Topic 5 - Water Quality Management: Spring 2012 Kazi Parvez Fattah
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Topic 5 - Water Quality Management
Spring 2012 Kazi Parvez Fattah
Water Sources
4/5/19
Historically the sources have been natural in nature, such as rivers, streams, lakes and aquifers Increase in population and scarcity of water in some parts of the world have made it necessary to look for alternative sources Some of the alternative sources investigated are discharges from wastewater treatment plants, urban storm water flows, saline water conversion This reuse of water is important as up to about 75% of treated potable water is returned to a discharge point after its use Water Quality Management
2
Water Quantities
Approximately 1385 million cubic kilometers of water are available on earth. 97.5% is salt water; 2.5% is freshwater Nearly 90% of this freshwater is not readily available (mostly as ice) Only 0.26% of the water on this world is available for humans and other organisms Only 0.014% of this water can be used for drinking water production, as most of it is stored in clouds or in the ground. Source: http://www.lenntech.com/specific-questions-water-quantities.htm
4/5/19
Water Quality Management
3
Water Consumption
The annual per capita water use for each part of the world: - North Americans use 1,280m3 - Europeans and Australians use 694 m3 - Asians use 535 m3 - South Americans use 311 m3 - Africans use 186 m3 Ref. http://www.lenntech.com/specific-questions-water-quantities.htm
4/5/19
Water Quality Management
4
Cost of Water
Ref. http://www.lenntech.com/specific-questions-water-quantities.htm
4/5/19
Water Quality Management
5
Desalination
Recovering water from salty water World-wide, 13,080 desalination plants produce more than 12 billion gallons of water a day (Ref. International Desalination Association)
Existing facilities and facilities under construction (not complete)
4/5/19
Abu Dhabi, United Arab Emirates Australia Cyprus United Kingdom United States Trinidad and Tobago Water Quality Management
6
Alkalinity
The quantitative capacity of a solution to neutralize acid A measure of the buffering capacity of water A measure to neutralize acidic pollution of water The alkalinity is equal to the stoichiometric sum of HCO -, CO 2-,OH- and (H+) 3 3
2
Alkalinity (moles / L) [ HCO3 ] 2[CO3 ] [OH ] [ H ] 4/5/19
Water Quality Management
7
Alkalinity..contd
Expressed as mg/L CaCO3
mg/L as CaCO3 = (mg/L of species) * (EWCaCO3/EWspecies)
The alkalinity is found by adding all the carbonate species and the hydroxide and then subtracting the hydrogen ions No need to multiply the CO32- (according to the previous equation) as it is already taken care of when converted in terms of EW. Example 4.8: A water contains 100mg/L CO32- and 75mg/L of HCO3- at a pH of 10. Calculate the alkalinity at 25°C. Approximate the alkalinity by ignoring [OH]- and [H]+
4/5/19
Water Quality Management
8
Hardness
It is the ability of a water to react with soap (to form lather) Occurs due to the presence of polyvalent cations
4/5/19
Ca, Mg bicarbonate and sulphates
It reduces the effectiveness of soap and detergent Causes the formation of “scaling” Total hardness is computed by the sum of all polyvalent cations
Water Quality Management
9
Types of Hardness
4/5/19
Carbonate hardness: component of total hardness associated with carbonate and bicarbonate Non carbonate hardness are other component of hardness. Also known as permanent hardness.
