FLOW SHEET OF SEWAGE TREATMENT PLANT MBR
pre Collection tank
Inflow
Sludge digester Bar Screen
Equalization
Recycle
Filter Press
Final water tank
Chlorination Dual Media Filter (PSF & ACF)
SPECIFICATION FOR 50 KLD STP (Membrane Bio Reactor System) Details of STP units It is proposed to install STP of capacity 50,000 litres/day. Following is the scheme for treating 50,000 Litres/day capacity sewage. The treated water can be utilized for gardening, etc. Various treatment units which have been envisaged in this sewage treatment plant are explained below. Characteristics considered: Flow
: 50KL/day
PH
:6-8
TSS
: 600 mg/l
BOD
: 350 mg/l
COD
: 600 mg/l
Oil & Grease
: 50 to 75 mg / Ltr.
No. of Hrs. operation: 24 1. Bar Screen 2. Collection Sump cum Equalization unit 3. Raw Sewage Pump 4. Membrane Bio Reactor system 5. Sludge Recycling Pump 6. Sludge collection tank 7. Sludge Dewatering 8. Pre collection tank 9. Filter feed pump 10. Pressure sand filter 11. Activated carbon filter 2
12. Chlorine Doser 13. Final Collection Tank 14. Treated water transfer pump 15. Blower Capacity 16. Inter Plant Piping 17. Electrical 1. Bar Screen * Size of the Unit
:
0.5m x 0.5m x 2.4m long
* Function
:
To separate coarse matter from the raw sewage.
2. Equalization tank * Size of the unit
:
2.4m x 3.5m x 3.5m SWD
* Volume of the Tank
:
25 m3
* Detention time available
:
12 Hr.s during Average flow
* Function
:
Equalizing the flow dampen the possible variation in the characteristics of the sewage and also to reduce initial organic load.
3. RAW SEWAGE PUMP The equalised and neutralised waste together with return sludge shall be pumped at a uniform rate of 5.0 Cu.m / Hr. into the Membrane bio-reactor tank. *Quantity
:
2 no. (1w + 1s)
*Duty
:
To transfer Raw effluent from Equalisation tank to Membrane Bio Reactor Tank
*Type
:
Vertical submersible pump. 3
*Motor
:
TEFC Motor with IP-55 protection and suitable for 400 / 440 V, 50 HZ A/c supply of Kirloskar.
*Material
:
*Accessories :
CI Body and impeller in Bronze. Air cock with priming funnel, Flexible Coupling with guard, Base frame, foundation bolts etc.
*Flow rate
:
5.0 Cu.m / hr
*Head
:
15 mtr
*Solids
:
35 mm maximum
*Temperature:
Ambient
4. Membrane Bio Reactor tank * Flow
:
50 m3 / day or 2.0833 m3/Hr
* F/M
:
0.08
* MLSS
:
13,000 mg/ Litre
* MOC
:
RCC
(i) Calculation of volume of the tank: BOD X Flow rate Volume
=
-------------------------------F/M X MLSS
Assume F/M = 0.08 &
MLSS = 13,000 mg/l 350 x 50
* Therefore Volume of the Tank required: -----------------=16.83m3 say 17m3 0.08 x 13,000 Assume SWD to be 3.0m Therefore plan area required
=
* Size of Aeration Tank required =
17/3.0 m = 5.66 m2 say 5.7m2 2.387m x 2.387 m x 3.0m SWD 4
(ii) Calculation of total organic load : * Average BOD of sewage at the inlet of Aeration tank neglecting BOD Reduction with pre-aeration: 350 mg/lit * Total organic load with 10% BOD reduction considered. : 315mg/lit. 315 x Flow rate Organic load
:
---------------------1000
* Total organic load in the system : 315 X 50/1000 = 15.75 Kgs/day. * Total oxygen required assuming that 2 Kgs of O2 /Kg of BOD Removed
: 2 X 15.75 = 31.5 Kg/day
(iii) Calculation of diffuser required: Assume alpha = 0.6 & β =0.7 Consider oxygen transfer at 3.0 SWD depth = 0.15% Density of Air: 1.2 Kg/m3 Percentage of Oxygen in Atmospheric air 23 31.5 ∴ Actual Air required for pre aeration
: -----------------------------------1.2x0.23x0.6x0.7x0.15x20
Assuming duration of air supply as 20 hours per day Air required = 90.579 m3/hr (iv) Calculation of diffuser required: Consideration 10 m3/hour diffusion of air through the diffuser 1 /m length. Number of diffusers required
= 90.579 /10 = 9.0579 or Say 9 diffusers.
5
* Type of aeration
= Membrane fine pore diffused aeration system.
