Water Terms

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A type of filtration process that is designed to remove particles from a fluid (usually a liquid or gas) with an extremely high level of efficiency. It is characterized by a specified pore size rating or particle size exclusion limit, below which particles are intended to be completely blocked or removed from the fluid.
A physical or chemical process in which atoms, molecules, or ions from a substance are taken up and incorporated into another substance, typically as they move from one phase (e.g., gas or liquid) to another (e.g., into a solid or liquid).
Tiny airborne particles or droplets that contain acidic compounds. These aerosols can be in the form of solid particles, liquid droplets, or a combination of both. They are typically produced as a result of various industrial processes, combustion, or natural sources and can be present in the atmosphere.
A measure of a substance's or solution's ability to resist changes in pH when exposed to an acidic or alkaline substance. In other words, it quantifies the capacity of a substance to neutralize or buffer against changes in acidity (low pH) or alkalinity (high pH). ANC is typically expressed in units of moles of acid or base per liter (mol/L).
A form of atmospheric precipitation that contains higher-than-normal levels of acidic compounds. It is primarily caused by emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) into the atmosphere, which undergo chemical reactions with water vapor, oxygen, and other atmospheric components to form sulfuric acid (H2SO4) and nitric acid (HNO3). When these acidic substances combine with rainwater, snow, fog, or other forms of precipitation, it results in acid rain.
Refers to water that has a low pH level, meaning it is acidic. The pH scale measures the acidity or alkalinity of a solution, with a pH of 7 considered neutral. A pH value below 7 indicates acidity, while a pH value above 7 indicates alkalinity.
A property of a substance or solution that describes its level of acidity, or the presence of acidic characteristics. It is determined by the concentration of hydrogen ions (H+) in the solution. Acidity is one of the fundamental parameters used in chemistry to quantify the acidic or basic nature of a substance.
Also known as activated charcoal, is a highly porous and adsorptive material that is used primarily for the removal of impurities and contaminants from liquids and gases. It is derived from various organic materials, such as wood, coconut shells, peat, sawdust, and other carbon-rich sources, through a process known as activation.
A treatment process that uses activated carbon to adsorb organic compounds, odors, and some chemicals from wastewater.
A biological treatment process that uses microorganisms to break down organic matter in wastewater. It involves aerating the wastewater to encourage microbial growth.
A surface-based process in which molecules or particles from a gas or liquid adhere or "stick" to the surface of a solid or liquid material. Unlike absorption, where substances are taken up within the bulk of a material (e.g., a sponge absorbing water), adsorption occurs only at the material's surface. This process is often driven by attractive forces between the adsorbate molecules (the substance being adsorbed) and the adsorbent (the material to which the adsorbate adheres).
An advanced and highly effective chemical treatment method used in water and wastewater treatment to remove or degrade organic and inorganic pollutants that are resistant to conventional treatment methods. AOPs rely on the generation of highly reactive hydroxyl radicals (•OH) or other powerful oxidizing species to break down and convert contaminants into less harmful substances or mineralize them into water and carbon dioxide.
A type of wastewater treatment system that uses aeration, or the introduction of air into wastewater, to facilitate the biological degradation of organic contaminants. It is a large, shallow basin or pond in which wastewater is treated by promoting the growth of aerobic (oxygen-dependent) microorganisms that consume and break down organic matter.
A tank or basin where wastewater is oxygenated to promote the growth of aerobic microorganisms that help break down organic matter.
The process of adding oxygen to wastewater to support aerobic biological treatment processes and enhance the decomposition of organic matter.
A biological process or condition that requires the presence of oxygen or the use of oxygen to sustain life, support chemical reactions, or generate energy. It is the opposite of anaerobic, which occurs in the absence of oxygen. Aerobic processes are vital in various biological, chemical, and environmental contexts.
The process of particles or small objects clumping together or coming together to form larger aggregates or clusters. It is a common phenomenon in various fields and can occur through a variety of mechanisms. The resulting agglomerates may be held together by physical forces, such as van der Waals forces, electrostatic forces, or adhesive properties, or they may be bound together by chemical interactions.
Water that has the potential to corrode or erode materials it comes into contact with. Aggressive water typically has characteristics that make it more corrosive than neutral or non-aggressive water. The aggressiveness of water is often related to its chemical composition and pH level.
A type of wastewater treatment pond where algae growth is encouraged to help remove nutrients like nitrogen and phosphorus from the water.
A measured or portioned fraction of a sample or substance that is taken from a larger quantity for the purpose of analysis, testing, or further experimentation. Aliquots are commonly used in scientific and laboratory settings to ensure precision and accuracy in measurements and to preserve the original sample for future reference or additional analyses.
A chemical property of a solution that measures its ability to resist changes in pH (acidity or basicity) when an acidic or basic substance is added to it. In other words, alkalinity indicates the capacity of a solution to neutralize acids or bases and maintain a relatively stable pH level.
Loose, unconsolidated material, such as sand, silt, clay, gravel, and other sediments, that is deposited by flowing water, typically rivers and streams, as well as by other agents of erosion like glaciers and wind. Alluvium is commonly found in river valleys, floodplains, and other low-lying areas where water has transported and deposited sediments over time.
Refers to conditions or processes that occur in the absence of oxygen (O2) or do not require oxygen to function. Anaerobic processes are a contrast to aerobic processes, which depend on the presence of oxygen. The term "anaerobic" is used in various scientific and biological contexts to describe different phenomena.
A biological process where microorganisms break down organic matter in the absence of oxygen. It produces biogas as a byproduct.
A negatively charged ion, or a particle, that has gained one or more electrons, resulting in an excess of negative electrical charge. Anions are a fundamental concept in chemistry and play a crucial role in various chemical reactions and in the structure of matter.
An electrode in an electrochemical cell or system where oxidation (loss of electrons) occurs during a chemical reaction. It is one of the two electrodes in an electrochemical cell, with the other electrode being the cathode, where reduction (gain of electrons) takes place. The anode is responsible for providing electrons to the external circuit of the cell and is associated with the flow of electrical current from the cell to the external circuit.
The ability of a substance to dissolve in water (H2O) to form a homogeneous solution. This property is essential in understanding how different compounds interact with water and is a fundamental concept in the field of chemistry.
A solution or a substance that is dissolved or mixed in water (H2O). In an aqueous solution, water is the solvent, while the dissolved substances, known as solutes, are typically chemical compounds or ions.
A geological formation or underground layer of rock, sediment, or soil that contains and transmits water, allowing it to be stored and extracted for various purposes, such as drinking water supply, irrigation, and industrial use. Aquifers are vital components of Earth's freshwater resources and are essential for supporting both human activities and ecosystems.
A class of organic compounds that are characterized by a specific ring-like molecular structure known as an aromatic ring or benzene ring. Aromatics are a subset of hydrocarbons, which are compounds composed solely of carbon (C) and hydrogen (H) atoms. Aromatic compounds are named after benzene, which is the simplest and most well-known member of this group.
The incorporation or biological transformation of certain pollutants or nutrients within the treatment process by microorganisms, plants, or other biological agents. This natural or engineered assimilation process helps to reduce or remove specific contaminants from wastewater, making it less harmful to the environment before discharge into natural water bodies or reuse for various purposes.
The ability of a water body, such as a river, lake, or ocean, to naturally absorb, dilute, and biologically process pollutants and contaminants present in wastewater effluents or discharges. This concept is vital for assessing the environmental impact of wastewater disposal and determining the maximum allowable pollutant load that can be released into a water body without causing harm to aquatic ecosystems or violating water quality standards.
Physical process in which solid particles, such as suspended solids or pollutants, are mechanically worn down or reduced in size through friction and collisions during their movement within a treatment system. This process is particularly relevant in certain wastewater treatment methods and equipment, where the abrasion of particles can contribute to the removal or transformation of contaminants.
The amount of chlorine that is present in a water sample and available to react with contaminants or microorganisms during disinfection processes. It is a crucial parameter for assessing the effectiveness of chlorine-based disinfection in wastewater treatment and ensuring that treated effluent meets regulatory standards for microbiological quality before discharge.

