Water Supply Exam Review Flashcards 2025

This set of vocabulary flashcards covers key concepts from water supply engineering, including environmental impacts on water safety, the WHO risk-based guidelines, conventional and modern treatment processes, and the mechanisms of colloid destabilisation and filtration.

v. Cholerae

A bacterial strain whose spread is facilitated by the displacement of populations, disruption of water supplies, and failure of sanitation systems during humanitarian crises or climate change.

Cyanobacterial blooms

Increased growth of blue-green algae caused by higher temperatures, raising risks of cyanotoxins and natural organic matter in water sources.

WHO Guidelines for Drinking-water Quality

Health protection strategies that derive numerical "guideline values" for water constituents based on a risk management approach from catchment to consumer.

Aeration

A process that controls substances producing taste and odours, corrosion, and removes offensive gases such as hydrogen sulphide.

Coagulation and Flocculation

The addition and mixing of alum or other chemicals into water to cause particles to stick together and form larger particles called floc.

Sedimentation

The stage in a sedimentation basin where flow slows down, allowing floc particles to settle to the bottom.

Filtration

The process of passing water through layers of sand and gravel to remove remaining particles, including bacteria and other organisms.

Disinfection

The addition of a small amount of chlorine to destroy surviving organisms and ensure the water remains bacteriologically safe through the distribution system.

Dissolved air flotation (DAF)

A modern water treatment process used as an alternative or advancement to conventional clarifiers.

Granular activated carbon (GAC) adsorption

A modern treatment process used to remove residual colour, taste, and odour from water.

Double layer compression

A type of colloid destabilisation involving the addition of an electrolyte to decrease the thickness of the electrical double layer surrounding each colloidal particle.

Charge neutralisation

The addition of ions with a charge opposite to that on colloidal particles to lead to adsorption and reduction of surface charge, allowing agglomeration.

Entrapment in a precipitate

A mechanism where soluble aluminium or iron salts precipitate as hydroxide flocs using colloid particles as nuclei, physically trapping other particles as they form.

Particle bridging

A process where large organic molecules (anionic or cationic polymers) with multiple electrical charges form bridges between colloidal particles.

Interception

A transport mechanism where a particle moving uniformly collides with a grain of filter media, typically affecting large particles.

Sedimentation (Filtration Mechanism)

The removal of large particles within filter media due to gravitational forces; efficiency depends on the ratio of settling velocity ($v_s$) to fluid velocity ($v$).

Diffusion

A mechanism resulting from Brownian motion that significantly affects the transport of very small particles toward filter media.

Brownian motion

The random movement of small particles suspended in a fluid due to collisions with the fluid molecules.

Hydrodynamic action

A mechanism arising from velocity gradients near filter media grains that rotates small particles and moves them toward the media due to pressure differences.

Surface overflow rate ($V_0$)

A calculation determined by $V_0 = Q/A$ used to evaluate particle removal efficiency in a sedimentation basin.