1. Please explain the reaction mechanism and kinetics for the treatment of municipal sewage
using constructed wetland. (20 points) 2. Please describe the commonly used treatment processes
in wastewater reclamation and reuse. (20 points) Please describe the commonly applied control
measures for the management of nonpoint source pollution from construction sites. (18 points) 3.
4. What is a TMDL? What is the MOS for TMDL calculation? How the TMDL is allocated
among different pollution sources? (17 points)
Solution
1.
Natural wetlands perform many functions that are beneficial to both humans and wildlife. One of
their most important functions is water filtration. As water flows through a wetland, it slows
down and many of the suspended solids become trapped by vegetation and settle out. Other
pollutants are transformed to less soluble forms taken up by plants or become inactive. Wetland
plants also increse the necessary conditions for microorganisms to live there. Through a series of
continual processes, these microrganisms also transform and remove pollutants from the water.
These are some of the design conditions for construstioc of welands:
Construct treatment wetlands should be done on uplands and outside floodplains in order to
avoid damage to natural wetlands and other aquatic resources,
• Consider the importance of treatment wetlands within the watershed like potential water quality
impacts, surrounding land uses and relation to local wildlife in that area
• Closely examine factors, such as soil suitability, hydrology, vegetation, and presence of
endangered species or critical habitat, when determining an appropriate location
• Use water control measures that will allow good results to changes in water quantity, quality,
depth and flow.
• The flow in that area to be maintained continually with regular inspection.
2.
There are three major stages in wastewater treatment
Primary:Raw sewage is first subjected to preliminary treatment where it is treated to remove
large objects. Primary treatment is the process wherein sludge settles by sedimentation, and all
floating material like oil is taken off from the surface. This produces a somewhat homogenous
liquid,
Secondary:
In this stage, aerobic or anaerobic bacteria feed on organic matter, thus removing most of it.
After this, if necessary, the water can be disinfected through chlorination which will kill off
microorganisms. Secondary treated water can be used for non-potable purposes like toilet-
flushing and gardening.
Tertiary:
In this treatment involves more advanced processes like reverse osmosis (RO) and
demineralisation. Dissolved solids and nutrients get further removed during these processes
The most used treatment processes are:
Activated Sludge Procees ASP:
Atmospheric air or pure oxygen is bubbled through primary treated sewage combined with
organisms to develop a biological floc which reduces the organic content of the sewage.
Extended Areation:
This is a modification for ASP as it .
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1. Please explain the reaction mechanism and kinetics for the treatme.pdf
1. 1. Please explain the reaction mechanism and kinetics for the treatment of municipal sewage
using constructed wetland. (20 points) 2. Please describe the commonly used treatment processes
in wastewater reclamation and reuse. (20 points) Please describe the commonly applied control
measures for the management of nonpoint source pollution from construction sites. (18 points) 3.
4. What is a TMDL? What is the MOS for TMDL calculation? How the TMDL is allocated
among different pollution sources? (17 points)
Solution
1.
Natural wetlands perform many functions that are beneficial to both humans and wildlife. One of
their most important functions is water filtration. As water flows through a wetland, it slows
down and many of the suspended solids become trapped by vegetation and settle out. Other
pollutants are transformed to less soluble forms taken up by plants or become inactive. Wetland
plants also increse the necessary conditions for microorganisms to live there. Through a series of
continual processes, these microrganisms also transform and remove pollutants from the water.
These are some of the design conditions for construstioc of welands:
Construct treatment wetlands should be done on uplands and outside floodplains in order to
avoid damage to natural wetlands and other aquatic resources,
• Consider the importance of treatment wetlands within the watershed like potential water quality
impacts, surrounding land uses and relation to local wildlife in that area
• Closely examine factors, such as soil suitability, hydrology, vegetation, and presence of
endangered species or critical habitat, when determining an appropriate location
• Use water control measures that will allow good results to changes in water quantity, quality,
depth and flow.
• The flow in that area to be maintained continually with regular inspection.
2.
There are three major stages in wastewater treatment
Primary:Raw sewage is first subjected to preliminary treatment where it is treated to remove
large objects. Primary treatment is the process wherein sludge settles by sedimentation, and all
floating material like oil is taken off from the surface. This produces a somewhat homogenous
liquid,
Secondary:
In this stage, aerobic or anaerobic bacteria feed on organic matter, thus removing most of it.
After this, if necessary, the water can be disinfected through chlorination which will kill off
microorganisms. Secondary treated water can be used for non-potable purposes like toilet-
2. flushing and gardening.
Tertiary:
In this treatment involves more advanced processes like reverse osmosis (RO) and
demineralisation. Dissolved solids and nutrients get further removed during these processes
The most used treatment processes are:
Activated Sludge Procees ASP:
Atmospheric air or pure oxygen is bubbled through primary treated sewage combined with
organisms to develop a biological floc which reduces the organic content of the sewage.
Extended Areation:
This is a modification for ASP as it contains both supply of air from outside either by natural or
mechanical means and the wate is completely stabilised in this process.
3.
At construction sites, soil that is piled up carelessly or not contained, along with discarded
materials, when natural rain or water falls on it the runoff from such areas is a major origin of
nonpoint source pollution.
Measures for controlling it:
4.
TMDL stands for Total Max Daily Load whch means in Environmental Engg. terms it is the max
amount of pollutant a gven water stream or river can recieve within given STD limits
Margin of Safety (MOS) for TMDL is (TMDL( minus )--some of waste load allocations and load
allocations in the area into that stream)
