Water & Waste treatment Calculation & Formula:
1. Filtration flow (m3/hr) = filtration flux(l/m2/h) X A X B(m2)
1000
A – Number of housing available in UF unit
B- membrane area per housing
2. Coagulant dosing Flow (l/h) = Total UF feed flow (m3/h) X Required dosing concentration(mg/l)
Chemical Stoke Concentration (g/l)
3. Coagulant dosing pump Speed(%) = Coagulant dosing flow (l/h) X 100
Flow at max .Speed (l/h)
4. Trans membrane pressure(TMP)
TMP filtration = PT feed – PT permeate
5. Permeability (lmh/bar) = Filtration Flux (lmh)
TMP (bar) X Temp Correction factor
Temp Correction Factor = 2.024 X 10^-3(42.5 + T)^1.5
6. Backwash Flow (m3/h) = Backwash flux (l/m2.h) X A X B(m2)
1000
7. CEB dosing flow (l/h) = Backwash flow (m3/h) X Chemical dilution (mg/l)
Chemical Stoke Concentration (g/l)
8. CIP Pump flow (m3/h) = (25 X UF unit membrane area(m2))
1000
9. CIP Tank Capacity = Feed flow (m3/h) X 5/60
Chemical Consumption :( Requirement)
1. Hypo = Backwash flow (m3/h) X 5min/60min X dosing concentration(mg/l)
Chemical Stoke Concentration (g/l)
Example:
323 m3/h X 5/60 X 25 mg/l
7 X 10000mg/l
= 323 X 0.0833 X 25
70
= 9.6 litter
Stoke required /month:
Hypo = 9.6 X 30 = 288 lts/month
Note: Same calculation we used for Caustic& HCl chemical requirement.
Specific Gravity for Chemicals:
1. Hypo : 1.20 g/cm3
2. Caustic : 1.43 g/cm3
3. HCl : 1.20 g/cm3
Note: Chemicals need to convert into Kgs value multiple with respected chemical specific gravity.
Example: (Hypo)
1. 288 X 1.20 = 345 kg/month
Flux:
Flux = Feed Flow (m3/h) X 1000 / membrane surface area(m2) X No of membranes
Ex:
Flux = 20 m3/h X 1000 / 64m2 X 5 = 62.5 lmh
UF Plant design: (Example )
Client Name : XXXXX
Capacity : 81 m3/h permeate
Mode of operation cross flow 10%
Recovery : 90 %
Feed capacity : 81/0.9 = 90 m3/hr
Feed with cross flow : 100 m3/hr
Application : Treated Effluent
Flux = 50 lmh
No of membrane : 90 m3/h X 1000 / 50 X 81(m2) = 23 nos
BW pump capacity : 23 X 170 lmh X 81m2 / 1000 = 317 m3/h
Chemical Cleaning:
1. Caustic : 317m3/h X 500 mg/l / 45 %
317m3/h X 500mg/l / 45 X 10000 mg/l
317 X 500 / 450 =350 lph
2. HCl : 317 X 500 / 330 = 480 lph
CIP Tank calculation :
Hold up volume for Individual membrane = 60 ltr
No of membrane in skid = 30
Hold up volume for membrane in skid = 30 X 60/1000 = 1.8 m3
1. 90 m3/h X 5min/60min = 8 m3/h
Slope Formula:
= Velocity= 0,0(Velocity / 0.849 X 100 X Hydraulic mean depth ^0.63) ^ 1/0.54
= 84.5 X 0.1027 ^1.85
= 84.9 X 0.0148 = 1.25652
Weisbach Formula :
hf =F(L/D) X (V2/2g)
F = h /(L/D) X (v2/2g)
hf – Head loss
F –Friction Factor
L –Length of pipe work
d- ID of pipe
V- velocity of fluid
g- acceleration due to gravity
Reynolds Number:
Re = Vol / u
Recovery Calculation:
Net permeate flow : 91 m3/h
Cross flow : 5 %
Recirculation : 20%
Recovery :
Feed flow = 91/0.85 =107 m3/hr
Feed pump capacity = 107 /0.05 = 112.35 with cross flow
Feed pump with reject recirculation = 107 X 0.2 =21.4
= 112.35 + 21.4
Feed pump capacity = 134 m3/hr
Filtration = 30 mins = 0.583 hrs
FFA = 20sec =0.0055hrs
B/W = 60 sec=0.0766hrs
FFB =20 sec=0.005hrs
Total =0.6106hrs
=24/0.6106 = 39.30 cycles/day
No of membrane = feed flow X1000 / Area X flux
= 107 X 1000 / 81 X 40
= 33 no’s
B/W = 33 X 170 X 81 / 1000
= 455 m3/hr
= 455 X 0.0166 X 39.3
= 297 m3/day
F.F.A = 134 X 0.0055 X39.3
= 29 m3/day
F.F.B = 134 X 0.0055 X 39.3
= 29 m3/day
Total Loss = BW + FFA + FFB
= 297 + 29 +29
= 355 m3/day
Total Production = 91 X 22.9 = 2084 m3/day
Total Loss = 355 m3/day
= 2084 +355 = 2439 m3/day
Recovery = 2084 / 2439
= 0.854 X 100
= 85.4%
Recovery % = feed flow – Total Loss / Feed Flow
Net Permeate Flow/Stream = Feed flow X Recovery
Flux Assumption:
Raw water = 70 -85 lmh
Effluent = 50 -65 lmh
Textile = 40-45 lmh
Pharma = 30 -35lmh
Note:
1 Daltons = 1 moss of proton = 1moss of neutron
Area of cylinder = 2 πrh (l)
volume of cylinder = πr2h(l)
Chemicals Selection:
1. NaOH – water contain more organic,bacteria,Algae
2. Silica Scaling – 1 to 2% Citric Acid
3. Hard scale & metal Oxides (Iron )
4. NaOH + EDTA =- Organic iron present as humic substance
