This is a modeling construct. All classes defined in the watr ontology are instances of `watr:Class`.
A `Class` must be associated with at least one label using the relation `rdfs:label`.
A unit process is a specific type of water treatment process that can be applied to water.
A `Unit Process` must be associated with at least one water treatment process using the relation `watr:hasProcess`.
A tank where water is aerated to remove gases and volatile organic compounds
Instances of AerationBasin must have the Aeration process.
Instances of AerationBasin must have the aerobic role.
A container to promote decomposition of organic waste in aerobic conditions
Instances of AerobicDigester must have the AerobicDigestion process.
A container to promote decomposition of organic waste in anaerobic conditions
Instances of AnaerobicDigester must have the AnaerobicDigestion process.
An electrode where oxidation occurs, often a sacrificial component in electrocoagulation.
A valve which operates using a spherical ball with a hole (also known as a bore) through the middle.
A device that stores energy for later use
A dewatering unit that uses a belt system to separate solids from liquids
Instances of BeltFilterPress must have the Filtration process.
A filter that uses biological processes to remove contaminants.
Instances of BiologicalAeratedFilter must have the BiologicallyActiveFiltration process.
Instances of Boiler must have the Incineration process.
A quarter-turn rotary valve used to isolate, start, stop, or regulate the flow of fluids
A filter system using a cartridge to remove contaminants from fluids
A dewatering unit that uses centrifugal force to separate solids from liquids
Instances of CentrifugalDewateringUnit must have the Centrifugation process.
A thickener that uses centrifugal force to separate solids from liquids
Instances of CentrifugalThickener must have the Centrifugation process.
A valve that normally allows fluid (liquid or gas) to flow through it in only one direction
A unit that uses chlorine or chlorine compounds for disinfection.
Instances of ChlorinationUnit must have the Chlorination process.
A basin where coagulation occurs to destabilize particles in water
Instances of CoagulationBasin must have the Coagulation process.
An equipment that produces both electricity and heat from the same energy source
Instances of Cogenerator must have the Cogeneration process.
An equipment that increases the pressure of a gas
A device used to condense a gaseous substance back into a liquid
Instances of Condenser must have the Condensation process.
An equipment used to prepare raw biogas from a digester by removing impurities
A sensor used to measure the electrical conductivity of a solution
A reactor in which contents are well mixed and reactants are added continuously
A piece of equipment for regulation of a system or component in normal operation, which executes one or more `Function`s.
An equipment used to produce solid crystals from a solution
Instances of Crystallizer must have the Crystallization process.
A system designed to recover a high percentage of Dimethyl Ether solvent in solvent-driven processes.
A thickener that uses dissolved air to separate solids from liquids
Instances of DissolvedAirFlotationThickener must have the Flotation process.
A sensor used to measure the efficiency of a system or equipment
A membrane capable of conducting electricity, used for in-situ cleaning or electro-oxidation processes.
A modular system designed for brine concentration and crystallization, integrating electrodialysis and crystallization.
Instances of ElectroDialyticCrystallizer must have the Crystallization process.
Instances of ElectroDialyticCrystallizer must have the Electrodialysis process.
A unit that uses electrocoagulation for contaminant removal.
Instances of ElectrocoagulationUnit must have the Electrocoagulation process.
A unit that uses electricity to drive ion movement through a membrane
Instances of ElectrodialysisUnit must have the Electrodialysis process.
An equipment that uses electricity to split liquids into constituent elements
Instances of Electrolyzer must have the Electrolysis process.
A device that generates an electromagnetic field, used as a pretreatment method for membrane scaling and fouling control.
This EnumerationKind describes methods of data processing, aggregation, or imputation
A device used to turn the liquid form of a substance into its gaseous form
Instances of Evaporator must have the Evaporation process.
A tank where flocculation occurs to aggregate particles in water
Instances of FlocculationBasin must have the Flocculation process.
A sensor used to measure the flow rate of liquids or gases
A sensor used to measure the frequency of a signal or mechanical vibration
A linear-motion valve primarily used for stopping, starting, and regulating (throttling) fluid flow
Granular Activated Carbon (GAC) Adsorber
A unit that uses granulated activated carbon to adsorb impurities from water.
Instances of GranulatedActivatedCarbonAdsorber must have the GranularActivatedCarbon process.
A thickener that combines gravity separation with a belt system
Machine that shreds solid waste into tiny particles
Instances of Grinder must have the Comminution process.
