Civil engineering competitive exam

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Civil engineering competitive exam

30 Sep 2019, 12:23

General study material
♦General study material, current affairs etc.

♦Important for ESE, MPSC, SSC, PWD, WRD
https://t.me/civil_engineering_exam_nontech

General study material

♦General study material, current affairs etc. ♦Important for ESE, MPSC, SSC, PWD, WRD

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Civil engineering competitive exam

28 Sep 2019, 20:59

Air pollution

♦️ Air pollution control

🔸 Particulate control technology

👉 Gravity settling chamber :-

~ dust particle > 50 μm

~ η 10 μm

~ η :- 2.5 μm

~ η :- 0.5 μm

~ η :-

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Civil engineering competitive exam

28 Sep 2019, 20:52

Air pollution

Dispersion of air pollutants into the atmosphere

👉 The rate of temperature with altitude is known as lapse rate

👉 Adiabatic Lapse rate :- Any warm air parcel if it rise in temperature for every 1 km rise, change of temperature is -9.8℃

♦️ Ringleman charts :- It measure density of smoke

♦️ Isokinetic sampling :- Collection of smoke using the probe across the c/s of stack

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Civil engineering competitive exam

28 Sep 2019, 20:48

Air pollution

♦️ Acid rain

👉 Acid rain results when gaseous emission SOx & NOx interact with water vapour and sunlight and are chemically converted to strong acidic compounds (H2SO4 & HNO3) along with other organic and inorganic chemicals.

👉 If pH of rain less than 5.6 is called acid rain

♦️ Global warming

🔸 The major green house gases

👉 Carbon dioxide :- 57%

👉 Methane :- 12%

👉 Nitrous oxide :- 6%

👉 Chlorofloro carbon (CFC) :- 25%

♦️ Ozone layer depletion

👉 Primary reason of ozone layer depletion is CFC

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Civil engineering competitive exam

28 Sep 2019, 20:46

Air pollution

♦️ Major air pollutants

🔸 Particulats

👉 particulates in atmosphere are measured by High volume air sampler

🔸 Carbon monoxide

👉 CO is analysed by NDIR (Non Dispersive Infrared) analyser.

🔸 Oxides of sulphur

👉 SOx are measured by West & Gaek method

🔸 Oxides of Nitrogen

👉 NOx are estimated by Jacob - Oscheisser method

🔸 Hydrocarbons

👉 Hydrocarbons estimated by Gas Chromatography

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Civil engineering competitive exam

28 Sep 2019, 20:44

Air pollution

Effects of air pollution on human

👉 Sulphur dioxide (SO2) :- It effects mucous membrane.

👉 Carbon monoxide (CO) :- It reacts with haemoglobin in blood to form toxic compound carboxyhemoglobin. It also affects the central nervous system.

👉 oxides of nitrogen :- It causes eye and nasal irritation and pulmonary discomfort

👉 Ozone :- It affect on respiratory system

👉 Lead :- It effects include gastrointestinal damage, liver and kidney damage

👉 Hydrocarbons :- It causes lung cancer

👉 Particulates :- It causes respiratory diseases

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Civil engineering competitive exam

28 Sep 2019, 19:53

Air pollution

♦️ Primary & Secondary air pollutants

🔸 Primary air pollutant

👉 Finer particles

👉 Coarse Particles

👉 Sulphur compounds

👉 Oxides of Nitrogen

👉 Carbon monoxide

👉 Halogen compounds

👉 Organic compounds

👉 Radioactive compounds

👉 Hydrocarbons

🔹 Secondary air pollutant

👉 Ozone

👉 Formaldehyde

👉 PAN (Peroxy acetyl nitrate)

👉 Photochemical Smog

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Civil engineering competitive exam

28 Sep 2019, 12:53

Waste water engineering

Solid waste management

🔸 Methods of disposal of solid waste

1. Land filling

👉 A minimum clearance distance is 6m from the surrounding area should be left during filling operation of flow laying areas.

