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OPERATION & MAINTENANCE MANUAL

EFFLUENT TREATMENT PLANT

1

INDEX

1. PREAMBLE

2. DESIGN BASIS

3. PROCESS DESCRIPTION

4. TECHNICAL SPECIFICATIONS

5. PROCESS START- UP & CONTROL

6. PREVENTIVE MAINTENANCE

7. EQUIPMENT MANUALS

8. DRAWINGS

2

PREAMBLE

3

PREAMBLE

The Effluent Treatment Plant has been designed to treat 240 KLD Effluent.

Salient features of treatment plant:

1. The treatment plant consists of Physical and biological processes. The biological process

consists of double stage anaerobic & aerobic systems.

2. For aeration, Diffused Aeration System with imported Diffusers and Air Purging Grids are

provided. Air is supplied through a twin lobe Air Blower of required capacity. This system

ensures fine bubble dispersion and better Oxygen transfer efficiency.

4

DESIGN BASIS

5

DESIGN BASIS:

I) FLOW : 800-1000/DAY

II) RAW EFFLUENT CHARACTERISTICS :

Parameter Unit Effluent Inlet

Flow ( KLD) m3/hr 800 - 1000

Ph - 5.0 to 9.0

TSS mg / lt. 200- 300

COD mg /lt. 350 - 400

BOD @ 27 ˚ C mg /lt. 150 – 250

Oil & Grease mg /lt. 10 - 20

III) TREATED EFFLUENT CHARACTERISTICS:

Parameter UNIT Sewage

Outlet

Suspended Solids mg /lt. < 5

Bio-Chemical Oxygen Demand (3 days at 27deg C ) mg /lt. < 20

6

PROCESS DESCRIPTION

7

ETP PROCESS DESCRIPTION

PHYSICAL TREATMENT

Effluent Treatment plant is constructed to treat 10, 00,000 liter per day waste water generated from

sugar factory by primary physico-chemical treatment and two stage biological treatments.

Raw waste water streams by gravity passes through bar screen chamber. Here large floatable

particles shall be separated manually .After screening, the effluent collected by gravity to the Oil

removal Tank where Oil and Grease shall be removed from the effluent by the mechanism

provided. The effluent is then passed to the Equalization tank .To keep the contents of the

equalization tank effluents in suspended from one number floating type aerator is provided in each

tank.

Effluent from equalization tank shall be fed to flash mixer unit where Lime solution is added to

raise the pH of the effluent. Over flow from flash mixer shall be collected in tube settlers to settle

the suspended solids. Settled sludge sent to sludge drying beds for dewatering. Overflow from

settling tank shall be collected in feed tank. Effluent from the feed tank shall be further treated

biologically to reduce COD and BOD.

BIOLOGICAL TREATMENT

Effluent shall be pumped to anaerobic fixed film digester from feed tank. Major part of organic

load shall be removed here. The anaerobic organisms will degrade the high concentrated organic

matter present in the effluent. In this digester plastic media is used as a medium for attachment of

microorganisms, which will in turn convert the complex organic matter into simple compounds like

CH4, CO2 & H2O. Outlet from anaerobic digester shall be further treated aerobically. Over Flow

from the anaerobic digester is passed to the biological system i.e. Bio-tower (BT). Bio-tower is

designed as a roughening tower for COD/BOD reduction from the influent. Bio-tower is

constructed with civil columns and beam supports .Bio-tower is filled with PVC structured fill

media .Effluent by gravity collected in the BT sump and effluent recycled to the top with the help

of Bio-tower recycling pump. While sprinkling from the top media attached microorganisms will

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degrade the organic matter as BOD. Part of effluent sent to next stage treatment by recycling

pipeline, Second stage biological system i.e. ASP System.

Activated sludge process system comprises of aeration tank followed by secondary clarifier. In

aeration tank organic load as BOD shall be degraded by the help of cultivated microbial culture.

