Report OF Sewage Treatment Plant

7/27/2019 Report OF Sewage Treatment Plant

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A REPORT

ON SEWAGE TREATMENT

PLANT

( INDUSTRIAL VISI T)


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The objective of sewage treatment is to produce a disposable effluent without causing harm to

the surrounding environment, and prevent pollution. Sewage treatment is the process of

removing contaminants from wastewater and household sewage, both runoffs (effluents),

domestic, commercial and institutional. It includes physical, chemical, and biological processes

to remove physical, chemical and biological contaminants. Its objective is to produce an

environmentally safe fluid waste stream (or treated effluent) and a solid waste (or treated

sludge) suitable for disposal or reuse (usually as farm fertilizer). Using advanced technology it

is now possible to re-use sewage effluent for drinking water.

USB TECHNOLOGY

I nlet chamber-This chamber is the main inlet chamber in which 1/3rd

of the sewage waste of

Ludhiana is being supplied, which has a 96 depth.

A scale is there to measure the level of the water.

ScreeningThe influent sewage water passes through a bar screen to remove all large objects

like cans, rags, sticks, plastic packets etc. carried in the sewage stream. There are two types of

screening i.e Manual Screening & Mechanical Screening.


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Manual screening

In manual Screening the solid waste which are trapped in this screen (in the pic.) is being

cleaned by the helpers using some tools.

Mechanical Screening- The raking action of a mechanical bar screen is typically paced

according to the accumulation on the bar screens and/or flow rate. The solids are collected and

later disposed in a landfill, or incinerated. Bar screens or mesh screens of varying sizes may be

used to optimize solids removal. If gross solids are not removed, they become entrained in pipes

and moving parts of the treatment plant, and can cause substantial damage and inefficiency in

the process.


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Pumping station.-This Sewage Treatment plant consist of 10 pumps , in which 5 pumps works

each on mechanical & manual

In the picture five pump can be seen (one sided) from where water is being pumped.

MEP ROOM- Main Electric Panel Room, where all the pumping pressure is being checked &

controlled.


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These pumping station pump the water to a desired place.

Secondary screeni ngAgain a screening is being done.Clarifiers and mechanized secondary

treatment are more efficient under uniform flow conditions. Equilisation basins may be used for

temporary storage of diurnal or wet-weather flow peaks. Basins provide a place to temporarily

hold incoming sewage during plant maintenance and a means of diluting and distributing batch

discharges of toxic or high-strength waste which might otherwise inhibit biological secondary

treatment (including portable toilet waste, vehicle holding tanks, and septic tank pumpers). Flow

equalization basins require variable discharge control, typically include provisions for bypass


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and cleaning, and may also include aerators

.ERP-It is made of glass cloth, which has less effect of scotching heat as well as cold weather.

These pipes contract as well as expand, which is useful for long run in the treatment plant. It

consist

Of 12 V cut notches (12 pipes), has a depth of 6.3 m and a size of 30*32m.

GAS PRODUCTION- Gas is being produced in the sewage water treatment plant, 200-300

meter cube per hour.


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.The above picture shows the gas tank holder.This treatment works for 24 hours which can fill

upto 3000 cylinder gas but unfortunately these gases are not being used for any useful purpose.

This gas is being exhausted in theair in the form of fire, which consist of only methane gas

Preaeration-


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The wastewater is aerated by air pumped through perforated pipes near the floor of theTanks. This aeration makes the water less dense, causing the grit to settle out. As the air jets are

Positioned such that the water is swirling as it moves down the tanks the suspended solids are

Prevented from settling out. The air also provides dissolved oxygen for the bacteria to use laterIn the process, but the wastewater is not in these tanks long enough for bacterial action to occur

Here. The grit is collected in hoppers and washed, after which it is used for on site land

reclamation and landscaping..

Odour control

In the absence of adequate oxygen bacteria in the wastewater break down essentially odourfree

compounds to odorous compounds: fats and carbohydrates go to alcohols, esters,


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aldehydes and carboxylic acids while proteins go to ammonia, amides, mercaptans and

hydrogen sulphide. All of these compounds can give off strong smells, but those formed

from protein degredation can emit very intense smells at concentrations in the parts per

billion range.The foul air containing these compounds is mostly formed in the pretreatment and primary

treatment phases. For this reason, the equipment used in these phases, as well as the fixedgrowth reactors and the sludge dewatering plant, are roofed over and the gases produced inthese areas are removed using extractor fans.

Ultraviolet (UV) light can be used instead of chlorine, iodine, or other chemicals. Water is being

kept undisturbed in order to settle down particle as well as to kill the germs and micro

organisams.

Because no chemicals are used, the treated water has no adverse effect on organisms that later

consume it, as may be the case with other methods. UV radiation causes damage to

the genetic structure of bacteria, viruses, and other pathogens, making them incapable of

reproduction. The key disadvantages of UV disinfection are the need for frequent lamp

maintenance and replacement and the need for a highly treated effluent to ensure that the target

microorganisms are not shielded from the UV radiation (i.e., any solids present in the treated

effluent may protect microorganisms from the UV light)


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.UV light is becoming the most common means of disinfection because of the concerns about the

impacts of chlorine in chlorinating residual organics in the wastewater and in chlorinating

organics in the receiving water.

