water pollution.ppt[1]

Water Pollution

Pollution

Old motto: “Solution to

Pollution is Dilution” decomposition will remove many (most) pollutants

ultimately. Current motto: “Solution to Pollution is

Prevention” especially important for groundwaters (little

decomposition) and with persistent pollutants.

“Under the belief that water could dilute any substance, industries and individuals during the 18th and 19th centuries often used rivers and lakes as garbage cans.

Industrial effluent, raw sewage and animal carcasses would often be dumped into waterways, without much thought of contamination and downstream neighbors.”

Currently, waterborne toxic chemicals pose the greatest threat to the safety of water supplies in industrialized nations.

There are many possible sources of chemical contamination. These include wastes from industrial chemical production, metal-plating

operations, and pesticide runoff from agricultural lands. Some specific pollutants include industrial chemicals such as chlorinated

hydrocarbons; heavy metals, including cadmium, lead, and mercury; saline water; bacteria, particularly coliforms; and general municipal and industrial wastes.

General Types of Water Pollutants

Pathogens, parasites Usually from sewage, feedlots, slaughterhouses Viruses Bacteria (cholera, ...)

Coliform bacteria usually not pathogenic, Used as indicators of pollution

Protozoan parasites (Giardia, Cryptosporidium)

09 April 2009 Water-Pollution.ppt 5

PathogensPathogen Source

cholera (a bacteria) human waste and contaminated algae in warm coastal waters

Cryptosporidium (a protozoan)

mammal fecal wastes

E. coli (a bacteria) human and animal fecal wastes

Giardia (a protozoan)

wildlife and human fecal wastes

Oxygen-demanding wastes Organic materials from sewage, slaughterhouses,

etc. Decomposed by bacteria

Bacteria require, consume dissolved oxygen “Biological Oxygen Demand” (BOD)

Measure of water quality Low in pristine water


Inorganic chemicals Mostly from industry Heavy metals

Lead, arsenic, mercury, copper ions, etc. Ammonia Acids

Sulfuric acid, nitric acid from acid deposition Also from industry

Bases (caustic alkalines)


Inorganic plant nutrients (fertilizers) From agriculture, lawns & gardens

Leaching into groundwater Run-off into surface waters

Stimulate growth of algae (algal blooms) Algae die, sink, become oxygen-demanding waste

Water-Pollution.ppt 10

Organic chemicals from industry, restaurants, cars, households,

farms Gasoline, oil Engine coolant (ethylene glycol) Solvents Detergents Pesticides

insecticides, herbicides, fungicides Polychlorinated Biphenyls (PCBs)


Sediments Erosion from construction sites, streets & roads,

farms, sewage Dense sediments sink, accumulate

Sedimentation in reservoirs Less dense sediments may stay in water

Reduce clarity (increase turbidity) Reduce light penetration & photosynthesis


Radioactive material From spills, waste from atomic weapons production

Hanford, Washington Savannah River Plant, South Carolina

From nuclear power plants (minor) Closely regulated

Heat (“thermal pollution”) Heated water from cooling of electrical generating

equipment Alters ecosystem of river, lake


Pollution: Source categories

point-source pollution enters at a specific location (point). ex: pipe from sewage treatment plant

non-point source pollution enters over a wide area, no single

point of entry can be specified ex: runoff from parking deck

regulatory difference between these two

Point Source Pollution

comes from a specific source, like a pipe

factories, industry, municipal treatment plants

can be monitored and controlled by a permit system

What is nonpoint source pollution?

