by-product plant manual for hrd

BY PRODUCT PLANT & BOD TECHNICAL MANUAL

TECHNICAL MANUAL OF BY-PRODUCT PLANT IN COB # 11 COMPLEX

The objective of By-product plant in COB # 11 is to clean the raw coke oven gas generated from coke oven battery with removal of impurities like tar, ammonia, hydrogen sulphide and naphthalene to the extent as it can be effectively used as fuel. The impurities thus removed from the system are separated in the form of saleable products viz. Crude Coal Tar, Ammonium Sulphate, Sulphur (99% pure) & Naphthalene. The coke oven gas is available at 300C at the outlet of byproduct plant.

The By-product plant consists of following Technological Units.

- Gas condensation/ Tar separation Plant- Gravel Filter Unit.- Stripper-Deacidifier Unit- Ammonia Scrubber & Ammonium Sulphate Plant- H2S Scrubber & Elemental Sulphur Plant.- Naphthalene Scrubber & recovery unit.- Storage

(a) Raw Material /catalyst Storage for

- Sulphuric Acid- Solar Oil- Caustic- Catalyst

(b) Finish Product Storage for

- Coal Tar- Ammonium Sulphate- Naphthalene - Sulphur

The By-product plant is equipped with adequate flexibility from the point of view of design, operation and maintenance. Adequate standby facilities are ensured for uninterrupted and smooth operation of the plant.


Coke Oven

BatteryDown comer

PGC

ETPGas

Exhauster

NH3 Scrubbe

rNaphthalene

Scrubber

NH3/Coal Water

StorageTar

Storage/ Loading StationGravel

Filter Plant

Tar Separation

Plant

Combined

Stripper

Naphthalene

Recovery Plant

Ammonium Sulphate

Plant

Elementary Sulphur Plant

Excess Coal Water

NH3- Flushing LiquorTar +

Liqour

Cond

ensa

te

Coal

W

ater

Stripped Water

Caus

tic

Soda

Deacidified

Water

Enriched Wash Oil

Ste

am

CRUDE COAL TAR

AMMONIUM SULPHATE

ELEMENTAL SULPHUR

NAPHTHALENEC. O Gas

(To Network)

Gas + Liquor

Gas

Effluent Water To BOD

H2S Scrubbe

r

Deacidifier

Enriched WaterStripped

Wash Oil

Tail Gas to

PGC

Vapour Su

lph

uric

Ac

id


GAS CONDENSATION PLANT, TAR SEPARATION PLANT & GRAVEL FILTER

Coke Oven Gas Circuit

(i) Coke Oven Gas (COG) generated from battery gets separated from tar & liquor in downcomer and is sucked by the exhauster through Primary Gas Cooler (PGC) & Electrostatic Tar Precipitator (E.T.P.). In primary gas cooler, gas is cooled indirectly first by cooling water followed by chilled water to 20 to 22 Deg C from about 82 0C (saturated). The primary gas coolers have tubes horizontally placed with certain inclination in a rectangular vertical box. The Coke Oven Gas flows in the shell side and cooling water/chilled water flow in the tube side of PGC. Most of the tar-liquor condensate is separated from C.O.Gas in the PGCs.

Cooling tower & chilled water plant have been installed for catering the requirement of primary gas cooler and Heat-exchangers of other units. The chilled water plant is housed in a separate room. Cooling tower & chilled water plant have standby provision.

System of hot tar-liquor emulsion flushing is there for each PGC for removal of naphthalene deposit on outside of water tubes. Arrangement of LP steam & Nitrogen purging to PGC are also made.

(ii) Electrostatic Tar Precipitator

Electrostatic Tar Precipitators (E.T.P.) is required to remove the remaining tar fog of gas & the same installed before exhauster. Arrangement for removal of deposited tar in the ETP tubes is provided. Insulator boxes are provided with electrical heating arrangement. Inert atmosphere by allowing N2 flow in Insulator boxes is to be maintained

(iii) Exhauster

Electric Motor driven exhauster sucks the coke oven gas leaving ETP and discharge the same with a positive head. The discharge head shall be worked out depending upon the pressure drops in the downstream equipment and desired pressure (700 mm to 1000 mmWG) of CO Gas at the Battery Limit of By-Product. The temperature of CO Gas at the discharge of exhauster should be kept minimum. Suction requirement for upstream of exhauster upto battery is 500 mm WG (indicative).

