Water Treatment Operator Class III flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Alkalinity

The capacity of water to neutralize acid, measured as mg/L CaCO3; it buffers pH changes and is consumed by alum coagulation.

Turbidity

A measure of water clarity caused by suspended particles, reported in NTU; high turbidity can shield pathogens from disinfection.

Hardness

The sum of dissolved calcium and magnesium in water, expressed as mg/L CaCO3; it causes scale and affects coagulant demand.

Coliform bacteria

Indicator organisms used to detect potential fecal contamination; their presence in finished water triggers repeat sampling and public notice.

Total organic carbon

The measure of organic matter in water that reacts with chlorine to form regulated disinfection byproducts such as THMs and HAAs.

Coagulation

The process of destabilizing suspended particles by adding chemicals like alum, allowing them to agglomerate into larger floc.

Flocculation

Gentle mixing that encourages destabilized particles to collide and grow into settleable floc, typically 15–45 minutes at low velocity gradient.

Jar test

A laboratory procedure that simulates coagulation, flocculation, and sedimentation to determine the optimal coagulant dose and pH.

Overflow rate

The flow divided by the clarifier surface area, expressed in gpm/ft²; it determines the settling velocity required for particle removal.

Sludge blanket

The layer of accumulated solids in a clarifier; its depth is controlled by sludge withdrawal to prevent carryover.

Filter backwash

Reversing flow through a filter to remove captured particles; it expands the bed 15–25% and typically lasts 10–15 minutes.

Filter run

The period between backwashes; it ends when effluent turbidity exceeds 0.3 NTU, headloss reaches its limit, or run time expires.

Media effective size

The sieve size that passes 10% of the filter media by weight; typical rapid sand effective size is 0.5–1.0 mm.

Log removal value

A measure of pathogen removal or inactivation expressed as log10; LRV 4 equals 99.99% removal.

CT

The product of disinfectant residual concentration (mg/L) and contact time (minutes), used to determine pathogen inactivation credit.

Chlorine demand

The difference between the chlorine dose applied and the residual remaining after a specified contact time, caused by reactions with impurities.

Breakpoint chlorination

The point at which enough chlorine has been added to oxidize all ammonia and a free chlorine residual begins to appear.

Trihalomethanes

Regulated disinfection byproducts formed when chlorine reacts with organic matter; total THM limit is 80 µg/L as a locational running annual average.

HOCl

Hypochlorous acid, the stronger form of free chlorine; its fraction decreases as pH rises above 7.5, reducing disinfection efficiency.

Chemical feed rate

The mass of chemical applied per day, calculated as dose (mg/L) × flow (MGD) × 8.34.

Secondary containment

A structure or dike around chemical storage tanks that captures spills or leaks, preventing environmental contamination.

Sodium hypochlorite degradation

The loss of chlorine strength over time, accelerated by heat, light, and high concentration; store in a cool, dark area and rotate stock.

Metering pump calibration

Verifying the actual volume delivered per unit time against the setpoint, typically by drawing down a measured volume over a timed interval.

Pump cavitation

The formation and collapse of vapor bubbles when local pressure drops below vapor pressure, causing noise, vibration, and impeller damage.

Pump curve

A graph of head versus flow for a pump; the operating point is where it intersects the system curve.

Water hammer

A pressure surge caused by sudden changes in flow velocity, such as rapid valve closure; mitigated by slow-closing valves or surge tanks.

Brake horsepower

The power required by a pump, calculated as (gpm × head in ft) ÷ (3960 × pump efficiency).

DPD method

A colorimetric test for chlorine residual using N,N-diethyl-p-phenylenediamine; high turbidity or manganese can interfere.

Control chart

A statistical tool that plots process data over time with control limits to detect trends, shifts, and out-of-control conditions.

Stage 2 DBPR

A regulation limiting locational running annual averages for TTHM (80 µg/L) and HAA5 (60 µg/L) in distribution systems.

Surface Water Treatment Rule

Requires 99.9% (3-log) removal/inactivation of Giardia and 99.99% (4-log) of viruses for surface water systems.

Consumer Confidence Report

An annual water quality report that must be delivered to customers by July 1, summarizing contaminant levels and compliance.