Point source pollution originates from specific, identifiable sources like pipes or ditches. Major point sources of water pollution include municipal sewage treatment plants and industrial facilities. Point source pollution can contaminate water with oxygen-depleting nutrients, pathogens, toxic chemicals, and heavy metals. However, point sources are easier to monitor and regulate compared to nonpoint sources since they come from specific locations.

1. Point Source Pollution
Point source pollution is contamination that enters the environment through any clear, specific location,
like smokestack, pipe, ditch, tunnel, or conduits. Point source pollution remains a major cause of pollution
to water. Point sources of water pollution include municipal sewage treatment plant discharges and
discharges from industrial plant.
Municipal sewage treatment plant point sources can contribute
pollution in the form of oxygen-depleting nutrients and in the
form of pathogens that cause serious health hazards in drinking
water and swimming areas. Industrial point sources can contribute
pollution in the form of toxic chemicals and heavy metals
. point sources of water pollution can be limited to ensure
protection of designated uses of a receiving water. Either standard
may be used to minimized the effluents concentration by proper
wastewater treatment processes like screening, grit chamber
sedimentation, flotation and biological treatment processes.
Point sources are as at specific locations, they are easy to identify, monitor and regulate. Developed world
control point source discharges of many harmful chemicals into aquatic system as well as in atmosphere.

2. Calculation of Point source Pollutions
In Point source pollution calculation law of conservation of mass can be used in any water or wastewater unit
operation. It relate influent flow rate and concentration to effluent flow rate and concentration by accounting for
removal or transformation phenomena. It can be applied to rivers, lakes, or other treatment basins, where the
problem is to find the concentration of a substance at a location or its rate of change in a section. According to this
law there are three general cases .
(i) Steady state conservative system: The simple system to analyze are the assumption that the substance is
conservative . It means the substance leave the system with out any change
Then input rate = output rate
Mathematically
Qw
(ii) Many contaminants undergo chemical, biological or nuclear reactions at
Cw Qm
QS
a rate sufficient to treat them non conservative substances. Then
Cm
Cs
Input = Out put + Decay rate . The decay rate is = -KC
where K is rate coefficient. The negative sign implies a loss of
substance with time or C = Ce-Kt so Decay rate = KCV
Accumulation
0 input and Decay output

3. Non Point Source Pollution (NPSP)
Non point source pollution can not be traced to any single site of discharge. They are usually large land areas that
pollute water by runoff, subsurface flow or deposition from the atmosphere. The runoff of chemicals into surface
water from cropland, live stocks feed lots, urban streets, lawns and parking lots, fugitive discharges from pipelines,
spraying, fertilizers, runoff from lands are the common examples of non point source pollution. There has been
little progress in controlling non point water pollution because of the difficulty extends of identifying and
controlling discharges from so many diffuse sources. Current concerns include the contamination of aquatic
environments by fertilizers and pesticides in runoff from agricultural lands, by oils and particulate matter from
urban streets and by atmospheric deposition of acids. The contamination of ground water resources, especially by
hazardous wastes is also of great concerns.
Major Non Point Source Pollution Categories
Categor S.S D. S BOD Nutrients Toxic Metals Pesticides Pathogens
Agriculture +++ +++ +++ +++ + +++ +++
Construction +++ n + + + n n n
Urban Runoff +++ ++ ++ +++ +++ +++ +++
Mining ++ ++ n n +++ n n
+++ = Potentially High Pollutant Source ++ = Moderate Pollutant Source
+ = Low pollutant Source and n = negligible pollutant source

