Absorption: The taking up of one substance into the body or volume of another — a gas dissolving into a liquid, for example, or a liquid soaking into a solid. Absorption acts through the entire volume of the absorbing material, which is what separates it from adsorption, where molecules cling only to a surface. Transferring oxygen into mixed liquor during aeration is a common water-treatment example. See also Adsorption.

Absorption Trench: An Absorption Trench is a trench that is dug into the earth, established along the natural contour of the land, and filled with dirt in the back. It may also contain an arch or slotted pipe, aggregate, and geo-textile. Absorption trenches treat wastewater from toilets, laundries, bathrooms, and kitchens. The length of the trench depends on the soil’s absorptive capacity and the local climatic conditions.

Acid Rain: The rain that becomes acidic as a result of combining sulfur oxide emissions from burning fossil fuels (coal, for example).

Acoustic Logging: This is a technique for locating a leak in a water main that involves installing listening devices at predetermined intervals along the main.

Acre-Feet (Acre-Foot): An expression of water quantity. One acre-foot covers 1 acre of ground 1 foot deep. An acre-foot contains 43,560 cubic feet, 1,233 cubic meters, or 325,851 US gallons. Also abbreviated ac-ft.

Activated Sludge: A method of treating water through biology that is frequently employed in municipal wastewater treatment facilities. When it comes to reducing certain pollutants like BOD and COD (see definitions below), private enterprises will occasionally use this method, although usually just because of compliance-related concerns.

Adsorption: The process of a dissolved substance attaching to the surface of a solid rather than being taken into it. In water treatment, adsorption is used to strip impurities from water by passing it through a solid medium — most commonly activated carbon — that attracts and holds onto those impurities. See also Absorption.

Advanced Wastewater Treatment: Treatment technology to produce an extremely high-quality discharge.

Aeration: The process of adding air to water to increase the level of oxygen. This can be done to improve the quality of the water or to stimulate the growth of microorganisms in wastewater treatment.

Aerobic: Refers to an environment that contains oxygen. In wastewater treatment, aerobic processes involve the use of oxygen to break down organic matter.

Aerobic Wastewater Treatment System: A treatment unit that uses oxygen-dependent bacteria to break down the organic matter in wastewater. Air is forced into the treatment tank so the bacteria stay active, which lets the system digest waste faster and more completely than an anaerobic septic tank. The effluent it produces is generally considered secondary-treatment quality. Often abbreviated ATU (aerobic treatment unit).

Air Gap:  The air space between the free-flowing discharge end of a supply pipe and an unpressurized receiving vessel.

Air Valve: The valve that is used on pipes to release air that has become trapped inside them as a result of filling or emptying them. On the pipeline’s high points, air valves are located.

Algal Bloom: An excessive growth of algae in a body of water. Algal blooms can cause problems in water treatment systems by clogging filters and consuming oxygen.

Alkalinity: This is a measure of water’s ability to neutralize acids. Alkalinity is important for maintaining the pH balance of water.

Altitude Valve: A valve fitted at a distribution storage tank that closes when the water reaches a preset level to stop the tank overflowing, and stays open while the level is below that point.

Alum (Aluminum Sulfate): The standard coagulant used in water treatment.

Ambient: The expected natural conditions that occur in water unaffected or uninfluenced by human activities.

Anaerobic: Refers to an environment that lacks oxygen. In wastewater treatment, anaerobic processes involve the breakdown of organic matter in the absence of oxygen.

Anionic: Refers to a substance that carries a negative charge. In water treatment, anionic substances are often used to remove impurities from the water by attracting them with their negative charge.

Aquifer: A layer of rock, sand, or gravel that contains water and is capable of yielding water to a well or spring.

Aquifer System: A body of interlayered permeable and poorly permeable geologic material that functions regionally as a single water-yielding hydraulic unit.

Arsenic: A heavy metal that is frequently subject to wastewater discharge permits but is less frequently encountered in industrial wastewater.

Artesian Water: Groundwater that is under pressure when tapped by a well, so it rises above the level at which it was first encountered. A well that taps it is an artesian well; where the water rises above ground without pumping, the well is free-flowing.

Aspiration: The process of drawing water into a pump using suction.

Atomization: The process of breaking a liquid into tiny droplets. This can be done using a spray nozzle or other mechanical means.

Attack Hydrant: A type of fire hydrant with flow and pressure appropriate for combating fires.

Autotrophic: A type of organism that is able to produce its own food using inorganic materials such as carbon dioxide.

Backflow: The reversal of the normal flow of water in a piping system.

Backflow Preventer: A device that prevents backflow from occurring in a piping system.

Backup: The accumulation of wastewater in a pipe or system due to a blockage or other issue.

Backwash: The process of reversing the flow of water through a filter to clean it.

Bactericide: A chemical or substance that kills bacteria.

Baffle: A device used to change the direction of flow in a pipe or tank.

Balance Tank: This is a tank or reservoir used to store water for the purpose of equalizing or balancing fluctuating demand.

Baseline Water Use: This is the water usage for all sites within an organization’s Water Management Action Plan over a 12-month period.

Basin: This is a groundwater reservoir defined by the overlying land surface and underlying aquifers that contain water stored in the reservoir.

Batch Treatment: A method of treating a specific volume of water or wastewater at one time.

Batch-Fed Digestion: A process in which a series of tanks are used to treat wastewater. Each tank is filled with wastewater, and the bacteria in the tank break down the organic matter.

Belt Press (Belt Press Filter): A machine that dewaters sludge by squeezing it between two porous belts running over a series of rollers, producing a drier cake for disposal or reuse. It removes water from sludge, not sludge from wastewater.

Bioaugmentation: The process of adding beneficial bacteria to a wastewater treatment system to improve the breakdown of organic matter.

Biofilm: A layer of microorganisms attached to the inside wall of a water distribution pipe, held in place by the slime matrix they secrete. The bacteria arrive from the water, either surviving treatment or entering the pipe through a break or cross-connection, but once attached they are distinct from the bacteria suspended in the bulk water and are far harder to disinfect.

Biofouling: The accumulation of microorganisms and other organic matter on a surface. In water treatment, biofouling can cause problems by clogging filters and reducing the effectiveness of treatment processes.

Biogas: A mixture of gases produced by the breakdown of organic matter in anaerobic conditions. Biogas can be used as a renewable energy source.

Biological Nutrient Removal (BNR): A process used in wastewater treatment to remove nutrients, such as nitrogen and phosphorus, from the water.

Biological Oxygen Demand (BOD): A measure of the amount of oxygen required by microorganisms to break down organic matter in water or wastewater.

Biological Treatment: A method of treating water or wastewater using microorganisms to break down organic matter.

Bioremediation: The use of microorganisms or other biological means to clean up polluted soil or water.

Biosolids: This is sewage sludge that has been treated to reduce disease-causing pathogens, thus becoming suitable for beneficial reuse.

Blackwater: Wastewater that contains human feces and urine.

Blow Out: The sudden rupture of a pressurized pipe wall, releasing its contents. On metallic mains, corrosion pitting thins the wall until it fails at that spot.

Boiler Feed Water: Water that is used to generate steam in a boiler.

Booster Pump Stations: This is a pump station built to increase the water pressure inside a lengthy pipeline. They can also be used to increase pressure in lengthy transfer mains. Typically, they would be utilized to increase low reticulation pressure at higher elevation places.

Bore (Ground Water Bore): This is a shaft built to draw water out of an aquifer. An artesian well is a well in which the water rises to the surface without the aid of a pump.

Bore Pump Station: This is a water pump station designed to extract water from an aquifer.

Breakout: The sudden release of wastewater from a pipe or system due to a blockage or other issue.

Breakpoint Chlorination: Dosing chlorine past the point at which the water’s chlorine demand — including ammonia and the chloramines it forms — has been satisfied and destroyed, so that any further chlorine added remains as a free chlorine residual.

Buffer: A substance that helps to maintain the pH balance of a solution by neutralizing acids or bases.

Bulkhead: A wall or partition used to divide a tank or other container.

Bypass: A temporary piping system that allows water or wastewater to be redirected around a blocked or damaged section of pipe.

Cadmium: This is a heavy metal that is often found in the metal finishing sector and is subject to wastewater discharge regulations. Arsenic (As), Chromium (Cr), Copper (Cu), Lead (Pb), Nickel (Ni), and Zinc are some more heavy metals (Zn).

Calcium Carbonate Equivalent (CCE): A reporting convention that expresses the concentration of an ion as the chemically equivalent mass of calcium carbonate, written “mg/L as CaCO₃.” It lets hardness, alkalinity and other constituents be compared on one scale.

Capacity: The maximum load a treatment plant or unit can handle and still meet its permit, covering both hydraulic loading (flow) and organic loading (BOD and solids). A plant can reach its organic capacity while still under its hydraulic capacity, or the reverse.

Carbon Filter: A device used to remove organic compounds and odors from wastewater by using a bed of activated carbon.

Carrying Capacity: The maximum population of a species that an ecosystem can support without being damaged.

Catch Basin: A structure that collects and channels stormwater runoff from streets, sidewalks, and other surfaces.

Centrifuge: This is a piece of equipment, generally driven by a motor, that puts an object in rotation around a fixed axis, applying a force perpendicular to the axis. Centrifuges are commonly used in water and wastewater treatment to dry sludges.

Chemical Oxygen Demand: This is an estimation of the organic content of wastewater. It specifically refers to the quantity of oxygen needed to chemically break down the organic material.

Chlorine Detention Chamber: This substantial concrete chamber is made to give dissolved chlorine gas time to kill microorganisms in sewage. Wastewater treatment facilities frequently use chlorine detention chambers for final effluent treatment before environmental discharge.

Chromium: This is a heavy metal that is frequently subject to wastewater discharge permits and is present in goods and businesses associated with metals (including stainless steel).

Circumferential Cracking: The majority of water and sewer pipes will exhibit this kind of breaking. As opposed to along its length, circumferential cracks occur around a pipe.

Clarifier: A device used to remove solid particles from wastewater by allowing them to settle to the bottom of a tank.

CMMS: Stands for Computerized Maintenance Management System, which is software that provides facilities and maintenance managers with the tools to organize and track everything from work orders, assets, equipment, preventive maintenance, inventory, workflows, safety compliance, teams, expenses, and other processes. The overall objective is to streamline processes, improve workflow, manage costs and increase efficiency in maintenance operations.

