Environmental Engineering – II

Prof. Rajesh BhagatAsst. Professor

Civil Engineering Department

Yeshwantrao Chavan College Of Engineering

Nagpur

B. E. (Civil Engg.) M. Tech. (Enviro. Engg.)

GCOE, Amravati VNIT, Nagpur

Experience & Achievement:

➢ Lecturer, KDKCOE, Nagpur

➢ Lecturer, PRPCOE, Amravati

➢ Assistant Professor, PCE, Nagpur

➢ Assistant Professor, Cummins College of Engg. For Women (MKSSS, Nagpur)

Mobile No.:- 8483002277 / 8483002288

Email ID :- rajeysh7bhagat@gmail.com

Website:- www.rajeysh7bhagat.wordpress.com

➢ Selected Scientist, NEERI-CSIR, Govt. of India.

➢ GATE Qualified Three Times

➢ Selected Junior Engineer, ZP Washim.

UNIT-I

1) Systems of sanitation: Conservancy and water carriage system. Patterns of

sewage collection systems.

2) Quantity of storm water and sanitary wastewater.

3) Hydraulic Design of sewers - capacity, size, grade, shapes and materials.

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UNIT-II

1) Sewer Appurtenances – manholes, street inlets, storm water overflows,

inverted siphons, flushing and ventilation.

2) Construction and Maintenance of sewers, equipment’s for maintenance &

safety equipment’s.

3) Sewage pumping.

4) House drainage systems, sanitary fitting and appliances, traps –function and

types, anti-syphonage, inspection chambers, Storm water drainage.

5) Rain water harvesting for individual houses & Different Methods.

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UNIT-III

1) Characteristics of wastewater.

2) Flow sheet of conventional sewage treatment plant.

3) Preliminary and primary treatment: Screens, Grit chambers, Primary

settling tank. Design of bar screens, grit chambers and primary settling tanks.

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UNIT-IV

1) Secondary Treatment: Principle of Biological Treatment. Activated

sludge process, Trickling Filter – Concept,

2) SD & SDB: Functioning and Basic Load Calculations. Sludge digestion,

Sludge drying beds.

3) Methods of disposal: Disposal on land and in water stream.

4) Self-purification capacity of stream.

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UNIT-V

1) Rural sanitation: Pit Privy, Aqua Privy, Bio-gas Recovery, Eco-Sanitation.

Septic tank including soak pit. Imhoff tanks.

2) Industrial Waste Water Treatment: Basic concepts of Industrial Waste Water

Treatment, flow equalization, neutralization. Common treatment alternatives for

industrial waste water.

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UNIT-VI

1) Introduction to Air Pollution,

2) Meteorological Parameters.

3) Monitoring methods.

4) Techniques of air pollution control.

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References:-

1. B.C. Punmia, Waste Water Engineering, Laxmi Publication

2. S.K. Garg, Environmental Engineering – Vol – II, Standard Publication

3. G.S. Birdie, Water Supply & Sanitary Engineering, Dhanpat Rai Pub Company

4. M.N. Rao & H.V.N. Rao, Air Pollution, McGraw Hill Publication.

5. M.J. Machghee, Water Supply & Sewage, McGraw Hill Publication.

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Construction of Sewer or Procedure for Laying Sewer:

Setting out alignment & gradient:

1) Setting out alignment is carried out starting from their outfall ends towards their starting

points. With this advantage of utilization of the tail sewers even during the initial periods of

its construction is possible.

2) Sewer lines are marked along designed layout routes on ground & pegs at regular interval.

3) The points are located where manholes are required to be constructed as per drawing, i.e.,

L-section of sewer.

4) Temporary benchmark is established with the help of levels.

Excavation of trenches:

1) Trenches are excavated manually or mechanically.

2) The width of trench depends upon the diameter of sewer & depth of sewer line below the

ground level.

3) The width of the trench at the bottom is generally kept 15 cm more than the diameter of the

sewer pipe, with minimum 60 cm width to facilitate joining of pipes.

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Construction of Sewer or Procedure for Laying Sewer:

Timbering of Trenches:

1) In case of loose soil the sides will collapse and hence shoring and strutting is necessary.

2) This is also necessary to prevent caving to reduce danger to workman.

Laying of Pipe:

1) Before laying sewer, it should be checked for any defect.

2) For firm grounds, sewer pipes are not to be embedded in concrete.

3) In ordinary or softer grounds, sewers are laid embedded in concrete.

4) After bedding concrete is laid in required alignment and levels.

5) The sewer pipes are then lowered down in to the trench either manually or with the help of

machines for bigger pipe diameters.

