD = 41.7 m3/hr = 0.012 m

3/sec

Peak Flow (Qpk) = 3.00 MLD = 125 m3/hr = 0.035 m

3/sec

Peak Flow Factor = (Qpk / Qav) = 3.00

INLET CHAMBER :

Unit to be designed for Peak Flow = 3.00 MLD = 125.0 m3/hr = 0.035 m3/sec

and to be checked for Average Flow = 1.00 MLD = 41.7 m3/hr = 0.012 m

3/sec

Capacity of Stilling Chamber = 30 sec on peak flow

Volume required = 0.035 x 30

= 1.04 m3

Providing SWD = 0.60 m

Length Provided = 1.60 m

Width Provided = 1.20 m

Providing Freeboard = 0.50 m

Volume Provided = 1.15 m3

OK

Provide Stilling Chamber of 1200 wide x 1600 Long x 600 SWD

COARSE SCREEN CHANNELS :

No. of units to be provided = 2 Nos. (1 Mechanical W + 1 Mechanical S)

Mechanical Screen Channel

Unit to be designed for Pk. Flow = 3.00 MLD = 125.0 m3/hr = 0.035 m3/sec

and to be checked for Avg. Flow = 1.00 MLD = 41.6667 m3/hr = 0.012 m

3/sec

PROCESS DESIGN CALCULATIONS FOR 1.0 MLD CAPACITY SEWAGE PUMPING STATION (SPS)

AT PALI, RAJASTHAN


As there will be one stream,

Design Flow at Peak Condn = 0.035 m3/sec = 0.035 m

3/sec

1

Design Flow at Avg. Condn = 0.012 m3/sec = 0.012 m

3/sec

1

Velocity thru Screen Channel for :

Q pk = 1.0 m/s

Q avg = 0.5 m/s

Area of screen channel reqd. for Qpk = 0.035 m3/sec = 0.035 m2

1 m/s

Area of screen channel reqd. for Qavg = 0.012 m3/sec = 0.02315 m2

0.5 m/s

Considering 50 mm opening and 10 mm thickness of bars,

Gross area required = 0.035 x 60 = 0.042 m2

50

Assuming width of channel as = 600 mm

Width of side frame on each side = 0 mm

Total width of channel = 600 mm

Liquid depth in screen = 69 mm Say 100 mm

Height of dead plate = 500 mm

Total depth of screen = 600 mm Say 600 mm

Angle of inclination with horizontol = 45 Deg

Provide length of Screen Chamber as = 6.00 m

Provide free board as = 300 mm on upstream side

AT PALI, RAJASTHAN


Provide Screen Channel of 600 wide x 600 SWD x 6000 Long

Check for Headloss in screen

Headloss thru screen under clean conditions

HL = 0.0729(V12 ‐ V22)

Net area available thru screen = 0.6 x 0.1 x 50

x 60

= 0.050 m2

Velocity thru screen at peak flow (V1) = 0.035 m/s

0.050

= 0.694 m/s

Approach velocity at peak flow (V2) = 0.035

0.6 x 0.6

= 0.096 m/s

Headloss (HL) = 0.034 m = 34.48 mm

Headloss thru screen under half clogged

conditions

HL = 0.0729(V12 ‐ V22)



0.60 x 0.6

= 0.096 m/s

Headloss (HL) = 0.140 m = 140 mm

COLLECTING TANK

AT PALI, RAJASTHAN


Unit to be designed for Peak Flow = 3.00 MLD = 125.0 m3/hr = 0.035 m

3/sec

Capacity of Collecting Tank = 20 minutes on peak flow

Volume required = 0.035 x 20 x 60

= 41.67 m3


Diameter required = 5.15 m

Diameter Provided = 5.20 m


OK

Provide Collecting Tank of size 5200 dia x 2000 SWD

Pumping Machinery in Collecting Tank

Type of pumps = Non clog sewage submersible

Total Flow = 125 m3/hr = 0.035 m3/sec

Dia of pumping main (as per tender) = 250 mm

Length of pipe from SPS to manhole = 500 m

Frictional Losses = 2.0 m

Static Head = 9.0 m

Other Miscellaneous Losses @ 20% = 2.2 m

Terminal head required = 1.0 m

Total Head required = 14.2 m Say 16 m

Number of pumps, for discharge 0.86 MLD = 2 Discharge per pump = 9.95 LPS

AT PALI, RAJASTHAN


HP required by Pump = 9.95 x 16 / 0.7 / 75

= 3.03 HP Say 3.3 HP


HP required by Pump = 4.98 x / 0.7 / 75

= 1.52 HP Say 1.7 HP

DESIGN PARAMETERS:

Average Flow (Qav) = 15.00 MLD = 625.0 m3/hr = 0.174 m3/sec

Peak Flow Factor = (Qpk / Qav) = 2.25

Peak Flow (Qpk) = 33.75 MLD = 1406.25 m3/hr = 0.391 m3/sec

QUALITY OF INLET WASTE :