A chamber used to remove grit from wastewater
Instances of GritChamber must have the Sedimentation process.
A sedimentation tank specifically designed for septic treatment
A membrane that selectively allows ions to pass through while blocking other substances
Instances of IonExchangeMembrane must have the IonExchange process.
A sensor used to detect the level of liquids or solids in a tank
A location where manual measurements are taken
A reactor that grows biofilm on membranes supplied with air
Instances of MembraneAeratedBiofilmReactor must have the Aeration process.
A filter system that combines a membrane process like microfiltration with a biological reactor
Instances of MembraneBioreactor must have either the Microfiltration or Ultrafiltration process.
Instances of MembraneBioreactor must have the Biofiltration process.
A filter system which removes contaminants from a liquid by passing it through a microporous membrane
Instances of MicrofiltrationUnit must have the Microfiltration process.
A tank where mixed liquor is stirred without aeration
Instances of MixingBasin must have the Mixing process.
Instances of MixingBasin must have the anoxic or anaerobic role.
Molybdenum Sulfide (MoS2)-based Membrane
A specific material demonstrating effectiveness in removing heavy metals and oxyanions with high selectivity.
MBBR process using suspended growth media a tank
Instances of MovingBedBioreactor must have the Biofiltration process.
A membrane integrating multiple processes (e.g., reduction, adsorption, filtration) for selective removal and recovery of contaminants.
A filter system that uses a membrane to soften water and remove organic contaminants
Modified activated sludge process that uses a ring-shaped channel to biologically remove pollutants
Instances of OxidationDitch must have the ActivatedSludge process.
A sensor used to measure Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD)
A sensor used to measure the concentration of oxygen
A unit that uses ozone for water treatment.
Instances of OzonationUnit must have the Ozonation process.
A type of reactor where the fluid flows in one direction through the tube
A plug flow reactor has at least one inlet fluid connection point
A plug flow reactor has at least one outlet fluid connection point
A valve with cylindrical or conically tapered plugs which can be rotated inside the valve body to control flow through the valve
A body of still water smaller than a lake, used for treatment or storage.
A device used to transfer pressure energy from one fluid to another
A device used to move fluids by mechanical action
A type of media filter that uses sand as the filter medium and operates at high filtration rates.
Instances of RapidSandFilter must have the RapidSandFiltration process.
A large natural or artificial body of water used for water supply
Instances of ReverseOsmosisMembrane must have the ReverseOsmosis process.
A thickener that uses a rotating drum to separate solids from liquids
Instances of RotaryDrumThickener must have the Filtration process.
Fixed-film process using a slowly rotating discs partially submerged in a tank
Instances of RotatingBiologicalContactor must have the Biofiltration process.
A sensor used to measure the rotational speed or position of an object
Instances of Screen must have the Screening process.
A type of activated sludge process for wastewater treatment
A SBR has at least 1 sludge return point
Instances of SequencingBatchReactor must have the ActivatedSludge process.
A SBR has at least 1 inlet fluid connection point
A SBR has at least 1 outlet fluid connection point
A SBR has at least 1 bidirectional fluid connection point
Large gate that slide vertically to control flow in channels, reservoirs, or treatment basins
A system that uses a solvent to selectively extract water from highly saline brines.
Instances of SolventExtractionSystem must have the SolventExtraction process.
A sensor used to measure the speed of an object or fluid
An experimental apparatus developed for research experiments, for example in Electrocoagulation (EC), in continuous flow mode.
A sensor used to measure the remaining charge in a battery or energy storage system
A device for mixing liquids without moving components
Instances of StaticMixer must have the Mixing process.
A valve that features three ports (connections)
A sensor used to measure the total organic compound concentration
A filter system that treats wastewater by trickling it over a bed of rocks or plastic
Instances of TricklingFilter must have the TricklingFiltration process.
A sensor used to measure the turbidity (clarity) of a fluid
A specific reactor used in Advanced Oxidation Processes (AOPs) combining UV light with hydrogen peroxide.
Instances of UVH2O2Reactor must have the AdvancedOxidation process.
A filter system that uses a pressure-driven barrier to separate particles and solutes in a fluid
Instances of UltrafiltrationUnit must have the Ultrafiltration process.
A unit using ultraviolet light for disinfection
Instances of UltravioletLightUnit must have the UVDisinfection process.