6) The levels of invert of sewer are checked by boning rod or traveler.

Dewatering of Trenches:

1) Trenches should not be wet & muddy while or before jointing of sewer. In such case

dewatering is done by pumping.

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Sewer Testing:

The various tests are carried out to check water tightness of the sewer & proper working.

Air Test:

1) Particular section is selected & plugs are provided at the upper & lower ends.

2) The air is forced in the pipes by suitable equipments such as pump.

3) Leaky joints are found by applying soap solution.

4) The escape of air from leaky joints formed bubble & which are visible.

5) Then joints are repaired.

Water Test:

1) For this sewer pipe sections are tested between the manholes to manhole under a test

pressure of about 1.5 m water head.

2) To carry this, the downstream end of the sewer is plugged and water is filled in the

manhole at upper end.

3) The depth of water in manhole is maintained about 1.5 m.

4) The sewer line is inspected and the joints which leak are repaired.

5) In color water test, color water is used & inspected.

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Hydraulic Test:

1) Most common test.

2) Lower end is provided with plug & at the upper manhole, water is filled upto a height of

about 600mm to 900mm in case of house sewer.

3) If there is no drop in water level for a period of about 10 minutes, means no leakages.

Smell Test:

1) Test is similar to air test but in this case air is mixed with some smelling gas.

2) Such air is allowed to pass through the sewer line & escape of air from leaky joints is

detected by smell and such joints are repaired.

Smoke Test:

1) Test is similar to air test but in this case smoke is used.

2) Smoke is allowed to pass through the sewer line.

Test for Straightness of alignment

1) By placing a mirror at one end of the sewer line and a lamp at the other end.

2) If the pipe line is straight, full circle of light will be observed.

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Sewer Appurtenances:-

1) Sewer appurtenances are the various essential accessories or devices for the proper

maintenances & efficient operation of sewerage system.

2) These appurtenances are necessary because if simply sewers are laid, the sewage can not

flow in it continuously for longer time. After some, it will be choked up and will require

cleaning of sewers. The various appurtenances are

1) Manholes.

2) Drop Manholes.

3) Flushing Tanks.

4) Lampholes.

5) Street Inlets.

6) Catch Basin.

7) Ventilating Shaft.

8) Grease & Oil Traps

9) Inverted Siphons.

10) Storm Water Regulators.

Manholes:-

1) A manhole is defined as the construction made to connect the ground level with the hole

or opening made in the sewer line so that a man can easily, conveniently and safely enter

through it and carry out the usual maintenances operation.

2) It consists of working chamber, an access shaft & a strong cover on the top.

3) The lower portion of a deep manhole is known as a working chamber and it provides a

working space to carry out cleaning and inspection of sewer line.

4) Access shaft provides access to the working chamber.

5) The manhole cover of RCC is provide to cover the opening.

Drop Manholes:-

1) When it is uneconomical or impracticable to arrange the connection with 60 cm of invert

of the sewer and manhole, then vertical shaft is constructed outside the manhole chamber

through which the sewage of branch sewer is allowed to enter the manhole.

2) Such a manholes which drop the level of invert of the incoming sewer by providing a

vertical shaft are called drop manhole.

3) The main purpose of drop manhole is to avoid the splashing of sewage on the man

working and on the masonry work.

Flushing Tank:-

1) An arrangement to hold and ten throw water into the sewer for the purpose of flushing

2) When the gradient of the sewers are flat and velocity of sewage is low, the suspended

matter starts settling and causes clogging of sewer, at such places, where self cleansing

velocity is not available, flushing tank are provided to flush the sewer.

3) Hand Operated Flushing Tank & Automatic Flushing Tank.

Lampholes:-

1) A lampholes are the opening or holes are constructed in a sewer for the purpose of

lowering a lamp inside it.

2) It is a vertical stoneware or concrete pipes which are connected to the sewer line through a

tee junction.

3) The pipes are surrounded by concrete to make them stable.

4) At the ground level, the manhole cover with frame is provided to take up the load of

traffic.

Street Inlets:-

1) It is an opening through which storm water and surface water flowing along the street are

admitted and conveyed to the storm water sewer or combined sewer by means of pipes.

2) These are placed at the road, gutters, generally at street junctions.

3) It should provide in a such way that it will not cause any interference with the traffic.

4) Curb Inlets, Gutter Inlets & Combined Inlets.

Inverted Siphon:-

Ventilating Shaft:-

Grease & Oil Traps:-

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House Drainage System:-

The foul matter should be quickly removed away from the sanitary fixtures so as to avoid the

putrefaction and production of bad smelling gases.

