Showing posts with label Enviromental engineering. Show all posts
Showing posts with label Enviromental engineering. Show all posts
Environmental Engineering Hand Written Notes
(a) Water Supply Engineering: (Environmental Engineering Hand Written Notes)
Sources of supply, yields, design of intakes and conductors; Estimation of demand; Water quality standards; Control of water-borne diseases; Primary and secondary treatment, detailing and maintenance of treatment units; Conveyance and distribution systems of treated water, leakages and control; Rural water supply; Institutional and industrial water supply.
(b) Waste Water Engineering: (Environmental Engineering Hand Written Notes)
Urban rain water disposal; Systems of sewage collection and disposal; Design of sewers and sewerage systems; pumping; Characteristics of sewage and its treatment, Disposal of products of sewage treatment, stream flow rejuvenation; Institutional and industrial sewage management; Plumbing Systems; Rural and semi-urban sanitation.
(c) Solid Waste Management: (Environmental Engineering Hand Written Notes)
Sources, classification, collection and disposal; Design and Management of landfills. (d) Air and Noise Pollution and Ecology: Sources and
effects of air pollution, monitoring of air pollution; Noise pollution and standards; Ecological chain and balance, Environmental assessment.
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Theory of filtration
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| source :pamirtimes.net |
Filters are classified as -
Gravity filter
Pressure filter
In gravity filters the head required to flow through filter media
is provided by the head of water over the filter media but in pressure filter head is provided by pressure applied from outside.
Theory of filtration
when water is passed through the filter medium removal of impurities takes place by the following mechanism.
Mechanical Straining
Sedimentation
Biological Changes
Electrolytic Changes
Mechanical Straining : Particle which are larger in size than the pores of filter are strained out . The arrested impurities including coagulated flocks forms a mat on the top of sand layer,which has pores sizes smaller than that of the sand grain.
Hence even the particle smaller than the pores sizes of sand gets removed .
Sedimentation : Due to the removal of the turbulence from the water up -to certain extent some particles settle down on the surface of sand grains making the filtered water free from suspended solids .
Biological Changes : During first few days upper layer of sand grain gets coated with sticky deposits of partially decomposed organic matter together with iron, manganese aluminum etc , which contains the algae ,plankton etc that uses nitrogen and phosphorous as nutrient and grow ,and due to photosynthetic reaction produces oxygen.
Electrolytic Changes : The sand grain in filter and impurities in water carry opposite charges ,thus because of their interaction the chemical characteristic of water changes and it becomes free from dissolved impurities.
During washing process these neutralized material are removed from the sand bed .The oxygen is utilized to oxidize the organic matter which are in particulate form or dissolved form ,thus a stable harmless compound is formed .The process
takes place in the layer termed as SCHMUTZDECKE.
Due to scarcity of organic matter ,bacteria by endogenous respiration also destroys each other and hence bacterial load is also reduced .
Types of valves
Sluice Valves /Gate valves
Sluice valves are also known as gate valves or shut -off valves .
These valves are provided to regulate the flow of water through the pipe by dividing the mainline into several sections. These valves usually placed at the summits of the pressure conducts where the pressure is low ,thereby requiring low strength and less cost.
Air Valves
The water flowing through the pipe line always carries some air with it .This air tends to accumulate at the summit of pipe line.
Due to the accumulation of air ,a backward pressure is created which causes a blockage to the flow of water .So the air relief is provided at the summit point on upstream of gate valve to release the air pressure . Air inlet valves are also provided on the downstream side of gate valve to compensate the negative pressure developed ,by allowing the air to enter into the pipe.
Check valve/ Reflux valves / Non Returning valve
These possess some automatic device which allows the water to flow in one direction only .This valve is provided in the pipe line which draws water from the pump. When the pump is operated ,the valve is opened but when the pump is suddenly stopped the valve is automatically closed and the water is prevented from returning to the pump.
Scour valve / Blow off valve / Drain valve
Scour valves are also known as wash - out valves .These are similar to the sluice valves ,but the function is different .Scour valves are provided at the dead end of the pipe line .The function of this valve is to remove the sand ,silt etc .
Sluice valves are also known as gate valves or shut -off valves .
These valves are provided to regulate the flow of water through the pipe by dividing the mainline into several sections. These valves usually placed at the summits of the pressure conducts where the pressure is low ,thereby requiring low strength and less cost.