* Function
= to aerate the contents of the MBR tank and to sustain the biological activity so as to reduce the organic load.
* Size of the unit
:
2.387m x 2.387 m x 3.0m SWD 2.387m x 2.387 m x 3.5m (Actual Size)
* Volume of the Tank
:
19.94 m3
* Detention time available
:
9.57 Hr.s during Average flow
* Function
:
to aerate and filter the sewage
through the membrane hollow fibre modules and hold the contents of the MBR tank and to sustain the biological activity so as to reduce the organic load. Hollow-fibre modules used are characteristically 4 inch (10cm) in diameter and 6 (1.83 m) feet long. Hollow-fibre units are almost always run with the feed stream on the outside of the fibre. Water passes through the membrane into the inside or "lumen" of the fibre. A number of hollow-fibres are collected together and "potted" in an epoxy resin at both ends and installed into an outer shell. The equivalent hollow-fibre module filled with fibres of 100-mm diameter X 5 No.s in each set (total 3 sets); with 0.08m Gap between each will provide an approximately 3000 m2 X 3 of membrane area. 5. SLUDGE RECYCLE PUMP * Volume of Sludge
:
17.5 m3/Day
* Discharge rate
:
2 m3/Hr @ 8-10m head (25 mm pipe dia) 6
* Function
:
To re-circulate the return Sludge to MBR tank to maintain the required MLSS & transfer excess sludge to filter press.
The wastewater after biological treatment still contains some solids, colour, odour and harmful micro-organisms. The pressure sand filter and activated carbon filter are used to remove the solids and colour. The disinfection process is used to remove the micro-organisms and odour. 6. SLUDGE HOLDING TANK Flow x BOD Bio-sludge produced /day
: -----------------------------Sludge concentration 50 x 350 = -----------------------------10,000 = 1.75 cum/day @ 1.0% concentration
20% of the sludge to be wasted Excess sludge to be wasted
:
0.35 m3/day @ 1%
Volume of sludge holding tank
:
2 m3
Size of the tank
:
0.9 m x 0.9 m x 2.5 m SWD
7. SLUDGE DEWATERING Flow x BOD Bio-sludge produced /day
: -----------------------------Sludge concentration 50 x 350 = -----------------------------10,000 7
= 1.75 cum/day @ 1.0% concentration 20% of the sludge to be wasted Excess sludge to be wasted
:
0.35 m3/day @ 1%
Total sludge to be dewatered
:
350 Lts/day @ 1%
Filter press of size 14” x 14” x 8 chambers provided. Filter press feed pump provided = 2 m3/hr @ 6.0 Kilogram/Sq.Cms (KSC) 8. TREATED SEWAGE COLLECTION / PREFILTRATION TANK * Size of the unit
:
3.0m x 3.0m x 3.0m SWD
* Volume of the unit
:
27 m3
* Detention time available
:
13 hours
* Function
:
To collect & store the settled supernatant / treated sewage from the tank.
9. FILTER FEED PUMP – 2 Nos. (1W + 1 SB) * Pumping Rate
:
6 m3/hr
* Pumping Head
:
23-25m
* Function
:
To pump the output water of MBR tank through Pressure sand & carbon filters.
* Type
:
Horizontal centrifugal non-clog Self priming, open impeller pumps of Kirloskar, Beacon make.
* Motor
:
TEFC Motor, with IP-55 protection and suitable for 400 / 440 V, 50 HZ A/c supply of Kirloskar make.
* Material
:
CI Body and impeller in Bronze 8
* Accessories
:
Air cock with priming funnel, Flexible Coupling with guard, Base frame, foundation bolts etc.
10. PRESSURE SAND FILTER Vertical down flow type with graded gravel with polystyrenes strainers. * Diameter
: 600 dia
* Depth of media
: 600 mm
* Test Pressure
: 5 Kg. / Sq.cm
* Velocity of filtration
: 8 cum / Sq. m / Hr.
* Flow rate
: 6.0 Cu.m / hr
* Quantity
: 1 no
* Duration of pumping considered : 8.2 hr / day * Make
: Ion exchange or equivalent
* Material
: Shall made out of 6 mm thick MS plate and dish end made out of 8 mm thick end plate whole unit shall be given 2 Coats for internal and external with epoxy/enamel-based paint over a coat of epoxy based primer.
* Under drain
: Perforated bottom plate with plastic strainers or central headers and laterals.
* Media
: Graded River sand and Gravel
* Flow direction
: Down flow.