Constant mixed liquor suspended solids (MLSS) will be maintained in aeration tank in definite

proportions by recycling the bio sludge trapped by the secondary clarifier. At aeration tank air shall

be supplied from air blower to the diffused aeration system. Floating type aerators are also provided

at lagoons for the supply oxygen to microorganisms. From dosing tank, nutrients like nitrogen &

phosphorous shall be added to the effluent at aeration tank in the ratio of BOD: N: P as 100: 5: 1

Recycling of bio-sludge from secondary Clarifier will be done by non clog, centrifugal, semi open

type continuous duty suitable capacity sludge recirculation pumps. The overflow from secondary

clarifier meets the norms prescribed by the Concerned Pollution Control Board for safe disposal.

The excess sludge from the primary settling tank& secondary clarifier shall be withdrawn to

proposed sludge drying beds where sludge get dewatered and dried sludge cakes can be used as a

good manure for gardening.

Outlet from secondary clarifier is collected in Chlorine Contact tank where chlorine Solution is

added to kill pathogen bacteria.

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TECHNICAL

SPECIFICATIONS

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1.0. UNITS & EQUIPMENTS OF E.T.P.

1.1. CIVIL UNITS

SR.NO PARTICULARS QUANTITY

1. Bar Screen Chamber One No.

2. Oil Removal Tank One No.

3. Oil Collection Pit One No.

4. Equalization Tank One No.

5. Lime Dosing Tank One No.

6. Flash Mixer Tank One No.

7. Tube Settler Tank One No.

8. Feed Tank One No.

9. Anaerobic Reactor One No.

10. Bio-Tower One No.

11. Settling Tank One No.

12. Aeration tank One No.

13. Secondary Clarifier One No.

14. Chlorine Contact Tank One No.

15. Sludge Drying Beds Six Nos.

16. Filtrate Chamber Two Nos.

17. Control Panel Room and Lab Two Nos.(1+1)

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1.2. MECHANICAL UNITS / EQUIPMENTS

SR.NO. PARTICULARS QUANTITY

1. Bar Screens Two Nos.

2. Oil & Grease Mechanism One No.

3. Flash Mixers Two Nos.

4. Lime Dosing Pump One No.

5. Tube Deck Media 12 M3.

6. Sludge Removal Pump Two Nos.

7. Floating Aerator Two Nos.

8. Raw Effluent Feed Pumps Two Nos.

9. AR Feed Pumps Two Nos.

10. Bio-Fills 300 M3/ 166 M3.

11. Bio-Tower Recycling pump Two Nos.

12. Settling Tank feed well One No.

13. Air Blowers Two Nos.

14. Diffusers Fifteen nos.

15. Nutrient Dosing System Two Nos.

16. Secondary Clarifier Mechanism One No.

17. Bio-Sludge Recycling Pump Two Nos.

2.0. TECHNICAL SPECIFICATIONS FOR UNITS & EQUIPMENTS

A. CIVIL UNITS

1. BAR SCREEN CHAMBER

Type : Rectangular

Volume : 5.07 M3.

Size : 1400 x 3000 x 1000mm + 300mmFree Board

Construction : RCC

Description : An open Tank with suitable size. Arrangement for bar screen

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fixing MOC of the tank is in complete RCC M20. Internal

water proof plaster and external sponge finish plastering.

External Green colour ISI grade Cement paint two coats.

Internal anti corrosive painting

Quantity : One No.

2. OIL REMOVAL & COLLECTION TANK

Type : Rectangular

Volume : Separation Tank – 27.2 M3

Collection Tank – 1.5 M3

Size : 2000 mm x 8500 mm x 1200 mm SWD + 400 mm FB

1000 mm x 1000 mm x 2000 mm SWD + 500 mm FB

Construction : R.C.C. M20 & MS EP

Quantity : One No.

3. LIME DOSING TANK

Type : Square

Volume : 4.05 M3

Size : 1000 mm x 1000mm x 1500mm SWD + 300 mm FB

Construction : MS EP

Quantity : One No.

4. EQUALISATION & COLLECTION TANK

Type : Rectangular

Volume : 600 M3



Quantity : One No.

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5. FASH MIXER TANK

Type : Square

Volume : 12.167 M3



Quantity : One No.