Tar & Ammoniacal Liquor Circuit

The coke oven gas in Gas collecting main is cooled to 820C by spraying flushing/Ammoniacal liquor. The Ammoniacal Liquor flows in a closed cycle from down comer to Solid Decanter; to Tar Decanter, Coal water tank and then back to Gas collecting


main via Ammoniacal/flushing liquor pump. Part of coal water is used for HPLA system in battery. Excess coal water is sent to Ammonia stripper via Gravel filter.

Major portion of tar content in Coke oven gas is condensed in Gas main by flushing liquor/ Ammoniacal liquor. The tar together with flushing liquor, gas condensate and coal fines from coke oven flowing through gas collecting main goes to solid decanter. The coal fines mixed with tar & flushing liquor is known as sludge. The solid decanter serves to separate sludge from Ammoniacal liquor and tar by settling. Sludge being heavier, settle at the bottom of solid decanter and sludge is continuously scrapped off by scrapping conveyors into barrel/ trolley from where it is removed by a dumper/truck. The Ammoniacal liquor and tar from the decanter overflows into tar decanter. The Ammoniacal liquor from tar decanter goes to gas mains of battery. Part of this liquor is used for HPLA system also. Surplus Ammoniacal liquor is generated due to moisture present in the coal. This excess Ammoniacal liquor is sent to Ammonia stripper via Gravel Filter.

The tar from the tar decanter flows continuously to the Tar Storage Tank for despatch.

Major Technological Equipment/Facilities for Gas Condensation Plant.

This plant comprises of the following major technological equipmentEQUIPMENT CAPACITY

Primary Gas Cooler 2 W + 1 S 24000 Nm3/Hr for Each PGC

Exhauster (650 Kw, 6.6 KV) 1 W + 1 S 47500 Nm3/Hr

Decanter 1 W + 1 SFlushing Liquor Pumps 2 W + 1 S 525 Nm3/HrE.T.P 1 W + 1 S 47500

Nm3/HrCentrifugal Pumps for transferring tar, liquor etc

1 W + 1 S

Tar Storage Tanks 1 W + 1 S 1600 M3Cooling Tower 2 W + 1 SCooling Water Pump 4 W + 3 SChilled Water Plant 2 W + 1 SChilled Water Pump 1 W + 1 S

Gravel Filter 1 W + 1 SHeat Exchanger

To prevent gaseous emission from various vessels, tanks equipment & vents, a suitable pollution control measures are taken.


AMMONIA & H2S REMOVAL AND RECOVERY SECTION

Ammonia & H2S Scrubbing Unit

Coke oven gas which is pressurized by Exhauster is sent to the inlet of the H2S scrubber. The lower section of H2S Scrubber is designed for final cooling stage to remove the temperature increased in exhauster. By means of a cooling loop comprising of cooling stage pumps & cooling Heat Exchanger in which circulating liquor is cooled by chilled water & the gas is cooled to a temperature of 20-220C.

The upper section of H2S scrubber is used to absorb the major amount of H2S. The absorption of H2S is performed by using NH3 which is included in the Coke Oven inlet Gas and which is offered additionally by feeding of ammonia rich solution from ammonia scrubber & lean solution from Deacidifier.

As the absorption of NH3/ H2S is exothermic in nature, the temperature of the outgoing gas is not allowed to increase by means of cooling heat exchanger. Further removal of H 2S and removal of major portion of NH3 is achieved in NH3 scrubbing system by means of stripped ammonia liquor.

Ammonia stripping & Deacidification Unit

The stripping columns is divided into two parts, free ammonia stripping process takes place in upper part and in the lower part decomposition of fixed ammonia takes place by means of caustic solution. The upper part of the column receives the deacidified solution from deacidifier & coal water (excess flushing liquor) from gravel filter unit after pre heated by outlet liquor of column. The stripped off NH3 enter the deacidifier.