Nonpoint Source (NPS) Pollution is pollution associated with stormwater or runoff

NPS pollution cannot be traced to a direct discharge point such as a wastewater treatment facility

Examples of NPS

oil & grease from cars fertilizers animal waste grass clippings septic systems sewage & cleaners from

boats household cleaning

products litter

Impact of Nonpoint Source Pollution

fish and wildlife recreational water

activities commercial fishing tourism drinking water quality

Potential Sources of Pollutants Found in Residential Areas

Nutrients: Fertilizers and septic systems

Pathogens: Pet waste and septic systems

Sediment: Construction, road sand, soil erosion

Toxic: Pesticides, household products

Debris: Litter and illegal dumping Thermal: heated runoff, removal of

streamside vegetation

Pollutants from Agriculture

Sediment Nutrients Pathogens Pesticides

Pollutant Transport Mechanisms

• NPS pollutants build up on land surfaces during dry weather

Atmospheric depositionFertilizer applicationsAnimal wasteAutomotive exhaust/fluid leaks

• Pollutants are washed off land surfaces during precipitation events (stormwater runoff)

• Stormwater runoff will flow to lakes and streams

Pollutants Found in RunoffSedimentSoil particles transported from their source

Biochemical Oxygen Demand (BOD) ● Oxygen depleting materialLeavesOrganic material

Toxics● Pesticides Herbicides Fungicides Insecticides

● Metals (naturally occurring in soil, automotive emissions/ tires) Lead Zinc Mercury

● Petroleum Hydrocarbons (automotive exhaust and fuel/oil)Debris

Litter and illegal dumping

Nutrients● Various types of materials that become dissolved and suspended in water (commonly found in fertilizer and plant material): Nitrogen (N) Phosphorus (P)

Bacteria/ PathogensOriginating from:● Pets● Waterfowl● Failing septic systems

Thermal StressHeated runoff, removal of streamside vegetation

Ground water pollution Pollution of aquifers Non-point and Point sources

Pollutants slow to break down in cold & dark


Water pollution

In lakes, reservoirs Low flow rate, long

residence time Deep, stratification Pollutants can accumulate,

concentrate


Water pollution

In streams, rivers Higher flow rate, dilution

effect Turbulent

Well mixed Well oxygenated

Long riverbanks, contact with land Subject to non-point source

pollutants Often flow near cities


ELEMENTAL POLLUTANTS

Some of these are recognized as nutrients required for animal and plant life, including some that are essential at low levels but toxic at higher levels

Some of the heavy metals are among the most harmful of the elemental pollutants and are of particular concern

Inorganic chemicals manufacture has the potential to contaminate water with trace elements.

Among the industries regulated for potential trace element pollution of water are those producing chlor-alkali, hydrofluoric acid, sodium dichromate(sulfate process and chloride ilmenite process), aluminum fluoride, chrome pigments, copper sulfate, nickel sulfate, sodium bisulfate, sodium hydrosulfate, sodium bisulfite, titanium dioxide, and hydrogen cyanide.

HEAVY METALS

Cadmium

Pollutant cadmium in water may arise from industrial discharges and mining wastes. Cadmium is widely used in metal plating. Cadmium is found in water in the +2 oxidation state.

The effects of acute cadmium poisoning in humans are very serious. Among them are high blood pressure, kidney damage, destruction of testicular tissue, and destruction of red blood cells.

It is believed that much of the physiological action of cadmium arises from its chemical similarity to zinc. Specifically, cadmium may replace zinc in some enzymes, thereby altering the stereostructure of the enzyme and impairing its catalytic activity. Disease symptoms ultimately result.

Lead

Inorganic lead arising from a number of industrial and mining sources occurs in water in the +2 oxidation state.

Lead from leaded gasoline used to be a major source of atmospheric and terrestrial lead, much of which eventually entered natural water systems.

In addition to pollutant sources, lead-bearing limestone and galena (PbS) contribute lead to natural waters in some locations.

Acute lead poisoning in humans may cause severe dysfunction of the kidney, reproductive system, liver, brain, and central nervous system leading to sickness or death.

Lead poisoning from environmental exposure is thought to have caused mental retardation in many children.

Mild lead poisoning causes anemia. The victim may have headaches and sore muscles, and may feel generally fatigued and irritable.

Except in isolated cases, lead is probably not a major problem in drinking water, although the potential exists in cases where old lead pipe is still in use. Lead used to be a constituent of solder and some pipe-joint formulations.