The drainage system should be able to prevent the entry of gases, vermin etc from the sewer

into the building.

Requirements of Good Drainage System in Buildings:

1) The drainage pipes should be strong and durable.

2) The pipes should be of non-absorbent materials.

3) The pipes and joints should be airtight to prevent the leakage of waste water or gases.

4) The network of pipes should have sufficient accessibility for inspection & cleaning.

5) The levels of building, sewer and other points of outlet should be fixed accurately.

6) As per as possible drains should not pass under the buildings.

7) The drains should be given proper ventilation to avoid air locks and syphonage.

8) The system should have traps at all necessary points.

Sanitary Fittings:-

The sanitary fittings are required in house drainage for the efficient collection and removal

of waste water from the house to house drain.

The following are some of the sanitary fittings.

1) Traps.

2) Water closets.

3) Flushing cisterns.

4) Urinals.

5) Inspection chambers.

6) Wash basins.

7) Sinks.

8) Bath tubs etc.

Traps:- -

A trap is a depressed or bent sanitary fitting which always remains full of water (water seal).

The function of a trap is to prevent the entry of bad smelling gases into the house.

The effectiveness depends upon the depth of water seal. ( 25 to 75mm )

Requirements of Good Trap:-

1) It should be capable of being easily cleaned.

2) It should be easily fixed with the drain.

3) It should be of simple construction.

4) It should possess self-cleansing property.

5) It should posses adequate water seal to fulfill the purpose of installation.

6) The internal and external surfaces should be of smooth finish.

7) It should be free from any inside projection which are likely to obstruct the passage of

flow of sewage.

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Types of Traps:-

Classification according to shape:-

1) P-Trap.

2) Q-Trap.

3) S-Trap.

Types of Traps:-

Classification according to use:-

1) Floor Trap:- Made of cast iron with grating at top and used to for admitting wastewater

from floor of bath & kitchen. This trap is also known as Nahni Trap

2) Gully Trap:- Made of stoneware & caste iron. Wastewater from sinks, bath, etc., enter

through back inlet & unfoul water from the sweeping of rooms, courtyards, etc. enter from

the top, where coarse screen is fitted to check the solid matter.

Types of Traps:-

Classification according to use:-

1) Floor Trap:-

2) Gully Trap:-

3) Intercepting Trap:- It is provided in inspection chamber outside the house to prevent the

entry of foul gases from the street sewers to the houses through the house drains. This trap

has water seal of about 100mm.

Types of Pipes Used in House Drainage:-

1) Soil Pipe:- Important section of house drainage system in house.

2) Vent Pipe:- Essential for ventilation purpose.

3) Rainwater Pipe:- Collect the rain water from the roof.

4) Fresh Air Inlet Pipe:- Provide for fresh air in the last manhole which connects the house

drain with public sewer.

5) Anti-siphonage Pipe:- This type of pipe is provided not to be happen the siphonic action.

Safety Equipments:-

1) Gas Mask:-

2) Oxygen Breathing Apparatus:-

3) Portable Lightening Equipments:-

4) Portable Air Blow:-

5) Inhalators :-

6) Safety Belt:-

System of House Plumbing:-

Following are three major system adopted in plumbing of drainage work in a building.

1) Single Stack System:- A single vertical soil pipe is fixed & all the waste matter from

baths, kitchens, water closet etc. is discharged into it. It also act as a vent pipe. The single

stack system is economical but it is entirely effective in the depth of water seal only.

2) One Pipe System:-

3) Two Pipe System:-

System of House Plumbing:-

Following are three major system adopted in plumbing of drainage work in a building.

One Pipe System:- Only one pipe with a ventilation pipe is provided which collects both the

foul soil waste as well as unfoul waste from the building. For multistory building, lavatory

blocks of various floors are so placed one over the other.

System of House Plumbing:-

Following are three major system adopted in plumbing of drainage work in a building.

Two Pipe System:- Two sets of pipes are laid. The soil fixture such as urinal & WC are

connected to the vertical soil pipe. Waste matter from baths, kitchen, etc. are connected by

another vertical waste pipe. Soil pipe & waste pipe requires separate vent pipe hence

requires four pipes & therefore becomes costly.

➢ Two pipe system is better than other system of plumbing for efficient conveyance of

sanitary waste with minimum of risk.

➢ One pipes system has a more economical layout of pipes but requires sufficient safeguard,

include proper ventilation, adequate water seal and direct connection between the sanitary

fixture & soil pipe to make drainage effective.

➢ Now days single stack system mostly used on grounds of economy easy planning of

plumbing system.

Pumping of Sewage:-

In sewerage sytem at some places the sewage can not flow under its gravitational force only

& it requires its lifting.