SBR-The Sequencing Batch Reactor (SBR) is one of the technological method used in the sewage

treatment plant. One of the obstacles in the acceptability of SBR process has traditionally been

the need for precise, automated and reliable control of various stages of the process. Recent

developments in the programmable logic controller (PLC) technology, however, have made thecontrol of an SBR process readily achievable. The SBR process is an activated sludge process in

which the sewage is introduced into a Reaction Tank (or SBR Tank), one batch at a time alsoknown as grid chamber i.e grid chamber 1 & 2.The Coarse Screen Chamber is provided ahead of sump. Screens will be provided in the Coarse

Screen Chamber to screen the raw influent. Necessary hand

operated sluice gate shall be provided to isolate the screen when it is under maintenance. The

Screened sewage is then allowed to flow to the Raw Sewage Collection Sump. The detentiontime stipulated as per the tender is adopted for the hydraulic design of wet well. The necessary


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pumps will be provided to pump the screened raw sewage for further treatment.

. Wastewater treatment is achieved by a timed sequence of operations which occur in the sameSBR Tank, consisting of filling, reaction (aeration), settling, decanting, idling, and sludge

wasting. The various stages in the sequence are as follows:

Stage 1: F il li ng

During this stage the SBR Tank is filled with the influent wastewater. In order to maintain

suitable F/M (food to microorganism) ratios, the wastewater should be admitted into the tank in

a rapid, controlled manner.


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This method functions similarly to a selector, which encourages the growth of certain

microorganisms with better settling characteristics.

Stage 2: Reaction

This stage involves the utilization of biochemical oxygen demand (BOD) and ammonia nitrogen,

where applicable, by microorganisms. The length of the aeration period and the sludge mass

determines the degree of treatment. The length of the aeration period depends on the strength of

the wastewater and the degree of nitrification (conversion of the ammonia to a less toxic form of

nitrate or nitrite) provided for in the treatment.

Stage 3: Settl ing

During this stage, aeration is stopped and the sludge settles leaving clear, treated effluent above

the sludge blanket. Duration for settling varies from 45 to 60 minutes depending on the number

of cycles per day.


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Stage 4: Decanting

At this stage of the process effluent is removed from the tank through the decanter, without

disturbing the settled sludge.

Stage 5: I dling

The SBR Tank waits idle until it is time to commence a new cycle with the filling stage.

Stage 6: Sludge Wasting

Excess activated sludge is wasted periodically during the SBR operation. As with any activatedsludge treatment process, sludge wasting is the main control of the effluent quality andmicroorganism population size.


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This is how the operator exerts control over the effluent quality by adjusting the mixed liquorsuspended solids (MLSS) concentration and the Mean Cell Residence Time (MCRT).

Explanation of cyclic operation:

A basic cycle comprises:

-Aeration (F/A)

A Typical Cycle

During the period of a cycle, the liquid is filled in the SBR Basin up to a set operating waterlevel. Aeration Blowers are started for aeration of the effluent. After the aeration cycle, the

biomass settles under perfect settling conditions. Once Settled the supernatant is removed from

the top using a DECANTER. Solids are wasted from the tanks during the decanting phase.

In this process, the SBR Tank acts as the equivalent of several components in the conventional

activated sludge treatment process, as follows:


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1. Aeration Tank:

the SBR Tank acts as an aeration tank during the reaction stage where the activated sludge is

mixed with the influent under aerated conditions.

2. Secondary Clar if ier: the SBR Tank acts as a secondary clarifier during the settling and

decanting stages where the mixed liquor is allowed to settle under quiescent conditions, and theoverflow is discharged to the next stage of treatment.

3. Sludge Return System:the activated sludge, following settling in the SBR Tank, is mixed with

the influent similar to the sludge return system, except that the feed is transferred to the sludge

rather than the sludge being transferred to the front end of the plant.


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BRIEFLY-

The treatment of wastewater is divided into three phases: pretreatment, primary treatment

and secondary treatment.

Pretreatment

Large solids (i.e. those with a diameter of more than 2cm) and grit (heavy solids) areremoved by screening. These are disposed of in landfills.

Primary treatment

The water is left to stand so that solids can sink to the bottom and oil and grease can rise tothe surface. The solids are scraped off the bottom and the scum is washed off with water

jets. These two substances are combined to form sludge.

Secondary treatment

The sludge is further treated in 'sludge digesters': large heated tanks in which its chemical

decomposition is catalysed by microorganisms. The sludge is largely converted to

'biogas', a mixture of CH4 and CO2, which is used to generate electricity for the plant.The liquid is treated by bacteria which break down the organic matter remaining in

solution. It is then sent to oxidation ponds where heterotrophic bacteria continue the

breakdown of the organics and solar UV light destroys the harmful bacteria.


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The role of the laboratory

A wide variety of analytical tests are used to determine the purity of the wastewater atvarious stages of treatment so that the possibility of harm to either people or the

environment is minimised.

Documents

Report OF Sewage Treatment Plant