Physical/Chemical Industrial Waste Treatment Operator key terms

A written authorization that lists hazards, required atmospheric tests, isolation steps, attendants, and rescue arrangements before a worker enters a tank, pit, or vault with limited exit.

The lowest concentration of a flammable gas or vapor in air that will ignite if a spark is present; readings near this value warn that the atmosphere is approaching flammable conditions.

A toxic, flammable gas with a rotten-egg odor that forms in septic wastewater and can deaden the sense of smell; it is a leading cause of confined-space fatalities at treatment facilities.

A procedure in which energy sources such as pumps, mixers, and valves are shut off, isolated, and marked with locks and tags so equipment cannot start while someone is servicing it.

A facility document describing safe storage, handling, labeling, and spill response for treatment chemicals, along with required protective equipment and employee training.

A standardized document supplied with each hazardous chemical that lists its hazards, first-aid measures, handling precautions, and spill response steps.

Gear such as gloves, goggles, face shields, aprons, and respirators worn to shield a worker from chemical splashes, fumes, and physical hazards during treatment tasks.

A laboratory measure of the oxygen consumed by microorganisms breaking down organic matter in a sample over a set period, usually five days, used to gauge organic strength.

A test measuring the oxygen equivalent of organic and some inorganic matter oxidized by a strong chemical agent; results are faster than biochemical oxygen demand and usually higher.

The mass of solid particles that can be captured by a standard filter and dried, representing material that is suspended rather than dissolved in the wastewater.

A scale from 0 to 14 expressing how acidic or alkaline a liquid is; treatment processes such as neutralization and precipitation depend on keeping it within a target range.

The raw or partially treated wastewater entering a treatment unit or the plant as a whole, whose characteristics set the load the process must handle.

The treated wastewater leaving a process unit or the plant, which is monitored against permit limits before discharge or reuse.

A regulatory permit that sets allowable pollutant concentrations, monitoring frequencies, and reporting duties for wastewater discharged to surface waters.

The first physical step that removes rags, plastics, and other large debris from wastewater using bar racks or rotating screens to protect downstream pumps and equipment.

A physical process that settles out sand, gravel, and other dense inorganic particles so they do not erode pumps or accumulate in basins and digesters.

A holding tank that stores incoming wastewater to smooth out swings in flow rate and pollutant strength, giving downstream treatment a steadier feed.

A settling process in which slow-moving wastewater allows suspended solids to sink to the bottom as sludge while clearer liquid flows over a weir at the top.

A physical separation method that injects fine air bubbles so light solids and oils float to the surface and can be skimmed off.

A chemical treatment step that adds a reagent to destabilize small particles so they can clump together, usually followed by gentle mixing and settling.

Slow, gentle stirring after coagulant addition that encourages destabilized particles to collide and form larger, settleable clumps called floc.

Adding an acid or base to bring wastewater pH toward a target range so it can be discharged safely or treated by later biological or chemical steps.

A treatment method that adds reagents to convert dissolved metals or other contaminants into insoluble solids, which are then removed by settling or filtration.

A millivolt reading that indicates whether a wastewater is chemically oxidizing or reducing, used to control dosing of oxidants such as chlorine or peroxide.

The average time a volume of wastewater spends inside a tank or process, calculated from tank volume divided by flow rate.

A final treatment step that kills or inactivates disease-causing organisms, commonly by chlorination or ultraviolet light, before discharge.

A measure of how cloudy a liquid is due to suspended particles, often read with a light-scattering meter as a quick indicator of solids removal performance.

A sample made by combining portions collected at intervals or in proportion to flow, giving a representative average rather than a single instant in time.

A single portion of wastewater collected at one moment and place, used when conditions change quickly or when rules require an instantaneous measurement.

A rotating-impeller machine that moves wastewater by converting rotational energy into flow; it can lose prime or cavitate if suction conditions are poor.

The formation and collapse of vapor bubbles in a pump when suction pressure is too low, producing noise, vibration, and damage to the impeller over time.

A device that prevents liquid from leaking where a rotating pump shaft passes through the casing, and which wears out and requires periodic replacement.

The solids-rich material removed from settling basins and other processes, which must be thickened, dewatered, and handled as a residual waste stream.

Dewatering equipment that pumps sludge between plates covered with cloth, squeezing out liquid under pressure to produce a drier cake for disposal.

A residual management option in which treated sludge or liquid waste is spread on soil at controlled rates to use its nutrients, subject to permit conditions.

An unintended release of wastewater from a collection system, often during heavy rain or a blockage, which must be contained, reported, and cleaned up.

Clean groundwater seeping into sewers and stormwater entering through illegal connections or defects, which adds flow the treatment plant must handle.

A periodic report submitting sampling results and other required data to the regulator to show whether the facility met its permit limits.