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source Kirloskar Brothers Limited |
Air Valves
The water flowing through the pipe line always carries some air with it .This air tends to accumulate at the summit of pipe line.
 |
| source Saudi Pipe Systems Co. |
Check valve/ Reflux valves / Non Returning valve
These possess some automatic device which allows the water to flow in one direction only .This valve is provided in the pipe line which draws water from the pump. When the pump is operated ,the valve is opened but when the pump is suddenly stopped the valve is automatically closed and the water is prevented from returning to the pump.
 |
| soucre IndiaMART |
Scour valve / Blow off valve / Drain valve
Scour valves are also known as wash - out valves .These are similar to the sluice valves ,but the function is different .Scour valves are provided at the dead end of the pipe line .The function of this valve is to remove the sand ,silt etc .
Various types of pressure pipes
Cast iron pipes
Steel pipes
These pipes can withstand high pressure as they are strong in tension but can not take heavy external load or vacuum .
Hence these pipes are used as pumping main . These pipes are susceptible to corrosion ,have high maintenance cost and shortened life ( 25 - 50 years) . These pipes are light weight hence offer low transportation cost .
Reinforced Concrete pipes
They can resist external compressive load and do not collapse under vacuum pressure .These are resistance to corrosion but undergo H2S corrosion .They are strong and have life of 75 years . They are strong and have life of 75 years .They are difficult to be repaired , are bulky and making connection in them is difficult job. They end to leak due to shrinkage cracks
and porosity.
Vitrified Clay pipes
These are not used as pressure pipes but are used to carry sewage and drainage at partial depth . These are free from corrosion and provide a smooth hydraulically efficient surface .
Asbestos pipes
These pipes are light hence easy to transport .These are highly resistance to corrosion ,highly flexible thus requires less joint in their layout. They provide a smooth hydraulically efficient surface and their discharge carrying capacity do not reduce with time.They are costly ,week, brittle and soft hence are liable to get damaged during transportation.
G I pipes
They can withstand acidic and alkaline action of water.
Hume steel pipes
These are thin steel pipes coated with cement mortar from inside using centrifugation . These are highly resistance against corrosion.
These pipes are resistant against corrosion ,have long life
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| credit IndiaMART |
(100 years) ,strong and durable moderate in cost ,easy to join .
They can not withstand pressure above 700 KN/㎡ ,are likely to
break during joining or transportation .These pipes are used as distribution Main .
Steel pipes
These pipes can withstand high pressure as they are strong in tension but can not take heavy external load or vacuum .
Hence these pipes are used as pumping main . These pipes are susceptible to corrosion ,have high maintenance cost and shortened life ( 25 - 50 years) . These pipes are light weight hence offer low transportation cost .
Reinforced Concrete pipes
They can resist external compressive load and do not collapse under vacuum pressure .These are resistance to corrosion but undergo H2S corrosion .They are strong and have life of 75 years . They are strong and have life of 75 years .They are difficult to be repaired , are bulky and making connection in them is difficult job. They end to leak due to shrinkage cracks
and porosity.
Vitrified Clay pipes
These are not used as pressure pipes but are used to carry sewage and drainage at partial depth . These are free from corrosion and provide a smooth hydraulically efficient surface .
Asbestos pipes
These pipes are light hence easy to transport .These are highly resistance to corrosion ,highly flexible thus requires less joint in their layout. They provide a smooth hydraulically efficient surface and their discharge carrying capacity do not reduce with time.They are costly ,week, brittle and soft hence are liable to get damaged during transportation.
G I pipes
They can withstand acidic and alkaline action of water.
Hume steel pipes
These are thin steel pipes coated with cement mortar from inside using centrifugation . These are highly resistance against corrosion.
Primary and Secondary Air Pollutants
Primary pollutants:
Secondary pollutants :
Primary pollutants are chemicals or pollutants emitted directly from the source.
Example: SO2, nitrogen oxides (NOx), carbon dioxide (CO2), volatile organic compounds (VOCs)
and other hazardous air pollutants (HAPs). Particulate matter emitted from combustion process
such as automobile exhaust , industrial process or heating and cooking is also considered as primary
pollutant.
 |
| source : google |
Pollutants that form from chemical or photochemical reactions in the
atmosphere are called secondary pollutants. Secondary pollutants are produced most efficiently on
bright, sunny days in the summer, when VOCs and NOx react photochemically in a complex series
of reactions in the presence of sunlight. Ozone is a important secondary pollutant because of its
potential adverse effects on vegetation, human health and property damage. Other secondary
pollutants are PAN, HNO3, formaldehyde etc.
Design Consideration of Septic Tanks
A Septic tank may be defined as as a primary sedimentation tanks with a longer detention period (12 to 36 hours).
Raw sewage is directly fed into these tanks and kept for approximately 12 to 36 hours in which solid settle down in the tank resulting in the formation of sludge which is being kept in the tank only and is acted upon anaerobic microorganism over a period of 6 to 12 months.