👉 Biodegradable solid waste is disposed by this method

👉 Methods of land filling

1. Area filling

2. Trench filling

3. Depression filling

2. composting

👉 It is biological method of decomposting solid waste.

🔸 Method of composting

👉 Indore method of composting :- Anaerobic process

👉 Bangalore method of composting :- Aerobic process

3. Incineration

👉 Combustible solid waste disposed by this method.

👉 Burning in the presence of air

4. Pyrolysis

👉 Burning in absence of air

👉 Plastic & rubber waste disposed by this method

5. Pulverization

👉 Non biodegradable and non combustible solid waste disposed by this method

👉 Cutting or shredding into small pieces.

6. Sea disposal

👉 Barged into sea & disposed into deep sea water

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Civil engineering competitive exam

28 Sep 2019, 12:25

waste water engineering

Solid waste management

👉 Waste generated by the community which is essentially solid and discarded as useless or unwanted is known as solid waste

🔸 Types of solid waste

👉 Municipal waste

👉 Industrial waste

👉 Hazardous waste

🔸 Solid waste management system

👉 Generation :- Indian communities generate solid waste at 0.4 to 0.8 kg/person/day

👉 Collection :- Bin system

👉 Transfer & Transport :- Hauling system

👉 Processing & Recovery :- Segregation of solid waste.

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Civil engineering competitive exam

28 Sep 2019, 11:55

Waste water engineering

Dilution factor & Type of treatment recommended for domestic waste

👉 > 500 :- No treatment

👉 300 - 500 :- Preliminary treatment

👉 150- 300 :- Primary Treatment

👉 < 150 :- Primary Treatment followed by secondary treatment

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Civil engineering competitive exam

28 Sep 2019, 11:32

Waste water engineering

Disposal of sewage treatment

♦️ Land treatment

👉 This method follows

~ When there is no fresh water body in the vicinity of community.

~ Soil is capable of absorbing waste (sandy or loamy soil are best)

~ Ground water table deep below the ground.

🔸 Sewage sikness

👉 continuous application of sewage on same land leads to sewage sikness.

👉 Remedies

~ Give rest to the soil

~ plough the soil after drying.

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Civil engineering competitive exam

28 Sep 2019, 11:22

Waste water engineering

Disposal of sewage treatment

🔸 Methods of disposing

👉 Dilution i.e. in water disposal

👉 Land disposal

♦️ Disposal by dilution

🔸 Disposing the waste water into high fresh water course the left overs in the waste water are removed by the water body on its own known as self purification capacity

🔸 Self purification of water bodies are due to

👉 Dilution & dispersion

👉 Sedimentation :- settleable solids will settle down into bed of the river.

👉 Sun light :- Algae plant by absorbing CO2 and releasing oxygen by a process as photo synthesis.

👉 Oxidation

👉 Reduction

🔸 Zones of pollution in river

👉 Zone I :-

~ Zone of degradation

~ DO levels reduce to 40% of original.

~ except fish, all organisms disappear.

~ Deoxygenation > Reoxygenation

👉 Zone II :-

~ Zone of active decomposition

~ DO level reduced to zero

~ heavy polluted zone

~ All aquatic organisms disappear (fish life will be absent).

👉 Zone III :-

~ Zone of recovery

~ DO level raised to 40% original

~ Fish appears in water.

~ Reoxygenation > Deoxygenation

👉 Zone IV :-

~ clear water zone

~ Reoxygenation only occur no Deoxygenation.

~ River is recoverd.

~ DO level rises to original

~ All aquatic organisms appears

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Civil engineering competitive exam

28 Sep 2019, 10:49

Waste water engineering

♦️ Oxidation ponds

👉 Oxidation pond are low cost waste water treatment units, stabilise the waste water under aerobic conditions.

👉 Oxidation ponds on the principle of Algal bacterial symbiosis.