4. Urban Non Point Source Pollution
Storm water runoff from urban areas contained higher concentration of different pollutants, like metals,
nutrients, oxygen demanding wastes and suspended solids. It also contains pathogenic microorganisms,
oil and petroleum hydrocarbons, pesticides and a variety of synthetic organics. The following measures
are help in reducing urban NPSP. (i) Public education and outreach (ii) Public participation (iii) Illicit
discharge determination and elimination (iv) Construction site runoff control (v) Post Construction runoff
to reduce soil erosion and (vi) Pollution prevention/ good house keeping to reduce pollution in runoff
from municipal operations. There are three major steps that can mitigate urban NPSP. (a) Reduce surface
runoff from urban sites (b) source control to reduce the amount of pollution pick up by runoff and © Best
management practices (BMP) to remove or treat pollutants in the runoff. Urban areas have a higher
percentage of impervious surfaces like roads side walls, driveways and parking lots. As a greater
percentage of precipitation falling in urban areas becomes surface runoff. Pollution control techniques
that reduce the amount of surface runoff can be effective at reducing erosion and pollution transport. In
addition to reducing surface runoff we can emphasize source control to reduce the amount of pollutants
deposited on impervious surfaces. Source control can be attained by increasing public education providing
waste disposal sites, introducing appropriate planning and regularity policy and enforcing pollution
control regulations. Streets sweeping least expensive source control techniques, reduces sediment loads
in runoff but fail to pick up the finer particles that are often the most significant source of pollution. Street
vacuuming is efficient in collecting the small particles, but expensive and often ineffective during wet
season. Street flushing is an effective way, but the catch basins have to cleaned periodically.

5. Mitigation Measure
Urban NPSP can be mitigated by the use of appropriate structural and non structural best management
practices. They are (i) Infiltration systems : Infiltration systems reduce the total amount of surface runoff
and the amount of sediment transport by increasing the amount of precipitation infiltrated into the soil.
(ii) Detention system: It reduce pollutant transport by retarding the rate of runoff and by encouraging the
settling of suspended solids. (iii) Retention system: Retention systems are wet ponds that are sized to
hold a typical (6 months) storm events. The ponds may be lined or unlined. The unlined ponds increase
infiltration and can help with ground water recharge. However, unlined ponds are not appropriate if the
surface runoff contains pollutants that could contaminate drinking water aquifer or in area where a high
water table would result in ground water flowing into ponds. (iv) constructed Wetlands: Constructed
wetlands are similar to retention system and wet ponds in that they have permanent standing water, but
have the added advantage that they incorporate biotic functions like nutrients uptake and microbial
degradation of pollutants. (v) Filtration System: Filtration systems use sand, soil, organic matter, carbon
or other materials to filter out pollutants. Filter systems can be incorporated into existing storm drainage
structures by adding underground vaults. (vi) Biofilter: Biofilter and other vegetated system such as grassy
swales and filter strips can be used to treat shallow flow or sheet flow by increasing infiltration and
reducing sediment transport. Large bioretention system add biological treatment such as nutrient uptake
and microbial degradation of pollutants. Most of the structural BMPs are designed to remove sediments
and pollutants that are transported in surface runoff along with sediments. The nonstructural BMPs focus
on reducing various pollutants. A public education program, with appropriate enforcement of pollution
control regulation is effective tools.

6. Mitigation Measure
Urban NPSP can be mitigated by the use of appropriate structural and non structural best management
practices. They are (i) Infiltration systems : Infiltration systems reduce the total amount of surface runoff
and the amount of sediment transport by increasing the amount of precipitation infiltrated into the soil.
(ii) Detention system: It reduce pollutant transport by retarding the rate of runoff and by encouraging the
settling of suspended solids. (iii) Retention system: Retention systems are wet ponds that are sized to
hold a typical (6 months) storm events. The ponds may be lined or unlined. The unlined ponds increase
infiltration and can help with ground water recharge. However, unlined ponds are not appropriate if the
surface runoff contains pollutants that could contaminate drinking water aquifer or in area where a high
water table would result in ground water flowing into ponds. (iv) constructed Wetlands: Constructed
wetlands are similar to retention system and wet ponds in that they have permanent standing water, but
have the added advantage that they incorporate biotic functions like nutrients uptake and microbial
degradation of pollutants. (v) Filtration System: Filtration systems use sand, soil, organic matter, carbon
or other materials to filter out pollutants. Filter systems can be incorporated into existing storm drainage
structures by adding underground vaults. (vi) Biofilter: Biofilter and other vegetated system such as grassy
swales and filter strips can be used to treat shallow flow or sheet flow by increasing infiltration and
reducing sediment transport. Large bioretention system add biological treatment such as nutrient uptake
and microbial degradation of pollutants. Most of the structural BMPs are designed to remove sediments
and pollutants that are transported in surface runoff along with sediments. The nonstructural BMPs focus
on reducing various pollutants. A public education program, with appropriate enforcement of pollution
control regulation is effective tools.