A device that regulates, directs or controls the flow of a fluid (gases or liquids) by opening, closing, or partially obstructing various passageways.
A type of AC motor drive that controls speed and torque by varying the frequency of the input electricity.
A sensor used to measure the volume of a substance
A marsh or bog-like area that is permanently or seasonally saturated with water, used for pre- or post-treatment.
A sensor used to measure the pH of a solution
An ontology for enumerationkinds used in the NAWI project
An ontology for water equipment used in the NAWI project
An ontology for water substances used in the NAWI project
Total uncertainty multiplied by coverage factor
Ratio of measured to known value (for spike/recovery tests)
Coefficient of determination for calibration curves
Combined standard uncertainty from all sources
Arithmetic mean (average) of data points
Most frequently occurring value in data points
Difference between maximum and minimum values
The associated property represents a count over an aggregation scope.
The associated property represents the maximum value over an aggregation scope.
The associated property represents the arithmetic mean over an aggregation scope.
The associated property represents the median value over an aggregation scope.
The associated property represents the minimum value over an aggregation scope.
The associated property represents the most frequently occurring value over an aggregation scope.
The associated property represents the percentile value over an aggregation scope.
The associated property represents the difference between maximum and minimum over an aggregation scope.
The associated property represents the standard deviation over an aggregation scope.
The associated property represents the sum over an aggregation scope.
The associated property represents the total amount of the characterized quantity or substance.
The associated property represents the variance over an aggregation scope.
A thickener that uses a belt system to separate solids from liquids
Instances of BeltThickener must have the Filtration process.
Aluminum sulfate (alum), a common coagulant
Ferric chloride, a coagulant for wastewater treatment
Polyaluminum chloride (PAC), a coagulant
Ammonia present as a dissolved nitrogen-bearing constituent of a treatment medium.
Bacteria: Microscopic single-celled organisms that can be found in water
Cyanide: A highly toxic chemical compound that can be harmful to aquatic life
Molecular oxygen dissolved in a treatment medium.
Inorganic carbon species present as constituents of a treatment medium.
Inorganic chemical matter present as a constituent of a treatment medium.
Nitrate present as an oxidized nitrogen-bearing constituent of a treatment medium.
Nitrite present as an intermediate nitrogen-bearing constituent of a treatment medium.
Nitrogen oxide species present as constituents of a treatment medium, including gaseous or dissolved forms.
Organic carbon present as a constituent of a treatment medium.
Parent class for filtering methods to remove outliers or unwanted data points
Absolute difference between measured and true/reference value
Systematic deviation from true value (trueness measure)
Average of absolute errors across multiple measurements
Error expressed as a percentage of the true/reference value
Square root of MSE, in same units as measurements
Tool to control water flow and isolate sections
A thickener that uses gravity to separate solids from liquids
Instances of GravityThickener must have the Sedimentation process.
Sodium sulfide, used to precipitate heavy metals
Class for high purity oxygen used in wastewater treatment
Propagate next valid observation backward to fill gaps
Propagate last valid observation forward to fill gaps
Linear interpolation between two adjacent data points
Use the value of the nearest known data point
Polynomial interpolation using multiple data points
Cubic spline interpolation for smooth curves
A filter system that uses a bed of material to filter out contaminants
Instances of MediaFiltrationUnit must have the MediaFiltration process.
Normalize by moving the decimal point of values
Scale data to a fixed range, typically [0, 1]
Standardize data to have mean=0 and standard deviation=1
Hydrogen peroxide, an oxidizing agent commonly used in advanced oxidation processes
Ratio of standard deviation to mean (relative precision)
Range within which true value likely falls with specified confidence level
Standard deviation under repeatability conditions (same operator, equipment, short time)
Standard deviation under reproducibility conditions (different operators, equipment, time)
A cleaning process that uses injected air to dislodge accumulated foulants or solids from filter media or membrane surfaces.
A cleaning process in which water, and sometimes air, is driven backward through a filter or membrane system to remove accumulated solids.
Removal of nutrients or metals using coagulants
A specific RO configuration explored for optimization, capable of adapting to unmeasured changes like feed salinity.
Biological degradation of organic materials under controlled aerobic conditions.
A post-disinfection process that removes excess chlorine compounds.
Drying of biosolids to reduce moisture content.
A novel integrated process combining electrodialysis and crystallization for energy-efficient Zero-Liquid Discharge (ZLD) by maintaining a saturated brine stream.