Biological Oxygen Demand (BOD5) = 300 mg/l

Chemical Oxygen Demand (COD) = 650 mg/l

Total Suspended Solids (TSS) = 600 mg/l

Fecal Coli form = 1 x 104 MPN / 100 ml

Total Kjeldahl Nitrogen ( TKN as N) = 55 mg/l

Total Phosphorous (TP) = 6 mg/l

OUTLET STANDARDS REQD. :

Biological Oxygen Demand (BOD5) = < 10 mg/l

Chemical Oxygen Demand (COD) = < 100 mg/l

Total Suspended Solids (TSS) = < 10 mg/l

Fecal Coliform = < 230 MPN / 100 ml

Total Nitrogen (as N) = < 10 mg/l

Total Phosphorous (TP) = < 1 mg/l

INLET CHAMBER :


and to be checked for Average Flow = 15.00 MLD = 625.0 m3/hr = 0.174 m3/sec



= 11.72 m3

PROCESS DESIGN CALCULATIONS FOR 15.0 MLD CAPACITY SEWAGE TREATMENT PLANT (STP)

BASED ON SEQUENTIAL BATCH REACTOR (SBR) TECHNOLOGY AT PALI, RAJASTHAN








OK


COARSE SCREEN CHANNELS :

No. of units to be provided = 2 Nos. (1 mechanical W + 1 Mechnaical S)

Mechnical Screen Channel


and to be checked for Avg. Flow = 15.00 MLD = 625 m3/hr = 0.174 m3/sec


Design Flow at Peak Condn = 0.391 m3/sec = 0.391 m3/sec

1

Design Flow at Avg. Condn = 0.174 m3/sec = 0.174 m3/sec

1


Q pk = 1.0 m/s

Q avg = 0.5 m/s


1 m/s


0.5 m/s



50






Liquid depth in screen = 469 mm Say 470 mm


Total depth of screen = 970 mm Say 1000 mm







HL = 0.0729(V12 ‐ V22)

Net area available thru screen = 1 x 0.47 x 50

x 60

= 0.392 m2


0.392

= 0.997 m/s


1 x 1

= 0.391 m/s

Headloss (HL) = 0.061 m = 61.39 mm


conditions

HL = 0.0729(V12 ‐ V22)





1.00 x 1

= 0.391 m/s


COLLECTING TANK


Capacity of Collecting Tank = 20 minutes on peak flow

Volume required = 0.391 x 20 x 60

= 468.75 m3


Diameter required = 15.45 m

Diameter Provided = 16.00 m


OK

Provide Collecting Tank of size 16000 dia x 2500 SWD

Pumping Machinery in Collecting Tank

Type of pumps = Non clog sewage submersible

Total Flow = 1406.25 m3/hr

Number of working pumps = 2

Number of standby pumps = 2

Discharge per pump = 703.125 m3/hr

= 11719 LPM = 195.3 LPS

Static Head = 11.5 m



Misc Losses @ 20% = 2.3 m

Required Head of Pump = 13.8 m

Take Head of pump = 15.0 m

Number of pumps, for discharge 15 MLD = 2 Discharge per pump = 173.61 LPS

BHP required by Pump = 173.61 x 15 / 0.7 / 75

= 49.6 BHP Say 54.6 BHP


BHP required by Pump = 86.81 x 15 / 0.7 / 75

= 24.8 BHP Say 27.3 BHP

STILLING CHAMBER :


and to be checked for Average Flow = 15.00 MLD = 625.0 m3/hr = 0.174 m3/sec



= 11.72 m3






OK


FINE SCREEN CHANNELS :


Mechanical Screen Channel




and to be checked for Avg. Flow = 15.00 MLD = 625 m3/hr = 0.174 m3/sec


Design Flow at Peak Condn = 0.391 m3/sec = 0.391 m3/sec

1

Design Flow at Avg. Condn = 0.174 m3/sec = 0.174 m3/sec

1


Q pk = 1.0 m/s

Q avg = 0.3 m/s


1 m/s


0.3 m/s



6




Liquid depth in screen = 789 mm = 800 mm


Total depth of screen = 850 mm = 850 mm









HL = 0.0729(V12 ‐ V22)

Net area available thru screen = 1.1 x 0.8 x 6

x 9

= 0.587 m2


0.587

= 0.666 m/s


1.4 x 0.85

= 0.328 m/s

Headloss (HL) = 0.024 m = 24.46 mm


conditions

HL = 0.0729(V12 ‐ V22)



1.40 x 0.85

= 0.328 m/s


GRIT REMOVAL UNIT :


Mechanical Grit Chamber


Surface Overflow Rate = 959 m3/day/m2



Plan Area required = 35.19 m2

Length required = 6 m Say 6 m

Width provided = 6 m

Area Provided = 36 m2 OK

HRT at peak Flow = 1 min

Volume Required = 23.44 m3

SWD Required = 0.65111 m

Say 0.7 m

Velocity thru Grit Channel = 0.09 m/sec

Provide Mechanical Grit Chambers of 6000 wide x 6000 Long x 700 SWD

SBR REACTORS :

Calculations for SBR Reactors shall be provided by the technology provider.