Coagulation: The process of adding chemicals to wastewater to cause small particles to clump together and form larger, heavier particles that can be more easily removed.

Collection System: The network of pipes and other infrastructure that is used to collect and transport wastewater to a treatment plant.

Combined Sewer: A sewer that carries both sanitary wastewater and stormwater runoff.

Comminution: The process of reducing the size of particles in water. Comminution is often used in water treatment to improve the effectiveness of other treatment processes.

Compatibility: The ability of different materials or substances to coexist without reacting negatively with each other.

Composting: The process of decomposing organic matter, such as food waste and yard trimmings, to create a nutrient-rich soil amendment.

Concrete Tank: A tank that is made of concrete and is used for storing or treating wastewater.

Conductivity: A measure of a substance’s ability to conduct electricity. In water treatment, conductivity is often used to measure the amount of dissolved solids in the water.

Connate Water: At the time of deposit, sedimentary rock contained pressurized water that was trapped in the pore spaces. Most of the time, it is heavily mineralized.

Contamination (Water): The introduction of any substance into water that makes it unfit or unsafe for its intended use — sewage, industrial waste, chemicals or pathogens.

Copper: A heavy metal commonly regulated by wastewater discharge permits. It is found in the metal finishing and electrical industries.

Correction Chamber: This substantial concrete chamber serves as a dosing point for the pH adjustment of processed water at a water treatment facility.

Corrosion: The gradual deterioration of a material, such as metal, due to chemical reactions with its environment.

Cross-Connection: A connection between a potable water supply and a non-potable water source that could allow contamination to occur.

Cured-In-Place Pipe (CIPP): A process in which a flexible liner is inserted into an existing pipe and cured to form a new, seamless pipe within the old pipe.

Cyanide: This is a poisonous substance that is frequently found in the trash from firms that polish metal. Wastewater permits are frequently used to regulate it.

DAF Unit (Dissolved Air Flotation Unit): This is a device that dissolves air under pressure in the water to remove suspended matter from water, such as oil or sediments, and then releases the air at atmospheric pressure in a flotation tank or basin.

Darcy’s Law: A formula for how much water flows through porous material. It states that the rate of viscous flow of a homogeneous fluid through isotropic porous media is proportional to, and in the direction of, the hydraulic gradient. Flow is assumed laminar and inertia is disregarded.

Dechlorination: The process of removing chlorine or other disinfectants from water or wastewater.

Delayed Inflow: Stormwater takes a few days or longer to pass through the sewage system. Sump pump discharge from cellar drainage and surface water entering ponded areas through manholes slowly falls under this category.

Denitrification: The process of removing nitrogen from water or wastewater by converting it to a gaseous form, such as nitrogen gas or nitrous oxide.

Desalination Plant: This is a facility for removing salt and other minerals from seawater to produce fresh water for human consumption or irrigation.

Design Flow: The specific flow rate a treatment plant or unit is sized for — typically an average or peak daily flow in MGD — and the basis on which every unit process is dimensioned.

Detention Time: This is the estimated amount of time water will stay in a tank at a specific flow rate.

Dewatering: The removal or separation of a portion of water present in a sludge or slurry.

Diffuser: A device used to disperse wastewater into a receiving water body, such as a river or lake.

Diffusion: This is the process by which both ionic and molecular species dissolved in water move from areas of higher concentration to areas of lower concentration.

Digester: This is a container that facilitates anaerobic digestion. It frequently consists of concrete and contains anaerobic microbes. Pumping in sewerage sludge on a regular basis ensures that the population of anaerobic bacteria has access to food. In the absence of oxygen, microbes break down biodegradable material in a process known as anaerobic digestion. The process is widely used to treat wastewater sludges and organic wastes because it provides volume and mass reduction of the input material. A conical floor can be included in the digester design to facilitate product removal and cleaning. The digestive process is typically facilitated by some sort of mixing equipment. Wastewater Treatment Facilities frequently have digesters on hand.

Direct Inflow: The portion of inflow that reaches the sanitary sewer through direct connections, producing an almost immediate rise in wastewater flow with rainfall. Sources include roof leaders, yard and areaway drains, manhole covers, cross-connections from catch basins and storm drains, and combined sewers.

Discharge: The release of wastewater into a receiving water body, such as a river or lake.

Disinfection: The process of killing or inactivating harmful microorganisms in water or wastewater.

Dissolved Air Flotation: This is a physical/chemical wastewater treatment method that can be utilized by industry to cheaply remove suspended solids, certain metals, and FOG (fats, oils, and grease).

Dissolved Oxygen (DO): The amount of oxygen that is dissolved in water, which is an important factor in the health of aquatic ecosystems.

Dissolved Solids: The total mass of dissolved material in water or wastewater, reported as a concentration in mg/L and measured as the residue left after evaporation. Water with too many dissolved solids becomes unfit for industrial or drinking use.

Diversion: The act of redirecting water or wastewater from one location to another.

Dosing Tank: A tank that holds septic tank effluent and releases it to the drainfield in measured doses by pump or siphon, so the field is loaded evenly rather than continuously. Chemicals are stored in a chemical feed or day tank, not a dosing tank.

Drainage: The removal of excess water from an area.

Drawdown: The lowering of the water level by pumping it. It is measured in feet for a given quantity of water pumped during a specified period, or after the pumping level has become constant.

Drinking Water (Potable Water): This is water that is suitable for human consumption.

Drinking Water Scheme: The infrastructure owned by a drinking water service provider and used to augment a drinking water supply through the treatment, conveyance, reticulation or storage of drinking water, in any combination.

Drinking Water Standards: Established by state agencies, the U.S. Public Health Service, and the Environmental Protection Agency (EPA) for drinking water in the United States.

Drip Irrigation: A method of watering plants in which water is delivered to the roots through a network of small tubes or emitters.

EAM (Enterprise Asset Management): The process of managing the lifecycle of physical assets to maximize their use; save money; improve quality and efficiency; and safeguard health, safety, and the environment.

Effluent: This is residual or wastewater, including sewage, that is treated before being used again or released into the environment and drained through sewer pipes.

Effluent Flow Rate: The volume of wastewater being discharged from a treatment facility or industrial process over a specific period of time.

Effluent Limitation: Any restriction imposed by the regulatory agency on quantities, discharge rates, or concentrations of pollutants discharged from point sources into state waters.

Effluent Quality: The physical, chemical, and biological characteristics of the wastewater being discharged from a treatment facility or industrial process.

Effluent Sampling: The process of collecting a representative sample of wastewater being discharged from a treatment facility or industrial process for analysis.

Effluent Treatment Process: The series of steps or stages used to treat wastewater before it is discharged into the environment.

Effluent Water: The water that is discharged from a treatment facility or industrial process after it has been treated.

Electrocoagulation: A process used to treat wastewater by using an electric current to generate coagulants, which can then be used to remove suspended solids and contaminants from the water.

Electrodialysis: A process used to separate ions in water using an electric current.

Electrolysis: A process used to separate water into hydrogen and oxygen by using an electric current.

Electrolytic Cell: A device used to separate water into hydrogen and oxygen through the process of electrolysis.

Electrolytic Treatment: The process of treating wastewater by using an electric current to separate contaminants from the water.

Electro-Osmosis Process: A process used to remove contaminants from water by using an electric current to create a flow of water through a membrane.

Elevated Storage Tank: A large tank that is used to store water at a higher elevation than the surrounding area, typically used in water distribution systems.

Emergency Overflow: A structure or system designed to release excess wastewater in the event of a malfunction or failure in the treatment process.

Emergency Relief Structure (ERS): This is used to prevent sewer overflows through maintenance holes or customer connections, for example through an Overflow Relief Gully (ORG), and to protect the sewer system from damage, particularly during extreme rain events.

Emergency Shutdown: The process of stopping a wastewater treatment facility or industrial process in the event of an emergency.

Emergency Treatment: The process of treating wastewater in the event of an emergency, such as a spill or release of hazardous materials.

Emergency Wastewater Treatment Facility: Portable or standby treatment capacity brought online when normal treatment is lost — after a plant outage, a spill or a flood — so wastewater is still treated before discharge.

Emulsion: A mixture of two or more liquids that are normally immiscible, such as oil and water. Emulsions can form in wastewater and can be difficult to separate.

End-Of-Pipe Treatment System: Pollution control applied to the effluent stream after the waste has been generated, immediately before discharge to the environment. The defining contrast is with source reduction, which changes the process so less waste is created in the first place.

Endotoxin: A toxic substance produced by bacteria that can cause illness or death in humans or animals. Endotoxins can be found in wastewater and can pose a risk if not properly treated.

Endotoxin Removal: The process of removing endotoxins, which are toxic substances produced by bacteria, from wastewater.

Enhanced Primary Treatment: Primary treatment improved by adding a coagulant and polymer ahead of the primary clarifiers, so more suspended solids and BOD settle out than plain sedimentation removes. Also called chemically enhanced primary treatment (CEPT).

Environmental Impact Assessment: A study that evaluates the potential environmental impacts of a proposed project or activity, such as a wastewater treatment facility.

Equalization Basin: A basin that smooths out swings in influent flow rate and pollutant load so downstream units see a near-constant feed. It is mixed and aerated on purpose: letting solids settle or the contents go septic is a failure mode, not the goal.

Equalization Basin System: The basins, pumps, mixers and level controls that together smooth influent flow and load ahead of treatment, releasing a steady feed regardless of how uneven the incoming flow is.

Equalization Tank: A tank used for flow equalization, holding surges of influent and releasing them at a controlled rate. Like an equalization basin, it is mixed and aerated to keep solids in suspension.

Erosion: The wearing away of the land surface by wind, water, ice, or other geologic agents. Erosion occurs naturally from weather or runoff but is often intensified by human land-use practices.

Evaporation: The process by which water becomes a vapor at a temperature below the boiling point.

Evaporation Pond: A pond used to treat wastewater by allowing the water to evaporate, leaving behind solids and contaminants.

Evaporation Process: The process of treating wastewater by converting it into a gas or vapor through the process of evaporation.

Evapotranspiration Process: The process by which water is evaporated from the surface of the earth, including from the leaves of plants and other vegetation, and then is returned to the atmosphere as vapor.

Excess Sludge: The excess solid material that is produced during the wastewater treatment process and must be disposed of.