The deacidifier strips off NH3, H2S, CO2, HCN from the rich solution received from H2S scrubber. These vapours from the deacidifier shall enter to the Ammonium Sulphate plant after proper cooling.

Ammonium sulphate production through Bubbler type saturator route

Ammonia, Hydrogen sulphide gas, CO2 & HCN from deacidifier is led to Saturator where Ammonia is recovered in the form of Ammonium sulphate. Ammonia and H2S enters in saturator from top and bubbles through a bath of mother liquor where a constant acidity is maintained by continuous addition of sulphuric acid. Sulphuric acid is stored in separate storage tanks. The sulphuric acid is fed to the saturators by gravity from overhead tank. Sulphuric acid is pumped to the overhead tank from ground level storage tank. The mother liquor is kept under constant circulation by centrifugal pumps to maintain uniform bath acidity and obtain uniform well developed crystals from the Saturator. From the Saturator the Hydrogen sulphide with HCN & CO2 enters the acid catcher, where the liquor droplets entrained in gas is removed. Ammonium sulphate crystals produced in the Saturator is


ejected out together with mother liquor to the crystal receiving tank. Ammonium sulphate slurry flows from crystal receiving tank by gravity to the centrifuge continuously for the separation of mother liquor and salt. Ammonium sulphate from the centrifuge is conveyed by belt conveyors to the dryer. Drying of ammonium sulphate is carried out in a stainless steel rotary drier by means of hot air operating with steam and through forced draft fans. From the drier, spent hot air with entrained dust particles is extracted by suction fan through cyclone separator and wet scrubbing unit to remove the fine ammonium sulphate salt before venting to atmosphere. Ammonium sulphate is transferred to the bagging bunker by a bucket elevator. Dried ammonium sulphate is bagged, weighed in automatic bagging and weighing machine and then sent to storage or dispatched by rail and road. The provision for both railway wagon loading and road truck loading are kept. Mechanized system for loading of bags is provided.

The Saturator, acid catcher and mother liquor tanks is of special steel alloy as per DIN 1.4465 or similar in order to resist corrosion. All process pumps are of Alloy-20 construction.

Sulphur Recovery Unit

H2S/HCN/CO2 vapor coming from drop separator (acid catcher) of saturator enters to Catalytic Oven Reactor for burning.

The operation of the cracking reactor is characterized by partial burning of sour gas with air to provide the required temperature for the catalytic cracking stage. Most of the nitrogen compounds are burnt and reduced to elemental nitrogen and passes the catalyst bed to crack the remaining ammonia and hydrogen cyanide.

Process gas leaving the catalytical area is post-burnt by providing secondary air, so that the required ratio of SO2/ H2S is adjusted before the gas is cooled in the waste heat boiler system (Process Gas Cooler). At the same time the first portion of elementary sulphur is generated, which is separated in the outlet area of the boiler.

The boiler is used to cool the process gas down to 250 to 2800C. A partial flow is taken between the Crack-Reactor and the boiler and mixed with the outlet of the LP boiler to obtain the correct inlet temperature for the Claus reactor. The boiler is equipped with an internal sulphur separator, where the liquid sulphur that has been built, is separated from the process gas.

The process gas leaving the boilers is directed to the first of two claus reactors. Both reactors are filled with alumina based catalyst. The conversion of sulphur dioxide and hydrogen sulphide to sulphur takes place by the selected temperature of 2500C.

As the claus reaction is of exothermic natures, the process gas is cooled after the 1st claus reactor stage in the Sulphur Condenser, followed by a sulphur separator and directed to the 2nd claus reactor stage. Before the process gas is led into the 2nd claus reactor stage, it is re-heated to enter the claus reactor with the required temperature.


The process gas, leaving the 2nd claus reactor stage is also cooled in the sulphur condenser, released from liquid sulphur in the 2nd sulphur separator and directed as tail gas to the crude gas main ahead of the primary coolers. By this mode of operation the combined process is free from emissions.