CHLORINE CONTACT TANK :

Volume of sewage treated = 15.00 MLD = 625.0 m3/hr

Design retention time in CCT = 30 min

Volume of Chlorination tank = 625 x 30

60

= 312.50 m3


Dia Provided = 11.6 m

Volume provided = 317.05 m3 OK


Provide Chlorine Contact Tank of size 11600 dia x 3000 SWD

CHLORINATOR:



Treated sewage flow rate = 625 m3/hr

Design chlorine dosage (for chlorinator

capacity only)= 5 ppm

Number of chlorinators = 1 nos. Working + 1 nos standby

Chlorine dosage rate = 625 x 5

1 x 1000

= 3.13 Kg/hr

Chlorinator capacity offered = 3.5 Kg/hr

Number of Standby chlorinators = 1 nos.

Total number of chlorinators = 2 nos.

Consumption of chlorine gas = 75 kg/day = 2250 kg/month

No. of Chlorine Tonners provided = 3 Nos

COMMON TREATED EFFLUENT CHAMBER :

Treated sewage flow rate = 625.0 m3/hr

Design retention time in effuent chamber = 30 min

Volume of treated effuent chamber = 625 x 30 = 312.50 m3

60


Dia Provided = 11.6 m

Volume provided = 317.05 m3 OK


Provide Effuent Treated Chamber of size 11600 dia x 3000 SWD

Pumping Machinery in Effuent Chamber

Type of pumps = Centrifugal Pump

Decant Flow = 1250.0 m3/hr



Number of working pumps = 2

Number of standby pumps = 1

Discharge per pump = 625 m3/hr

= 10417 LPM = 173.6 LPS

Static Head = 27.2 m

Misc Losses @ 20% = 5.44

Required Head of Pump = 32.64

Provide Head of pump = 33.0 m

HP required for the pump = 173.6 x 33 x 0.746

75 x 0.7

= 87.7 BHP Say 96.5 HP

SLUDGE CALCULATIONS :

Total Sludge as per CTECH calculations = 4763 kg/day

Sludge Consistency = 0.80%

Density of Sludge = 1050 kg/m3

Volume of Sludge = 4763 x 100 / 0.8 / 1050

= 567.0 m3/day

SLUDGE SUMP (SLUDGE HOLDING TANK) :

Hydraulic Retention Time of Tank = 6 hours

Quantity of sludge produced in a day = 567.0 m3/day

Volume required = 567.0 x 6 / 24.0

= 141.80 m3


Provide Dia = 8.50 m




OK


Provide Sludge Holding Tank of Size 8500 Dia x 2500 SWD

SLUDGE SUMP AIR BLOWER:

Volume of Sludge Sump = 141.80 m3

Design air agitation = 1.20 Nm3/hr/m3

No. of working blowers = 1 No

No. of standby blowers = 1 No

Required capacity of blowers = 141.8 x 1.2 / 1.0

170.2 Nm3/hr

Capacity of Blowers offered = 180 Nm3/hr

HP of air blower required = 5.2 HP

CENTRIFUGE & CENTRIFUGE FEED PUMPS:

Sludge produced per day = 567.0 m3/day

Max Number of hours of operation = 12 hours per day

Sludge flowrate = 47.25 m3/hrs

No. of working centrifuge considered = 1 no.

No. of standby centrifuge considered = 1 no.

Capacity of centrifuge required = 47.25

1

= 47.25 m3/hrs

Capacity of centrifuge offered = 50 m3/hrs

HP of centrifuge drive = 15 HP



Actual Working hours of centrifuge = 11.34 hrs/day

< 12 hrs/day OK

Capacity of centrifuge feed pumps offered = 50 m3/hrs = 13.89 LPS

No. of working pumps = 1 no.

No. of standby pumps = 1 no.

Static Head = 20 m

HP required for the pump = 13.89 x 20 x 0.746

75 x 0.4

= 6.9 BHP Say 7.6 HP

POLYELECTROLYTE DOSING SYSTEM:

Quantity of sludge to be dewatered in a day = 4763 Kg/day

Considering Polymer dose = 2 Kg/Ton of dry sludge

Quantity of poly required = 4763 x 2

1000

Quantity of poly required = 9.526 Kg/day

Considering strength of poly solution = 0.10%

Volume of polyelectrolyte solution = 9.526

0.10% x 1000

Volume of polyelectrolyte solution = 9.526 m3

Considering nos. of tanks = 2 nos

Volume of each dosing tank = 4.76 m3

Considering SWD of tank = 1.5 m

Length / Width provided = 1.8 m


Provide Polymer dosing tanks of = 1800 wide x 1800 Long x 1500 SWD



Working hours of centrifuge = 11.34 hrs

Reqd capacity of Poly dosing pumps = 9.526 x 1000

11.34 x 1

= 840.01 Lph

Capacity of poly dosing pumps offered = 850 LPH

No. of working pumps for each tank = 1 no.

process calculations

Documents