The unwanted and potentially hazardous reversal of the flow of water or wastewater within a plumbing system, water distribution network, or treatment facility. Backflow occurs when water or contaminants from a non-potable source flow backward into the clean water supply or treatment processes. This can compromise the safety and quality of drinking water, posing health and environmental risks.
The resistance or pressure that opposes the flow of water or other fluids within a wastewater treatment system, particularly in pipelines, pumps, and other equipment. Back pressure can have significant implications for the performance and efficiency of wastewater treatment processes and equipment.
The unintended and potentially harmful reversal of the flow of water or wastewater within a plumbing system, water distribution network, or treatment plant. It occurs when a partial vacuum or negative pressure condition develops in the system, causing contaminated water or substances to be drawn back into the clean water supply or treatment facilities. Back siphonage can pose serious health and safety risks, particularly when it allows contaminants to enter drinking water sources or treatment processes.
The process of reversing the flow of water or other fluids through a filter or a treatment system to remove accumulated solids, debris, or contaminants from the filtration media. Backwashing is a common operation in various wastewater treatment processes, particularly in filtration systems, to maintain the efficiency and effectiveness of the treatment process.
The alkaline or basic substances used in treatment processes to neutralize acidity, adjust pH levels, or enhance the removal of certain contaminants from wastewater. Bases are chemicals that have the ability to raise the pH of acidic or neutral wastewater, making it less acidic and more suitable for subsequent treatment or discharge.
Solid particles and sediments that are transported by flowing water within a treatment system or natural water body, such as a river or stream. Bed load consists of coarse particles that are too heavy to be suspended in the water column and instead move along the bottom or bed of the water body.
The bottom or substrate of a natural water body, such as a river, lake, pond, or ocean. It is the lowest level of a water body, where the bed or sediment interacts with the water column above it. The benthic zone is an ecologically important area and plays a role in the treatment and processing of organic matter and contaminants in aquatic ecosystems.
Chemical compounds that contain bicarbonate ions (HCO3-). These ions are a form of dissolved inorganic carbon (DIC) commonly found in natural water sources, and they play a significant role in the pH buffering capacity of water and in various chemical reactions that occur during wastewater treatment processes.
A measure of the amount of oxygen required by microorganisms to biologically degrade organic matter in wastewater. It is used to assess wastewater strength.
A vessel or tank where biological processes occur, such as the breakdown of organic matter by microorganisms in activated sludge.
A chemical substance or agent that is used to control, inhibit, or eliminate the growth and activity of microorganisms, including bacteria, algae, fungi, and other unwanted biological entities in wastewater. Biocides are employed to prevent biological fouling, microbial contamination, and the formation of biofilms in various components of wastewater treatment systems.
A complex and slimy matrix of microorganisms, such as bacteria, fungi, algae, and other microbial species, that attach to surfaces in water treatment systems. Biofilms can form on various components within wastewater treatment facilities, including pipes, tanks, membranes, and equipment. They can have both beneficial and detrimental effects on treatment processes, depending on the specific microbial community and conditions.
Microorganisms and biological substances that are present in wastewater and can potentially pose health risks or interfere with treatment processes. These contaminants may include bacteria, viruses, protozoa, algae, fungi, and other microorganisms.
Treatment process that combines the adsorptive capabilities of activated carbon with biological treatment methods to remove a wide range of organic and inorganic contaminants from wastewater. BAC systems are designed to harness the synergistic effects of both physical adsorption on activated carbon and biological degradation of pollutants by microorganisms.
Use of living organisms, typically aquatic organisms or microbiota, to assess the health and quality of water in natural water bodies or within wastewater treatment systems. Biomonitoring involves the observation, measurement, and analysis of biological responses and indicators as a means of evaluating water quality and the effects of environmental changes or pollution.
The nutrient-rich organic material produced as a byproduct of wastewater treatment. It can be treated and used as fertilizer or soil conditioner.
Wastewater generated from toilets and urinals in residential, commercial, and industrial buildings. It is characterized by its high organic content, which includes human waste and toilet paper, and may contain pathogens and various contaminants. Blackwater is distinct from graywater, which is wastewater from sinks, showers, baths, and laundry.
A condition or issue that can occur in filtration systems, particularly in cases where solid particles, debris, or other materials accumulate on the surface of a filtration medium, obstructing the flow of water and reducing the efficiency of the filtration process.
Specific chlorination process used to disinfect wastewater by effectively removing ammonia and organic nitrogen compounds, such as urea and amino acids. This process is commonly employed in wastewater treatment to eliminate nitrogen-containing contaminants and reduce the potential for the formation of disinfection byproducts.
The process of treating wastewater that contains high concentrations of dissolved salts, typically in the form of sodium chloride (table salt) or other salts. Brine wastewater is generated in various industrial processes, such as desalination, mining, food processing, and oil and gas production, as well as in some water softening and water purification systems. The treatment of brine wastewater is necessary to reduce its environmental impact and comply with regulatory standards.
A solution or chemical substance that helps stabilize the pH (acidity or alkalinity) of wastewater. Buffering agents are added to wastewater treatment processes to prevent rapid fluctuations in pH levels, which can have adverse effects on treatment efficiency and the environment.