Additional volume is provided at the bottom of the tank for the accumulation of sludge .
Oil and grease present in the waste water rises to the surface and leads to the formation of sum layer which acts as thermal insulator and reduces the extent to which odor gases are escaped out from the system.
Gases from during the digestion are collected from the top of the tank.
 |
| source : google |
Rate of flow of sewage is taken as 40 to 70 lpcd, if sullage is also considered ,rate of flow is 90 -150 lpcd.
Rate of accumulation of sludge is 30 to 70 l/c/year.
Detention time is 12 to 36 hours.
Cleaning period is 6 to 12 months .
L/B ratio is in range 2 to 3 .
Width of the tank should not be less than .9 m.
Depth is in the range of 1 to 1.8 m.
Free boat = .3m is provided over the design depth .
Effluent of the septic tank is disposed either in soak pit or in dispersion trench.
Soak pit and dispersion trench is sufficiently permeable so as to allow easy percolation of the effluent into the ground.
Percolation rate is defined as time taken in minutes by the effluents to seep into the ground by the distance of 1 cm.
Soak pit is used when percolation rate is less than 30 minute.and dispersion trenches are used when percolation rate is given by
Q = 204/√t L/㎡/day
where t= percolation rate (min).
Surface area =Q 0/Q*
INCINERATION AND THERMAL PYROLISIS
In this method ,disposal of refuse is carried out by burning it at high temperature either in the presence or absence of oxygen .
If the burning is done in the presence of oxygen ,it is termed as incineration and if it is done in limited or no supply of oxygen ,it is termed as thermal pyrolysis.
This method is generally adopted for the disposal of refuse having high calorific value.
cost involved in this method of disposal is comparatively more than the other method.
 |
| Source :google |
 |
| SourceSlideShare |
cost involved in this method of disposal is comparatively more than the other method.
COMPOSTING
Composting is a biological method of disposal of refuse in which decomposition can be carried out either aerobically or anaerobically .The end product of the composting is termed as compost,manure or humus.
 |
| source google |
If composting is carried out aerobically ,mixing of refuse is ensured either manually or mechanically.Aerobic composting
is completed normally within 2-3 month and is also termed as INDORE process. If composting is done anaerobically ,mixing of refuse is avoided.Anaerobic composting is completed within 5-6 month and it is also termed as BANGALORE process.
for optimum composting ,C/N ratio should be within 30-50.
The above range is on the basis of the fact that microorganism utility carbon 30-50 times faster than nitrogen.
C/N= 30 to 50.
If C/N is more ,nitrogen is utilized prior to carbon leading to the deficiency of the nutrient required for the growth of microorganism which in turn leaves the decomposition incomplete.
If C/N ratio is less ,carbon is utilized prior to that of nitrogen
and the left over nitrogen and combines with the hydrogen resulting in the formation of ammonia which is disastrous for methane formers which in turn again leaves the decomposition incomplete.
PHYSICAL WATER QUALITY PARAMETERS
The parameters which can be felt or sensed by any of four sensed are referred as physical water quality parameters
SUSPENDED SOLIDS
TURBIDITY
COLOUR
TASTE AND ODOUR
TEMPERATURE
SUSPENDED SOLIDS
SOURCE
Suspended solids in water comes from inorganic particle like silt clay etc,organic particle like plant fibers,algae plankton etc ,immiscible liquid like oils,grease etc.
IMPACTS
it makes the water aesthetically displeasing .it provide adsorption sites for chemical and biological reagents .they may be biologically active and form disease causing organism .it leads to incrustation in pipes and reduces their discharge carrying capacity .
MEASUREMENT
Measurement of suspended solid is done by gravimetric technique i.e. suspended solide measured by weighing them.
Total solid are calculated by evaporating the simple at 104 C
and measuring the residue.Suspended solids is obtained by filtration and heating the residue on filter at 104 C .
Dissolved solids =total solids -suspended solid .
Organic solids both in total and suspended form can be determined by firing the test sample and residue in muffle furnace at 600-650 C .At this temperature organic organic solids will be vapourised leaving behind inorganic solids.
LIMITS
Acceptable limit for total solid =500 mg/l
Cause for rejection limit for total solid =2000 mg/l
AS per Enviromental protection Agency permissible limit of suspended solids is 30 mg/l.
TURBIDITY
Turbidity is the measure of extent to which light is either absorbed or scattered by suspended materials in water however it is not a direct quantitative measure of suspened solids .
IMPACTS
a. Disinfection of turbid water is difficult because the suspended solids may partially shield the organisms from disinfectant .