6. TUBE SETTLER TANK

Type : Rectangular

Volume : 50.4 M3

Size : 4500 mm x 4000 mm x 3000mm SWD + 300 mm FB


Quantity : One No.

7. FEED TANK

Type : Square

Volume : 44.8 M3


Construction : RCC M 20

Quantity : One No.

8. ANAEROBIC REACTOR

Type : Circular, Closed

Volume : 841 M3

Size : 10400 mm x 8900 mm SWD + 1000 mm FB.

Construction : R.C.C M 20

Quantity : One No.

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9. BIO-TOWER

Type : Rectangular

Volume : 384 M3

Size : 8000 mm x 8000 mm x 5500 mm SWD + 1000 mm FB.


Quantity : One No.

10. SETTLING TANK

Type : Circular

Volume : 100 M3

Size : 4600 mm x 2500 mm SWD + 500 mm FB


Quantity : One No.

11. AERATION TANK

Type : Rectangular

Volume : 250 M3



Quantity : One No.

12. SECONDARY CLARIFIER

Type : Circular

Volume : 381 M3

Size : 9000 mm x 2500 mm SWD + 500 mm FB


Quantity : One No.

15

13. CHLORINE CONTACT TANK

Type : Rectangular

Volume : 50.4 M3



Quantity : One No.

14. SLUDGE DRYING BEDS

Type : Square/Rectangular

Total Area : 210M2

Size : 5000 mm x 5000 mm x 1400 mm

Construction : BBM

Quantity : Six Nos.

15. FILTERATE CHAMBER

Type : Rectangular

Volume : 9 M3

Size : 1500 mm x 1500 mm x 2000 mm


Quantity : Two Nos.

B. MECHANICAL UNITS

I. BAR SCREEN

Application : Screening floatable solids

Location : At Screen Chamber

Type : Manual

Tank Size : 1400 x 3000 x 1000 mm + 500 FB

MOC : MSEP

16

Quantity : One No.

II. OIL & REMOVAL MECHANISM

Application : To Trap Oil & Fat

Location : Oil & Fat Removal tank

Type : Semi automatic & scraping type

Tank Size : 4.5 x 4.0 x 2.5 mm SWD + 0.3 FB

Rated Power : 0.5 HP

Make : Gaitsu

Quantity : One No.

III. FLASH MIXER

Tank Size : 1500 x 1500 x 1500 mm SWD + 300 mm FB

Speed : High

Drive : 1.0 HP

Quantity : Two Nos.

IV. LIME DOSING PUMP

Application : Dosing of Lime

Location : Flash Mixer tank

Capacity : 0-500 LPH

Drive : 0.5 HP

Make : Positive Metering

Quantity : One No.

V. TUBE DECK MEDIA

Model : PVC CD TS60

MOC : UV Stabilized virgin PVC Base

Structure : Hexagonal

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Colour : Black

Height of media : 750 mm

Working Temp. : 55 0C

Quantity : M3

Make : Cooldek

VI. SLUDGE REMOVAL PUMP

Application : Sludge Removal from TST

Location : At TST

Capacity : 20 M3/Hr

Head : 10 mtrs.

MOC of Pump : CI

Drive : 3 HP

Motor Make : Siemens

Pump Make : Johnson

Accessories : Fabricated MS base-plate, coupling guard.

Quantity : Two Nos

VII. FLOATING AERATOR

Application : Mixing & homogenization

Location : At Equalization tank

Type : Slow speed

Shaft : Fully mechanized MS solid shaft with FRP coating or epoxy

Painting

Base : Fabricated & mechanized base frame

Impeller : Inverted cone type world renowned SIMCAR design with non

Clogging blades .The impeller is mechanized at centre.

Impeller MS with FRP coating or epoxy painting.

Floats : FRP coated floats with necessary hooks and nylon ropes.

Wetted Parts : FRP coated /lined of Epoxy painting.

Geared Motors : Bonfligliloli / Elicon & Siemens /Equaliser

Rated Power : 7.5 HP

Quantity : Two Nos

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VIII. RAW EFFLUENT FEED PUMP

Application : Raw effluent feed to FMT

Location : At Equalization Tank

Capacity : 42M3 /Hr.

