SEWAGE TREATMENT PLANT

SEWAGE TREATMENT PLANT

FLOW CHART OF THE COMPONENTS OF THE 

 SEWAGE

TREATMENT PLANT VISITED

1.RAW SEWAGE 2.SUMP HOUSE PUMP  3.COARSE BAR SCREEN  4.FINE BAR SCREEN 5.GRIT CHAMBER   6.WET WELL  7.PUMP  8.INLET  9.AERATION (AIR DIFFUSION METHOD 10.SETTLING  11.CHLORINE

ADDITION  12.KHADI

RAW SEWAGE  

Raw sewage is wastewater that has not been treated. It comes from residential properties, like houses and apartments, as well as commercial buildings and industrial and agricultural processes. Essentially, it is the liquid waste that comes from houses and businesses. Not surprisingly, it can contain a wide variety of contaminants and present a health hazard if left untreated where humans or animals can come into contact with it. For example, sewage may overflow from a sanitary sewer after a period of very heavy rainfall.

 Raw sewage often contains urine and feces from toilet flushing as well as other types of human waste; it may also contain such things as toilet paper

SUMP HOUSE PUMP

 Sewage lift/pump stations are used for pumping wastewater or sewage from a lower to higher elevation, particularly where the elevation of the source is not sufficient for gravity flow and/or when the use of gravity conveyance will result in excessive excavation and higher construction costs.

 Sewage lift stations/pump stations may be used as a matter of economics or to overcome inadequate hydraulic head when it is obvious that no other solution is practical. For instance, it may be more economical to utilize a sewage pump station to pump or lift the sewage over a ridge and let it flow by gravity to a sewage treatment plant, or to elevate sewage to pass through a sewage treatment system by gravity.

BAR SCREEN:

A bar screen is a mechanical filter used to remove large objects, such as rags and plastics, from wastewater. It is part of the primary filtration flow and typically is the first, or preliminary, level of filtration, being installed at the influent to a wastewater treatment plant. They typically consist of a series of vertical steel bars spaced between 1 and 3 inches apart

Coarse bar screen

Fine bar screen

GRIT CHAMBER

A chamber designed to remove sand, gravel, or other heavy solids that have subsiding velocities or specific gravities substantially greater than those of the organic solids in wastewater

Pretreatment may include a sand or grit channel or chamber, where the velocity of the incoming sewage is adjusted to allow the settlement of sand, grit, stones, and broken glass. These particles are removed because they may damage pumps and other equipment. For small sanitary sewer systems, the grit chambers may not be necessary, but grit removal is desirable at larger plants.

AERATION (AIR DIFFUSION)

Fine bubble diffusers produce a plethora of very small air bubbles which rise slowly from the floor of a wastewater treatment plant or sewage treatment plant aeration tank and provide substantial and efficient mass transfer of oxygen to the water. The oxygen, combined with the food source, sewage, allows the bacteria to produce enzymes which help break down the waste so that it can settle in the secondary clarifiers or be filtered by membranes. A fine bubble diffuser is commonly manufactured in various forms: tube, disc, plate, and dome.

SETTING TANK

A sedimentation tank allows suspended particles to settle out of water or wastewater as it flows slowly through the tank, thereby providing some degree of purification. A layer of accumulated solids, called sludge, forms at the bottom of the tank and is periodically removed.

Suspended solids present in water having specific gravity greater than that of water tend to settle down by gravity as soon as the turbulence is retarded by offering storage.

Basin in which the flow is retarded is called setting tank.

Theoretical average time for which the water is detained in the settling tank is called the detention period

CHLORINATION

 Water chlorination is the process of adding chlorine or hypochlorite to water. This method is used to kill certain bacteria and other microbes in tap water as chlorine is highly toxic. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, typhoid etc

DETERMINATION OF INITIAL & FINAL SETTING TIMES

DETERMINATION OF INITIAL &  FINAL SETTING TIMES

AIM - To determine the initial and final setting times of cement

IS CODE - IS: 4031 (Part 5) 1988

APPARATUS - 

1. Vicat apparatus conforming to IS: 5513-1976. 

2.Balance of capacity 1kg and sensitivity 1 gram. 

3.Gauging trowel conforming to IS: 10086-1982

DIAGRAM:

PROCEDURE :

1.Unless otherwise specified this test shall be conducted at a temperature of 27 + 20C and 65 + 5% of relative humidity of the Laboratory. 

2.Prepare a paste of 300 grams of cement with 0.85 times the water required to a give a paste of standard consistency IS: 4031 (Part 4) 1988. 

3.The time of gauging in any case shall not be less than 3 minutes not more than 5 minutes and the gauging shall be completed before any sign of setting occurs. 

4.Count the time of gauging from the time of adding water to the dry cement until commencing to fill the mould 

5.Fill the vicat mould with this paste making it level with the top of the mould.  Slightly shake the mould to expel the air. 6.In filling the mould the operator hands and the blade the gauging trowel shall only be used.

Initial Setting Time :

1.Immediately place the test block with the non-porous resting plate, under the rod bearing the initial setting needle. 2.Lower the needle and quickly release allowing it to penetrate in to the mould.  In the beginning the needle will completely pierce the mould

3.Repeat this procedure until the needle fails to pierce the mould for 5 + 0.5mm. 

4.Record the period elapsed between the time of adding water to the cement to the time when needle fails to pierce the mould by 5 + 0.5mm as the initial setting time.

Final Setting Time 

1.Replace the needle of the vicat apparatus by the needle with an annular ring 

2.Lower the needle and quickly release. 

3.Repeat the process until the annular ring makes an impression on the mould. 

4.Record the period elapsed between the time of adding water to the cement to the time when the annular ring fails to make the impression on the mould as the final setting time.

ULTRASONIC PULSE VELOCITY TEST PROCEDURE

ULTRASONIC PULSE VELOCITY METHOD

It is simple and quick test in which pulse velocity is determined passing through concrete.
1. The ultrasonic pulse or waves are generated from pulse generator.
2. These waves transmit through transmitter end into the concrete mass and receive at receiver end as shown in figure.
3. The digital display shows the time required to pass the waves through concrete mass.
4. The pulse velocity is then calculated by dividing path or wavelength by time of travel.
5. The average pulse velocity of wave propagation is calculated by testing concrete at two more locations.

 Depending on pulse velocity, quality of concrete is decided as follows;

Sr. No.	Velocity (Km/s)	Quality of concrete	Comp. Strength (N/mm2)
1 2 3 4	4.0 and above 3.5 to 4.0 3.0 to 3.5 3.0 and below	Very good Good Medium Poor	30-35 25-30 20-25 15-20

REBOUND HAMMER TEST PROCEDURE

Rebound Hammer Test:
i) Initially the plunger of rebound hammer is Kept touching to the target concrete surface
ii) Then the tubular casing of hammer is pushed towards concrete, so that the spring gets wind up around the plunger
iii) Now release the mass attached to plunger using dash pot ,so that hammer will impact on concrete surface and rebound back depending on strength of concrete.
iv) Due to backward motion of hammer, pointer on graduated scale will move in same direction.
v) Observe the distance travelled by pointer/rider on graduated scale as rebound Number.
vi) If this rebound Number is less ,the strength of concrete will be less ,But if it is more ,then concrete possess sufficient strength.