Total Hardness = Carbonate hardness + Non carbonate hardness Most carbonate hardness are associated with divalent cations, such as calcium and magnesium Expressed as mg/L as CaCO3 or meq/L
Water Quality Management
10
Hard Water Classification
4/5/19
Water Quality Management
11
Relationship Between Hardness and Alkalinity
4/5/19
Water Quality Management
12
Example of Hardness
Ion
Example 4-11. Given the following analysis of a groundwater, construct a bar chart of the constituents, expressed as CaCO 3. mg/L as mg/L as ion CaCO3
Ca2+
103.0
258
Mg2+
5.5
23
Na+
16.0
35
HCO3-
255.0
209
SO42-
49.0
51
Cl-
37.0
52
4/5/19
Water Quality Management
13
Water Supply
4/5/19
Surface water Ground water Sea water Rain water harvesting
Water Quality Management
14
Surface Water
Surface water is among the most important sources of water being used for drinking water Not abundant in nature Easy to collect Unaffected surface water is relatively pure in nature 4/5/19
Water Quality Management
15
Ground Water
Groundwater is abundant It is filtered through natural aquifer Relatively pure It can be contaminated through leaching of metals and organics from the minerals and waste disposal sites Salt water intrusion can be a problem
Source. jnuenvis.nic.in/subject/freshwater/groundwater.htm
4/5/19
Water Quality Management
16
Sea Water
4/5/19
Abundant in nature High salinity Technological means are available to use sea water as a source Expensive (desalination, reverse osmosis) It limits the adaptation of sea water as a source of drinking water Not suitable for places far away from sea
Source. http://www.power-technology.com/projects/taweelah/
Water Quality Management
17
Rain Water Harvesting
It is the gathering, accumulating or sorting of rainwater Usually collected on the roof of the house and stored in large tanks Very good quality water Can be used for drinking with minimum treatment Suitable for isolated places
Adopted in urban areas as well
Not suitable for places having low rainfall 4/5/19
Water Quality Management
18
Groundwater - Surface water - Seawater Physical characteristics
Chemical characteristics
Groundwater typically reasonable levels of turbidity and color
Surface water prone to physical interference and therefore has high levels of turbidity and color
Seawater affected by physical interference
high concentrations of leached contaminants (both metal and inorganic ions)
have high chemical contamination depending upon the hydro geological pattern
have very high salinity
prone to high microbial contamination
can have high microbial contamination
Microbiological typically free characteristics from microbial contamination 4/5/19
Water Quality Management
19
Water Pollution
4/5/19
Water Quality Management
20
Water Pollution in Jumeira, UAE
4/5/19
Water Quality Management
21
Water Pollution Sources
Point sources
Discharge of pipes (domestic wastewater, industrial discharges) Concentrated animal feed lots
Non-point sources
Urban runoff (road silt, oil, etc.) Agricultural runoff (fertilizer, pesticides)
4/5/19
Source: http://visual.merriamwebster.com/earth/environment/water-pollution.php
Water Quality Management
22
Depletion of Dissolved Oxygen
4/5/19
Oxygen remains in water as dissolved form In natural water (surface water), there are organic matter present that consume dissolved oxygen Water receives oxygen through diffusion from air If the oxygen level falls too low, aquatic life can be harmed
Water Quality Management
23
Streeter-Phelps equation
Combines oxygen consumption and reoxygenation to describe deficit as a function of time
k n Ln k t k d La k d t kr t kr t e e k t D e e Da e kr kn kr kd
D = oxygen deficit at any time, mg/L Da = oxygen deficit immediately below pollutant discharge location, mg/L La = ultimate oxygen demand immediately below pollutant discharge location, mg/L kd = deoxygenation constant, d-1 kr = reoxygenation constant, d-1 kn = nitrogenous deoxigenation coeficient, d-1 Ln = ultimate nitrogenous oxygen demand immediately below pollutant discharge location, mg/L 4/5/19 Water Quality Management
n
r
24
Waste Mixing in Water Bodies