Head : 15 mtrs.

MOC of pump : CI

Pump internals : SS

Drive : 7.5 HP


Pump Make : Johnson

Accessories : Fabricated MS base plate. Coupling guard foundation bolts

etc.

Quantity : Two Nos.

IX. AR FEED PUMPS

Application : Effluent to the Anaerobic Reactor

Location : At Feed Tank

Capacity : 20M3 /Hr.

Head : 10 mtrs.

MOC of pump : CI

Pump internals : SS

Drive : 3.0 HP


Pump Make : Johnson

Accessories : Fabricated MS base plate. Coupling guard foundation bolts

etc.

Quantity : Two Nos.

X. BIO-FILLS

Application : Medium for bacterial attachment and it increases the

Contact Time

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Location : Biotower

MOC : PVC

Specific surface area : 93M2/M3

Void Ration (M2/M3) : More than 97%

Thickness : 0.6mm & 0.3mm

Standard Dimensions : 1200 x 600 x 600mm

Max. width of support: 100/150mm

Dry weight : 30kg/m3

Make : Cooldeck / Equivalent

Quantity : 166 M3 & 300 M3Hr.

XI. BIO-TOWER RECYCLING PUMP

Application : Recycling at Bio-tower

Location : At Bio-tower

Capacity : 60M3/Hr

Head : 10 mtrs.

MOC of Pump : CI

Drive : 7.5 HP


Pump Make : Johnson

Accessories : Fabricated MS base plate, coupling, foundation bolts etc.

Quantity : Two Nos.

XII. SETTLING TANK FEED WELL

Application :

Location : At Settling Tank

Tank Size : 4600 Dia x 2500 mm + 500 mm FB

MOC : MS epoxy painted.

Type : Vertical, Cylindrical

Quantity : One No.

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XIII. AIR BLOWERS

Location : Near Aeration Tank

Medium Handled : Air

Make : Everest/ Usha/ Equivalent

Air Flow : 300M3/hr

Delivery Pressure : 0.45kg/cm2

Duty : Continuous

Cooling : Air Cooled

Motor HP : 10 HP

Accessories : All accessories as per requirement

Quantity : One No.

XIV. DIFFUSERS

Type : Membrane type air diffuser

Construction : The diffuser is a single piece injection

Moulded poly propylene body. A membrane

sleeve surrounds the moulded tube an is kept in

position by two stainless steel clamps. The design of

the membrane sleeve prohibits clogging of the pores which

are self cleaning when air flow/pressure is interrupted .

Make : Rehau, Germany/Equivalent

Distribution : Air distribution channel extending over the

Effective length guarantees an even distribution of air

Quantity : 25 Nos.

XV. NUTRIENT DOSING SYSTEM

Application : Dosing of Lime

Location : Flash Mixer tank

Capacity : 0-100 LPH

Drive : 0.5 HP

Make : Positive Metering

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Quantity : Two Nos.

XVI. SECONDARY CLARIFIER MECHANISM

Application : To scrap the settled sludge at the bottom of the

clarifier & to collect the sludge in centre

Location : At secondary clarifier

Size : Suitable to10000mm dia tank.

Access Bridge : The full span structural bridge 1000mm support at

centre &5mm thick plate upto railing centre to with

hand railing

Drive : Centre drive

Gearbox/Motor : Elicon/Siemens/Equivalent

Scraping : MS epoxy painted the centre pipe having two

Scraper arms with neoprene rubber squeezes. The floor is

scrapped twice on revolution to collect sludge at the centre.

Feed Well : MS epoxy painted feed well supported from

the bridge with baffle plate

Painting : All wetted parts will be one coat of epoxy Primer & two

coats of epoxy paints & other parts are two coats of enamel

paints. The scraper arms lifting hand operated mechanism is

provided so that in case over loading the complete assembly

can be lifted manually up to 300mm.

Rated power : 1.0 HP & Gear Box

Quantity : One No.