Excess Sludge Disposal: The process of disposing of excess sludge, which is the solid material produced during the wastewater treatment process that must be removed.

Excess Sludge Management: The process of managing excess sludge, including its storage, transportation, and disposal.

Extended Aeration: A wastewater treatment process in which microorganisms are used to break down organic matter in the water. The process involves adding oxygen to the water to help the microorganisms grow and multiply and allowing the water to remain in the treatment facility for an extended period of time.

External Pressure Filter System: A filtration system in which water is forced through the media inside a closed vessel under applied pressure, rather than passing through under gravity head alone.

Extraction Well: A well used to pump water out of the ground for treatment and distribution.

Extractive Sampling: A method of collecting a representative sample of wastewater by removing a small amount of the water from the flow and analyzing it in a laboratory.

Facility: This is a region with a set of assets that are connected in some way. The grounds and infrastructure (such as parking lots and fences) surrounding a single main building could make up a modest facility. A more complicated facility (like a depot or a water treatment plant) could have numerous buildings and/or other kinds of assets.

Fecal Coliform: A type of bacteria that is commonly found in the feces of warm-blooded animals and is used as an indicator of the presence of fecal contamination in water.

Fecal Contamination: The presence of fecal matter in water, which can contain harmful bacteria and other pathogens.

Feed Hydrant: This is a term used to describe a fire hydrant suitable for supplying water to the suction of a fire fighting appliance.

Field Capacity: The capacity of soil to hold water. It is measured as the ratio of the weight of water retained by the soil to the weight of the dry soil.

Filtration: The process of removing solid particles from water by passing it through a filter.

Fire Fighting Appliance: This is a term used to describe a fire truck with a booster pump used to boost water pressure for fire fighting.

Fire Fighting Flow: This is the flow rate required for fire fighting purposes established by assessing the building material type, building design, and size and referring to the Fire Fighting Regulations.

Fire Hydrant: This is a source of water provided in most urban, suburban, and rural areas with municipal water service to enable firefighters to tap into the municipal water supply to assist in extinguishing a fire.

Fixed Film Treatment Process: The process of treating wastewater using the fixed film treatment process, in which microorganisms grow on a fixed surface, such as a sheet of plastic or a series of tubes, and are used to break down organic matter in the water.

Flocculant: A chemical that is used in the process of flocculation to encourage the formation of flocs in wastewater.

Flocculation: The gentle mixing that follows coagulation, bringing destabilized particles into contact so they collide and grow into larger, heavier flocs that settle or filter out. Coagulation is the chemical addition step; flocculation is the slow-mix step after it.

Flocs: Large, heavy particles that are formed in wastewater during the process of flocculation and can be more easily removed from the water.

Flow Equalization: The process of regulating the flow of wastewater in order to stabilize the treatment process.

Flow Measurement: Determining the rate or volume of water or wastewater moving past a point — instantaneous flow rate for process control, totalized volume over a period for permit reporting. Measured with meters, flumes and weirs.

Flow Meter: A device used to measure the flow rate of water or wastewater.

Fluidized Bed Treatment Process: The process of treating wastewater using the fluidized bed treatment process, in which microorganisms are suspended in a bed of material, such as sand or gravel, and are used to break down organic matter in the water.

Flume: A flow rate measurement device.

Food-To-Microorganisms (F/M) Ratio: A calculation for controlling the activated sludge process based on the food (BODs or COD) availability per pound of mixed liquid volatile suspended solids.

Force Main: A pipe that carries wastewater under pressure from the discharge side of a pump to a point of gravity flow downstream.

Forced Aeration Process: The process of treating wastewater using the forced aeration process, in which air is forced into the water to provide oxygen to the microorganisms that are used to break down organic matter.

Forward Osmosis: A membrane process driven by osmotic pressure rather than applied pressure. A concentrated draw solution on the far side of a semipermeable membrane pulls water across from the feed; the draw solute is then recovered and the clean water separated.

Foul Water: Water that has been contaminated with sewage or other waste products.

Foul Water Pumping Station: A facility used to pump wastewater that has been contaminated with sewage or other waste products.

Foul Water Sewer: A sewer that carries wastewater that has been contaminated with sewage or other waste products.

Foul Water Storage Tank: A tank used to store wastewater that has been contaminated with sewage or other waste products.

Foul Water Treatment Plant: A facility designed to treat wastewater that has been contaminated with sewage or other waste products.

Foul Water Treatment Process Chemicals: The chemicals used in the foul water treatment process to remove contaminants from wastewater that has been contaminated with sewage or other waste products.

Freeboard: The distance between the top of a wastewater treatment tank and the water level.

Frequency Of Sampling: The rate at which wastewater is sampled for analysis.

Gallons Per Day: A volumetric flow rate that is defined as the rate at which a certain amount of fluid, expressed in gallons, crosses a given surface or is delivered to a given object or space during a period of time equal to one day.

Gallons Per Minute: A volumetric flow rate: the number of gallons crossing a given point in one minute. Commonly abbreviated GPM and used for pump ratings and instantaneous flow, as opposed to gallons per day for permit and daily-volume reporting.

Grab Sample: An individual sample collected at a randomly selected time.

Granular Activated Carbon: This is a substance used to remove wastewater’s organics. This substance that resembles charcoal can be used in filtration systems to get rid of solvent contamination.

Gravity Filter: A filter in which the water passes down through the media under its own head, with gravity supplying only the driving force — the separation is done by the media. The counterpart is a pressure filter, in which water is forced through under applied pressure.

Gravity Flow: The movement of water or wastewater due to the force of gravity.

Gravity Separation: The process of separating solid particles from water using gravity.

Grease Trap: A device used to remove grease and oil from wastewater.

Green Infrastructure Assessment Program: An ongoing program focused on evaluating green infrastructure systems and technologies to identify their effectiveness and potential for improvement.

Greywater: This is water that has been used in household activities such as washing dishes, laundry, and bathing, but has not come into contact with human waste.

Greywater Recycling: The process of collecting and treating greywater for reuse in non-potable applications such as irrigation or toilet flushing.

Greywater Treatment: The process of treating greywater to remove contaminants and make it suitable for reuse.

Grit: Heavy inorganic solids, such as sand, gravel, eggshells, or metal filings.

Grit Chamber: A structure used to remove grit, which is a type of inorganic material that can be found in wastewater, such as sand, gravel, and small stones.

Groundwater: Water that is found underground in soil or rock formations.

Groundwater Contamination: The presence of pollutants in groundwater, which can occur through the release of chemicals or other contaminants into the ground.

Groundwater Hydrology: This is the area of hydrology that deals with groundwater, including its occurrence, movements, replenishment, and depletion, as well as the characteristics of rocks that affect how it moves and is stored and how it is studied and used.

Groundwater Recharge: The process of replenishing groundwater supplies by adding water to the ground through infiltration or other methods.

Head Loss: The amount of energy used by water in moving from one point to another.

Headworks: The portion of a wastewater treatment plant where incoming wastewater is collected and prepared for treatment.

Highlift Pump Station: This is a pump station designed to pump treated water into the water reticulation system at pressure either directly or via a Water Tower.

Holding Pond: This is a small basin or pond designed to hold sediment-laden or contaminated water until it can be treated to meet water quality standards or used in some other way.

Hydraulic Analysis: The process of analyzing the flow of water or wastewater in a system to understand its behavior and identify any issues or inefficiencies.

Hydraulic Design: The design of systems and equipment for the treatment and management of water or wastewater, taking into account factors such as flow rates, hydraulic gradients, and hydraulic retention times.

Hydraulic Engineering: The branch of civil engineering concerned with the flow, conveyance and control of fluids — channels, dams, pipe networks, pumping and hydraulic structures. Treatment process design belongs to environmental or sanitary engineering.

Hydraulic Flow Control Valve: A valve used to regulate the flow of water or wastewater in a system.

Hydraulic Flow Meter: A device used to measure the flow rate of water or wastewater in a system.

Hydraulic Gradient: The slope of the hydraulic grade line: the change in hydraulic head (elevation head plus pressure head) per unit distance along the flow path. It is a dimensionless slope, not a pressure difference.

Hydraulic Loading: The amount of water that is processed by a wastewater treatment plant or another system in a given period of time.

Hydraulic Modeling: The use of computer simulations to model the flow of water or wastewater in a system and predict its behavior under different conditions.

Hydraulic Pump: A device used to move water or wastewater through a system using pressure.

Hydraulic Pump Station: A facility used to house and operate pumps for the movement of water or wastewater through a system.

Hydraulic Retention Time (HRT): The average time wastewater stays in a reactor, equal to the reactor volume divided by the influent flow rate (V/Q). It is a design and operating parameter, not a measure of removal efficiency.

Hydrocyclone: A device used to separate solid particles from water using centrifugal force.

Hydrodynamic Separator: A device used to separate solid particles from water using a combination of gravity and hydraulic forces.

Hydrogen Peroxide: A chemical commonly used in wastewater treatment as a disinfectant or oxidizing agent.

Hydrogen Sulfide: A gas produced by the decomposition of organic matter in wastewater, which has a characteristic rotten egg smell.

Hydrograph: This is a graph that shows the flow of a stream over time. The stream can be creek or river flows, as well as sewage flow.

Hydrologic Cycle (Water Cycle): The process by which water moves through the atmosphere, the Earth, and finally back to the atmosphere. These procedures include condensation, evaporation, transpiration, storage, infiltration, and percolation.

Hydrology: The science dealing with the properties, distribution, and circulation of water.

Hydrolysis: The process of breaking down organic matter in wastewater using enzymes and bacteria.

Hydrolysis Reactor: A vessel in which enzymes and bacteria break complex organic solids down into simpler soluble compounds, ahead of anaerobic digestion. The hydrolysis step is usually the rate-limiting one in digestion, which is why it is sometimes given a reactor of its own.

Hydromechanical Pre-Treatment: The process of mechanically removing large solid particles from wastewater using devices such as screens and grit chambers, as a pre-treatment step before biological treatment.

Impoundment: A body of water used for collecting and storing water for later use, such as a pond that is enclosed by a dam, dike, floodgate, or other barriers.

Industrial Wastewater: Wastewater generated by industrial processes, such as manufacturing or refining.

Industrial Wastewater Management: The process of managing the treatment and disposal of wastewater generated by industrial processes.

Industrial Wastewater Treatment Equipment: The equipment used in the treatment of wastewater generated by industrial processes, such as filters, screens, or sedimentation tanks.