The solid material that is separated from liquid during the dewatering process in various treatment methods, especially in sludge treatment. This solid material often has a higher concentration of solids and reduced moisture content compared to the initial sludge or wastewater. Cake can be further processed or disposed of in an environmentally responsible manner.
A type of filtration system that uses cylindrical filter elements, often resembling candles, to separate solid particles and impurities from liquid wastewater. Candle filters are commonly used in various industrial applications, including wastewater treatment and the filtration of liquids in processes like chemical manufacturing, food and beverage production, and pharmaceuticals.
The phenomenon in which liquids are drawn or transported through narrow capillary channels or porous materials due to the combined effects of adhesion, cohesion, and surface tension. Capillary action can play a role in various treatment processes and is particularly relevant in situations where the movement of liquid through small spaces or materials is beneficial.
Specialized filtration membranes that utilize capillary action to separate solids, contaminants, and impurities from liquids. Capillary membranes have a unique structure that includes fine, hollow fibers or tubes with narrow channels (capillaries) running through them. These membranes are commonly used in various wastewater treatment processes, including microfiltration and ultrafiltration.
Carbonate ions are a type of inorganic chemical species that can influence the water chemistry and treatment processes used in the field of wastewater treatment. Understanding the carbonate content in wastewater is important for process optimization and ensuring compliance with water quality standards.
A substance or chemical compound that has the potential to cause cancer or increase the risk of developing cancer in humans or animals when exposed to it over an extended period of time. Carcinogens can be present in industrial wastewater and other effluents, posing a significant environmental and public health concern.
A type of filtration system that utilizes replaceable filter cartridges to separate solid particles and impurities from liquid wastewater. Cartridge filters are commonly used in both industrial and domestic wastewater treatment applications.
A substance that accelerates or facilitates chemical reactions, often without being consumed in the process. Catalysts play a crucial role in various wastewater treatment processes by promoting the breakdown or transformation of contaminants and pollutants into less harmful or more easily removable forms. Catalysts are particularly important in advanced oxidation processes (AOPs) and other chemical treatment methods.
A type of drainage structure or receptacle designed to collect and control the flow of stormwater runoff, preventing flooding and directing water into the appropriate wastewater or stormwater management system. Catch basins are an essential part of urban and industrial infrastructure for managing rainfall and preventing pollution.
One of the two electrodes used in an electrochemical cell. The other electrode is called the anode. The cathode plays a crucial role in these processes by facilitating specific chemical reactions that are used to treat wastewater and remove contaminants.
A positively charged ion, specifically one that is present in the wastewater and can be involved in various chemical reactions and processes within the treatment system. Cations are ions with a net positive charge because they have lost one or more electrons.
A separation process that utilizes centrifugal force to separate solid particles and liquid from a wastewater mixture. It is a mechanical separation technique commonly employed to dewater sludge, remove suspended solids, and separate liquids from solids in various wastewater treatment applications.
A unit of measurement used to quantify the number of viable microorganisms, such as bacteria or yeast, in a given sample. CFUs are used to estimate the microbial population density in a specific volume of wastewater, sludge, or other samples in laboratory testing and research related to wastewater treatment.
Also known as a non-return valve or one-way valve, is a mechanical device used in wastewater treatment systems to control the flow of wastewater or other fluids in one direction only. Check valves allow fluids to flow in one direction while preventing backflow, which is the reverse flow of fluids in the opposite direction.
Also known as chelants or sequestrants, in the context of wastewater treatment, refer to chemical compounds that have the ability to form stable complexes or chelates with metal ions. These agents are used in wastewater treatment processes to control and mitigate the effects of metal ions, such as heavy metals, that may be present in the wastewater.
A measure of the amount of oxygen required to chemically oxidize and break down organic and inorganic substances in wastewater.
A treatment method that involves adding chemicals to wastewater to precipitate and remove specific contaminants, such as heavy metals.
Chemical compounds formed by the reaction between ammonia (NH3) and chlorine (Cl2) or chlorine derivatives (e.g., sodium hypochlorite). Chloramines are used as disinfectants in water and wastewater treatment to control microbial growth and ensure the safety of treated water.
The process of adding chlorine or chlorine-based compounds to wastewater to disinfect it and control the growth of pathogenic microorganisms. Chlorination is a common method used to ensure the safety of treated wastewater before its release into the environment or distribution to end-users.
The concentration of chlorine remaining in water after disinfection, measured to ensure the continued effectiveness of disinfection.
The clearness or transparency of the treated wastewater or effluent. It is a measure of how free the water is from suspended solids, particles, and turbidity, which can affect the visual appearance and quality of the water.
A critical chemical process that involves the addition of coagulants to wastewater to destabilize and aggregate suspended particles and colloids. The primary purpose of coagulation is to facilitate the removal of these particles from the water, making it clearer and suitable for subsequent treatment processes or discharge into the environment.
The process of merging or combining small droplets of liquid into larger droplets. Coalescence is an important phenomenon that occurs in various treatment processes to separate or remove immiscible liquids, particularly in situations where the separation of oil and water is necessary.
A group of bacteria used as indicators of water quality; their presence can indicate the possible contamination of water by fecal matter.
A numerical value or rating that indicates the level of fecal contamination in water. It is used as a measure of the microbiological quality of water and serves as an indicator of the potential presence of pathogenic microorganisms that can cause waterborne diseases.
A network of underground pipes that collect and transport domestic and industrial wastewater from various sources to a centralized wastewater treatment facility. These sewers play a crucial role in the initial collection and conveyance of wastewater for treatment and disposal.
Tiny particles or substances suspended in water that are larger than individual molecules but smaller than the particles that can be effectively removed by conventional filtration. Colloidal particles are intermediate in size between dissolved substances and larger, visible particles or solids.
A method of collecting multiple individual wastewater samples over a specified period and combining them to create a representative or composite sample. This approach is used to obtain a more accurate and representative analysis of wastewater quality over time, as opposed to relying on single grab samples taken at a single point in time.
The amount or level of a specific substance or pollutant present in wastewater. Concentration is typically expressed as the quantity of the substance per unit volume or weight of the wastewater. Monitoring and controlling the concentration of various substances in wastewater are essential for assessing water quality, ensuring compliance with regulatory standards, and optimizing treatment processes.
A physical process where water vapor in wastewater or in the air is converted into liquid water. While condensation itself is not a primary wastewater treatment method, it can be associated with various treatment processes and may have implications for water recovery and energy conservation in wastewater treatment facilities.
A measure of the water's ability to conduct an electric current. It is a critical water quality parameter used to assess the concentration of dissolved ions or salts in wastewater. Monitoring conductivity is valuable for various purposes, including process control, water quality assessment, and regulatory compliance.
The withdrawal and utilization of water from its source in a manner that does not allow for its immediate return to the same source or location. Consumptive use typically results in the loss of water from the source, as it is either used up in industrial processes, evaporated, incorporated into products, or otherwise removed from the natural water cycle.
The duration during which wastewater or a specific treatment process component comes into contact with a treatment agent, such as a chemical reagent or a physical treatment unit. Contact time is a critical parameter that affects the efficiency and effectiveness of various treatment processes in wastewater treatment plants.
Any substances or components present in wastewater that are undesirable or potentially harmful to the environment, human health, or the treatment process itself. Contaminants can encompass a wide range of pollutants, impurities, and substances that need to be removed or reduced to achieve clean and safe wastewater effluent.
Heat rejection devices that remove excess heat from industrial processes or air conditioning systems by evaporating a small portion of the recirculating water, which results in cooling the remaining water. Cooling tower wastewater treatment is essential to maintain efficient cooling tower operation, prevent scale, corrosion, and biological growth, and minimize environmental impact.
The propensity of wastewater to cause corrosion or deterioration of materials, equipment, and infrastructure that come into contact with it. Corrosive wastewater can damage pipes, tanks, pumps, valves, and other components in wastewater treatment facilities, posing operational and maintenance challenges. Managing corrosive wastewater is important to ensure the longevity and reliability of treatment infrastructure.
A filtration process that separates suspended solids, contaminants, and other particulate matter from a liquid (usually wastewater) using a specialized filtration system. Unlike conventional filtration methods where liquid passes through a stationary filter medium, cross-flow filtration involves a continuous flow of liquid parallel to the filter surface. This dynamic filtration process helps maintain the efficiency of the filtration system by preventing clogging and extending filter lifespan.