An advanced oxidation process often combined with EC to enhance contaminant removal and inactivation, particularly for viruses.
A process that uses a stream of fluid flowing upward to separate a mixture of particles based on their size, shape, and density.
A dynamic and cyclic design to mitigate scaling and balance salt/foulant load, enabling high recovery.
Five-Stage BARDENPHO (BARnard DENitrification and PHOsphorus removal)
A five-stage biological nutrient removal process specifically designed for nitrogen and phosphorus.
A process that combusts a constantly moving bed of biosolids.
Four-Stage BARDENPHO (BARnard DENitrification and PHOsphorus removal)
A four-stage biological nutrient removal process with two anoxic and two aerobic zones.
A method for treating acid mine drainage involving neutralization.
Beneficial reuse of biosolids by spreading on agricultural land.
Modification of AO a with internal recycle.
A thermal membrane process, often subject to CFD modeling for optimization of heat and mass transfer.
A process that combusts biosolids as they move through a series of stacked hearths with controlled air flow.
pH adjustment to neutral, typically with a base, used in processes like high-density sludge treatment.
Osmotically Assisted Reverse Osmosis (OARO)
A process with validated Computational Fluid Dynamics (CFD) models for cost optimization.
A process that flushes retained liquid, solids, or gas from equipment or piping to restore operating conditions or prepare for another cycle.
A process that returns a portion of a treated or intermediate flow back upstream to maintain hydraulic, solids, or biological performance.
Mechanism by which contaminants are transformed through the gain of electrons.
A filtration process that uses a bed of sand to remove impurities at low flow rates.
Chemical precipitation of calcium/magnesium
Gas stripping for removal of dissolved gases such as ammonia and volatile organic compounds.
Heat-based pathogen inactivation such as pasteurization.
A process that breaks down complex organic matter into soluble compounds using heat and pressure.
Variant of A2O with modified recycle streams for phosphorus removal.
Class for reducing agents used in water treatment
Solids handling (e.g., biosolids disposal)
A tank used to remove solids from liquids through sedimentation
Instances of SedimentationTank must have the Sedimentation process.
A septic tank for on-site wastewater treatment
Mixed liquor is the mixture of wastewater and activated sludge in the aeration basin of a wastewater treatment plant. It contains suspended solids and water.
Decrease the sampling frequency of data to a lower rate
Resample data to a different frequency or time interval
Align data points from different sources to common timestamps
Increase the sampling frequency of data to a higher rate
The `hasAccuracy` relation is used to link to a numerical `Property` whose value indicates the maximum expected deviation between the measured value and the true value in engineering units.
The `hasAggregation` relation associates a property with water-specific aggregation semantics such as total, mean, maximum, or minimum.
The `hasBias` relation is used to link to a numerical `Property` whose value indicates the systematic offset or drift in measurements relative to the true value.
The `hasCalibrationCurve` relation is used to link to a `Property` that describes the mathematical relationship or lookup table between raw sensor output and calibrated engineering units.
The `hasDropRate` relation is used to link to a `Property` describes the amount of data points lost within a range of time due to latencies or other factors.
The `hasNumericRange` relation is used to link to a numerical `Property` whose value indicates the span between the minimum and maximum measurable values in engineering units.
The `hasNumericResolution` relation is used to link to a numerical `Property` whose value indicates the smallest distinguishable difference between two measured values in engineering units.
The `hasPrecision` relation is used to link to a numerical `Property` whose value indicates the repeatability or reproducibility of measurements under identical conditions.
The `hasProcessedData` relation is used to link to a `Property` that describes any data processing, filtering, or transformation applied to the raw measurement values.
The `hasResponseTime` relation is used to link to a numerical `Property` whose value indicates the time required for the sensor or measurement system to respond to a step change in the measured variable.
The `hasTemporalRange` relation is used to link to a numerical `Property` whose value indicates the start and end times for which data has been recorded.
The `hasTemporalResolution` relation is used to link to a numerical `Property` whose value indicates the minimum time interval between successive measurements or data points.
The `hasVariableRange` relation is used to link to a numerical `Property` whose value indicates the expected range of variation for the measured variable under normal operating conditions.
Calcium hydroxide (lime), used to increase pH
A sensor used to measure the concentration of specific substances (e.g., Total Dissolved Solids)
Organic chemical matter present as a constituent of a treatment medium.
Particulate matter present as a constituent of a medium.