11. CARBON FILTER Vertical down flow type with graded gravel with polystyrenes strainers. * Diameter
: 600 dia
* Depth of media
: As per requirements
* Test Pressure
: 5 Kg. / Sq.cm
* Velocity of filtration
: 8 cum / Sq. m / Hr. 9
* Flow rate
: 6.0 Cu.m / hr
* Quantity
: 1 no
* Duration of pumping considered : 8.2 hr / day * Make
: Ion exchange or equivalent
* Material
: Shall made out of 6 mm thick MS plate and dish end made out of 8 mm thick plate, whole unit shall be given 2 Coats for internal and external with epoxy / enamel - based paint over a coat of epoxy based primer.
* Under drain
: Perforated bottom plate with plastic strainers or central headers and laterals.
* Media
: Ionized Activated carbon with Gravel support
* Flow direction
: Down flow.
12. CHLORINE DOSER In order to disinfect the treated effluent various disinfection methods like chlorination, ozonation, etc can be used. However chlorination is proved to be cheaper and relatively effective. Hence the same system is adopted. The Chlorine can be administered in the form of liquid or solid (bleaching powder) into the treated effluent channel. An automatic electronic metering system can be adopted. The chlorine demand is calculated based on the ‘break point chlorination’ and to allow residual chlorine of more than 1 mg/l in the treated effluent. * Quantity
: 1 no.
* Make
: Asia LMI / Ion exchange
* Flow
: 0 – 4 Litres / Hour
* Material
: FRP
* Accessories
: Foot valve with strainer, Electronic diaphragm type metering Pump 10
Detention time
= 30 minutes
∴ Volume required = 17.5 X (0.5/24) = 0.365m3 Provide chlorine contact tank of size, Length= 1.0 m & width of the tank= 0.456m and depth of 1.0m (1m including a free board of 0.2 m) * Total flow
:
17.5 m3/day
* Duration of pumping considered
:
24 hr / day
* Pumping rate
:
0.729 m3/hr
13. TREATED WATER SUMP * Stone of the unit
: 4.16 m x 4.16 m x 3.0m SWD 4.16 m x 4.16 m x 3.5m (Actual Size)
* Volume of the unit
: 52 m3
* Detention time available
: 25 Hours
* Function
: To collect & store the final treated (after disinfection) water to pump to either garden or toilet flushing.
14. TREATED WATER TRANSFER PUMP * Volume of Treated water
: 50 m3/day
* Discharge rate
: 10.0 m3/Hr @ 10-12m head (50mm pipe dia)
* Function
: To pump the treated water from the treated water collection sump to Garden and also to toilet flushing over head tank.
15. BLOWER CAPACITY : Blower capacity required
:
76 x 1.25
(For MBR tank) = 95 m3/hr (4.5% extra) 11
Blower capacity required
:
60.5 x 1.25
(For equalization + Sludge Holding Tank + Treated Water tank) = 75.625m3/hr. Note: The capacity of twin lobe roots air blower suitable to discharge about 85m3/hr @ 0.5 KSC – 2 Nos. (1W + 1SB) is provided for MBR. The common blower of twin lobe roots air blower suitable to discharge about 68m3/hr @ 0.5 KSC – 2 Nos. (1W + 1SB) is provided for supply of the air required for other primary, intermittent & final storage units of the treatment plant (Equalisation Tank, Pre-filtration & Filtered Water tank+ Sludge Holding Tank). 16. INTER PLANT PIPING Provide PVC pipes of 4-6 Kilogram/sq.cm.s pressure rating including necessary specials like tee’s, bends, elbows, flanges etc. 17. ELECTRICALS: Provide & install motor control centre with necessary cabling, earthing etc. complete.
CIVIL STRUCTURE WITH DIMENSION Sl.
Civil Structure
Dimension
Units
No. 1. 2. 3. 4.
Bar Screen Equalization tank MBR Tank Sludge holding tank
0.5m x 0.5m x 2.4m long 2.4m x 3.5m x 3.5m SWD 2.387m x 2.387 m x 3.0m SWD 0.9 m x 0.9 m x 2.5 m SWD
1 1 1
5. 6. 7. 8. 9.
Prefilteration tank Pressure sand Carbon filter Treated Water tank Filter press
3.0m x 3.0m x 3.0m SWD D =0.6m, Ht= 0.6m D =0.6m, Ht= 0.6m 4.16m x 4.16m x 3.5m 14”x14”x7”
1 1 1 1 1
18. Characteristics of treated effluent
12
As the design includes tertiary treatment units also, the treated sewage characteristics will be well within the standards prescribed by Karnataka State Pollution Control Board specified norms for sewage as follows.
BOD(5 day 200 C)
< 10 mg/l
Turbidity
< 2 NTU
pH
= 6.5 to 7.5
E-coli
= Absent
Residual chlorine
> Min 1 or >1, but <3
TSS
< 20 Mg / Ltr.
Oil & Grease
< 10 Mg / Ltr.
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