👉 It is best work in tropical climatic zones (Temperature zone)

👉 BOD loading rate or organic loading rate depends on latitude of a place.

👉 Detention time :- 2 to 6 weeks (20 - 30 days)

👉 Depth :- 1 to 1.5 m

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Civil engineering competitive exam

28 Sep 2019, 10:31

Waste water engineering

♦️ Septic tank

👉 Septic tanks are used in unsewered areas.

👉 Septic tanks are best suitable if the number of users are less than 300.

👉 Septic tank undertakes process anaerobic digestion of solids

👉 The BOD5 of the effluent obtained from septic tank is of order of 100 - 200 mg/l

👉 Detention time :- 24 to 48 hrs.

👉 Rate of sludge accumulation :- 30 to 40 l/person/year

👉 Length to width ratio :- 2 to 3

👉 Depth :- 1.2 to 1.8 m

👉 Free board :- 0.3 to 0.5 m

👉 Cleaning period :- 6 month to 1 year

♦️ Imhoff tank (Two storey digestion tank)

👉 It is improvement over septic tank.

👉 If Number of users are more than 300, Imhoff tank is preferred.

👉 Imhoff tank is a two compartment

~ upper compartment :- Settling of solids

~ lower compartment :- anaerobic digestion of settled solid.

👉 Detention time :- 2 to 4 hrs (usually 2hr)

👉 Depth :- 9 to 11 m

👉 L/B ratio :- 3 to 5 (L
≯ 30 m)

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Civil engineering competitive exam

28 Sep 2019, 09:50

Waste water engineering

Sludge Treatment

🔸 Sludge Treatment is aimed to achieve volume reduction & strength reduction.

🔸 Volume & strength reduction of sludges are achieved by

👉 sludge Thickening :- By concentrating the sludge by expulsion of water.

👉 Sludge digestion :- By anaerobic decomposition to reduce strength.

👉 Sludge conditioning :- To improve drainblility of sludges

👉 Sludge dewatering and drying :- Remove remaining moisture from sludge.

♦️ Strength reduction

👉 Strength reduction of sludge i.e. BOD removal is carried out by anaerobic decomposition known sludge digestion.

👉 Sludge digestion occur in two stages i.e. Acids fermentation and Methane fermentation.

🔸 Sludge digester

👉 Sludge are anaerobically digested by using a reactor known as sludge digester.

👉 Diameter of tank :- 3 to 60m

👉 Height of tank :- 6 to 12m

👉 Digestion period depends upon type of microorganisms

~ mesophilic organisms :- 30 to 60 days (Temperature 20℃ - 40℃)

~ Thermophilic organisms :- 15 to 25 days (Temperature 45℃ - 60℃)

👉 Gas production

~ 70% Methane

~ 30% Carbon dioxide

👉 Calorific value (energy content) :- 5200 to 5800 kcal/m3 of CH4

🔸 Digested sludge are dewatered and dried by using solar drying beds known as sludge drying bed.

🔸 Elutriation :- Washing of sludge before dewatering by mechanical driers.

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Civil engineering competitive exam

28 Sep 2019, 09:08

Waste water engineering

♦️ Secondary clarifier

👉 It is Secondary settling tank.

👉 Secondary Clarify follows Type IV settling.

👉 Type IV settling is known as compression settling

👉 Design of secondary clarifier is based on Solids Flux Rate

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Civil engineering competitive exam

28 Sep 2019, 08:27

Waste water engineering

♦️ Trickling Filter

🔸 Trickling Filter works on the principle of attached culture system.

🔸 Detachment of attached biofilm from the surface is called Sloughing

🔸 BOD removal efficiency is 75 to 80%

🔸 Types of Trickling Filter

1. Conventional or Standard rate Trickling Filter :-

👉 Depth of filter media :- 1.2 to 2.4 m

👉 Size of media :- 25 to 75 mm

👉 Land required :- More

👉 Hydraulic loading :- 22 to 44 ML/hect/day

👉 Organic loading :- 900 to 1200 kg of BOD/hect-m.