The following reactions take place during the process.NH3 + O2 (N2) + H2O

HCN + O2 (N2) + H2O + CO2

H2S + O2 SO2 + H2ONH3 N2 + (H2)

HCN + H2O N2 + (H2) + (CO)H2S + O2 SO2 + H2O + 519 KJ

2H2S + SO2 3/x Sx + 2H2O + 147 KJH2S + O2 SO2 + H2O + 519 KJ

2H2S + SO2 3/x Sx + 2H2O + 147 KJ

The produced liquid sulphur from the boiler, the sulphur condenser and the two sulphur separators is led via a sealing pot to a storage tank to process further for producing Sulphur blocks.

Major Technological Equipment/Facilities

EQUIPMENT CAPACITYNH3 and H2S Scrubbing Unit

H2S Scrubber 1 W 47500 Nm3/Hr Gas Processing

NH3 Scrubber 1 W 47500 Nm3/Hr Gas Processing

Enriched water Pumps 1 W + 1 SPre Enriched Water Pumps 1 W + 1 SInternal Cooling Pump 1 W + 1 SFinal Cooling Pump 1 W + 1 SEnriched water Tank 2 WHeat Exchangers 6 W + 3 S

Ammonia stripping & Deacidification UnitDe acidifiers 1 W + 1 SCombined Stripper 1 W + 1 SDeacidifier Discharge pumps 1 W + 1 SStripper Discharge Pumps 1 W + 1 SStripped water Tank 1 WStripper water pump 1 W + 1 SDeacidfier Water Tank 1 WDeacidifier Water Pumps 1 W + 1 SStripped waste Water Tank 1 WStripped waste water pumps 1W + 1 SHeat Exchangers 8 W + 8 S


Ammonia Recovery PlantSaturator with acid Catcher 1W + 1 SThickener 1 WCentrifuge 1W + 1 SSal conveyor system 1WBagging system 1WMother liquor pumps 1W + 1 SWet Scrubbing system 1WSeal pot 1W

Sulphur Recovery UnitCatalytic Oven Reactor 1 WClaus reactors 2 WProcess Gas Cooler 1 WSulphur Condenser 1 WProcess Gas Heater 1 WCOG Blower 1W + 1 SAir Blower 1W + 1 SVapor Blower 1W + 1 SSulphur Storage Tank 1 WSulphur Drain Pumps 1W + 1 SSulphur Solidification Unit 1 W

NAPHTHALENE RECOVERY AND REMOVAL SECTION

Naphthalene Scrubber

The Coke oven gas from H2S and NH3 scrubbers is taken to Naphthalene scrubber for naphthalene recovery to the extent of 0.05 gm/Nm3 max. Most part of Naphthalene in CO gas is separated out with tar in Hydraulic mains of coke oven battery, Primary Gas Cooler and the remaining portion in Naphthalene scrubber. The scrubber is packed with suitable expanded metal packing to provide larger surface area. A measured quantity of makeup solar oil is added to fresh oil tank and proportionate quantity of Naphthalene rich solar oil is removed from the bottom section of scrubber to storage tank. Rich solar oil is sent to Naphthalene stripping section for recovery of naphthalene by steam stripping and to get lean solar oil for further use in scrubber.

Naphthalene Stripping

A portion of Naphthalene rich solar oil is discharged continuously from the scrubbing unit to storage buffer tank. The rich solar oil is fed continuously to the Naphthalene Stripper.

The Naphthalene rich solar oil fed to the Naphthalene stripper where naphthalene is stripped off by steam. Almost naphthalene free solar oil is taken out from stripping column for reuse in Naphthalene scrubber after proper cooling.


The vapour coming out from Naphthalene stripper contains Naphthalene with oil & water vapour which is condensed in water cooled condenser. Naphthalene rich oil getting separated from water in a separator is allowed to cool in water jacketed Naphthalene tray. Naphthalene crystallises by indirect cooling. The oil content in the Naphthalene is 1 % max. Contaminated water from separator goes back to tar separator unit.