Why it necessary to pump the sewage in sewerage system:-

1) In low laying areas sewage can not flow by gravity into mains & submains, therefore

sewage need to pump from lower branch to main sewer.

2) When basement are provided in the buildings, the sewage is pumped to the sewer line.

3) When ground is flat and not getting self cleansing velocity.

4) At the treatment plant to rise it upto the plant for treatment.

5) To lay the sewer along the ridge of hill or obstruction so as to avoid the construction of

a tunnel.

6) At the outfall, if level of water course is higher that level of outlet of sewer.

Types of Pumps:-

1) Centrifugal Pump

2) Reciprocating Pump

3) Air Lift Pump

4) Pneumatic Pump

Why sewage pumping is different from water pumping:-

1) Foul characteristics.

2) Suspended matter & floating matter can clog the pumps.

3) Organic & inorganic matter can cause corrosion & erosion.

4) Disease bacteria may cause health hazards.

5) Sewage flow is continuously varying.

6) Larger size sump well can not be constructed otherwise organic & inorganic matter will

settle in the bottom & produces foul smell as well as choking.

Rainwater Harvesting

1) To address the problem of water scarcity and effective conservation of rain water.

2) The process of collecting and storing rain water in a scientific and controlled manner for

future use.

3) Rain water is collected from the roof top of a building, community, structures,

landscapes, open fields, green parks, storm water drains, roads, pavement etc. and stored

ready for re-use as required.

4) Collected water can be filtered and directly be put into a percolation pit or open well or

dispersion trench to recharge the ground water.

5) It reduces runoff and flooding of storm drains.

6) collected water can be used for flushing toilets, general cleaning, garden irrigation and

washing clothes.

1. Rain water is collected on rooftops.

2. This water is guided into overflow pipes.

3. These pipes connect to an underground tank.

RAIN WATER HARVESTING TECHNIQUES :

➢ Pits:- Recharge pits are constructed for recharging the shallow aquifer. These are

constructed 1 to 2 m, wide and to 3 m. deep which are back filled with boulders, gravels,

coarse sand.

➢ Trenches:- Trench may be 0.5 to 1 m. wide, 1 to 1.5m. deep and 10 to 20 m. long

depending up availability of water. These are back filled with filter. materials.

➢ Dug wells:- Existing dug wells may be utilized as recharge structure and water should pass

through filter media before putting into dug well.

➢ Hand pumps :- The existing hand pumps may be used for recharging the shallow/deep

aquifers, if the availability of water is limited. Water should pass through filter media

before diverting it into hand pumps.

➢ Recharge wells :- Recharge wells of 100 to 300 mm. diameter are generally constructed

for recharging the deeper aquifers and water is passed through filter media to avoid

choking of recharge wells.

➢ Recharge Shafts :- For recharging the shallow aquifer which are located below clayey

surface, recharge shafts of 0.5 to 3 m. diameter and 10 to 15 m. deep are constructed and

back filled with boulders, gravels & coarse sand.

➢ Lateral shafts with bore wells :- For recharging the upper as well as deeper aquifers

lateral shafts of 1.5 to 2 m. wide & 10 to 30 m. long depending upon availability of

water with one or two bore wells are constructed. The lateral shafts is back filled with

boulders, gravels & coarse sand.

➢ Spreading techniques :- When permeable strata starts from top then this technique is

used. Spread the water in streams/Nalas by making check dams, nala bunds, cement

plugs, gabion structures or a percolation pond may be constructed.

Wastewater Recharge:- (Groundwater Recharge by Wastewater)

1) Lack of specific criteria & guidelines governing the artificial recharge of groundwater

with recycled wastewater is currently hampering the implementation of large scale

groundwater recharge operation.

2) Groundwater recharge with wastewater or reclaimed water and direct potable water

reuse share many of the public health concerns encountered in drinking water withdrawn

from polluted water source like river & reservoir.

3) Certain pretreatment is needed before groundwater recharge by wastewater.

TYPICAL QUESTIONS

1) Enlist the sewer appurtenances? Explain Manholes & Drophole?

2) What is a street inlet? State & explain it?

3) What is trap? State & explain various types of traps used in house plumbing?

4) Why the sewer should be properly ventilated? How it could be done? Explain?

5) Describe the various types of joints in sewers?

6) Explain in brief the various steps involved in layout and construction of sewer lines?

7) What are the different types of pump used for pumping of sewage?

8) Write a short note on a) Water Test b) Testing & maintenance of sewer line

c) Inverted siphon d) Antisyphonage e) Automatic Flushing Tank

f) Storm water regulators