2.In natural bodies ,turbidity interferes with light penetration and hence with the photosynthetic reactions.
MEASUREMENT
Measuring of turbidity is done using the following method
a.Turbidity rod method
b.Jackson's turbidimeter
c.Baylish Turbidity meter
d.Nephlometer
LIMITS
Acceptable limit =1NTU
Cause for rejection =10 NTU
COLOUR
Source
Color is caused be suspended and dissolved matter in water reffered as apparent color.After suspended matter causing color is removed by centrifugation, the color obtained is called true color.
MEASUREMENT
Measurement of color is done by color matching techniques (tintometer ).the color testing is done within 72 hours of collection as otherwise biological or physical properties may change.
LIMIT
Acceptable limit is 5 TCU
Cause for rejection is 25 TCU.
TASTE AND ODOUR
Source
Taste and odour are caused by dissolve gases like Hydrogen sulphide methane ,organic matter or from inorganic matter.
Sulpher imparts rotten egg like taste and odour .Algae secretes oily substances that may result in bad taste and odour.
IMPACT
The taste and odour causing compounds may be carcinogenic.
Measurement
Odour is generally measured by an instrument known as osmoscope by diluting the water sample up to an extant it is hardly detectable.Intensity of taste and odour is expressed by TON .It represents the dilution ratio at which is hardly detectable.
Limit
Acceptable limit=1TON
Cause for rejection=3TON
TEMPERATURE
Temperature affects the chemical and biological reaction.An increase in 10 C almost doubles the biological activity .For water supply ,the temperature should be betwwen should be between 10-25 C.
 |
| Credit HiAdvance Philippines |
TURBIDITY
COLOUR
TASTE AND ODOUR
TEMPERATURE
SUSPENDED SOLIDS
SOURCE
Suspended solids in water comes from inorganic particle like silt clay etc,organic particle like plant fibers,algae plankton etc ,immiscible liquid like oils,grease etc.
IMPACTS
it makes the water aesthetically displeasing .it provide adsorption sites for chemical and biological reagents .they may be biologically active and form disease causing organism .it leads to incrustation in pipes and reduces their discharge carrying capacity .
MEASUREMENT
Measurement of suspended solid is done by gravimetric technique i.e. suspended solide measured by weighing them.
Total solid are calculated by evaporating the simple at 104 C
and measuring the residue.Suspended solids is obtained by filtration and heating the residue on filter at 104 C .
Dissolved solids =total solids -suspended solid .
Organic solids both in total and suspended form can be determined by firing the test sample and residue in muffle furnace at 600-650 C .At this temperature organic organic solids will be vapourised leaving behind inorganic solids.
LIMITS
Acceptable limit for total solid =500 mg/l
Cause for rejection limit for total solid =2000 mg/l
AS per Enviromental protection Agency permissible limit of suspended solids is 30 mg/l.
TURBIDITY
Turbidity is the measure of extent to which light is either absorbed or scattered by suspended materials in water however it is not a direct quantitative measure of suspened solids .
IMPACTS
a. Disinfection of turbid water is difficult because the suspended solids may partially shield the organisms from disinfectant .
2.In natural bodies ,turbidity interferes with light penetration and hence with the photosynthetic reactions.
MEASUREMENT
Measuring of turbidity is done using the following method
a.Turbidity rod method
b.Jackson's turbidimeter
c.Baylish Turbidity meter
d.Nephlometer
LIMITS
Acceptable limit =1NTU
Cause for rejection =10 NTU
COLOUR
Source
Color is caused be suspended and dissolved matter in water reffered as apparent color.After suspended matter causing color is removed by centrifugation, the color obtained is called true color.
MEASUREMENT
Measurement of color is done by color matching techniques (tintometer ).the color testing is done within 72 hours of collection as otherwise biological or physical properties may change.
LIMIT
Acceptable limit is 5 TCU
Cause for rejection is 25 TCU.
TASTE AND ODOUR
Source
Taste and odour are caused by dissolve gases like Hydrogen sulphide methane ,organic matter or from inorganic matter.
Sulpher imparts rotten egg like taste and odour .Algae secretes oily substances that may result in bad taste and odour.
IMPACT
The taste and odour causing compounds may be carcinogenic.
Measurement
Odour is generally measured by an instrument known as osmoscope by diluting the water sample up to an extant it is hardly detectable.Intensity of taste and odour is expressed by TON .It represents the dilution ratio at which is hardly detectable.
Limit
Acceptable limit=1TON
Cause for rejection=3TON
TEMPERATURE
Temperature affects the chemical and biological reaction.An increase in 10 C almost doubles the biological activity .For water supply ,the temperature should be betwwen should be between 10-25 C.
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