Infiltration: The flow of water from the surface into the ground or into a wastewater system.

Inflow: Stormwater that enters a sanitary sewer through direct connections — roof leaders, area and foundation drains, manhole covers, and cross-connections from storm drains. Distinct from infiltration, which seeps in through cracks and defective joints.

Influent: The wastewater that enters a treatment plant or system.

Infrared Spectroscopy: An analytical technique used to identify and characterize substances based on the absorption of infrared radiation.

Injection Well: A well used to inject treated wastewater or other fluids into the ground.

Inlet Chamber: The purpose of this chamber is to receive water from a reservoir.

Intermediate Pump Station: A facility used to house and operate pumps for the movement of wastewater between different treatment units or stages.

Intermittent Sand Filter: A type of sand filter used in wastewater treatment that operates in an intermittent cycle, with periods of flow and periods of rest.

Internal Recycle: The process of recirculating treated wastewater within a treatment plant or system.

Ion Exchange Process: The reversible interchange of ions between water and a solid resin bed as the water passes through. Used for softening, and also for demineralization and for removing nitrate, arsenic, uranium and radium.

Iron And Manganese Removal: The removal of dissolved iron and manganese from source water, usually by oxidation followed by filtration. Driven by the secondary drinking water standards (0.3 mg/L iron, 0.05 mg/L manganese) because these metals stain fixtures and laundry and give water a metallic taste and color.

Irrigation: The controlled application of water to land for agricultural purposes through a manmade system, supplying the water that rainfall does not. Where treated effluent is the source, it is called effluent irrigation or water reuse.

Irrigation Channel: This open channel carries water so that agricultural areas can be irrigated.

Jar Test: This is a laboratory procedure used to estimate proper coagulant dosage.

Jockey Pump: A small pressure-maintenance pump that holds system pressure so the main pump does not start on minor leakage. It is deliberately sized below the flow of a single sprinkler or outlet, so a real demand still causes the pressure drop that starts the main pump. It is not a backup pump.

Jockey Pump Station: A facility used to house and operate jockey pumps.

Jump Up: This is also known as a vertical riser, and is often used to describe a sewerage house connection branch.

Karst: A type of landscape characterized by sinkholes, underground streams, and caverns, formed by the dissolution of soluble rocks such as limestone.

Kinematic Viscosity: The ratio of the dynamic viscosity of a fluid to its density.

Kinetic Energy: The energy of a moving body, equal to the work done to accelerate the body from a state of rest.

Kjeldahl Method: The analytical method used to measure Total Kjeldahl Nitrogen — organic nitrogen plus ammonia. Acid digestion converts organic nitrogen to ammonium, which is then distilled and titrated or measured colorimetrically.

Knockout Drum: A vessel used to separate liquids and gases by gravity separation, based on the difference in densities.

Lagoon: A large, shallow pond or basin used for the treatment of wastewater by means of natural processes such as aeration, sedimentation, and evaporation.

Lagoon Maintenance: The regular maintenance and repair of wastewater lagoons, including cleaning, inspections, and repairs of pumps and other equipment.

Landfill: A site where solid waste is deposited and compacted in layers, and covered with a layer of soil at the end of each day. Landfills are designed to contain and isolate waste materials from the environment.

Landfill Maintenance: The regular maintenance and repair of landfills, including inspections, repairs, and the management of leachate and other waste materials.

Leachate: Liquids that have come into contact with solid waste and have picked up dissolved or suspended materials as they pass through the waste. Leachate can contain contaminants that can be harmful to the environment if released into the surface or groundwater.

Leak Detection: The process of identifying and locating leaks in a wastewater collection or treatment system.

Leak Repair: The repair of leaks in a wastewater collection or treatment system.

License: A document that grants the bearer permission to carry out the functions of a wastewater treatment plant operator and is issued by the State Board of Waterworks/Wastewater Works Operators.

Lift Station: A facility that pumps wastewater from a lower elevation to a higher elevation, such as from a low-lying area to a treatment plant.

Lift Station Maintenance: The regular maintenance and repair of lift stations, including cleaning, inspections, and repairs of pumps and other equipment.

Lime Stabilization: Adding lime to wastewater sludge to raise the pH, typically to 12 or above, which inactivates pathogens, halts biological activity, controls odor and reduces vector attraction. It stabilizes the sludge rather than destroying organic matter, and it adds mass.

Line Cleaning: The process of removing debris and other blockages from wastewater pipes and sewers.

Line Repair: The repair of damaged or broken wastewater pipes or sewers.

Lining: The process of applying a protective layer or coating to the inside of a wastewater pipe to prevent corrosion or leaks.

Liquid Waste Management: The management and disposal of liquid waste, such as wastewater and sewage, in a safe and environmentally responsible manner.

Liters Per Day: A volumetric flow rate: the number of liters passing a given point in one day. Abbreviated L/d and used for permit limits and daily-volume reporting.

Liters Per Minute: A volumetric flow rate: the number of liters passing a given point in one minute. Abbreviated L/min and used for pump ratings and instantaneous flow. One L/min equals 1,440 L/d.

Long-Term Average Wet Weather Flow (LTAWWF): The long-term average flow of wastewater during wet weather conditions.

Longitudinal Cracking: This is cracking that runs along the length of a pipe or road.

Low-Pressure Sewer System: A sewer system that uses small-diameter pipes and low-pressure pumps to convey wastewater to a treatment plant.

Low-Pressure Sewer System Maintenance: The regular maintenance and repair of low-pressure sewer systems, including cleaning, inspections, and repairs of pumps and other equipment.

LTAWWF Calculation: The calculation of the long-term average wet weather flow (LTAWWF) of a wastewater treatment plant or system.

Lysimeter: A device used to measure the amount of water that is lost from the soil by evaporation or transpiration.

Lysimeter Maintenance: The regular maintenance and repair of lysimeters, including cleaning, inspections, and repairs of pumps and other equipment.

Main: A large pipe that carries wastewater from smaller pipes or sewers to a treatment plant.

Mainline Cleaning: The cleaning of wastewater mains and other large pipes to remove debris and other blockages.

Mainline Inspection: The inspection of wastewater mains and other large pipes to identify and assess any damage or defects.

Mainline Repair: The repair of damaged or broken wastewater mains and other large pipes.

Maintenance: The regular inspection, repair, and upkeep of wastewater treatment plants and other facilities to ensure that they are operating efficiently and effectively.

Maintenance Equipment: Specialized tools and equipment that are used in the maintenance of a wastewater treatment plant or another facility, such as hand tools, power tools, and diagnostic equipment.

Maintenance Plan: A detailed plan outlining the maintenance activities that need to be performed on a regular basis to keep a wastewater treatment plant or other facility operating efficiently and effectively.

Maintenance Schedule: The plan that assigns each maintenance task to an interval or trigger — calendar time, runtime hours, or a condition reading — and drives the work orders a CMMS generates from the asset register.

Management Of Change (MOC): A process for managing and documenting changes to a wastewater treatment plant or another facility, including changes to equipment, processes, and procedures.

Manhole: A large, access-point opening in a wastewater collection system, typically located in the street or on private property. Manholes allow maintenance workers to access the sewer system for cleaning and inspection purposes.

Maximum Daily Flow (MDF): The maximum flow of wastewater that a treatment plant or system is designed to handle in a single day.

Maximum Hourly Flow (MHF): The maximum flow of wastewater that a treatment plant or system is designed to handle in a single hour.

Mean Cell Residence Time (MCRT): The average length of time a mixed liquor-suspended solids particle remains in the activated sludge process. May also be known as sludge retention time.

Mechanical Equipment Maintenance: The regular maintenance and repair of mechanical equipment in a wastewater treatment plant or other facilities, including pumps, motors, and other mechanical components.

Membrane Bioreactor (MBR): A wastewater treatment system that uses a membrane to separate solids from liquids, in order to produce a high-quality effluent. It combines biological treatment with physical treatment involving membrane filtration, and is used primarily to treat BOD, COD, and suspended solids to very low levels where effluent may be able to be reused or recycled.

Membrane Filtration: Separation by passing water through a semipermeable membrane. The class is defined by pore size and driving pressure: microfiltration and ultrafiltration remove particles and microorganisms, nanofiltration removes hardness and larger dissolved molecules, and reverse osmosis removes dissolved salts.

Mercury: A toxic metal that can be present in wastewater and can be harmful to the environment if not properly treated.

Metabolism: The chemical reactions that occur within an organism to sustain life and support growth.

Metals: Elements that are found in wastewater and can be harmful to the environment if not properly treated. Examples of metals that may be present in wastewater include copper, lead, and zinc.

Metering Pump: A chemical solution feed pump that adds a measured amount of solution with each stroke or rotation of the pump.

Microorganism: A tiny living organism, such as a bacterium or virus, that is too small to be seen with the naked eye. Microorganisms play a key role in the treatment of wastewater.

Minimum Flow (MF): The minimum flow of wastewater that is required to maintain the operation of a treatment plant or system.

Mixed Liquor: The mixture of wastewater and microorganisms that is found in a wastewater treatment plant.

Molecular Weight: The weight of a molecule, typically measured in atomic mass units (AMUs).

Monitoring Equipment Maintenance: The regular maintenance and repair of monitoring equipment in a wastewater treatment plant or another facility, including sensors, meters, and other monitoring devices.

Municipal Solid Waste: Solid waste that is produced by households and businesses in a community, and that is collected and disposed of by a municipality.

Municipal Wastewater Treatment Plant: A facility that treats wastewater from households and businesses in a community, to remove contaminants and make the water safe to discharge into the environment.

Nephelometric Turbidity Unit: The standard unit to measure turbidity or how cloudy water is. It’s used as a visual indicator of how well a wastewater treatment system is working.

Nickel: A heavy metal commonly regulated by wastewater discharge permits. It can be found in metals-related industries and products, including stainless steel. Other heavy metals include Arsenic (As), Cadmium (Cd), Chromium (Cr), Copper (Cu), Lead (Pb), and Zinc (Zn).

Nitrate: A chemical compound that is formed during the nitrification process in wastewater treatment. Nitrate is less toxic than nitrite, but it can still be harmful to the environment if present at high levels.

Nitrification: A process in which bacteria convert ammonia to nitrite and then to nitrate in the treatment of wastewater.