XVII. BIO-SLUDGE RECYCLING PUMP

Application : Recycling sludge at clarifier

Location : At secondary clarifier mechanism

Capacity : 45M3/Hr

Head : 10 mtrs.

MOC of Pump : CI

Drive : 5 HP

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Pump Make : Johnson

Accessories : Fabricated MS base plate, coupling, foundation bolts etc.

Quantity : Two Nos.

3.0 ELECTRICAL LOAD LIST

Sl. No. PARTICULARS Quantity Each

Load as HP

Total

Load as HP

1. Oil & Grease Removal Mechanism 1 0.5 0.5

2. Flash Mixer 1 1.0 1.0

3. Lime Dosing Pump 1 0.5 0.5

4. Sludge removal Pumps (1W+1Sb) 2 3.0 6.0

5. Floating Aerator 2 7.5 15.0

6. Raw Effluent Feed Pump 2 7.5 15.0

7. AR Feed Pump (1W+ 1Sb) 2 3.0 6.0

8. BT Recycling Pump (1 W+1Sb) 2 7.5 15.0

9. Air Blowers (1W+1Sb) 2 10.0 20.0

10. Nutrient Dosing Pumps 2 1.0 1.0

11 Secondary Clarifier mechanism 1 1.0 1.0

12. Bio-Sludge Recycling Pump 2 5.0 10.0

Working Load : 47.5 H.P (62.7 KW)

Total Load : 91.0 H.P (121.3 KW)

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PROCESS START-UP

&

CONTROL

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PROCESS START-UP and CONTROL

As the effluent does not contain organisms to stabilize the Organics present in the effluent it is

necessary to develop sufficient microbial mass or activated sludge in the aeration tank.

PRE-COMMISSIONING TESTS

The process is to be started with properly prepared cow dung solution for the microbial growth.

Addition of sewage directly also help for the growth of bacteria.

Before a new plant is commissioned it is necessary that all operational and maintenance personnel

should understand the function and location of each process unit, mechanical equipment and

rooting of the pipelines. Following checks should be made before the commissioning of the plant.

All the mechanical equipments are to be tested for good working condition, properly

lubricated.

All the tanks and piping are to be clean to ensure from any chocking.

All the process units and mechanical Equipments should be tested with water for any

leakages and load testing of equipments including motor directions.

Check all the instruments for normal operation.

Check all the interlocks if any for proper tripping.

ROUTINE INSPECTION

Remove accumulation of foreign material from the inlet channel and outlet overflow weirs

regularly.

All the vertical walls and channels should be cleaned regularly.

All the mechanical equipment should be inspected regularly for oil levels in the gearboxes

and for any abnormal sound and vibrations. Foundation bolts and coupling bolts are to be

checked.

Inspect sludge collection and other equipments annually for the induction of corrosion.

Check the alignment of equipments incase of any noise or foul operation.

Check oil & grease for equipments25

EMERGENCY INSPECTION

In case of serious problem with any unit, feeding should be stopped immediately to that unit.

Remove all the waste water from the unit and inspect carefully the structure, unusual deposition if

any and all moving parts of the equipments. Once the inspection is completed run the equipment in

idle condition and check for any abnormalities. Once it is clear the equipment can be taken back in

to operation.

PLANT START UP

Before starting the plant, it is essential that performance of the equipments shall be checked for

proper functioning and for any equipment abnormalities.

a. No Load Run of Motors

This is required to be carried out to ensure that the motors are running smoothly without any

problems. To carry out the inspection of motors, disconnect the coupling/belts. Then the motors

shall be kick started and stopped to observe their direction of rotation. If the direction is anti-clock

wise the terminal box shall be opened to change the phase connections. The motors shall run for

about 30 min on no load to check for any abnormality. During this run, one shall observe no load

current of motors, vibrations, noise and bearing temperature for signs of any defects. If no

abnormality is observed, then motors shall be coupled with equipments for testing on onload. If

any defect is observed immediately inform to the supplier/manufacturer for repair/replacement of

the motor.

b. On Load Trail

All the equipments shall be tested onload with normal water before admitting effluent in to the

system. If any abnormality is observed, it shall be taken care before admitting the effluent. During

trial runs with water, motor load and temperature, bearing conditions and vibrations shall be

observed.