A specialized unit or process used to reduce the alkalinity of water or wastewater by removing alkaline substances, typically bicarbonates, carbonates, and hydroxides. The primary purpose of a dealkalinizer is to adjust the pH and chemical composition of water to meet specific treatment requirements, prevent scaling in downstream processes, and improve the overall effectiveness of water or wastewater treatment.
The process of separating and removing the clarified or treated water (known as effluent or supernatant) from settled solids or sludge in a settling or sedimentation tank. The purpose of decanting is to collect and discharge the treated water while leaving behind the solid particles that have settled at the bottom of the tank. This process is a critical step in wastewater treatment to ensure the quality of the effluent and to further treat or dispose of the separated solids.
A chemical or additive used to reduce or eliminate foam formation in water or wastewater. Foam can be an unwanted side effect of various treatment processes and can lead to operational issues, reduced treatment efficiency, and safety hazards. De-foaming agents work by disrupting or breaking down the surface tension of the foam, causing it to collapse or dissipate.
A process that removes ions (charged particles) from water, effectively reducing its electrical conductivity. Deionization is primarily used to produce high-purity water for various industrial, laboratory, and manufacturing applications where the presence of ions can be detrimental. It is often used in combination with other water treatment methods to achieve ultra-pure water.
A water treatment process that removes dissolved minerals and salts from water. It is primarily used to produce high-purity or deionized water for various industrial, laboratory, and manufacturing applications where the presence of minerals can be detrimental. Demineralization is achieved through a combination of ion exchange and regeneration processes.
A biological process in which nitrate (NO3-) is converted into nitrogen gas (N2) or nitrogen oxide (NO) gas, reducing the nitrogen content in wastewater.
The mass per unit volume of a substance, typically expressed in units such as kilograms per cubic meter (kg/m³) or grams per milliliter (g/mL). The density of wastewater is a fundamental physical property that plays a crucial role in various aspects of wastewater treatment and can provide valuable information about the composition and characteristics of the wastewater.
A process that removes salts and minerals from saline water, making it suitable for various purposes, including drinking water supply, irrigation, and industrial use. While desalination is commonly associated with the treatment of seawater to produce freshwater, it can also be applied to brackish water or wastewater with high salt content.
A process that involves the removal or release of contaminants, typically adsorbed or absorbed onto a solid medium or surface, such as activated carbon, soil, or filter media. The goal of desorption is to recover or regenerate the adsorbent material and to release the captured contaminants for further treatment or disposal.
The period during which water or wastewater remains within a specific treatment unit or reactor. It is a critical parameter in the design and operation of wastewater treatment processes and plays a significant role in determining the effectiveness of various treatment steps. Detention time is typically expressed in units of time, such as minutes or hours.
Chemicals or cleaning agents commonly used for household, industrial, and commercial cleaning purposes. Wastewater from these activities can contain a range of contaminants, including surfactants, grease, oils, and other pollutants, which need to be removed or treated before discharge into the environment or public sewage systems.
The process of removing water from sludge or slurry, resulting in the reduction of its volume and the production of a more solid or dry material. Dewatering is a crucial step in wastewater treatment because it reduces the volume of residual solids, making them easier and more cost-effective to handle, transport, and dispose of.
A device or system used to distribute air or oxygen into wastewater in an aeration tank or basin. The purpose of a diffuser is to introduce air or oxygen efficiently and evenly, promoting the growth of aerobic microorganisms and facilitating the biological treatment of wastewater. Diffusers are a critical component of wastewater treatment plants, especially in the activated sludge process.
The portion of rainfall, snowmelt, or other forms of precipitation that flows directly into water bodies, stormwater drains, or natural drainage systems without undergoing any form of treatment or filtration. Direct runoff carries with it various contaminants, including sediment, pollutants, and debris, and it can contribute to water pollution and erosion.
The controlled release or disposal of treated wastewater or effluent from a treatment facility into the environment or a receiving water body. Discharge is the final step in the wastewater treatment process and involves the release of treated water that should meet regulatory standards to minimize its impact on the environment and public health.
A legal document issued by regulatory authorities that outlines the conditions and limits for discharging treated wastewater into a receiving water body.
The process of killing or inactivating pathogenic microorganisms in treated wastewater before discharge. Common disinfection methods include chlorination, ultraviolet (UV) irradiation, and ozonation.
Chemical compounds formed when disinfectants, such as chlorine, react with organic and inorganic substances in water during disinfection.
A water treatment process that uses fine air bubbles to float and remove suspended particles and oils from wastewater.
The total amount of inorganic and organic materials that are dissolved in water. These materials are present in wastewater in a dissolved form, meaning they are not visible as separate particles or solids but are evenly distributed throughout the water. Dissolved solids can include a wide range of substances, such as minerals, salts, organic compounds, and other dissolved materials.
The process of removing sediments and contaminants from the bottom of water bodies, such as rivers, lakes, reservoirs, and harbors, to improve water quality, navigation, or ecosystem health. While dredging itself is not a wastewater treatment process, it is often employed to address issues related to sediment accumulation and pollution in aquatic environments.

Treated wastewater that is discharged from the treatment plant into a receiving body of water or released into the environment.
Regulatory standards that specify the maximum allowable levels of specific pollutants in wastewater discharges.
The measurement of the treated wastewater's compliance with regulatory standards and its suitability for discharge into the environment.
The practice of treating wastewater to a high standard and using it for non-potable purposes, such as irrigation or industrial processes.
A mechanical device used to create a vacuum or low-pressure zone in a system by discharging a high-velocity stream of water or air. Ejectors are employed in various aspects of wastewater treatment processes, particularly for the purpose of mixing, aeration, and enhancing the flow of wastewater and liquids within treatment systems.
An advanced water purification technology used to remove dissolved ions and impurities from water, including wastewater. It is a chemical-free process that combines ion exchange and electrical current to produce high-quality, deionized water. While it is primarily used for producing ultrapure water in industries like electronics and pharmaceuticals, it can also be employed in wastewater treatment processes to further purify treated effluent or to recover valuable ions.
A substance or chemical agent that is used to break down or disperse emulsions in wastewater. Emulsions are mixtures of immiscible liquids, such as oil and water, stabilized by the presence of emulsifying agents. Emulsifiers are employed to facilitate the separation of oil and water phases in wastewater, making it easier to treat and remove contaminants.
A stable mixture of two immiscible liquids, typically oil and water, held together by an emulsifying agent. Emulsions can be challenging to treat because the two phases (oil and water) do not naturally separate, making it difficult to remove the oil or other contaminants from the water phase. Emulsion wastewater treatment involves methods and processes designed to break the emulsion, allowing for the separation and removal of oil and other hydrophobic substances from the water phase.
A storage tank used to balance the flow of wastewater and reduce sudden surges or shock loads to the treatment system.
Also known as evaporation lagoons or evaporation basins, are a type of wastewater treatment facility designed to manage and treat liquid waste, typically industrial or municipal wastewater, through the natural process of evaporation. The main objective of evaporation ponds is to reduce the volume of liquid waste and concentrate the contaminants in the remaining sludge or solids for further treatment or disposal.
A variation of the activated sludge process characterized by longer treatment times and lower biomass concentrations, resulting in stable treatment performance.

