07 Water Pollution

Any physical, biological, or chemical change in water quality that adversely affects living organisms or makes water unsuitable for desired uses

Water Pollution

All industries that generate wastewater e.g. from factories due to use of water in manufacturing, power plants from their cooling and washing activities, and sewage treatment plants. They discharge pollution from specific locations, such as drain pipes, ditches, or sewer outfalls.

Point Sources

Scattered or diffuse, having no specific location where they discharge into a particular body of water

Nonpoint Sources

Contaminants carried by air currents and precipitated into watersheds or directly onto surface waters as rain, snow, or dry particles

Atmospheric Deposition

Bacteria, viruses, parasites from human and animal excreta

Infectious Agents

Pesticides, plastics, detergents, oil and gasoline from industrial, household, and farm use

Organic Chemicals

Acids, caustics, salts, metals from industrial effluents, household cleansers, surface runoff

Inorganic Chemicals

Uranium, thorium, cesium, iodine, radon from mining and processing of ores, power plants, weapons

Radioactive Materials

Soil, silt from land erosion

Sediment

Nitrates, phosphates, ammonium from agricultural and urban fertilizers, sewage manure

Plant Nutrients

Animal manure and plant residues from sewage, agricultural runoff, paper mills, food processing

Oxygen-Demanding Wastes

Heat from power plants, industrial cooling

Thermal

The most serious water pollutants in terms of human health worldwide

Pathogenic Organisms

Typhoid, cholera, bacterial and amoebic dysentery, enteritis, polio, infectious hepatitis, and schistosomiasis

Waterborne Diseases

Any of the many types that live in the colon or intestines of humans and other animals

Coliform Bacteria

The most common of coliform bacteria

Escherichia coli (E.coli)

The amount of dissolved oxygen that must be present in water in order for microorganisms to decompose the organic matter in the water

Biochemical Oxygen Demand (BOD)

Uses a strong oxidizing agent to completely breakdown all organic matter in a water sample

Chemical Oxygen Demand (COD)

A method of assaying pollution levels by measuring oxygen content directly

Dissolved Oxygen (DO)

The oxygen decline downstream

Oxygen Sag

Water so oxygen-depleted that only the most resistant microorganisms and invertebrates can survive

Dead Zone

Rivers and lakes that have clear water and low biological productivity

Oligotrophic

Waters that are rich in organisms and organic materials

Eutrophic

Human-caused increase in biological productivity

Cultural Eutrophication

Elevated phosphorus and nitrogen levels stimulate “blooms” of algae or thick growths of aquatic plants and can result in collapse of the aquatic ecosystem

Eutrophication Undesirable Results

Oxygen-depleted zones such as those in the Gulf of Mexico at the mouth of the Mississippi River

Hypoxic Zones

Heavy metals such as mercury, lead, tin, and cadmium

Toxic Inorganic Chemicals

Metals are highly persistent, therefore, they can accumulate in food webs and have a cumulative effect in top predators

Metal Persistence

Soluble salts including toxic selenium and arsenic

Nonmetallic Salts

Salt buildup affecting irrigated farmland

Salinization

Watery and inflamed eyes, gastrointestinal cramps, gradual loss of strength, dry skin and skin tumors, anemia, confusion, and eventually death

Arsenic Poisoning Symptoms

Acids released as by-products of industrial processes

Acids and Bases Source

Reported in lakes in the Adirondack Mountains and eastern Quebec

Acid Precipitation Damage

Include drugs, pesticides, and other industrial substances

Organic Pollutants

Improper disposal of industrial and household wastes and runoff of pesticides from farm fields

Toxic Organic Chemicals Source

Disastrous for ecosystems and local economies

Oil Spills

Fill lakes and reservoirs, obstruct shipping channels, clog hydroelectric turbines, and make purification of drinking water more costly

Sediments Effects

Raising or lowering water temperatures from normal levels can adversely affect water quality and aquatic life

Thermal Pollution

Heated water discharged into rivers and lakes

Thermal Plume

The cheapest and most effective way to reduce pollution is to avoid producing it or releasing it to the environment in the first place

Source Reduction

Agriculture, urban runoff, construction sites, and land disposal

Controlling Nonpoint Sources

Physically separates large solids from the waste stream

Primary Treatment

Biological degradation of dissolved organic compounds

Secondary Treatment

A bed of stones or corrugated plastic sheets through which water drips and microorganisms decompose organic material

Trickling Filter

Effluent mixed with a bacteria-rich slurry in an aeration tank

Activated Sludge Process

A hybrid between a traditional septic tank and a full sewer system

Effluent Sewerage

Can cut secondary treatment cost to one-third of mechanical treatment costs

Constructed Wetlands

Water passed through fine filters or membranes to screen out dissolved impurities

Filtration

Heating or boiling water full of dissolved minerals to obtain pure water vapor

Distillation

Remediation means finding remedies for problems

Water Remediation

Confine or restrain dirty water or liquid in situ or cap the surface with an impermeable layer

Containment Methods

Pump out polluted water so it can be treated

Extraction Techniques

Living organisms used effectively and inexpensively to clean contaminated water

Bioremediation

coal mining

is an especially important source of acid water pollution