Nitrification-Aerobic Denitrification (NAD) Process: A wastewater treatment process that combines nitrification and aerobic denitrification to remove nitrogen from wastewater.

Nitrifying Bacteria: Bacteria that are responsible for the nitrification process in wastewater treatment, converting ammonia to nitrite and then to nitrate.

Nitrobacter: A type of nitrifying bacteria that converts nitrite to nitrate in the wastewater treatment process.

Nitrogen: An element that is found in wastewater and can be harmful to the environment if not properly treated. Nitrogen is an essential nutrient for plants, but high levels of nitrogen in water can lead to algal blooms and other environmental problems.

Nitrogenous Waste: Wastewater that contains high levels of nitrogenous compounds, such as sewage or agricultural runoff.

Nitrosomonas: A type of nitrifying bacteria that converts ammonia to nitrite in the wastewater treatment process.

Non-Point Source Pollution: Pollution that originates from diffuse sources, rather than from a single, identifiable point. Examples of non-point source pollution include agricultural runoff and stormwater runoff.

Non-Revenue Water: Water that is lost or unaccounted for in a water distribution system, due to leaks, metering errors, or other causes.

NPDES Permit: National Pollutant Discharge Elimination System permit, authorizes the discharge of treated wastes and specifies the conditions that must be met for discharge.

Nutrient Balance: The balance between the amount of nutrients that are added to a wastewater treatment system and the amount of nutrients that are removed.

Odor: A distinctive, often unpleasant smell. Odors can be caused by various substances in wastewater, such as sulfur compounds or organic matter.

Odor Control: The management of odors in wastewater treatment plants and other facilities, typically through the use of chemicals, biofilters, or other techniques.

Odor Threshold: The lowest concentration of an odorant that can be detected by the human nose.

Odorant: An odor-causing compound present in wastewater or in the off-gas above it — hydrogen sulfide, mercaptans, amines and volatile fatty acids are the common ones. These are the compounds that odor control is designed to capture or destroy.

Operating Pressure: This is the internal main pressure that occurs at a particular time and at a particular point in a water supply system.

Operation and Maintenance Plan (O&M): This term refers to the operational procedures and maintenance plans for a wastewater treatment system.

Organic Load: The amount of organic matter in wastewater, typically measured in terms of biochemical oxygen demand (BOD).

Organic Matter: Matter that is derived from living organisms or their remains, such as plant and animal material. Organic matter can be present in wastewater and can be harmful to the environment if not properly treated.

Overflow Relief Gully (ORG): This is a type of exterior drain which allows sewage to overflow to the exterior of the residence if a sewer blockage occurs.

Oxidation: A chemical reaction in which a substance is combined with oxygen, typically resulting in the release of energy. Oxidation reactions play a key role in the treatment of wastewater.

Oxidation Ditch: A wastewater treatment system that uses an aeration process to promote the growth of microorganisms that consume organic matter.

Oxidation Pond: A wastewater treatment system that uses natural processes, such as sunlight and bacteria, to break down organic matter.

Oxidation-Reduction Potential (ORP): A millivolt measurement of a solution’s tendency to gain or lose electrons during a chemical reaction. In metal finishing it is the control parameter for treating effluent containing hexavalent chromium. Also called redox potential.

Oxygen Demand: The amount of oxygen that is required to break down organic matter in wastewater.

Oxygen Dosing Station: Equipment that injects pure oxygen or air into a rising main or force main to keep the sewage aerobic. Holding dissolved oxygen up suppresses septicity and the hydrogen sulfide generation that corrodes concrete and causes odor complaints.

Ozone: A highly reactive form of oxygen that is used in some wastewater treatment processes to kill bacteria and remove contaminants.

Ozone-Based Wastewater Treatment: A wastewater treatment process that uses ozone to kill bacteria and remove contaminants.

Package Sewage Treatment Plant: A package sewage treatment plant is a compact sewage treatment system suitable for treating the waste generated by populations of up to 5000 people.

Parts Per Billion: A unit of concentration for pollutants in the wastewater. It’s the equivalent of one microgram in 1 liter (ug/l).

Parts Per Million: A unit of concentration for pollutants in the wastewater. It’s the equivalent of 1 milligram in 1 liter (mg/l).

Pathogen: A disease-causing microorganism, such as a bacterium or virus. Pathogens can be present in wastewater and can be harmful to humans and the environment if not properly treated.

Penstock Valve: This is a large square slide style valve used as a flow stop, as in a well inlet, mounted flush to a wall.

Percolation: The movement of water through soil or other porous materials.

Permit: A legal authorization or permission granted by a government agency for the operation of a wastewater treatment plant or other facilities.

pH: A measure of the acidity or basicity of a solution on a scale of 0 to 14. A pH of 7 is neutral, below 7 acidic, above 7 basic. Each whole number is a tenfold change in hydrogen ion concentration.

pH Adjustment: The process of adjusting the pH of wastewater to meet regulatory standards or to optimize treatment processes.

Phosphorus: An element that is found in wastewater and can be harmful to the environment if not properly treated. Phosphorus is an essential nutrient for plants, but high levels of phosphorus in water can lead to algal blooms and other environmental problems.

Physical Treatment: Wastewater treatment processes that rely on physical processes, such as sedimentation or filtration, to remove contaminants.

Pipe Fitting: A component of a pipeline, other than a pipe, which allows pipeline deviation, change of direction, or bore.

Pipefitting: The occupation of installing or repairing piping or tubing systems that convey liquid, gas, and occasionally solid materials. This work involves selecting and preparing pipe or tubing, joining it together by various means, and locating and repair of leaks.

Pollution: Any water in the state that has had its physical, thermal, chemical, or biological characteristics changed, or that has been contaminated, in a way that endangers people, animals, plants, or the public’s health, safety, or welfare, or makes it unusable for any legitimate or reasonable purpose.

Polyvinyl Chloride: The most common material used for wastewater piping. It is a type of plastic.

Potable Water: This is water that is of a high enough standard to be used or consumed without running the danger of doing any short-term or long-term damage.

Pounds Per Square Inch: A measurement of pressure. It’s often used when discussing physical wastewater treatment technologies involving filtration but is also used with pumps. Filtration system PSI can indicate when it’s time to backwash or change a filter.

Precipitate: The insoluble solid formed when a dissolved constituent is converted to an insoluble form — metal hydroxides or phosphate solids produced by dosing lime, alum or ferric salts — and then removed by settling or filtration.

Pressure Main: A pipeline that transports a liquid at a pressure higher than atmospheric pressure, usually water or sewage.

Pressure Reducing Valve (PRV): A valve used to reduce the pressure to a pre-set downstream pressure.

Pressure Relief Valve (PRelV): A type of valve that is used to control pressure spikes in the water main line. When a predetermined maximum pressure is achieved, a pressure relief valve is intended to open. Safety Relief Valves are another name for these valves.

Pressure Sustaining Valve (PSV): A valve that maintains a preset minimum pressure on its upstream side, throttling closed to protect pressure ahead of it. The opposite of a pressure reducing valve, which controls pressure downstream.

Preventive Maintenance (PM): Regularly scheduled servicing of machinery or other equipment using appropriate tools, tests, and lubricants. This type of maintenance can prolong the useful life of equipment and machinery and increase its efficiency by detecting and correcting problems before they cause a breakdown of the equipment.

Primary Clarifier: A large tank or basin that is used to separate large solids from wastewater during primary treatment.

Primary Sludge: The solids that are removed from wastewater during primary treatment.

Primary Treatment: The first stage of wastewater treatment, in which large solids are removed through processes such as sedimentation and grit removal.

Probable Maximum Flood (PMF): The theoretical upper-bound flood for a drainage basin, produced by the most severe combination of critical meteorological and hydrologic conditions reasonably possible there. It is generally derived from the Probable Maximum Precipitation and is used for dam and spillway design, not as a likely event.

Process And Instrumentation Diagram: A system engineering schematic for wastewater treatment. It is a schematic flow diagram that illustrates the connections between various instruments and pieces of equipment.

Process Control: The use of sensors, automation, and other techniques to monitor and control the operation of a wastewater treatment plant or other facilities.

Process Efficiency: How completely a treatment process removes a given contaminant, calculated as (influent minus effluent) divided by influent, times 100, and reported as percent removal.

Process Optimization: The optimization of wastewater treatment processes to improve efficiency and reduce costs.

Property Connection Sewer: A short sewer, owned and operated by a Water Agency, which connects the main sewer or Sewer Access Point to the Customer Sanitary Drain; it includes a junction on the main sewer, a property connection fitting, in some cases a vertical riser, and sufficient straight pipes to ensure the property connection fitting is within the lot to be serviced.

Property Service: Is defined by the WSAA as the section of a property’s water service that runs from the reticulation main to the placement of the meter.

Publicly Owned Treatment Work: City or municipal sewage treatment facilities are referred to as publicly owned treatment works. The majority of industries are normally governed by these POTWs because they discharge wastewater to these facilities.

Pump And Treat: A method of contaminant remediation that involves pumping contaminated groundwater to the surface for treatment.

Pumping Station: A facility that is used to pump wastewater from one location to another, such as from a collection system to a treatment plant.

Purge: The removal of sludge or other materials from a wastewater treatment system.

Purge Rate: The rate at which sludge or other materials are removed from a wastewater treatment system.

Purification: Treatment that removes contaminants from water until it meets a defined standard for its intended use — drinking, process water or discharge. The endpoint is the standard, not an absolute.

Purveyor: This is an agency or person that supplies potable water.

Pyrolysis: The chemical decomposition of organic matter through the application of heat.

Pyrolysis Gas: Gas that is produced through the pyrolysis of organic matter.

Quality Assurance: The systematic measures that are taken to ensure the quality of wastewater treatment processes and products.

Quality Control: The specific technical activities that measure whether a process is meeting its defined standard — blanks, duplicates, spikes and calibration checks in the lab, and the sampling and instrument checks that go with them.

Quality Management: The management system through which an organization directs and controls quality: the policy, the planning, quality assurance, quality control, and the improvement loop that closes on them.

Quench: The process of rapidly cooling a material, typically through the use of water or other cooling agents.

Quenching Tank: A tank or basin that is used to cool wastewater or other materials through the use of water or other cooling agents.

Recarbonation: The process of adding carbon dioxide to wastewater or other solutions to adjust the pH or remove contaminants.

Recharge: The addition of water into a groundwater system.

Recirculation: The process of returning wastewater or other materials to an earlier stage of treatment.