4/5/19
Treated/un-treated waste is often mixed with the receiving water body (like a river or stream) Waste has high BOD, whereas receiving body normally has low/no BOD Solution to pollution is dilution
Water Quality Management
25
Management Strategies
4/5/19
Identify the lowest DO that is acceptable to aquatic species in the receiving body Solve the DO sag curve and known mixing Worst case scenario: low river volume, high waste volume Only parameters engineer can control Initial ultimate BOD D – initial deficit in dissolved oxygen o Available tools Further processing of waste to reduce BOD Aeration of waste prior to discharge to reduce initial deficit
Water Quality Management
26
Streeter-Phelps Example
4/5/19
Text book Problem 5-36
Water Quality Management
27
Spring 2012 Kazi Parvez Fattah
Water Sources
4/5/19
Historically the sources have been natural in nature, such as rivers, streams, lakes and aquifers Increase in population and scarcity of water in some parts of the world have made it necessary to look for alternative sources Some of the alternative sources investigated are discharges from wastewater treatment plants, urban storm water flows, saline water conversion This reuse of water is important as up to about 75% of treated potable water is returned to a discharge point after its use Water Quality Management
2
Water Quantities
Approximately 1385 million cubic kilometers of water are available on earth. 97.5% is salt water; 2.5% is freshwater Nearly 90% of this freshwater is not readily available (mostly as ice) Only 0.26% of the water on this world is available for humans and other organisms Only 0.014% of this water can be used for drinking water production, as most of it is stored in clouds or in the ground. Source: http://www.lenntech.com/specific-questions-water-quantities.htm
4/5/19
Water Quality Management
3
Water Consumption
The annual per capita water use for each part of the world: - North Americans use 1,280m3 - Europeans and Australians use 694 m3 - Asians use 535 m3 - South Americans use 311 m3 - Africans use 186 m3 Ref. http://www.lenntech.com/specific-questions-water-quantities.htm
4/5/19
Water Quality Management
4
Cost of Water
Ref. http://www.lenntech.com/specific-questions-water-quantities.htm
4/5/19
Water Quality Management
5
Desalination
Recovering water from salty water World-wide, 13,080 desalination plants produce more than 12 billion gallons of water a day (Ref. International Desalination Association)
Existing facilities and facilities under construction (not complete)
4/5/19
Abu Dhabi, United Arab Emirates Australia Cyprus United Kingdom United States Trinidad and Tobago Water Quality Management
6
Alkalinity
The quantitative capacity of a solution to neutralize acid A measure of the buffering capacity of water A measure to neutralize acidic pollution of water The alkalinity is equal to the stoichiometric sum of HCO -, CO 2-,OH- and (H+) 3 3
2
Alkalinity (moles / L) [ HCO3 ] 2[CO3 ] [OH ] [ H ] 4/5/19
Water Quality Management
7
Alkalinity..contd
Expressed as mg/L CaCO3
mg/L as CaCO3 = (mg/L of species) * (EWCaCO3/EWspecies)
The alkalinity is found by adding all the carbonate species and the hydroxide and then subtracting the hydrogen ions No need to multiply the CO32- (according to the previous equation) as it is already taken care of when converted in terms of EW. Example 4.8: A water contains 100mg/L CO32- and 75mg/L of HCO3- at a pH of 10. Calculate the alkalinity at 25°C. Approximate the alkalinity by ignoring [OH]- and [H]+
4/5/19
Water Quality Management
8
Hardness
It is the ability of a water to react with soap (to form lather) Occurs due to the presence of polyvalent cations
4/5/19
Ca, Mg bicarbonate and sulphates
It reduces the effectiveness of soap and detergent Causes the formation of “scaling” Total hardness is computed by the sum of all polyvalent cations
Water Quality Management
9
Types of Hardness
4/5/19
Carbonate hardness: component of total hardness associated with carbonate and bicarbonate Non carbonate hardness are other component of hardness. Also known as permanent hardness.