Major Technological Equipment/Facilities Naphthalene Scrubbing unit)

EQUIPMENT CAPACITYNaphthalene Scrubber

Naphthalene Scrubber 1 W 47500 Nm3/Hr Gas Processing

Solar Oil Circulation Pumps 4 WEnriched Solar Oil Tank 1 WEnriched Solar Oil Pump 1 W + 1 SStripped Solar Oil tank 1 WStripped Solar Oil Pump 1 W + 1 SFresh Solar Oil Tank 1 WHeat Exchanger 1 W

Naphthalene stripping UnitStripper 1 WWash Oil Stripper 1 WCondenser 1 WSeparator 1 WHeat Exchanger 2 W + 2 S

Technological Parameters:

i) Coke Oven Gas Processing Capacity: 47460 Nm3/hr (Indicative) Including Charging gas and Tail Gas

ii) Design Basis: Following overload factors have been considered:a) Gas Condensation unit consisting of PGC, ETP have 1.15 times of gas

Processing Capacity.b) Exhauster Have 1.15 times of gas Processing Capacity.

c) Other units of by-product plant like H2S, NH3 & Naphthalene Scrubber have 1.07 times of gas Processing Capacity.

d) Gas Velocity in gas line is 16 to 20 m/sec.

iii) Raw Coke Oven Gas temperature at inlet of PGC: 82 0C Max.

iv) Raw Coke Oven Gas Composition & Impurities at the inlet of By-Product Plant (Indicative):

a) Composition of Raw Coke Oven Gas (% by Volume):Hydrogen : 52-59Carbon monoxide : 6-7Carbon dioxide : 3-4Oxygen : 0.3-0.7Methane : 24-28


Nitrogen : 4-7CnHm : 1.5-2.5

b) Impurities of Raw Coke Oven Gas (gm/Nm3):Tar : 100-120Benzol Hydrocarbons : 30-36Hydrogen Sulphide : 3-4Ammonia : 10-12Naphthalene : 8-10

v) Impurities in clean Coke Oven Gas (At the outlet of By-Product plant)Residual Impurities gm/Nm3

Tar : 0.02 (Max.)Hydrogen Sulphide : 0.80 (Max.)Ammonia : 0.03 (Max.)Naphthalene : 0.05 (Max.)Benzol Hydrocarbons : 28-34

vi) Quality of flushing Liquor supplied to Coke Oven Battery.pH : 9-9.5Suspended Solids : <100 ppmPressure : 5-6 kg/cm2

Temperature : 80-82 0C

vii) Yield of Finished Products:Crude Tar : 33.83 kg/TDCAmmonium Sulphate : 15.04 kg/TDCElementary Sulphur : 1.05 kg/TDCNaphthalene : 0.11 kg/TDC

viii) Quality of Finished Product:

i Crude Tar: Moisture Content, : Less than 4 % (Max)Specific gravity at 40 0C : 1.18

ii Ammonium Sulphate : As Per IS 826iii Sulphur : 99 % Purityiv Naphthalene : Purity of Naphthalene (Min.Oil

Content)ix) Chemical Consumptions:

i Sulpuric Acid : 1.55 T/Hrii Solar Oil or Wash Oil : 49 Kg/hriii Caustic Soda : 415 Kg/hr


BOD PLANT OF COB # 11COMPLEX

Effluents generated from the Coke Oven and By Product Plant of COB # 11 Complex are treated at BOD Plant for removal of Ammonia, Phenol, Tar & Oil, Cyanide etc. Treated effluents discharged into the Reservoir No – 2 for internal re-circulation and re-use.BASIC PRINCIPLE OF THE BOD PLANT:

Physical Treatment Chemical Treatment Biological Treatment

(Three Stage Biological System – 1st Stage Activated Sludge Process, Followed by Nitrification and De-Nitrification Processes)