Mercury

Because of its toxicity, mobilization as methylated forms by anaerobic bacteria, and other pollution factors, mercury generates a great deal of concern as a heavymetal pollutant.

Mercury is found as a trace component of many minerals, with continental rocks containing an average of around 80 parts per billion, or slightly less, of this element. Cinnabar, red mercuric sulfide, is the chief commercial mercury ore. Fossil fuel coal and lignite contain mercury, often at levels of 100 parts per billion or even higher, a matter of some concern with increased use of these fuels for energy resources.

Metallic mercury is used as an electrode in the electrolytic generation of chlorine gas, in laboratory vacuum apparatus, and in other applications.

Significant quantities of inorganic mercury(I) and mercury(II) compounds are used annually.

Organic mercury compounds used to be widely applied as pesticides, particularly fungicides. These mercury compounds include aryl mercurials such as phenyl mercuric dimethyldithiocarbamate (formerly used in paper mills as a slimicide and as a mold retardant for paper), and alkyl-mercurials such as ethylmercuric chloride, C2H5HgCl, which was used as a seed fungicide. Because of their resistance to degradation and their mobility, the alkyl mercury compounds are generally considered to be more of an environmental threat than either the aryl or inorganic compounds.

Mercury enters the environment from a large number of miscellaneous sources related to human use of the element. These include discarded laboratory chemicals,batteries, broken thermometers, amalgam tooth fillings, and formerly lawn fungicides and pharmaceutical products.

Taken individually, each of these sources may not contribute much of the toxic metal, but the total effect can be substantial.

Sewage effluent sometimes contains up to 10 times the level of mercury found in typical natural waters.

The toxicity of mercury was tragically illustrated in the Minamata Bay area of Japan during the period 1953–1960.

Among the toxicological effects of mercury are neurological damage, including irritability, paralysis, blindness, or insanity; chromosome breakage; and birth defects. The milder symptoms of mercury poisoning such as depression and irritability have a psychopathological character.

Some forms of mercury are relatively nontoxic and were formerly used as medicines, for example, in the treatment of syphilis. Other forms of mercury, such as soluble Hg(II) salts and methylmercury compounds, are highly toxic.

Minamata disease

Methyl mercury induced Minamata Disease

(1956 - )

Patients: 12,615Clinical symptoms:Sensory disturbance Constriction of the visual fieldCoordination disturbanceDysarthriaHearing disturbanceTremor

Minamata Disease Archives

Fetal Minamata disease

DNT patients: 16 (>64)

Children, born of women who ate polluted fish, developed Fetal Minamata disease.

They suffered with more serious symptoms than their mothers.

S. Kuwahara, 1998

Mental RetardationPrimitive reflex Coordination disturbanceDysarthriaLimb deformationGrowth disorderChoreoathetosisHyper salivation

Clinical symptoms:

Uses of mercury

Electrical products-switches, wiring, thermostats, batteries, etc.

Dentistry Medical products-antiseptics, laxatives Thermometers Pharmaceutical preservatives- thimerosal Industrial processes- byproduct of coal-

burning power plants, fossil fuel combustion

Effects of Mercury

Neurological complications on a developing fetus

Sensory disturbances (blindness) Lack of coordination (slurred speech) Reproductive failure Impaired growth Loss of motor skills Loss of IQ points Cardiovascular problems

Different forms of mercury

Elemental mercury-does not affect humans Inorganic mercury-does not affect humans,

gets transformed by bacteria into methylmercury

Methylmercury-also called organic mercury, poisonous, absorbed into tissue

The most significant water pollutant metalloid element is arsenic, a toxic element that has been the chemical villain of more than a few murder plots.

Acute arsenic poisoning can result from the ingestion of more than about 100 mg of the element.

Chronic poisoning occurs with the ingestion of small amounts of arsenic over a long period of time.