Substances that can accumulate in wastewater systems and cause blockages. FOG removal is essential to prevent sewer system backups.
The material or substance used as the filtering component in a filtration system. The filter medium is responsible for physically removing suspended solids, contaminants, and impurities from wastewater as it passes through the filtration process. The choice of filter medium depends on the specific requirements of the treatment process and the nature of the wastewater being treated.
The liquid or effluent that passes through a filter or filtration system after the removal of suspended solids, contaminants, and particulate matter. It is the purified or clarified liquid that results from the filtration process.
A physical separation process used to remove suspended solids, particles, and impurities from wastewater or effluent. This process involves passing the wastewater through a porous medium or filter media that traps and retains the solid particles while allowing the clean liquid (filtrate) to pass through. Filtration is an essential unit operation in wastewater treatment, and it plays a key role in improving water quality and meeting regulatory standards.
The aggregation or clumping together of small, suspended particles in wastewater to form larger, settleable particles known as flocs. The formation of floc is an essential step in the process of coagulation and flocculation, which is used to remove fine suspended solids and colloidal particles from wastewater.
A separation process that uses the phenomenon of buoyancy to remove suspended or colloidal particles, fats, oils, and other substances from wastewater. It is particularly effective for the removal of small and light particles that are difficult to remove by sedimentation or other conventional methods.
The movement or transfer of wastewater through various stages and processes within a treatment facility. It encompasses the entire journey of wastewater, from its entry into the treatment plant to its final discharge or reuse. Understanding and managing the flow of wastewater is essential for efficient treatment, environmental protection, and compliance with regulatory standards.
The rate at which water or liquid passes through a filtration membrane in a membrane-based treatment process. Flux is a critical parameter in membrane filtration and separation processes, as it directly impacts the efficiency and performance of the system.
The accumulation or deposition of unwanted substances on the surface or within the pores of a filtration membrane. Fouling occurs when particles, microorganisms, organic matter, or other contaminants in the wastewater adhere to and block the membrane, reducing its permeability and efficiency.
Also known as potable water or drinking water. Impurities, contaminants, microorganisms, and other substances are removed from the water to ensure its quality meets health and regulatory standards.

A process that utilizes specially designed carbon particles to adsorb and remove various contaminants and impurities from wastewater. GAC is an effective and widely used method for treating wastewater, particularly for the removal of organic compounds, taste and odor compounds, and certain chemical contaminants.
Includes wastewater from sources such as sinks, showers, bathtubs, washing machines, and dishwashers. This treated graywater can then be reused for non-potable purposes, such as landscape irrigation, toilet flushing, and cooling systems, thereby conserving freshwater resources.
A facility or component of the wastewater treatment process that removes heavy, inorganic solids (such as sand and gravel) from the influent to prevent damage to equipment and pipelines.
The release or disposal of treated wastewater or effluent into the subsurface, where it can infiltrate into the underlying groundwater system. Groundwater discharge is a method of final disposal for treated wastewater that is often used when surface water discharge or land application is not feasible or environmentally sustainable.
The process of treating contaminated groundwater to remove pollutants and contaminants, making it safe for various uses, including drinking water supply, industrial processes, or environmental remediation. Groundwater is water that exists beneath the Earth's surface in saturated soil or rock layers known as aquifers.

The time it takes for a substance or pollutant to undergo a reduction in concentration by half due to natural decay, degradation, or transformation processes. Half-life is a common concept used to describe the persistence of pollutants in the environment and their potential for removal or attenuation through various treatment methods.
Water that contains elevated levels of dissolved minerals, particularly calcium (Ca) and magnesium (Mg) ions. Hard water can lead to various issues in industrial processes, boiler systems, and plumbing, so treatment is often necessary to mitigate these problems.
Include elements like lead, cadmium, mercury, chromium, and arsenic, are toxic at certain concentrations and can pose serious health and environmental risks if released into water bodies.
A form of water in which the hydrogen atoms have been replaced by deuterium (D2O), a stable isotope of hydrogen. Heavy water is chemically similar to regular water (H2O) but is denser due to the increased mass of deuterium.
A type of engineered containment structure designed to temporarily store wastewater before it undergoes further treatment, discharge, or other management activities. Holding ponds are also known as retention ponds, settling basins, or lagoons, and they serve various purposes in wastewater treatment and environmental management.
The average time wastewater spends in a treatment unit or system, often measured in hours. It affects the efficiency of treatment processes.
Organic compounds composed primarily of hydrogen and carbon atoms. Hydrocarbons can enter wastewater streams from various sources, including industrial processes, oil and gas production, transportation activities, and accidental spills. Effective treatment is essential to prevent the environmental and health risks associated with hydrocarbon contamination.
A condition found in natural aquatic environments. Hypoxic waters refer to areas of water bodies, such as lakes, rivers, or coastal zones, where oxygen levels have become severely depleted, resulting in low dissolved oxygen concentrations. This condition can have detrimental effects on aquatic ecosystems and is often caused by factors unrelated to wastewater treatment.

Materials or surfaces that do not allow the passage of water or other liquids. Impermeable surfaces are essential in various aspects of wastewater treatment infrastructure to prevent the escape of wastewater, contaminants, or pollutants into the surrounding environment.
A substance, parameter, or measurement used to assess the quality or characteristics of wastewater. Indicators play a crucial role in monitoring and controlling the treatment process, ensuring that treated water meets regulatory standards and is safe for discharge into the environment or for other intended uses.
The process of discharging treated or untreated wastewater into a receiving environment or system that is separate from the natural environment, such as surface waters (rivers, lakes, oceans) or groundwater. Instead, the discharge is directed into a municipal sewer system or other man-made conveyance system, which then transports the wastewater to a wastewater treatment plant for further processing.
The process of allowing wastewater to percolate or seep into the ground or a subsurface medium for treatment and disposal. Infiltration can occur naturally or be facilitated through engineered systems to treat and filter wastewater before it recharges groundwater or is further treated.
The raw, untreated wastewater that enters a treatment plant.
A coarse screen or bar rack that removes large debris and objects from raw wastewater as it enters the treatment plant.
A molecule that has an unequal number of protons and electrons, resulting in a net electrical charge. Ions can be either positively charged, known as cations, or negatively charged, known as anions, depending on whether they have more protons (for cations) or more electrons (for anions).
A process that involves the removal or exchange of ions (charged particles) from wastewater using ion exchange resins or other specialized materials. This method is effective for removing specific contaminants and adjusting the chemical composition of wastewater to meet treatment goals and regulatory requirements.

A laboratory procedure used to determine the optimal chemical dosages and treatment conditions for coagulation and flocculation processes. Coagulation and flocculation are essential steps in wastewater treatment that involve the addition of chemicals to destabilize and aggregate suspended particles, colloids, and impurities in the water, making them easier to remove through sedimentation or filtration.

