Transcript Water Pollution - Bioenviroclasswiki

Water Pollution
Part - II
Water pollution from Agriculture
• Fertilizer runoff causes water enrichment.
• Animal wastes and plant residues in waterways
produce high BODs and high levels of suspended
solids as well as water enrichment.
• Chemical pesticides used in agriculture may leach
into the soil and from there into waterways.
• Soil erosion from fields and rangeland cause
sediment pollution in waterways.
Water Pollution from Agriculture
What is going into the water from farm
operations?
•Pesticides
•Fertilizers
•Manure
•sediments
Municipal Water Pollution
What is going into the water from
urban runoff?
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Salt from roadways
Untreated garbage
Animal wastes, organic wastes, leaves
Construction sediments and traffic emissions.
Zinc from weathering of aging pipes and gutters
Copper from brake linings, worn pipings
Used motor oil
Fertilizers
Industrial wastes in water
• Food processing industries produce organic wastes that are readily
decomposed but have a high BOD.
• Paper and paper mills produce waste that have high BOD and also toxic
compounds and sludge. The paper industries have however begun using
methods of production of paper without the use of chlorine as a bleaching
agent and that produce less toxic effluent.
• The electronics industry uses special techniques such as ion exchange and
electrolytic recovery method to reclaim the toxic metal such as copper,
lead and manganese.
Water Quality: DO
You can make a difference
Read preventing water pollution in page
number 519
Case in Point : Green Chemistry
Groundwater pollution
• Roughly half of the United States obtain the
drinking water from groundwater, which is also
withdrawn for irrigation and industry.
• The most common pollutants of groundwater
such as pesticides, fertilizers, organic compounds
seep into groundwater from municipal sanitary
landfills, underground storage tanks, backyards,
golf courses, and intensively cultivated lands.
• Underground petroleum storage tanks may be
leaking at service stations in the United States.
Groundwater Pollution
Once groundwater is contaminated, it does not readily cleanse itself by
natural processes. Methyl tertiary butyl ether, a gasoline additive is a
common groundwater pollutant it is caused mainly from leaking
Lake Maracaibo, Venezuela
It is the largest lake in South America. It receives water from several rivers, and
water flows from it into the Caribbean Sea.
This lake suffers from the effects of oil pollution and human wastes as well as
contamination from farms and factories.
Until recently raw sewage from the city was discharged directly into it,
contributing to the nutrient overload.
Modern sewage-treatment facilities were installed during the 1990s to take care
of human wastes, but other problems need to be
Addressed.
Po River, Italy
The Po River, which flows across northern Italy, empties into the Adriatic Sea.
Source of pollution
•Many cities including Milan, dump their treated and untreated sewage into the
Po.
•Industrial waste
•Agricultural wastes.
•Soil erosion and sediment deposition
•Po is the source of drinking water
•Po has jeopardized tourism and fishing in the Adriatic Sea.
•It has closed swimming in some places.
Ganges River, India
• http://www.youtube.com/watch?v=wb_yDBm
RgmU
• Watch this video to know how the holy river
Ganges has been polluted over the years.
Ganges River, India
Used for bathing and washing
clothing
Sewage and industrial waste
discharged into river
Ganga Action Plan initiated by
government
Construction of 29 sewage
treatment plants
Kwale, Kenya
Many Africans have serious health problems from drinking surface water
contaminated with disease-causing organisms.
Cholera and serious diarrhea outbreaks very common.
Installation of village wells with hand pumps to provide clean drinking
water (ground water).
Acute drought lowered water levels in the early 2000s, drying up many
wells.
Arsenic poisoning in Bangladesh
Naturally occurring in the
ground water.
Improving Water QualityPurification of Drinking Water
• In US most
municipal water
supplies are treated
• Collected from
water or reservoir
• Treated
Improving Water QualityPurification of Drinking Water
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Treated water distributed to
customers
Sewer lines bring sewage to treatment
plant
Sewage treated at sewage treatment
plant
Turbid water is treated with aluminum
sulfate a chemical coagulant that
causes the suspended particles to
settle down.
Then filtered through sand to remove
remaining suspended particles.
Then disinfected by adding chlorine.
Purification of Drinking Water
• Chlorine Dilemma
– Chlorine kills disease causing organisms
– Chlorine byproducts are linked to numerous
cancers, miscarriages and birth defects
– Peru stopped using chlorine
• 1991- huge cholera epidemic that infected 300,000
people and at least 3500 died since resumed
• Fluoridation
– Prevents tooth decay
– Linked to cancer, kidney disease
Purification of drinking water
• One alternative to chlorination is to use
chloramine, a disinfectant produced by
combining chlorine with ammonia. It does not
form potentially harmful by products, it may
cause lead level in drinking water system.
• Another way is to filter water through
activated carbon granules.
• Fluoridation.
Municipal Sewage Treatment
Treatment of Human Waste
• Primary treatment: taking out solids
– grating (removes debris)
– moving screen (takes out smaller pieces)
– grit tank (sand and gravel settle)
– primary sedimentation tank (sludge settles)
Secondary treatment: biological
degradation
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aeration tank (or filter bed, sewage lagoon)
fluid is mixed with a bacteria rich slurry
air is pumped in which promotes bacterial growth
bacteria and sludge is removed off the bottom (some is
returned to inoculate the aeration tanks)
– water is sometimes chlorinated to kill bacteria, then
released
Tertiary Treatment: removal of plant
nutrients
– removal of nitrates, phosphates and other
nutrients which can cause algal blooms
– this can be accomplished by passage through a
wetland or lagoon
• Sewage treatment works well except:
– water in storm drains gets no treatment
– during storms, raw sewage is dumped
– treated water still has environmental effects
Municipal Sewage Treatment
Septic Tanks
A house-by-house alternative to sewer systems
Water is pumped into a tank
oils rise to top, solids to bottom
middle water is pumped into a series of pipes where it can evaporate and
be worked on by bacteria
Works well if maintained, but can leak into ground water
Individual Septic SystemDrain Field
Septic Tank and Field
Combined sewer system
• It is one in which human and industrial wastes
are mixed.
• Is it good to have this practice or not? Explain
• (Refer to Page number 519)
• Read the article Preventing water pollution
and how you can make a difference and
discuss with your partner as to whether you
are practicing or plan to practice.
Laws Controlling Water Pollution
• Citizen Watchdogs to Monitor Pollution
• Safe Drinking Water Act (1974)
– Set uniform federal standards for drinking water
– Maximum contaminant level
• Clean Water Act (1972)
– EPA sets up and monitors National Emissions
Limitations
– Effectively improved water quality from point
sources
Laws that Protect Groundwater
• Safe Drinking Water Act
• Resource, Conservation and Recovery Act
Case-In-Point Green Chemistry