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c. Plant Shut Down

In case plant needs to be shut down for a considerable period of time, following should be

observed.

Effluent feed shall be stopped to ETP and divert the flow to stand by storage tanks as per

requirement. All the effluent from the system shall be pumped out/drained and all the tanks shall be

cleaned/washed.

PROCESS

The following procedure shall be followed for starting up the biological system:

Aerobic System

Aerobic reactor shall be filled with reactor. Sufficient culture (Sludge or cow dung solution) shall

be added. Aeration shall be started with blowers to provide oxygen to the attached microorganisms.

Initially feed shall be started with 2% and wait for 3 days. The condition shall be observed for a

positive response then increase the feed to 5%. Then wait for another 3 days and gradually increase

the feed rate@10% for every 3 days. During this process bacterial growth should be checked

regularly and if any abnormalities are observed immediately feed shall be stopped for some time

and observe the conditions if conditions get stabilized admit the effluent. MLSS and SVI shall be

monitored regularly. Air blowers should run continuously. Once the growth is observed feed the

nutrient as per required.

Anaerobic System

Anaerobic reactor shall be filled with reactor. Sufficient culture (Sludge or cow dung solution) shall

be added. Aeration shall be started with blowers to provide oxygen to the attached microorganisms.

Initially feed shall be started with 2% and wait for 3 days. The condition shall be observed for a

positive response then increase the feed to 5%. Then wait for another 3 days and gradually increase

the feed rate@10% for every 3 days. During this process bacterial growth should be checked

regularly and if any abnormalities are observed immediately feed shall be stopped for some time

and observe the conditions if conditions get stabilized admit the effluent. MLSS and SVI shall be

27

monitored regularly. Air blowers should run continuously. Once the growth is observed feed the

nutrient as per required.

Asp Process Control

Activated Sludge Process comprises of Aeration tank followed by Secondary Clarifier, which shall

be proposed to meet the requirements. In aeration tank organic load as BOD will be degraded by

the help of cultivated microbial culture. Constant Mixed Liquor Suspended Solids (MLSS) shall be

maintained in aeration tank in definite proportions by recycling the bio sludge trapped by the

secondary clarifier. At aeration tank air supplied from air blower/diffused aeration and also floating

type aerators shall be provided to supply oxygen to microorganisms.

From dosing tank, nutrients as Nitrogen & Phosphorous shall be added to effluent at Aeration Tank

at the ratio of BOD: N: P as 100: 5: 1

Recycling of bio-sludge from secondary clarifier shall be done by non-clog, centrifugal, semi open

type continuous duty & suitable capacity sludge re circulation pump. The overflow from secondary

clarifier –II shall be collected in supernatant tank where chlorine solution shall be added to kill

pathogenic micro-organisms. From here effluent fed to Duel media pressure filter with the help of

pressure pumps to trap suspended solids and connected to Activated Carbon Filter to remove

odour, residual chlorine etc. Outlet from carbon filter shall be treated water & collected in polishing

pond. Treated water meets the norms prescribed by the pollution control board for safe disposal for

on land irrigation / green development.

The excess sludge from DAF, Primary & Secondary Clarifiers shall be withdrawn by gravity to

sludge drying beds for dewatering. Dewatered and dried sludge cakes shall be used as good

manure.

Constant Solids or MLSS

MLSS should be determined by taking a representative sample at three or more locations in the

aeration tank, so that it represents the mixed liquor in the tank.

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F/M ratio

Load is measured by BOD or COD tests. COD test needs shorter time than that of BOD test. Once

in the laboratory COD/BOD ratio is established by a series of daily experiments for a period of one

month or so, BOD can also be calculated by the ratio of COD/BOD.

Micro organisms are measured as MLVSS (Mixed Liquor volatile suspended solids). However

MLSS can also be used.