The energy associated with the movement of wastewater within the treatment processes. This energy is often harnessed or controlled to facilitate various physical and chemical processes involved in treating wastewater.

Water that is used in laboratories for a variety of purposes related to the analysis, testing, and research of wastewater and water quality. Laboratory water is typically of high purity and is used to ensure accurate and reliable results in analytical procedures and experiments.
A human-made pond or basin designed to treat and stabilize wastewater through natural biological and physical processes. Lagoons are commonly used in small to medium-sized wastewater treatment systems, including municipal, industrial, and agricultural facilities. They provide a cost-effective and environmentally friendly method for treating wastewater in areas where space and resources are available.
The addition of oxygen to wastewater lagoons to promote biological treatment by enhancing the activity of aerobic microorganisms.
The smooth and orderly movement of wastewater or any fluid within a conduit or pipeline. It is characterized by fluid layers that move in parallel, with minimal mixing between adjacent layers. In laminar flow, the fluid particles follow a well-defined and predictable path, and the flow pattern is typically steady and non-turbulent.
Also known as a tube settler, slant plate clarifier, inclined plate settler, and gravity settler. It is a type of wastewater treatment equipment used for the separation of solid particles from liquid in a clarifying or sedimentation process. Lamella clarifiers are designed to increase the settling area available for particles to settle out of the wastewater, thereby improving the efficiency of the sedimentation process.
A measure used in the field of water chemistry to assess the potential for calcium carbonate (CaCO3) to either dissolve into solution (corrosion) or precipitate out of solution (scale formation) in water. It is primarily applied in the context of water treatment and is especially important for the management of water quality in swimming pools and in industrial water systems, including those used in wastewater treatment.
Wastewater that is generated when rainwater or other liquids percolate through solid waste materials, such as landfills, compost piles, or contaminated soil. As the water seeps through these materials, it picks up various contaminants, including organic matter, dissolved chemicals, heavy metals, and other pollutants. Leachate can be highly contaminated and poses a risk to the environment and public health if not properly managed and treated.
A process in which a liquid, often water, is used to extract soluble substances or components from solid materials. It is commonly used in various industrial processes, mining operations, and in agricultural practices. However, the wastewater generated during leaching processes can be contaminated with dissolved chemicals, heavy metals, or other pollutants and needs to be properly treated to prevent environmental harm.

Physical separation process used to remove suspended solids, oils, greases, and other contaminants from wastewater. This method relies on the attachment of these pollutants to air bubbles, which then rise to the surface of the water, forming a froth layer that can be skimmed off. Mechanical flotation is particularly effective in treating wastewater from various industrial processes, municipal sewage treatment, and the removal of contaminants from water bodies.
A physical component or material that is used in various treatment processes to facilitate the removal of contaminants and impurities from wastewater. These media can take different forms and serve different functions within the treatment system. The choice of media depends on the specific treatment objectives and the nature of the wastewater being treated.
A membrane-based filtration process used to separate suspended solids, bacteria, and other contaminants from wastewater. Microfiltration is one of several membrane filtration techniques, each of which uses membranes with different pore sizes to achieve specific separation objectives. In the case of microfiltration, the membranes have relatively large pores compared to other membrane types, such as ultrafiltration (UF) or nanofiltration (NF), but still small enough to effectively remove particles and microorganisms from water.
A type of water that contains minerals, trace elements, and other dissolved substances that are naturally present in the source from which it is derived. It is often considered a healthy and refreshing beverage due to its natural mineral content and potential health benefits.
Domestic and industrial wastewater generated by homes, businesses, and institutions within a municipality or urban area. The primary objective of municipal discharge wastewater treatment is to remove contaminants and pollutants from the wastewater before it is safely discharged into the environment, typically into rivers, lakes, or oceans, or to be reused for non-potable purposes like irrigation.

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The use of nanoscale materials and processes to treat and purify water, including wastewater.
The process of adjusting the pH (acidity or alkalinity) of wastewater to a level that is suitable for subsequent treatment processes or for safe discharge into the environment. Wastewater often contains acidic or alkaline compounds that can be harmful to the environment, biological treatment processes, or equipment in the treatment plant. Neutralization aims to bring the pH of the wastewater closer to a neutral range (around pH 7) to ensure effective treatment and compliance with environmental regulations.
The biological conversion of ammonia (NH3) to nitrate (NO3-) in wastewater treatment, typically accomplished through two-step microbial processes.
Water that is not suitable for human consumption or other potable (drinkable) uses. Non-potable water has undergone some level of treatment but may still contain contaminants or properties that make it unsuitable for drinking, cooking, or personal hygiene. Instead, non-potable water is typically used for various other purposes where high-quality, treated water is not required.

The presence of carbon-based compounds, primarily derived from living organisms, in the wastewater. Organic matter can take various forms in wastewater, including dissolved organic substances and suspended organic solids. These organic compounds are typically introduced into wastewater through domestic sewage, industrial processes, and agricultural runoff. Managing and removing organic matter is a crucial aspect of wastewater treatment to protect the environment and public health.
A natural process in which solvent molecules, typically water, move through a semipermeable membrane from a region of lower solute concentration to a region of higher solute concentration. This movement occurs to equalize the solute concentration on both sides of the membrane and achieve a state of equilibrium.
The point where treated or untreated wastewater is discharged from a wastewater treatment facility or a sewer system into a receiving body of water, such as a river, lake, ocean, or other watercourse. The outfall is the final destination where the treated effluent or the untreated wastewater is released into the environment.
A critical parameter used to assess the performance and efficiency of settling tanks or clarifiers within a wastewater treatment plant. It is a measurement that helps determine the effectiveness of the sedimentation process in removing suspended solids from wastewater.
A chemical reaction that involves the loss of electrons by a substance, atom, or molecule. It is one of the fundamental processes in chemistry and plays a crucial role in various natural and industrial processes. Oxidation often occurs when a substance combines with oxygen or undergoes a reaction in which it transfers electrons to another substance, which is called reduction.

