MT Water/Wastewater Operator key terms

The rapid mixing of a chemical such as alum or ferric chloride into raw water to neutralize particle charges so that tiny suspended solids begin to clump together. It is the first step of conventional clarification.

Gentle, slow stirring after coagulation that encourages small destabilized particles to collide and grow into larger, settleable masses called floc. Mixing energy is kept low so the floc is not sheared apart before settling.

A measure of how cloudy water is because suspended particles scatter light. It is reported in nephelometric turbidity units (NTU) and serves as both a treatment performance indicator and a regulatory limit for filtered water.

A quiet tank where floc and other solids settle to the bottom as sludge before water flows on to filters. Detention time and flow distribution are managed so particles have time to reach the floor.

Reversing flow upward through a filter bed to dislodge trapped particles and flush them to waste. Backwash is triggered by head loss, turbidity breakthrough, or a set run time, and the filter is then returned to service.

The drop in pressure or water level as water moves through a filter bed or pipe. Rising head loss across a filter signals clogging and is one of the triggers for backwashing.

Compounds such as trihalomethanes and haloacetic acids that form when disinfectants like chlorine react with naturally occurring organic matter in water. Utilities control them by removing precursors and managing disinfectant doses.

The product of disinfectant residual concentration (C) and contact time (T) used to demonstrate that a required level of pathogen inactivation has been achieved. CT requirements vary by disinfectant, target organism, and water temperature.

A storage tank or basin that holds finished water long enough to provide the contact time needed for disinfection and to buffer supply against demand variations. It is usually the last treatment step before high-service pumps.

A measurement of the carbon content of organic compounds in water. High levels can feed biological growth in the distribution system and react with disinfectants to form byproducts, so utilities often target removal during treatment.

Water that has completed all treatment processes and meets quality standards for entry into the distribution system. Its quality is monitored at the plant and at points throughout the system.

The network of pipes, pumps, valves, tanks, and meters that delivers finished water from the treatment plant to customers. Operators must maintain adequate pressure, disinfectant residual, and water quality throughout it.

Adding a small dose of disinfectant at points within the distribution system to maintain a residual that protects against contamination and biological growth far from the treatment plant.

The concentration of disinfectant remaining in water as it travels through the distribution system. A detectable residual is required in most systems and is checked at sample sites to confirm protection against microbial contamination.

Any actual or potential link between a potable water supply and a source of contamination, such as a hose submerged in a chemical tank. Backflow prevention devices and air gaps are used to eliminate the hazard.

Devices or physical arrangements, such as air gaps, reduced-pressure-zone assemblies, and vacuum breakers, that stop contaminated water from flowing backward into the drinking water supply when pressure conditions reverse.

An instrument that displays the pressure of water in a pipe, pump discharge, or filter. Operators use gauge readings to confirm adequate system pressure, detect head loss, and identify pump or valve problems.

A sudden pressure wave in a pipeline caused by rapidly stopping or starting flow, such as a fast valve closure or pump trip. Surges can damage pipes and appurtenances and are managed with slow valve operation and surge controls.

Deliberately running water at high velocity through mains to scour out sediment, stale water, and biofilm. Flushing is often scheduled after repairs or in low-flow areas and may be combined with disinfection.

Wastewater or water flowing into a treatment unit or plant. Its flow rate and characteristics are measured to set process controls and to calculate loading and removal efficiency.

Treated water leaving a treatment process or plant and discharged to a receiving water or reuse system. Effluent quality is monitored against permit limits before release.

The amount of dissolved oxygen consumed by microorganisms while breaking down organic matter in a water sample over a set period, usually five days. It is a common measure of organic strength in wastewater and treatment performance.

A secondary treatment process in which a mixed population of microorganisms consumes organic matter in an aerated tank, after which the biomass is settled and partly returned to the aeration basin to maintain the population.

Settled biomass collected in the secondary clarifier and pumped back to the aeration tank to keep the microbial population high enough to treat incoming organic load. The amount returned is a key process control adjustment.

Excess biomass that is deliberately removed from the activated sludge system to control the solids inventory and maintain the desired sludge age. It is typically thickened and dewatered before disposal.

The solids-rich material separated from water or wastewater during settling, thickening, or dewatering. Sludge is stabilized and disposed of or beneficially reused, and its handling is a major operating cost.

The average length of time solids remain in an activated sludge system, calculated as the mass of solids in the aeration tank divided by the mass leaving daily. It influences treatment stability and settling behavior.

The concentration of solids, mostly microorganisms, in the aeration tank of an activated sludge system. It is measured regularly and used with sludge age to control how much biomass is kept in the process.

Two sources of unwanted clear water entering a sewer: infiltration seeps in through defective pipes and joints, while inflow enters directly through connections like roof drains and manhole covers during storms.

An unauthorized release of untreated sewage from a collection system before it reaches the treatment plant, often caused by blockages, root intrusion, or storm-driven flows. Overflows must be reported and corrected promptly.

Blowing non-toxic smoke into a sewer line to reveal defects such as broken pipes, illegal connections, and cross-connections with storm drains. Smoke escaping at ground level or inside buildings indicates a problem to repair.

A facility with pumps that raise wastewater so it can continue flowing by gravity to a treatment plant. Operators monitor wet-well levels, pumps, and alarms to prevent overflows and equipment damage.

The federal permitting program that sets limits on pollutants in wastewater and stormwater discharged to surface waters. Permits define monitoring requirements, reporting, and effluent limits that facilities must meet.

The highest concentration of a contaminant allowed in drinking water delivered to consumers under federal and state rules. Some contaminants instead have a treatment technique requirement when a numeric level is not practical.

An annual report that community water systems must provide to customers summarizing water quality results, detected contaminants, and other required information. It must be delivered by a set deadline each year.

The controlled procedure for entering spaces such as manholes, wet wells, and vaults that have limited entry and exit and are not designed for continuous occupancy. Entry requires atmospheric testing, ventilation, a permit, and an attendant.

A toxic, flammable gas with a rotten-egg odor that forms in sewers and digesters as organic matter decays without oxygen. It is deadly in confined spaces and can also corrode concrete.

The safety practice of isolating energy sources, such as electrical disconnects or valves, and attaching a personal lock and tag before servicing equipment. It prevents unexpected startup or release of stored energy that could injure workers.

The documented record of who collected, handled, and transported a water or wastewater sample from collection through analysis. It preserves sample integrity and supports enforcement or compliance decisions.