There is some evidence that this element is also carcinogenic. Arsenic occurs in the Earth’s crust at an average level of 2–5 ppm. The combustion of fossil fuels, particularly coal, introduces large quantities of

arsenic into the environment, much of it reaching natural waters. Arsenic occurs with phosphate minerals and enters into the environment along with some phosphorus compounds.

Some formerly used pesticides, particularly those from before World War II, contain highly toxic arsenic compounds.

The most common of these are lead arsenate, Pb3(AsO4)2; sodium arsenite, Na3AsO3; and Paris Green, Cu3(AsO3)2.

Arsenic

Another major source of arsenic is mine tailings. Arsenic produced as a by-product of copper,gold, and lead

refining exceeds the commercial demand for arsenic, and it accumulates as waste material.

Like mercury, arsenic can be converted by bacteria to more mobile and toxic methyl derivatives according to the following reactions:

Arsenic

Organotin Compounds

Of all the metals, tin has the greatest number of organometallic compounds in commercial use, with global production on the order of 40,000 metric tons per year.

In addition to synthetic organotin compounds, methylated tin species can be produced biologically in the environment.

Major industrial uses of organotin compounds include applications of tin compounds in fungicides, acaricides, disinfectants, antifouling paints, stabilizers to lessen the effects of heat and light in PVC plastics, catalysts, and precursors for the formation of films of SnO2 on glass.

Tributyl tin chloride and related tributyl tin (TBT) compounds have bactericidal, fungicidal, and insecticidal properties and are of particular environmental significance because of their use as industrial biocides.

In addition to tributyl tin chloride, other tributyl tin compounds used as biocides include the hydroxide, the naphthenate, bis(tributyltin) oxide, and tris(tributylstannyl) phosphate. TBT has been widely used in boat and ship hull coatings to prevent the growth of fouling organisms.

Organotin Compounds Other applications include preservation of wood, leather, paper, and

textiles. Antifungal TBT compounds have been used as slimicides in cooling tower

water. Obviously, the many applications of organotin compounds for a variety of

uses pose a significant potential for environmental pollution. Because of their applications near or in contact with bodies of water,

organotin compounds are potentially significant water pollutants and have been linked to endocrine disruption in shellfish, oysters, and snails. Because of such concerns, several countries, including the U.S., England, and France, prohibited TBT application on vessels smaller than 25 meters in length during the 1980s.

In response to concerns over water pollution, in 1998 the International Maritime Organization agreed to ban organotin antifouling paints on all ships by 2003.

Bioaccumulation: build-up in concentration of something with each step of the food chain Crosses the blood/brain barrier and placenta Eliminated from living tissue very slowly Is contained in fish flesh and is not reduced or

removed by cleaning, trimming or cooking Bioconcentration: comparison between

creature’s concentration and concentration in environment (i.e. seawater)

Water pollution

Prevention Better to NOT pollute than to clean up later

Clean up is expensive Clean up is never complete


Sewage Treatment

Primary Screens and settling tanks remove grit & suspended

organic matter. Secondary

Sewage aerated; aerobic bacteria consume organic matter

Leave dissolved inorganics, NO3, PO4, etc. Tertiary

Filters most dissolved inorganics and remaining dissolved organic compounds


Sewage Treatment

Primary Screens and settling tanks remove grit &

suspended organic matter.


Sewage Treatment

Secondary Sewage aerated; aerobic bacteria consume organic matter Leave dissolved inorganics, NO3, PO4, etc.


Sewage Treatment

Tertiary Filters most dissolved

inorganics and remaining dissolved organic compounds

Can be done biologically in wetlands Natural Artificial


Water Quality

Improvement since 1970 Surface waters no longer regarded as open sewers

More and better sewage treatment systems Less dumping of industrial waste

Clean Water Act of 1972, 1977 Make all U.S. surface waters “fishable and swimmable,”

Goal not fully met


water pollution.ppt[1]

Documents

source categories5ointsource

water supplies

industrial wastes

bacteria bacteria

rganic chemicals irom

mercury saline water

specific source

s pollution