Microorganisms, such as bacteria, viruses, fungi, and parasites, that can cause diseases in humans, animals, and plants. These harmful microorganisms have the ability to invade, multiply within, and disrupt the normal functioning of the host organism, leading to illness and often the spread of infection.
The movement of water through porous materials, such as soil, sand, gravel, or rock, as it infiltrates downward from the surface into the subsurface or groundwater system. This natural process is a fundamental part of the Earth's hydrological cycle and plays a critical role in replenishing underground aquifers, maintaining soil moisture, and sustaining ecosystems.
The ability of a material or medium to allow the passage or flow of water or other liquids through it. Permeability is an important property in various wastewater treatment processes, particularly in filtration, drainage, and the movement of liquids through filter media or soil. It plays a critical role in determining the efficiency of these processes.
Ensuring that wastewater treatment operations adhere to regulatory standards and conditions outlined in discharge permits.
A measure of the acidity or alkalinity of wastewater. Proper pH control is crucial for efficient treatment processes.
The process of altering the acidity or alkalinity of wastewater to optimize treatment processes or meet regulatory requirements.
A small-scale, controlled experiment or trial that is conducted to assess and evaluate the performance, feasibility, and effectiveness of a specific wastewater treatment process, technology, or equipment before full-scale implementation. Pilot testing provides valuable data and insights that help engineers, operators, and decision-makers make informed decisions about the design and operation of a wastewater treatment system.
Treated and purified water that is safe for human consumption and conforms to drinking water quality standards.
A solid material that forms in wastewater when certain dissolved or suspended substances undergo a chemical reaction and come out of solution. This solid material, known as a precipitate, can include various compounds and particles, such as salts, metals, or other contaminants that were previously dissolved or dispersed in the water. The formation of precipitates is a common process in wastewater treatment, and it is used to remove or reduce specific pollutants from the wastewater.
The initial stage of the treatment process where raw wastewater undergoes a series of preliminary treatment steps to remove or reduce large, undesirable materials and substances that can interfere with or damage downstream treatment processes. The primary purpose of pretreatment is to protect equipment, prevent clogging or damage to pipes and pumps, and ensure that the wastewater is suitable for further treatment.
A settling tank in the primary treatment stage where gravity allows suspended solids to settle and form a sludge layer.
The initial stage of wastewater treatment that involves physical processes to remove large solids and debris. This typically includes screening and sedimentation.
The water used within an industrial or manufacturing process that becomes contaminated with various substances, pollutants, or contaminants during its use. This water requires specialized treatment to remove or mitigate the contaminants before it can be safely discharged or reused. The treatment of process water is a critical aspect of industrial wastewater management to protect the environment and comply with regulatory requirements.
Treated and purified water that is produced as the final output of the treatment process. This water, often referred to as "effluent," is suitable for various uses, depending on the treatment level achieved and local regulatory standards. The goal of wastewater treatment is to transform raw or contaminated wastewater into product water that is safe for discharge into the environment or for reuse in various applications.

Mercury Nitrate solution that is commonly used in gilding.

Untreated water that enters a wastewater treatment facility or plant from various sources, such as municipal sewage, industrial discharges, stormwater runoff, or other inflows. Raw water contains a wide range of contaminants, impurities, and pollutants, and it is in its natural, untreated state. The primary purpose of wastewater treatment is to process and clean raw water to remove or reduce these contaminants and make the water safe for discharge into the environment or for other beneficial uses.
The process of reintroducing oxygen into wastewater after it has undergone various treatment stages that may have reduced its oxygen content. This reintroduction of oxygen is essential to restore adequate oxygen levels in the treated water, promoting the survival of beneficial aerobic microorganisms and maintaining the overall health of aquatic ecosystems when the treated water is discharged into natural water bodies.
Refers to a term derived from "reduction-oxidation" reactions, which are chemical processes involving the transfer of electrons between substances. Redox reactions play a significant role in various aspects of wastewater treatment, particularly in the removal of contaminants, the treatment of odorous compounds, and the control of biological processes.
The extra capacity or capability that is intentionally built into a wastewater treatment plant or system to handle variations in influent flow rates, loads, or other operational conditions. It provides a buffer or safety margin that allows the treatment facility to maintain efficient and effective treatment even during periods of peak or unexpected demand.
The handling and disposal of treated wastewater solids, including sludge and biosolids, in an environmentally responsible manner.
A mechanical device consisting of rotating discs that are partially submerged in wastewater to support the growth of microorganisms for biological treatment.
Water that has accumulated as surface runoff, often as a result of rainfall or the melting of snow or ice. Surface runoff is water that does not infiltrate into the ground but instead flows over the surface of the land and collects in natural or man-made drainage systems. In the context of wastewater treatment, run-off may refer to stormwater or other types of untreated water that need to be managed or treated to prevent pollution of the environment.

The concentration of dissolved salts, primarily sodium chloride (table salt), in water. It is typically expressed in terms of the amount of salt (in grams) dissolved in a unit volume of water (usually expressed in parts per thousand, or ppt, or as a percentage). Salinity is an important parameter in various fields, including oceanography, ecology, agriculture, and water quality assessment.
A physical process used to remove suspended solids and other impurities from wastewater. It is a widely used and effective treatment method in both municipal and industrial wastewater treatment plants. Sand filtration involves passing the wastewater through a bed of sand to trap and separate particles and contaminants, producing cleaner effluent.
The formation of mineral deposits or precipitates that can accumulate on the surfaces of equipment, pipes, and other infrastructure within the treatment system. These deposits are composed of minerals such as calcium carbonate, calcium sulfate, or iron oxides, and they can hinder the efficient operation of wastewater treatment processes.
The initial treatment process that uses screens or grates to remove large objects, debris, and trash from wastewater.
A settling tank in the secondary treatment stage where microorganisms, suspended solids, and biomass settle and separate from the treated wastewater.
The biological treatment stage that removes dissolved and suspended organic matter. Common methods include activated sludge, trickling filters, and lagoons.
A process in which suspended solids in wastewater settle to the bottom of a tank or basin due to gravity.
Materials or membranes that allow the selective passage of certain substances or molecules while blocking or restricting the passage of others. Semipermeable membranes are commonly used in various treatment processes to separate and purify water from dissolved or suspended contaminants.
The physical or chemical processes employed to remove or separate various components, contaminants, or substances from the influent wastewater. These processes aim to separate solids from liquids, remove pollutants, and improve the overall quality of the treated water. Separation is a fundamental step in the wastewater treatment process and is typically followed by additional treatment steps to further purify the water.
The suspended or particulate matter in wastewater that has the ability to settle and accumulate at the bottom of a sedimentation basin, settling tank, or clarifier when allowed to stand undisturbed. These solids are relatively large and heavy particles that can be effectively separated from the liquid phase through the process of sedimentation.
The physical process by which suspended solids or particles in wastewater settle and separate from the liquid phase due to the force of gravity. This process is used to remove solid materials, such as sand, silt, and organic matter, from the wastewater, resulting in the formation of a settled sludge or sediment at the bottom of a sedimentation basin, clarifier, or settling tank.
A type of wastewater treatment equipment used for the separation and removal of suspended solids and particulate matter from liquid. It employs a series of inclined plates or lamellae, which are set at an angle within a tank or basin.
The solid waste material generated during wastewater treatment. It may be further processed or disposed of, often through dewatering, incineration, or landfilling.
The process of reducing the moisture content of sludge to make it more manageable for disposal. Methods include centrifugation, belt presses, and drying beds.
The biological process that stabilizes and reduces the volume of sewage sludge, producing methane gas and a more stable material for disposal or reuse.
The process of properly managing and disposing of the residual sludge generated during wastewater treatment.
Water that contains low concentrations of dissolved minerals, particularly calcium and magnesium ions. It is the opposite of hard water, which contains higher levels of these minerals. The term "soft" in this context refers to the water's reduced ability to form scale or soap scum and its tendency to lather more readily with soap.
The process of reducing the hardness of water by removing or reducing the concentration of calcium (Ca2+) and magnesium (Mg2+) ions. This is typically achieved through a chemical process called "lime softening" or "chemical softening," which involves the addition of chemicals to the water to precipitate and remove these hardness ions.
The maximum amount of a substance (usually a solid) that can dissolve in a given solvent (usually a liquid) at a specific temperature and pressure to form a homogeneous solution. It is a fundamental property of substances and plays a critical role in various chemical and physical processes.
A device or system used to introduce air or other gases into the liquid wastewater. The primary purpose of a sparger in this context is to provide aeration to the wastewater, which is essential for various treatment processes, particularly in the biological treatment of sewage and industrial wastewaters.
Wastewater treatment ponds that use natural processes, such as sunlight and microbial activity, to treat wastewater.
Named after the British scientist Sir George Gabriel Stokes, is a fundamental equation used in fluid dynamics to describe the drag force experienced by small spherical particles as they settle through a viscous fluid (such as water) under the influence of gravity. In wastewater treatment, Stokes' Law is often applied to estimate the settling velocity of solid particles, such as sediment or sludge particles, in sedimentation tanks or clarifiers.
Any natural water source found on the Earth's surface, such as rivers, lakes, reservoirs, ponds, streams, and wetlands. It is in contrast to groundwater, which is water that is located beneath the Earth's surface in underground aquifers. Surface water is a critical component of the Earth's hydrological cycle and plays a vital role in supporting ecosystems, providing drinking water, irrigation, industrial processes, and recreational activities.
Tiny solid particles or materials that are suspended or floating within the liquid wastewater. These solids are typically made up of a variety of organic and inorganic substances and are a key parameter in assessing the quality of wastewater. The measurement and removal of suspended solids are essential components of wastewater treatment processes.