Total Hardness = Carbonate hardness + Non carbonate hardness Most carbonate hardness are associated with divalent cations, such as calcium and magnesium Expressed as mg/L as CaCO3 or meq/L
Water Quality Management
10
Hard Water Classification
4/5/19
Water Quality Management
11
Relationship Between Hardness and Alkalinity
4/5/19
Water Quality Management
12
Example of Hardness
Ion
Example 4-11. Given the following analysis of a groundwater, construct a bar chart of the constituents, expressed as CaCO 3. mg/L as mg/L as ion CaCO3
Ca2+
103.0
258
Mg2+
5.5
23
Na+
16.0
35
HCO3-
255.0
209
SO42-
49.0
51
Cl-
37.0
52
4/5/19
Water Quality Management
13
Water Supply
4/5/19
Surface water Ground water Sea water Rain water harvesting
Water Quality Management
14
Surface Water
Surface water is among the most important sources of water being used for drinking water Not abundant in nature Easy to collect Unaffected surface water is relatively pure in nature 4/5/19
Water Quality Management
15
Ground Water
Groundwater is abundant It is filtered through natural aquifer Relatively pure It can be contaminated through leaching of metals and organics from the minerals and waste disposal sites Salt water intrusion can be a problem
Source. jnuenvis.nic.in/subject/freshwater/groundwater.htm
4/5/19
Water Quality Management
16
Sea Water
4/5/19
Abundant in nature High salinity Technological means are available to use sea water as a source Expensive (desalination, reverse osmosis) It limits the adaptation of sea water as a source of drinking water Not suitable for places far away from sea
Source. http://www.power-technology.com/projects/taweelah/
Water Quality Management
17
Rain Water Harvesting
It is the gathering, accumulating or sorting of rainwater Usually collected on the roof of the house and stored in large tanks Very good quality water Can be used for drinking with minimum treatment Suitable for isolated places
Adopted in urban areas as well
Not suitable for places having low rainfall 4/5/19
Water Quality Management
18
Groundwater - Surface water - Seawater Physical characteristics
Chemical characteristics
Groundwater typically reasonable levels of turbidity and color
Surface water prone to physical interference and therefore has high levels of turbidity and color
Seawater affected by physical interference
high concentrations of leached contaminants (both metal and inorganic ions)
have high chemical contamination depending upon the hydro geological pattern
have very high salinity
prone to high microbial contamination
can have high microbial contamination
Microbiological typically free characteristics from microbial contamination 4/5/19
Water Quality Management
19
Water Pollution
4/5/19
Water Quality Management
20
Water Pollution in Jumeira, UAE
4/5/19
Water Quality Management
21
Water Pollution Sources
Point sources
Discharge of pipes (domestic wastewater, industrial discharges) Concentrated animal feed lots
Non-point sources
Urban runoff (road silt, oil, etc.) Agricultural runoff (fertilizer, pesticides)
4/5/19
Source: http://visual.merriamwebster.com/earth/environment/water-pollution.php
Water Quality Management
22
Depletion of Dissolved Oxygen
4/5/19
Oxygen remains in water as dissolved form In natural water (surface water), there are organic matter present that consume dissolved oxygen Water receives oxygen through diffusion from air If the oxygen level falls too low, aquatic life can be harmed
Water Quality Management
23
Streeter-Phelps equation
Combines oxygen consumption and reoxygenation to describe deficit as a function of time
k n Ln k t k d La k d t kr t kr t e e k t D e e Da e kr kn kr kd
D = oxygen deficit at any time, mg/L Da = oxygen deficit immediately below pollutant discharge location, mg/L La = ultimate oxygen demand immediately below pollutant discharge location, mg/L kd = deoxygenation constant, d-1 kr = reoxygenation constant, d-1 kn = nitrogenous deoxigenation coeficient, d-1 Ln = ultimate nitrogenous oxygen demand immediately below pollutant discharge location, mg/L 4/5/19 Water Quality Management
n
r
24
Waste Mixing in Water Bodies
4/5/19
Treated/un-treated waste is often mixed with the receiving water body (like a river or stream) Waste has high BOD, whereas receiving body normally has low/no BOD Solution to pollution is dilution
Water Quality Management
25
Management Strategies
4/5/19
Identify the lowest DO that is acceptable to aquatic species in the receiving body Solve the DO sag curve and known mixing Worst case scenario: low river volume, high waste volume Only parameters engineer can control Initial ultimate BOD D – initial deficit in dissolved oxygen o Available tools Further processing of waste to reduce BOD Aeration of waste prior to discharge to reduce initial deficit
Water Quality Management
26
Streeter-Phelps Example
4/5/19
Text book Problem 5-36
Water Quality Management
27
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