Measuring MLSS is an even cruder approximation of the living organic matter than measuring

MLVSS

MLVSS is normally 70-80% of the MLSS. The following data is required to calculate F/M ratio.

BOD concentration, mg/l in waste water flowing to the aeration tank

Q, flow rate, m3 /day

MLVSS in mg/l

The following formula is used to calculate F/M ratio

F/M ratio = (BOD, mg/l) * (Q, m3/day)

(MLVSS, mg/l) * V, m3

Where, V = aeration tank volume, m3

SLUDGE VOLUME INDEX (SVI)

Settled sludge volume reading

SVI = on 1 liter graduated cylinder

After 30 minutes X 1000

MLSS concentration

SVI range usually 100 to 150: although higher values may provide good plant operation

Any changes in SVI reading are more important than the reading itself.29

If the SVI increases, this means slower settling and it could indicate

- A decreasing sludge age

- Presence of filamentous organisms

- Or changing whether conditions.

SVI can be decreased by reducing by draining of the sludge.

If the SVI decreased (less than 100), there will be pin point flock in the supernatant. This is small

flow that is left behind the rest of sludge settled too fast. It is called stragger floc.

Settling Tank – Sludge Return

Settling tank serves a dual purpose in the activated sludge process; viz. it provides a clarified

effluent and it also concentrates the MLSS for its return to aeration tank.

To ensure that settling tank is working effectively.

Check F/M ratio. BOD and COD test results from samples taken over several days should

be used for calculation.

Compare the F/M ratio with obtained in the past and watch for changes.

Check oxygen uptake rate. If it is increasing or decreasing, change RAS (Return Activated

Sludge).

Changes in RAS must be gradual.

Return of Activated Sludge

RAS is determined using solid balance equation.

RAS = Plant flow X MLVSS

Return solids – MLVSS consent

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PREVENTIVE

MAINTENANCE

31

PREVENTIVE MAINTENANCE

EMERGENCY INSPECTION

In case of serious problem with any unit, feeding should be stopped immediately to that unit. Drain

all the waste water from the unit and inspect carefully the structure, unusual deposition, each and

every part, mechanical equipment attached to that unit, etc. All the mechanical equipment should

be made in good working condition. The unit should be cleaned properly before making the same

operational again.

PREVENTIVE MAINTENANCE

The main purpose of preventive maintenance is to avoid break-downs of equipments so as to

minimize the shut down timings. The preventive maintenance shall help in reducing the cost of

break-downs and operational time.

Preventive maintenance of equipment supplied is to be carried out as per the manufacturer’s

operation manuals for this equipment. Specific guidelines for preventive maintenance for major

equipment are suggested in the table below. These guidelines should be adhered wherever

applicable.

PREVENTIVE MAINTENANCE SCHEDULE

Sr.

No

Equipment Maintenance Frequency

01. Centrifugal

Pumps

a. Alignment Check

b. Oil Check / Refill

c. Gland Tightening/ Replacement

d. Chocking Clearance

At Commissioning Stage /

Quarterly

Weekly

Weekly

Quarterly / Monthly / As

Required

02. Air Blowers a. Alignment Check

b. Oil Check / Refill

c. V–Belt Tightening/Replacement

d. Suction Filter Cleaning

At Commissioning Stage /

Monthly

Weekly

Weekly

32

Monthly / As Required

03. Dosing

Tanks

Emptying and Cleaning Quarterly

04. Electrical

Connections

Routine Check Half Yearly

All butterfly valves shall be lubricated and operated regularly for easy operation.

In case of any abnormal sound, vibrations, temperatures in rotating equipment, the same

shall be stopped immediately and check for gear box oil level, bed and foundation bolts,

coupling bolts and Impeller/rotors conditions.

Plant operator shall monitor the amperage/low voltage regularly and motors may be stopped

in case voltage falls below 380.

Spare parts for the equipment that are recommended by the manufacturer shall be kept in

stock for ready use.

33

DRAWINGS

34

LIST OF DRAWINGS ENCLOSED

1. ETP Process Flow Diagram

2. ETP Layout Diagram

3. P & I Diagram

35