TAR/OIL SEPARATION

TANK

BOD PLANT FLOW DIAGRAMSKIMMED TAR & OIL

SUMP

EQUALISATION TANK WITH SKIMMER

DISSOLVED AIR

FLOATATION UNIT

pH ADJUSTMEN

T TANK-1

AMMONIA STRIPPING

TOWER

SETTLING TANK-II

AERATION TANK-II

SETTLING TANK-I

AERATION TANK-I

AMMONIA FIXING CUM

pH ADJUSTMEN

T TANK

BACTERIAL CULTURE

PREPARATION TANK

SLUDGE SUMP-I

SLUDGE SUMP-II

SLUDGE THICKNER

THICKNED SLUDGE SUMP

SLUDGE DRYING BED

DENITRIFICATION TANK

SETTLING TANK-III

AERATION TANK-III

SLUDGE SUMP-III

SKIMMED TAR/OIL

SKIMMED TAR & OIL TO SLOP OIL TANK

EFFLEUNT

NaOH

MAGNESIUM

CARBONATE

BACTERIAL CULTURE

PREPARATION TANK

TREATED SEWAGE TREATED EFFLUENT

SLUDGE RECIRULATION

SLU

DG

E RE

CIRU

LATI

ON

EXCESSSLUDGE OVERFLO

WUNDERFLOW

UN

DER

FLOW

OVERFLOW

METHANOL

ACIDNUTRIEN

T

EXCESSSLUDGE SLUDGE FOR

DISPOSALTREATED

EFFLUENT FOR DISPOSAL AERATION

TANK 1


MAJOR UNITS OF BOD PLANT: Tar and Oil Separation Unit Equalization Tanks Dissolved Air Flotation (DAF) Unit Skimmed Oil sump pH Adjustment Tank Ammonia Stripping Tower Ammonia Fixing Tank Aeration Tank – I Settling Tank – I Aeration Tank – II Settling Tank – II De-Nitrification Tank Settling Tank - III Aeration Tank - III Sludge Sumps Thickener Sludge Drying Bed Chemical House, MCC Room, PLC Room, Office, Laboratory, Chemical Dosing Units Treated Effluent Collection Sump Slop Oil Tank Biological Culture Tank

TECHNICAL FEATURES Capacity: 40 m3/hr Un-treated Effluents from BPP and COB # 11 and 50 m3/hr Treated Sewage Water from STP.TREATMENT SCHEME: Effluents generated from Coke oven and By-Product Plant (COB#11 complex) contains pollutants such as Ammonia, phenol, Tar & oil, cyanide etc. Main function of BOD Plant is to remove tar and oils by physical and chemical systems and subsequent biological degradation of Phenols , Ammonia and cyanide. Initially effluents are received in tar & oil separation tank. The capacity of the tank is suitable for one hour detention period. The effluent collected in this collection sump pumped to subsequent tar-oil separator. Tar-oil separator unit is provided with skimming facilities. From this unit effluents flow by gravity to equalization tank. The equalization tank capacity with residence time of 24 hours for designed flow of 40 m 3/Hr. The equalization tank consists of three compartments, two compartments each having six hours holding while the third compartment having twelve hours holding capacity. The equalization tank is provided with necessary tar/oil skimming arrangement, and epoxy painting in the inside faces of each compartment. From the equalization tank effluents are pumped to dissolve air floatation unit for removal of emulsified oils. This unit consists of recirculation pump, air compressor and all other required accessories. A skimmed tar & oil sump is also provided for collection and storage of skimmed tar & oil.