Recovery: The process of reclaiming or salvaging a material or resource.

Recovery Rate: The percentage of a material or resource that is recovered during a treatment process.

Recycle: The reuse of a material or resource, typically after it has undergone some form of treatment.

Recycling Rate: The percentage of a material or resource that is recycled during a treatment process.

Redox: A term used to describe chemical reactions in which the oxidation state of a molecule changes.

Redox Potential: A millivolt measurement of a solution’s tendency to gain or lose electrons, read against a reference electrode. Also called oxidation-reduction potential, or ORP.

Reducing Agent: A substance that donates electrons and is itself oxidized. In wastewater practice, sulfur dioxide, sodium bisulfite and sodium metabisulfite are used to dechlorinate effluent, and ferrous sulfate to reduce hexavalent chromium.

Reduction: The gain of electrons by a chemical species, lowering its oxidation state. The counterpart of oxidation; the two always occur together in a redox reaction.

Reflux: The process of returning a liquid or gas to an earlier stage of a process, typically for the purpose of further treatment or separation.

Reflux Valve: A type of valve that permits flow in only one direction. Reflux valves are also known as check valves.

Refuse: Solid waste — garbage, rubbish and trash. Sewage is waterborne liquid waste and is not refuse; the two are separate streams handled by entirely different systems.

Refuse-Derived Fuel (RDF): Fuel produced by shredding municipal solid waste and screening out the noncombustibles such as glass and metals, leaving a combustible fraction. The processing is mechanical; combustion or pyrolysis is what happens to RDF afterward, not how it is made.

Remediation: The process of cleaning up or mitigating the effects of pollution or contamination.

Renewable Energy: Energy that is derived from natural resources, such as sunlight or wind, that can be replenished on a human timescale.

Reservoir: A natural or artificial pond, lake, tank, or basin used to collect and store water. The water behind a dam is also referred to as a reservoir of water, as are large volumes of groundwater.

Residual: The amount of a substance that remains in a solution after treatment.

Residual Pressure: This is a term used in AS 2419.1 and refers to the pressure remaining in a pipe during flow conditions. It is often referred to during water supply adequacy testing for fire fighting flow.

Residual Sludge: The sludge that remains after the treatment of wastewater or other materials.

Residual Solids: The solids that remain in wastewater after treatment.

Resource Recovery: The process of recovering resources, such as energy or materials, from wastewater or other sources.

Respirometry: Measuring the rate at which microorganisms consume oxygen, used to assess biomass activity, toxicity and treatability. Oxygen uptake rate (OUR) and specific oxygen uptake rate (SOUR) are the routine forms of the test.

Retention Basin: A basin that holds a permanent pool of water and releases storage only by infiltration, evaporation or a controlled outlet above the pool. The permanent pool is what distinguishes it from a detention basin, which drains empty between storms.

Retention Time: The amount of time that wastewater or other materials spend in a treatment process or system.

Return Activated Sludge (RAS): Settled activated sludge drawn from the secondary clarifier and returned to the head of the aeration basin to maintain the mixed liquor solids inventory and the food-to-microorganism ratio. It is returned to sustain the biomass, not for further treatment.

Reuse: The use of wastewater or other materials for a different purpose, typically after it has undergone some form of treatment.

Reuse Water: Water that has been treated and is suitable for reuse, such as for irrigation or toilet flushing.

Reverse Filtration: Passing flow through a filter in the direction opposite to normal service flow, in order to lift and flush the accumulated solids out of the media. This is what happens during a backwash.

Reverse Flow: The flow of a liquid or gas in the opposite direction to which it would normally flow.

Reverse Osmosis: A membrane process used to desalinate water and remove dissolved solids. In natural osmosis, water — the solvent, not the solutes — crosses a semipermeable membrane from the dilute side toward the concentrated side until the two balance; osmotic pressure is what drives it. Reverse osmosis applies pressure greater than the osmotic pressure to the concentrated feed, forcing water the other way, through the membrane and into the permeate, while the membrane rejects the dissolved salts.

Reverse Osmosis Concentrate: The rejected stream leaving a reverse osmosis system, carrying the salts and contaminants the membrane held back. Also called the reject or the retentate.

Reverse Osmosis Membrane: A semipermeable membrane that is used in the reverse osmosis process to remove contaminants from water.

Reverse Osmosis Permeate: The purified water that is produced by a reverse osmosis system.

Reverse Osmosis Reject: Another name for reverse osmosis concentrate — the stream that does not pass through the membrane and leaves carrying the rejected salts. See Reverse Osmosis Concentrate.

Reverse Osmosis Retentate: Another name for reverse osmosis concentrate, emphasizing what the membrane retains rather than what it rejects. See Reverse Osmosis Concentrate.

Rising Main: This is a similar phrase to Pressure Main. Although rising mains are sometimes used to refer to water pressure mains, the word is more frequently used to describe a sewer pressure main.

River Basin: This is a term used to designate the area drained by a river and its tributaries.

Rotating Biological Contactor: This is a biological treatment method most frequently employed in sewage systems in urban areas to lower BOD.

Roughing Filter: A filter that is used to remove coarse particles from wastewater or other materials.

Runoff: Water that flows over the surface of the ground, rather than being absorbed into the soil.

Runoff Coefficient: A measure of the amount of runoff that is produced by a surface, based on its slope, permeability, and other factors.

Sand Filter: A device designed to purify water by making it pass through a layer of sand.

Sanitary Wastewater: Sewage and industrial wastes that are emitted from homes as well as from commercial, institutional, and similar institutions.

Schmutzdecke: A layer of biological growth and solids that develops on top of a slow sand filter allows the filter to successfully remove turbidity without the need of chemical coagulation.

Scum: The mixture of floatable solids and water removed from the surface of the settling tank.

Sediment: Transported and deposited particles derived from rocks, soil, or biological material.

Sediment Control: Measures taken to prevent or minimize the erosion and sedimentation of soil into water bodies. Sediment control can be achieved through a variety of methods such as erosion control blankets, silt fences, and sediment basins.

Sedimentation: The process that reduces the velocity of water in basins so suspended material can settle out by gravity.

Seepage: The surfacing and submerging of water at the surface of the ground. Water flow in saturated material is referred to as seepage. Percolation, which is mostly the movement of water in unsaturated material, is different from it.

Septic System: A system that is used to treat and dispose of wastewater from homes and businesses in areas that do not have access to a centralized sewage treatment plant. A septic system typically consists of a tank and a drain field, and relies on natural processes to break down and treat the wastewater.

Septic Tank: A buried tank that receives raw wastewater from a building and separates it by settling. Solids sink to form a sludge layer, grease and oils float to form a scum layer, and the clarified middle layer flows out to the drainfield. Neither layer leaves on its own; both accumulate until the tank is pumped out.

Sequencing Batch Reactors: A biological treatment approach built on the activated sludge technique. Small towns and food processing facilities that release their waste into streams or rivers also utilize it sometimes.

Service Pipe: A water pipe that transports water from the reticulation main to the user, according to the WSAA. When it comes to fire services, the service pipe under the supervision of a Water Agency typically ends at the isolating valve of the fire protection system or the water meter.

Settleability: A process control test used to gauge how well the activated sludge settles. The settled sludge volume (SSV) and the sludge volume index are calculated using readings taken between 30 and 60 minutes (SVI).

Settled Sludge Volume (SSV): The volume (in percent) occupied by an activated sludge sample after 30 to 60 minutes of settling; normally written as SSV with a subscript to indicate the time of the reading used for calculation (SSV60 or SSV30).

Sewage: This is domestic or industrial wastewater which is discharged to a sewer system.

Sewage Lift Station: A facility that pumps sewage from a lower elevation to a higher elevation, allowing it to flow through gravity to the treatment plant.

Sewage Pump Station (SPS): A pump station designed to pump sewage either directly or via an intermediate pump station to a Wastewater Treatment Plant.

Sewage Treatment Plant: A facility that removes contaminants from sewage to produce effluent that is safe to be released into the environment.

Sewer Access Point: A pit or a shaft designed to allow access to a sewer for maintenance.

Sewer Camera Inspection: The use of a specialized camera to inspect the inside of a sewer pipe or other underground infrastructure. Sewer camera inspections can be used to identify blockages, cracks, roots, and other problems that may require repair or maintenance.

Sewer Cleaning: Removing debris, grease and roots from sewer pipes to keep sewage flowing and prevent blockages. Methods include rodding, high-pressure jetting, bucket machine or dragline, and vacuum removal.

Sewer Flow Monitor: To help with calculating the inflow and infiltration into the sewer system, a sewer flow monitor is a tool. At critical places in the system, monitors are put in place to continually record the flow depth and flow velocity. The sewage flow rate can be connected with rainfall occurrences using rainfall data. The hydrograph shows the changes in sewage flow over time.

Sewer Grate: A metal or plastic cover that is placed over a sewer opening to prevent debris and other objects from entering the pipe, and to allow people and vehicles to pass over it safely.

Sewer Jetting: The use of high-pressure water jets to clean and clear debris, grease, and other obstructions from sewer pipes. Sewer jetting can be an effective method for maintaining the flow of sewage and preventing blockages in the system.

Sewer Lamphole: A point of entry at the end of a reticulation sewer line that provides restricted access to enable inspection or the removal of blockages.

Sewer Lateral: The pipe that connects a building’s plumbing system to the main sewer line.

Sewer Main: The large pipe that carries wastewater from multiple buildings or properties to the treatment plant.

Sewer Maintenance Hole: A sewer access point with a detachable cover that provides access for both people and machines to a sewer that is generally underground.

Sewer Maintenance Shaft: An alternative to Sewer Maintenance Holes when necessary. It is a Sewer Access Point on a sewer between Sewer Maintenance Holes that are larger than inspection openings, provides equipment access but not personal access to the sewer, and allows for a limited change in grade or direction.

Sewer Manhole: An opening in the top of a sewer pipe or chamber that allows access to the inside of the pipe for maintenance and repair purposes. Sewer manholes are typically covered with a manhole cover to prevent accidents and unauthorized access.

Sewer Overflow: The release of untreated or partially treated sewage from a sewer system due to a blockage, malfunction, or other issues. Sewer overflows can cause environmental and public health problems and can be caused by a variety of factors such as grease buildup, debris, and roots growing into the pipes.