An advanced treatment stage that further refines the effluent to remove nutrients (nitrogen and phosphorus) and other contaminants. Methods may include filtration, chemical precipitation, or advanced oxidation processes.
A pretreatment process that uses heat and pressure to break down organic matter in sludge, enhancing its digestibility.
A laboratory analytical technique used to determine the concentration of specific chemical substances or parameters in wastewater samples. It involves the controlled addition of a reagent of known concentration (called a titrant) to the wastewater sample until a chemical reaction reaches its endpoint. The endpoint is typically indicated by a change in color, pH, or other observable properties, and it signifies that the reaction has completed and the titration is balanced.
The total amount of inorganic and organic substances that are dissolved in water. TDS includes a wide range of dissolved materials, such as ions, minerals, salts, metals, and organic compounds, that are present in wastewater in a dissolved form. The measurement of TDS is a key parameter in assessing the quality of wastewater and the effectiveness of treatment processes.
The total content of both suspended solids and dissolved solids present in a given volume of wastewater. It is a critical parameter used to evaluate the overall concentration of solid materials in wastewater and is essential for assessing the effectiveness of wastewater treatment processes and compliance with regulatory standards.
Often referred to as a "wastewater treatment plant" or "sewage treatment plant," is a specialized facility designed to treat and process wastewater from various sources, such as domestic, industrial, and commercial sources. The primary purpose of a wastewater treatment plant is to remove contaminants, pollutants, and impurities from the wastewater to produce treated water that can be safely discharged into the environment or reused for specific purposes. These facilities play a crucial role in protecting public health, safeguarding the environment, and ensuring the responsible management of water resources.
A type of biological treatment system in which wastewater is distributed over a bed of rocks or plastic media, allowing microorganisms to attach and treat the wastewater as it trickles over the media.
Inclined, closely spaced, parallel tubes or channels that are installed in sedimentation or clarifier tanks to enhance the settling and separation of solid particles from liquid wastewater. These tube settlers are designed to increase the effective settling area within the tank, improve sedimentation efficiency, and reduce the retention time required for the clarification of wastewater.
The cloudiness or haziness of wastewater due to the presence of suspended particles or solids that scatter and absorb light. It is a key water quality parameter that is used to assess the clarity and cleanliness of wastewater. High levels of turbidity can indicate the presence of suspended solids, colloidal particles, or other contaminants in the wastewater and may be a cause for concern in terms of water quality and treatment efficiency.

The use of ultrasonic waves to clean equipment, membranes, or surfaces in wastewater treatment processes.

The measure of a liquid's resistance to flow. It quantifies the thickness or internal friction of the wastewater, indicating how easily it flows through pipes, channels, or treatment processes. Viscosity is an important property to consider in wastewater treatment as it can impact the efficiency of various unit operations and processes within a treatment plant.
Organic compounds that can readily evaporate into the air and may be present in industrial wastewater streams.

Also known as sewage or effluent, is water that has been used and contaminated by human activities, industrial processes, or natural processes, rendering it unsuitable for immediate use or release into the environment without proper treatment and purification. It is water that contains various pollutants, contaminants, and substances that can be harmful to the environment, human health, and aquatic life.
Measurable characteristics of water, including temperature, turbidity, dissolved oxygen, and various chemical concentrations, used to assess water quality.
Also known as water reuse or reclaimed water, is the process of treating and purifying wastewater to make it suitable for a specific beneficial use rather than discharging it into the environment or a natural water body. This practice helps conserve water resources, reduce the demand on freshwater sources, and mitigate environmental pollution. Water recycling is an important strategy for sustainable water management in various sectors.
A simple and common hydraulic structure used to control the flow of water or wastewater in open channels, such as rivers, streams, or open channels within a wastewater treatment plant. Weirs are designed to measure and regulate the flow rate, allow for the collection of samples, and facilitate the removal of floating debris or solids from the water. They are an essential component of various wastewater treatment processes, including primary and secondary sedimentation, and play a role in maintaining proper water levels and controlling the hydraulic characteristics of treatment units.
A component of a flow measurement and control system that incorporates a weir structure into a specially designed box or enclosure such as a slant plate clarifier. Weir boxes are used to accurately measure and control the flow of water or wastewater in open channels, typically in wastewater treatment plants. They provide a controlled environment for flow measurement, allowing for accurate monitoring and sampling of wastewater flows.

Absolute Filtration

Absorption

Acid Aerosol

Acid Neutralizing Capacity

Acid Rain

Acid Water

Acidity

Activated Carbon

Activated Carbon Adsorption

Activated Sludge

Adsorption

Advanced Oxidation Process

Aerated Lagoon

Aeration Basin

Aeration

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Agglomeration

Aggressive Water

Algae Pond

Aliquot

Alkalinity

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Anaerobic Digestion

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Aqueous

Aquifer

Aromatics

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Assimilative Capacity

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Back Flow

Back Pressure

Back Siphonage

Back Washing

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Bed Load

Benthic Zone

Bicarbonates

Biochemical Oxygen Demand (BOD)

Biochemical Reactor

Biocide

Biofilm

Biological Contaminants

Biologically Activated Carbon

Biomonitoring

Biosolids

Blackwater

Blinding

Breakpoint Chlorination

Brine

Buffer

Cake

Candle Filter

Capillary Action

Capillary Membranes

Carbonates

Carcinogen

Cartridge Filter

Catalyst

Catch Basin

Cathode

Cation

Centrifugation

Colony-Forming Unit (CFU)

Check Valve

Chelating Agent

Chemical Oxygen Demand (COD)

Chemical Precipitation

Chloramines

Chlorination

Chlorine Residual

Clarity

Coagulation

Coalescence

Coliform Bacteria