👉 Recirculation system :- Not provided.

2. High rate Trickling Filter

👉 Depth of filter media :- 1.2 to 1.8 m

👉 Size of media :- 25 to 60 mm

👉 Land required :- Less

👉 Hydraulic loading :- 110 to 330 ML/hect/day

👉 Organic loading :- 6000 to 18000 kg of BOD/hect-m.

👉 Recirculation system :- always provided for Increase loading

🔸 operational problems

👉 Psychoda problems :- fly nuisance.

👉 Odour nuisance :- The remedy is Chlorination of sewage.

👉 Ponding problems :- Filters media gets clogged due to growth of alage and fungi and this is called Ponding.

~ Adding chlorine or copper sulphate to the sewage kills alage there by Ponding can be avoided

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Civil engineering competitive exam

28 Sep 2019, 07:47

waste water engineering

♦️ Activated sludge process (ASP)

🔸 Activated sludge :- It is sludge containing large concentration of highly active aerobic micro organisms.

🔸 ASP works on the principle of suspended culture system.

🔸 Components of ASP

A) Primary settling tank :-

~ Detention time - 1.5 to 2 hr.

B) Aeration tank :-

~ Detention time- 4 to 8 hr

C) Secondary sedimentation tank :-

~ Detention time- 1.5 to 2 hr.

D) Sludge thickener & sludge digestion tank

🔸 Activated sludge process parameters

1. Hydraulic retention time (HRT) :- It is the ratio of volume of tank to the rate of sewage flow into the tank.

2. Volumetric loading rate or BOD loading rate :- It is ratio of BOD applied to unit volume of aeration tank.

3. Food to microorganism ratio (F/M) :- It is defined as the ratio of kg of BOD applied per day to kg of MLSS in aeration tank.

4. Mean cell residence time (Sludge age) :- It is defined as mass of cell in the reactors to mass of cells wasted per day.

5. Sludge volume index :- It is the volume occupied in ml by 1 gm MLSS after settling for 30 minute from 1L sewage sample is known as sludge volume index.

🔸 Usual values adpoted

👉 F/M :- 0.4 to 0.3

👉 MCRT :- 5 to 15 days

👉 Efficiency :- 85 - 95%

👉 Recycling ratio :- 0.25 - 0.5

🔸 Operational problems associated with ASP

1. Rising of sludge :- Settled sludge contains large number of live cells. They oxidise the dead cells and release nitrogen. The nitrogen causes the sludge to risep and increases the Xe value.

~ Remedies :- Increase Qr & Decrease Q

2. Bulking of sludge :- Large number of dead cell in settled sludge and growth of filamentous organisms. Occurs when SVI ≃ 150

~ Remedies :- Bring down SVI (≃ 150), Increase pH, Increase DO, decrease F/M ratio.

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Civil engineering competitive exam

27 Sep 2019, 15:30

Waste water engineering

Microorganisms Based on oxygen consuming

👉 Aerobic organisms :- It survives in the presence of oxygen.

👉 Anaerobic organisms :- It survives in the absence of oxygen.

👉 Facultative organisms It survives with or without oxygen.

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Civil engineering competitive exam

27 Sep 2019, 15:23

waste water engineering

Secondary treatment (Biological treatment)

🔸 Unit based on aerobic treatment

1. Trickling filter

2. Activated sludge process

3. Oxidation pond

🔸 Unit based on anaerobic treatment

1. Septic tank

2. Imhoff tank

3. USAB Reactors

🔸 Aerobic treatment of waste water

1. Suspended culture system

👉 In suspended culture system, Biomass is an suspension in the liquid containing organic matter.

👉 E.g. Activated sludge process.

2 Attached culture system

👉 In Attached culture system, biomass is attached to medium and sewage containing organic matter is passed through medium.

👉 E.g. Trickling filter, Rotating biological contactors, Biotowers etc.

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