Since the skimmed tar & oil contains major portion as water, this skimmed tar & oil is pumped to slop oil tank for separation of water & tar / oil. In the slop oil tank skimmed tar & oil allowed to remain for few days for separation of tar and oil. Tar/oil floating on the top surface is taken out through tapping connection provided for this and sent for secondary use. Water from the bottom of the tank taken out and sent back to the treatment plant.From the dissolved air flotation unit effluents flow by gravity to pH adjustment tank. Alkali is added to raise the pH around 11. This tank is provided with agitator and pH indicating instrument. pH adjusted effluents are pumped to ammonia stripping tower.Stripping of ammonia is carried out in an ammonia stripping tower. The tower is of induced draft cross flow type and provided with suitable packing, effluent distribution piping, collection basin, adequate capacity aeration fan and all other accessories. The ammonia stripped effluents from collecting basin sent to ammonia fixing cum pH adjustment tank. The residual free ammonia is fixed and pH is brought down to neutral pH by addition of sulphuric acid. The tank is provided with agitator and pH indicating instrument. Effluents form ammonia fixing tank are pumped to 1st stage aeration tank i.e. aeration tank-I. Under normal operation condition part of treated effluent or treated sewage water is added at the outlet of ammonia fixing cum pH adjustment tank at the rate of 40 m3/hr before entering into the biological treatment facilities. The aeration tank-I is aerated along with the return sludge by mechanical surface aerator. The tank is made of RCC and necessary arrangements are provided in the tank for receiving the return sludge and required nutrients.The effluents from aeration tank-I flow to settling tank-I where solid particles are settled out. Overflow from settling tank-I flow to aeration tank-II whereas the underflow is taken to sludge sump-I. The settling tank is of RCC construction and provided with necessary scrapping arrangement, overflow weir, inlet and sludge outlet pipes, constant bleed arrangement and all other accessories required. From the sludge sump-I sludge is recirculated to aeration tank 1 and excess sludge is disposed to sludge thickener inlet. The aeration tank-II is used as 2nd stage of the activated sludge process. The tank consists of aerators and other facilities for receiving the return sludge and required magnesium carbonate solution. Bacterial culture tanks provided at the platform of aeration tanks.Effluents from aeration tank-II flow to settling tank-II. The settling tank-II is similar to settling tank-I. Facilities for collecting settled sludge from settling tank-II and pumping it to aeration tank-II & sludge thickener inlet, sump is provided. The nitrified effluents from aeration tank-II flow to nitrification tank. The tank is operated under anaerobic condition. Requisite quantity of methanol is added as carbon source. Effluents from de-nitrification tank flow to settling tank-III. The settling tank-III is similar to settling tank-I. Similar facilities for collecting settled sludge from settling tank-III and pumping it to sludge thickener inlet, sump, and pumps provided. From the de-nitrification tank, effluent flow to aeration tank-III, where surface aerators are provided in the aeration tank to supply required dissolved oxygen in the treated effluent before disposal.A sludge thickener is provided for thickening the excess sludge received from different sludge sumps. The thickener is provided with sludge collection arrangement and all other accessories. The overflow from sludge thickener is fed at the inlet of aeration tank-IThe underflow from sludge thickener is collected in a thickened sludge sump from where it is pumped to sludge drying bed unit for dewatering of the sludge.


DESIGN SPECIFICATION:

Inlet Concentration Outlet ConcentrationpH 7.5 to 9.0 6.0 to 8.0Temp. 50 - 60 Deg. C Ambient TempPhenol 500 mg/l 1 mg/lCyanides 50 mg/l 0.2 mg/lTar & Oil 100 – 350 mg/l 10 mg/lTotal Ammonia 500 mg/l Ammonical N2 :50mg/lSS - 100 mg/lBOD - 30 mg/lCOD - 250 mg/l


TAR/OIL SEPARATION

TANK

BOD PLANT FLOW DIAGRAMSKIMMED TAR & OIL

SUMP

EQUALISATION TANK WITH SKIMMER

DISSOLVED AIR

FLOATATION UNIT

pH ADJUSTMEN

T TANK-1

AMMONIA STRIPPING

TOWER

SETTLING TANK-II

AERATION TANK-II

SETTLING TANK-I

AERATION TANK-I

AMMONIA FIXING CUM

pH ADJUSTMEN

T TANK

BACTERIAL CULTURE

PREPARATION TANK

SLUDGE SUMP-I

SLUDGE SUMP-II

SLUDGE THICKNER

THICKNED SLUDGE SUMP

SLUDGE DRYING BED

DENITRIFICATION TANK

SETTLING TANK-III

AERATION TANK-III

SLUDGE SUMP-III

SKIMMED TAR/OIL

SKIMMED TAR & OIL TO SLOP OIL TANK

EFFLEUNT

NaOH

MAGNESIUM

CARBONATE

BACTERIAL CULTURE

PREPARATION TANK

TREATED SEWAGE TREATED EFFLUENT

SLUDGE RECIRULATION

SLU

DG

E RE

CIRU

LATI

ON

EXCESSSLUDGE OVERFLO

WUNDERFLOW

UN

DER

FLOW

OVERFLOW

METHANOL

ACIDNUTRIEN

T

EXCESSSLUDGE SLUDGE FOR

DISPOSALTREATED

EFFLUENT FOR DISPOSAL AERATION

TANK 1

by-product plant manual for hrd

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