Sewer Pipe: A pipe that is used to transport sewage or wastewater from homes and businesses to a treatment plant. Sewer pipes are typically made of concrete, PVC, or other materials that are resistant to corrosion and degradation.

Sewer Pipe Lining: Installing a new inner liner inside an existing sewer pipe to rehabilitate it without excavation, by cured-in-place pipe (CIPP) or slip lining. Pipe bursting is a separate trenchless method: it fractures and displaces the old pipe and pulls a new one into the void, so nothing is lined.

Sewer Relining: This is a Renewal Activity, where a PVC pipe is inserted or extruded into a clay or concrete Gravity Sewer, nearing the end of its life.

Sewer Robot Inspection: The use of a small, remotely-operated robot to inspect the inside of a sewer pipe or other underground infrastructure. Sewer robot inspections can provide a detailed view of the condition of the pipes and can be used to identify issues that may not be visible with traditional inspection methods.

Sewer Smoke Testing: A method of testing the integrity of a sewer system by injecting a non-toxic smoke into the pipes and observing where it exits. Smoke testing can help to identify leaks, blockages, and other issues in the sewer system.

Sewer Surcharge: The overloading of the sewer past its intended capacity as a result of inflow and infiltration of water is referred to as sewer surcharge. Sewage overflows at manholes and customers’ overflow relief gullys are frequently caused by surcharging sewers.

Sewer System Assessment: The evaluation of a sewer system to determine its condition and capacity, and identify any problems or deficiencies that need to be addressed. Sewer system assessments may include inspections, flow monitoring, and other techniques to gather data about the system.

Sewer System Capacity: The maximum flow of wastewater that a sewer system can handle without experiencing overflow or other problems. Sewer system capacity may be affected by factors such as the size and condition of the pipes, the elevation and slope of the terrain, and the volume of wastewater generated by the connected properties.

Sewer System Efficiency: The effectiveness of a sewer system in carrying away wastewater and preventing spills or overflows. Sewer system efficiency may be impacted by factors such as the condition of the pipes, the presence of blockages or leaks, and the design of the system.

Sewer System Maintenance: The activities performed to keep a sewer system in good working order and prevent problems such as blockages, leaks, and overflows. Sewer system maintenance may include activities such as cleaning, inspecting, and repairing pipes, as well as monitoring flow and identifying and addressing potential issues.

Sewer System Mapping: The process of creating a detailed map of a sewer system, including the location and size of pipes, manholes, and other features. Sewer system mapping can be used to help plan and implement maintenance and repair activities, and to identify potential problems or vulnerabilities in the system.

Sewerage Treatment System (Sewerage Network): This is the infrastructure used to receive, transport, and treat sewage or effluent, including sewers, access chambers, machinery, outfalls, pumps, structures, and vents.

Sludge: The semi-solid material that is left over after the treatment of sewage. It contains organic matter, nutrients, and other contaminants that need to be removed or processed before it can be safely disposed of or used as a fertilizer.

Sludge Blanket: A layer of sludge that forms at the bottom of a wastewater treatment tank or basin.

Sludge Blanket Depth: The thickness of the sludge blanket at the bottom of a wastewater treatment tank or basin.

Sludge Digestion: The process of breaking down sludge through the action of bacteria and other microorganisms, which reduces its volume and produces biogas that can be used as fuel. Sludge digestion can be accomplished through anaerobic digestion, which takes place in the absence of oxygen, or aerobic digestion, which requires oxygen.

Sludge Drying: The process of removing water from sludge through evaporation or other methods, in order to reduce its volume and make it easier to handle and transport. Sludge drying can be accomplished through a variety of methods such as belt drying, drum drying, and solar drying.

Sludge Drying Bed: In a water treatment or wastewater treatment facility, wet sludge is left to dry in an open area known as a sludge drying bed.

Sludge Handling: The process of transporting, storing, and disposing of sludge after it has been produced at a wastewater treatment plant. Sludge handling may include activities such as dewatering, drying, incineration, or land application.

Sludge Thickening: The process of increasing the solids content of sludge through the removal of water.

Sludge Treatment: The process of treating sludge to reduce its volume, stabilize it, or make it safe to dispose of.

Sludge Volume Index (SVI): A measure of the settling characteristics of sludge, used to evaluate the efficiency of sludge treatment processes.

Softening: The process of removing calcium and magnesium ions from water, typically to improve its quality or to reduce the risk of scaling.

Soil Moisture (Soil Water): Water diffused in the soil. It is found in the upper part of the zone of aeration from which water is discharged by transpiration from plants or by soil evaporation.

Specific Heat: The heat required to raise the temperature of one gram of a substance by one degree Celsius. Water’s specific heat is 1 calorie per gram per degree Celsius (4.184 J/g·°C), which is high enough that water resists temperature change and moderates the systems it flows through.

Spiral Cracking: This is one type of pipe failure. As the name implies, it appears as a crack that spirals around a pipe’s exterior.

Steady Inflow: Water discharged from cellar and foundation drains, cooling water discharges, and drains from springs and swampy areas. This type of inflow is steady and is identified and measured along with infiltration.

Stop Valve (Isolating Valve): A valve operated to shut off flow in a pipe, permanently or temporarily. Gate, ball, butterfly, plug and globe valves are the common types. A check valve is not a stop valve: it acts automatically on flow reversal and cannot be used to isolate a line.

Stormwater: Rainwater or snowmelt that runs off the ground surface into a storm drainage system. It picks up oil, grease, sediment, nutrients and chemicals along the way. Historically it discharged untreated, and much of it still does, but municipal stormwater permits now require structural and non-structural controls to treat it before it reaches receiving water.

Stormwater Detention: The temporary storage of stormwater in a pond, basin, or other structure to allow it to be released slowly over time, rather than all at once. Stormwater detention can help to reduce erosion, flooding, and other problems caused by rapid runoff.

Stormwater Infiltration: The process of allowing stormwater to percolate into the ground, rather than flowing over the surface and into a stormwater drainage system. Infiltration can help to recharge groundwater, improve water quality, and reduce the volume of stormwater runoff.

Stormwater Management: The process of planning, designing, and implementing measures to control, treat, and prevent pollution of stormwater runoff.

Stormwater Pond: A basin or pond that is used to store and treat stormwater runoff. Stormwater ponds may include features such as wetland plants, sediment basins, and other features to help filter and treat the water.

Stormwater Retention: Storing stormwater in a basin that keeps a permanent pool, with runoff leaving only by infiltration, evaporation or reuse rather than by surface discharge. Detention, by contrast, holds runoff temporarily and then releases it.

Stormwater Runoff: Water that flows over the surface of the ground and into a stormwater drainage system, rather than being absorbed into the ground. Stormwater runoff can carry pollutants such as oil, grease, and chemicals, which can harm aquatic life and water quality.

Supervisory Control and Data Acquisition (SCADA): A computer system used to remotely monitor and control equipment and processes in a wastewater treatment plant or other facilities. SCADA systems typically include sensors, actuators, and other devices that collect and transmit data about the operation of the facility, as well as a central computer that processes the data and sends control signals to the equipment.

Surface Water: Lakes, bays, ponds, impounding reservoirs, springs, rivers, streams, creeks, estuaries, wetlands, marshes, inlets, canals, gulfs inside the territorial limits of the state, and all other bodies of surface water, natural or artificial, inland or coastal, fresh or salt, navigable or non-navigable, and including the beds and banks of all watercourses and bodies of surface water that are wholly or partially inside or bordering the state or subject to the jurisdiction of the state; except that waters in treatment systems which are authorized by state or federal law, regulation, or permit, and which are created for the purpose of water treatment, are not considered to be waters in the state.

Tertiary Treatment: The third stage of wastewater treatment, in which the effluent from the secondary treatment stage is further clarified and disinfected to remove remaining contaminants and pathogens. Tertiary treatment may include processes such as filtration, disinfection, and nutrient removal.

Thermal Pollution: The degradation of water quality by the introduction of a heated effluent. Primarily the result of the discharge of cooling waters from industrial processes (particularly from electrical power generation); waste heat eventually results from virtually every energy conversion.

Total Dissolved Solids: The inorganic salts, present as dissolved ions, plus small amounts of dissolved organic matter, present in solution in water — individually far too small to see. Removal routes include reverse osmosis, ion exchange, distillation, electrodialysis and capacitive deionization.

Total Inflow: This is the sum of the direct inflow at any point in the system plus any flow discharged from the system upstream through overflows, pumping station bypasses, and the like.

Total Kjeldahl Nitrogen: The sum of organic nitrogen plus ammonia nitrogen in a sample, measured by Kjeldahl digestion. It excludes nitrate and nitrite. Commonly abbreviated TKN and often a surcharge parameter for industrial dischargers.

Total Organic Carbon: A direct measurement of how much organic matter is in wastewater.

Total Suspended Solids: The solids retained on a standard glass-fiber filter and dried at 103 to 105 degrees Celsius, reported in mg/L. TSS is defined by that test, not by what is visible — most of the particles it captures cannot be seen individually. Abbreviated TSS.

Total Toxic Organics: A component of wastewater that describes the total amount of hazardous organic chemicals present. A particular list of substances that are classified as hazardous organic compounds has been created by the EPA.

Transpiration: The process by which water vapor escapes from the living plant, principally the leaves, and enters the atmosphere.

Treatment Plant: A facility that is used to treat and process wastewater and sewage to remove contaminants and pathogens before it is released into the environment. Treatment plants may use a variety of methods such as physical, chemical, and biological processes to purify the wastewater.

Trenchless Technology: A method of repairing or replacing underground pipes or other infrastructure without having to dig a trench. Trenchless technology can include methods such as pipe bursting, pipe relining, and horizontal directional drilling.

Trickling Filter: A type of wastewater treatment system that uses a bed of media, such as gravel or plastic, to support the growth of microorganisms that break down organic matter in the wastewater. As the wastewater trickles over the media, the microorganisms consume the organic matter, converting it into biomass and other products.

Turbidity: A measure of the cloudiness or haziness of a water sample, typically expressed in Nephelometric Turbidity Units (NTUs). High turbidity can indicate the presence of sediment, algae, or other contaminants in the water, and can affect its clarity and quality.

Ultrafiltration: A type of membrane filtration that’s similar to reverse osmosis, but not as restrictive. It will not remove the smallest dissolved solids from water (for example salt) unless they can be chemically treated first.

