Water Pollution: Sources, Categories, and Treatment

Vocabulary flashcards covering key definitions, mechanisms, parameters, and treatment techniques from the Water Pollution lecture.

Water Pollution

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

Point Sources

Discrete, identifiable locations—such as factory drain pipes, ditches, power plant outfalls, or sewer pipes—that discharge pollution directly into water bodies.

Nonpoint Sources

Scattered or diffuse sources having no specific discharge location into a water body, such as runoff from agricultural fields, pastures, golf courses, lawns, and construction sites.

Pathogenic Organisms

Disease-causing agents—including bacteria, viruses, and parasites originating mainly from untreated human and animal excreta—that represent the most serious water pollutants for human health worldwide.

Coliform Bacteria

A group of bacteria residing in the colon or intestines of mammals (such as Escherichia coli) used as indicator organisms to evaluate water samples for the probable presence of infectious pathogens.

Dissolved Oxygen (DO)

The amount of free oxygen present in water, where concentrations of $6\,\text{ppm}$ or higher support desirable game fish, while levels below $2\,\text{ppm}$ support mainly decomposers and detritus feeders.

Biochemical Oxygen Demand (BOD)

A water quality test measuring the amount of dissolved oxygen consumed by microorganisms to decompose organic material, typically evaluated over a $5\text{-day}$ incubation period.

Chemical Oxygen Demand (COD)

A rapid chemical test that breaks down both active bacteria and inactive organic matter using a strong oxidizing agent (dichromate ion in $50\%$ sulfuric acid).

Oxygen Sag

The progressive decline in dissolved oxygen concentrations downstream from a pollution discharge site resulting from decomposers metabolizing organic waste.

Dead Zone

An extremely oxygen-depleted, hypoxic area downstream from heavy nutrient or organic waste discharges where only the most resistant microorganisms and invertebrates can survive.

Oligotrophic

A condition describing rivers and lakes with clear water and low biological productivity due to limited nutrient concentrations.

Eutrophic

A condition describing aquatic systems that are rich in nutrients, organisms, and organic matter, exhibiting high biological productivity.

Cultural Eutrophication

Human-caused acceleration of biological productivity and nutrient enrichment in a body of water, primarily driven by sewage inputs, fertilizer runoff, and decomposing organic matter.

Thermal Pollution

Any artificial increase or decrease in normal water temperature that adversely alters aquatic ecosystems, lowers oxygen solubility, or stresses sensitive aquatic species.

Thermal Plume

A body of heated cooling water discharged from power plants, refineries, or factories into natural water systems, causing ecological disruption and oxygen loss.

Sediment Pollution

Soil and silt eroded from land surfaces that cloud waterways, obstruct shipping channels, reduce plant photosynthesis, and smother gravel spawning beds for fish.

Republic Act No. 9275

The official designation for the Philippine Clean Water Act of 2004, which establishes standards and management policies to protect water resources from pollution.

Primary Treatment

The initial mechanical step of municipal sewage treatment that uses gratings, screens, grit tanks, and sedimentation tanks to physically separate large debris and suspended solids.

Secondary Treatment

The biological stage of municipal wastewater treatment where dissolved organic compounds are decomposed using trickling filters, aeration tanks, or sewage lagoons.

Activated Sludge Process

A secondary treatment technique where primary effluent is aerated and combined with a bacteria-rich slurry to accelerate microbial breakdown of organic wastes.

Effluent Sewerage

A low-cost hybrid sanitation system where household septic tanks digest solid wastes and the remaining liquid effluent is pumped to a central municipal facility for processing.

Constructed Wetlands

Engineered natural wastewater treatment systems that rely on aquatic plants, sunlight, and air exposure for $20$ to $30\text{ days}$ to purify effluent at low cost.

Bioremediation

The use of living organisms to detoxify, extract, or consume pollutants in contaminated water, frequently operated inside controlled tanks or troughs.

Containment Methods

Remediation strategies that confine polluted water in situ or cap ground surfaces with impermeable materials to keep water from dispersing or contacting clean aquifers.

Extraction Techniques

Remediation approaches that pump contaminated water to the surface to eliminate or neutralize pollutants via chemical or physical operations.