ND Water/Wastewater Operator key terms

The process of adding chemicals such as alum or ferric chloride to raw water so that tiny suspended particles clump together into larger, heavier masses that can be removed.

Gentle, slow stirring of chemically treated water that encourages small clumps to collide and grow into larger floc particles heavy enough to settle out.

A treatment step where water sits quietly in a basin so suspended solids and floc settle to the bottom as sludge, leaving clearer water to flow onward.

Passing water through beds of sand, anthracite, or other media to trap remaining particles and organisms that did not settle out during earlier treatment steps.

Reversing or forcefully flushing flow through a filter to lift and wash captured solids out of the media, restoring the filter's ability to remove particles.

The granular material, usually sand and anthracite, that forms the filtering layer in a filter bed and traps particles as water passes through it.

A measure of how cloudy water is because of suspended particles; high turbidity can shield pathogens from disinfection and is a key treatment performance indicator.

Nephelometric Turbidity Unit, the standard unit for reporting turbidity measured by light scatter; lower values indicate clearer water.

Killing or inactivating disease-causing organisms in water, typically with chlorine or another disinfectant, to protect public health.

A disinfection measurement equal to disinfectant concentration multiplied by contact time; regulators set minimum CT values for inactivating specific pathogens.

The amount of chlorine still present in treated water after it leaves the plant, providing ongoing protection against contamination in the distribution system.

A bench-scale test using multiple stirred jars with different chemical doses to determine the best coagulant dose and treatment conditions for a water source.

A microorganism such as a bacterium, virus, or protozoan that can cause disease; treatment barriers are designed to remove or inactivate these organisms.

The network of pipes, pumps, storage tanks, valves, and meters that delivers finished drinking water from the treatment plant to customers.

A large pipe in the distribution network that carries treated water along streets and feeds smaller service lines to individual buildings.

The pipe that connects a building or property to the public water main and delivers water to the customer's plumbing.

A device installed on a service line that measures the volume of water a customer uses for billing and leak detection purposes.

A valved connection on a water main that provides water for firefighting and can be used for flushing mains and testing system flow.

Deliberately releasing water through hydrants or blowoffs to remove sediment and stale water and to refresh disinfectant residual in the mains.

A portion of a distribution system served at a controlled pressure range by pumps, pressure-reducing valves, or elevated storage.

A pump placed within the distribution system to raise water pressure in an area where gravity or existing pumping does not provide adequate service.

Any actual or potential link between the drinking water system and a source of contamination that could allow backflow into potable water.

Reverse flow of water or other substances into the drinking water system, caused by backsiphonage or backpressure.

A physical separation between a potable water outlet and the flood level of a receiving vessel, providing the highest level of backflow protection.

A wastewater treatment process where a mixed community of microorganisms consumes organic matter in aerated tanks, and solids are separated and returned to the process.

Supplying air or oxygen to wastewater so aerobic microorganisms can break down organic material and so mixing keeps the biomass in contact with the waste.

A machine that supplies large volumes of air to aeration tanks or air-scouring systems; it is one of the largest energy users at a wastewater plant.

Mixed Liquor Suspended Solids, the concentration of suspended solids, mostly microorganisms, in the aerated wastewater mixture in an activated sludge tank.

Settled sludge from the secondary clarifier that is returned to the aeration tank to maintain the microorganism population needed to treat incoming waste.

Excess sludge removed from the treatment process to control the amount of solids in the system and maintain the desired sludge age.

The average time solids remain in the activated sludge system, a key control parameter affecting treatment performance and sludge settling.

A bed of rock or plastic media over which wastewater trickles, allowing microorganisms growing on the media to consume organic matter.

A settling tank where solids separate from liquid; primary clarifiers settle raw wastewater solids and secondary clarifiers settle biological sludge.

Biochemical Oxygen Demand, a test measuring how much oxygen microorganisms consume breaking down organic matter in a water sample; higher BOD means more organic pollution.

Total Suspended Solids, the concentration of solid particles suspended in water or wastewater, measured by filtering and weighing the residue.

A collection pipe that carries wastewater downhill by gravity, requiring a continuous slope between manholes to maintain flow velocity.

A facility with pumps that raises wastewater to a higher elevation so it can continue flowing by gravity through the collection system.

A pressurized pipe that carries wastewater pumped from a lift station to a point where gravity flow can resume.

An access opening in a sewer or water main that allows workers to inspect, clean, and maintain the pipe below.

The inside bottom elevation of a pipe, often noted at manholes to describe the depth and slope of the sewer line.

Groundwater seeping into sewers through defects (infiltration) plus stormwater entering through connections like roof drains (inflow), which adds flow to the system.

A release of untreated wastewater from the collection system before it reaches treatment, often caused by blockages, infiltration, or capacity limits.

A space large enough to enter, with limited entry or exit, not designed for continuous occupancy; entry requires hazard evaluation and often a permit.

A dangerous condition in a confined space such as low oxygen, flammable gas, or toxic gas that must be tested before and during entry.

A procedure for isolating and marking energy sources before maintenance so equipment cannot be started or energized while workers are exposed.

Clothing and gear such as gloves, eye protection, and respirators worn to protect workers from chemical, biological, and physical hazards on the job.

Enforceable federal limits on contaminants in drinking water that may harm health, including maximum contaminant levels and required treatment techniques.

The highest level of a regulated contaminant allowed in drinking water, set as close to the health goal as feasible using available technology.

An annual report that community water systems must provide to customers describing water quality, contaminant levels, and sources of their drinking water.

The federal permitting program that limits what pollutants a wastewater treatment plant may release into receiving waters under the Clean Water Act.

A legal document setting limits and monitoring requirements for wastewater or treated water released to a receiving water body.

A state-issued credential showing that an operator has met education, experience, and examination requirements to run a water or wastewater facility.

Required training hours that certified operators complete to renew their credentials and stay current on treatment, safety, and regulations.

An instrument that measures the rate or volume of water or wastewater moving through a pipe, used for process control, billing, and permit reporting.

A graph showing how a pump's flow and head change across its operating range, used to select pumps and diagnose performance problems.

Formation and collapse of vapor bubbles in a pump when suction pressure is too low, causing noise, vibration, and damage to the impeller.

Scheduled inspection, lubrication, and servicing of equipment done to prevent failures and extend the life of pumps, valves, and other assets.

A documented record tracking a sample from collection through analysis, showing who handled it and when, to keep results legally defensible.

A sample made by combining portions collected at intervals or across locations, giving an average picture of water or wastewater quality over time.

A calculation used to find the pounds of a substance in water, multiplying concentration in mg/L by volume in million gallons by 8.34.