UV Disinfection: A method of disinfecting water or wastewater using ultraviolet (UV) light. UV disinfection can be an effective method for killing bacteria, viruses, and other pathogens in water without the use of chemicals.

Valve Box: A buried sleeve or vault set over the stem of an underground valve so it can be reached and operated from grade, with only its cover showing flush with the ground surface.

Valves: Devices that are used to regulate the flow of liquids, gases, or other materials through a pipe or system. Valves are often used in wastewater treatment plants to control the flow of water and sewage and may be manually or automatically operated.

Vapor Recovery Unit (VRU): A device that is used to capture and recover volatile organic compounds (VOCs) and other gases that are emitted during the treatment of wastewater. VRUs are often used to prevent air pollution and reduce the risk of explosions and other hazards.

Vapor Treatment System: A system that is used to treat and remove volatile organic compounds (VOCs) and other gases from the air. Vapor treatment systems may include a variety of technologies such as adsorption, absorption, and catalytic oxidation.

Vaporization: The change of a substance from a liquid or solid state to a gaseous state.

Variable Frequency Drive (VFD): An electronic device that is used to control the speed and torque of an electric motor by varying the frequency of the power supply. VFDs are often used in wastewater treatment plants to control the speed of pumps and other equipment and can help to save energy and improve efficiency.

Vent Stack: A vertical pipe that is used to vent gases from a plumbing system, such as a sewer or septic system. Vent stacks are typically located on the roof of a building and allow the gases to be released into the air, rather than accumulating in the pipes and creating a hazard.

Ventilation System: A system of fans, ducts, and vents that is used to circulate air and remove odors and gases from a wastewater treatment plant or other facilities. Ventilation systems are important for maintaining a safe and healthy working environment and preventing the build-up of harmful gases.

Venturi Effect: The principle that the velocity of a fluid increases as it flows through a constricted section of a pipe or channel, and the pressure decreases. The Venturi effect is often used in wastewater treatment plants to create a vacuum or suction force, which can be used to move liquids and gases.

Volatile Organic Compound (VOC): A chemical compound that evaporates easily at room temperature and can be harmful to human health and the environment. VOCs are often found in wastewater and can be released into the air during treatment processes.

Vortex: A whirling mass of fluid, such as water, that rotates around an axis. Vortexes can be created in wastewater treatment plants by using mechanical devices such as vortex generators or by using natural forces such as gravity.

Vulnerability Assessment: The process of evaluating the potential risks and impacts of a particular hazard or threat on a wastewater treatment plant or other facilities. Vulnerability assessments may consider factors such as the likelihood of the hazard occurring, the potential consequences, and the ability of the facility to withstand or recover from the hazard.

Waste Activated Sludge (WAS): A type of sludge that is produced in the treatment of wastewater and that contains a high concentration of organic matter. WAS is often treated and stabilized through processes such as anaerobic digestion or thermal drying.

Waste Stabilization Pond: A pond or basin that is used to treat wastewater or sewage by allowing it to flow through a series of ponds or basins that are designed to encourage the growth of microorganisms and other biological processes that break down the organic matter in the wastewater. Waste stabilization ponds are often used in areas where conventional treatment methods are not feasible.

Wastewater: Water that has been used and is no longer suitable for its intended purpose. Wastewater may contain a variety of contaminants and is often treated in a wastewater treatment plant to remove these contaminants before the water is discharged back into the environment.

Wastewater Treatment: The process of purifying wastewater and sewage to remove contaminants and pathogens before it is released into the environment. Wastewater treatment may include a variety of physical, chemical, and biological processes, depending on the type and level of contaminants present in the water.

Wastewater Treatment Plant (WWTP): A facility that is designed to treat and purify wastewater to meet certain standards before it is released back into the environment. WWTPs may use a variety of treatment processes, such as biological treatment, chemical treatment, and mechanical filtration, to remove contaminants from the wastewater.

Water Cycle: The process by which water moves sequentially from the atmosphere (condensation) to the Earth (precipitation), then back to the atmosphere (evaporation). Additionally known as the hydrologic cycle.

Water Flow Metering Station: An asset used to measure the amount of water flowing through a pipeline is a water flow metering station.

Water Hammer: When fluid flow velocities fluctuate, the pressure in a pipeline rises. This is known as a water hammer. The pressure surge’s magnitude increases with how quickly the velocities change. Pump stops and starts, valve openings, and closings, or abrupt air release are all causes of pressure spikes in pipe systems.

Water Hydrant: The term water hydrant is a synonym for a fire hydrant.

Water Main: The pressurized distribution or transmission pipe in a public water system, from which service connections to individual properties are taken.

Water Meter: A device used to measure the volume of water usage.

Water Property Service: This is a section of a water service pipe between the water reticulation main and the water meter.

Water Pump Station: A water pump station (or water pumping station) is an asset designed to pump water from one location to another.

Water Quality: A term used to characterize water’s chemical, physical, and biological properties in relation to whether or not it is suitable for a given usage.

Water Quality Standard: A plan for water quality management containing four major elements: water use, criteria to protect users, implementation plans, and enforcement plans. An antidegradation statement is sometimes prepared to protect existing high-quality waters.

Water Reticulation Main: This is a main water main that connects a distribution main with service pipes. Reticulation mains are typically between 100mm and 375mm in diameter.

Water Reticulation Network: A water reticulation network is a network of pumps, pipes, and water storage designed to store and distribute water.

Water Service: A water service is a pipeline that connects a property to a water main.

Water Service Pipe: A water service pipe is a pipe that extends from a potable water source to the interior of a building.

Water Supply: This is the process of self-provision or provision by third parties in the water industry, commonly a Council or Water Authority, of water resources of various qualities to different users.

Water Supply Facility: This is a group of related water supply assets located within close proximity.

Water Supply System (Water Supply Network): This is a system designed to collect, store, purify and distribute water.

Water Transfer Main: A water main used as part of the water supply system to move large amounts of water from a source or storage to another water facility is known as a water transfer main. There are no property services connected to the water transfer main, which is not a component of the reticulation system. Water from a well, untreated surface water or potable water are all possible.

Water Treatment Plant: This is a facility designed to produce potable water for a Water Reticulation Network.

Water Valve: This is a valve that regulates the flow of water through a pipe.

Watershed: The area of land that contributes surface runoff to a given point in a drainage system.

Weir: This is a small overflow-type dam commonly used to raise the level of a river or stream.

Wet Scrubber: A device that is used to remove pollutants and contaminants from the air by spraying the air with a wet mist or slurry. Wet scrubbers are often used in wastewater treatment plants to remove odors and gases, and can be effective at removing a variety of contaminants including particulates, acids, and VOCs.

Wet Weather Flow: The increased volume of wastewater that is generated during wet weather events, such as rain or snow. Wet weather flow can put additional strain on wastewater treatment plants and may require special treatment processes to manage.

Wet Well: The storage chamber at a pump station that holds incoming wastewater between pump cycles. It is built to keep solids moving through, not to settle them: the floor is steeply sloped or hoppered, and fill time and pump cycling are set so solids stay in suspension and are pumped out rather than deposited.

Wetland: An area of land that is saturated with water, either permanently or seasonally, and is characterized by the presence of wetland plants and animals. Wetlands can provide a variety of ecosystem services such as water purification, flood control, and wildlife habitat.

Wetland Restoration: The process of repairing and improving a wetland that has been damaged or degraded. Wetland restoration can include a variety of activities such as removing invasive species, planting native vegetation, and improving the hydrology of the wetland.

Whole Effluent Toxicity (WET) Test: A laboratory test that is used to measure the toxic effects of wastewater effluent on aquatic organisms. WET tests are often used to evaluate the effectiveness of a wastewater treatment plant in removing toxins and other contaminants from the water.

Work Authorization: A written document that outlines the scope of work that is to be performed on a wastewater treatment plant or other facilities, and includes details such as the location, duration, and specific tasks to be completed. Work authorizations are often used to ensure that the work is performed safely and efficiently.

Work Order: A written request for maintenance, repair, or other work to be performed on a wastewater treatment plant or other facilities. Work orders may include details such as the location, nature of the work, and any special instructions or requirements.

Workforce: The group of people who are employed in a particular industry or field. In the wastewater industry, the workforce may include engineers, technicians, operators, and other professionals who work to design, build, operate, and maintain wastewater treatment plants and other wastewater infrastructure.

Xenobiotic: A chemical compound that is foreign to a living organism or to a natural ecosystem. In wastewater, xenobiotics include pharmaceuticals, pesticides, and industrial solvents that biological treatment processes are not always able to break down.

Yield: The quantity of water that can be reliably drawn from a well, aquifer, reservoir, or catchment over a given period of time.

Zebra Mussels: A small, invasive species of freshwater mussel that is native to Eastern Europe and has spread to many other parts of the world. Zebra mussels can clog water pipes and cause damage to water treatment infrastructure, and they can be a significant problem in the wastewater industry.

Zero Discharge: A goal or policy of discharging no wastewater or other waste materials into the environment. Zero discharge may be achieved through the use of advanced treatment technologies or through the recycling or reuse of waste materials.

Zinc: A chemical element that is commonly used in the production of galvanized steel and other alloys. In the wastewater industry, zinc may be present in wastewater as a result of industrial processes or the corrosion of galvanized pipes. Zinc can be harmful to aquatic life if present at high levels and may need to be removed during wastewater treatment.

Zinc Oxide: A compound formed when zinc is exposed to oxygen. In water and wastewater it appears as a corrosion product from galvanized pipe and as a constituent of some industrial discharges. It is not a treatment chemical: the standard coagulants are alum, polyaluminum chloride, ferric chloride or sulfate, ferrous sulfate and lime.

Zone: A specific area or region within a wastewater treatment plant or other wastewater infrastructure. Zones may be used to separate different treatment processes or to isolate specific areas for maintenance or repair.

Zone Of Aeration: A region in the Earth above the water table. Water in the zone of aeration is under atmospheric pressure and would not flow into a well.

Zoogleal Slime: The biological slime that forms on fixed-film treatment devices. It contains a wide variety of organisms essential to the treatment process.

Zooplankton: Small, aquatic animals that are found in both freshwater and marine environments. Zooplankton plays a key role in the ecosystem of a water body and may be used as indicators of the health of a water system. In the wastewater industry, zooplankton may be used as indicators of the effectiveness of wastewater treatment processes.

Part of the eWorkOrders Learning Center