Solid particulate matter suspended in water rather than dissolved, including organic and inorganic material carried in the fluid.
A unit used to remove water from solid material
Instances of DewateringUnit must have the Dewatering process.
A container to promote decomposition of organic waste
Instances of Digester must have the Digestion process.
A unit used to eliminate or reduce harmful microorganisms
Instances of DisinfectionUnit must have the Disinfection process.
A component where electrochemical reactions occur in electrified processes.
Class for flocculants used in wastewater treatment
Class for chemicals used to remove heavy metals
Class for chemicals used for odor control
Class for oxidizing agents used in water treatment
Anaerobic-anoxic-aerobic process for simultaneous biological nitrogen and phosphorus removal.
Two-stage process with anoxic zone followed by aerobic zone for biological nitrogen removal.
A process by which substances bind to a surface.
Processes combining UV light with oxidants (e.g., UV-AOP) to destroy contaminants.
A biological process that breaks down organic matter in the presence of oxygen.
A biological process that breaks down organic matter in the absence of oxygen.
A biologically activated filtration column.
A disinfection process that uses chlorine or chlorine compounds.
A process that combusts biosolids or biogas to produce electricity and heat simultaneously.
Process of reducing solid materials into smaller particles through mechanical forces such as crushing, grinding, impact, shear, or compression.
A process of turning a vapor into a liquid.
An electrified pretreatment technology using sacrificial anodes to release coagulant precursors for contaminant removal.
A process that uses a direct electric current to drive an otherwise non-spontaneous chemical reaction.
A unit process that gently mixes water to allow coagulated particles to form larger clumps.
A unit process that uses buoyancy to separate solids from water, often using air bubbles.
A unit process that transfers gases, such as oxygen or carbon dioxide, into or out of water.
A process that uses an activated carbon filter to adsorb impurities from water.
A process reaction in which a water molecule is consumed to split a larger molecule into smaller fragments.
A process in which ions are exchanged between a solution and an ion-exchange resin or membrane.
A water treatment process that uses ozone as an oxidant.
A filtration process that uses a bed of sand to remove impurities at high flow rates.
A unit process that removes large solids from water, such as leaves, branches, and other debris.
A process of turning a liquid into a solid (e.g., freezing).
A non-membrane, non-thermal method using a solvent to selectively extract water from highly saline brines.
A process to increase the solids content of a sludge or slurry.
Trickling filter using any media (e.g., plastic, sand, gravel, etc.)
A disinfection process that uses ultraviolet light to inactivate microorganisms.
A unit process that adjusts the pH of water to a desired level using chemicals.
A tank with at least one inlet and one outlet
A tank may have a drain connection point
A tank may have an overflow connection point
A tank has an inlet fluid connection point
A tank has an outlet fluid connection point
The `hasMeasurementRange` relation is used to link to a numerical `Property` whose value indicates the expected range of variation that can physically be measured, e.g. by a sensor.
Solid material present as a constituent of a treatment medium.
Class for disinfectants used in wastewater treatment
A semi-solid slurry composed of water and solids.
A unit process that aerates (i.e., transfers oxygen into water).
A process that uses centrifugal force to separate substances of different densities.
A unit process that adds chemicals to water to cause small particles to clump together.
A process to remove or separate water from another material, typically solids.
A process of turning a liquid into a vapor.
A process that uses a semi-permeable membrane to separate substances.
A tank that has at least two outlets (e.g. overflow and underflow)
Instances of SeparationTank must have the Separation process.
A separation tank has at least two outlet connection points
Class for pH adjusters used in wastewater treatment
Class for coagulants used in wastewater treatment
Parent class for normalization methods to scale data to a standard range
A human-readable label for the process type.
A human-readable definition of the process type.
Generic process for unspecified disposal of biosolids (e.g., incineration, land application, landfilling, etc.).
Addition of chemicals, such as coagulant, polymer, disinfectant, etc.
A maintenance-oriented process that removes accumulated solids, foulants, or residual materials from water treatment equipment.
A process that combusts biosolids or biogas.
A process of forming solid crystals from a solution.
A biological process that breaks down organic matter over a long duration in a tank.
A process that uses ion-exchange membranes and an electric potential to separate ions from water.
A filtration process that uses a bed of media (as opposed to a membrane-based process).
A unit process that mixes water with chemicals or other substances to achieve a desired effect.
A unit process that adds oxidizing agents to water to remove contaminants or improve water quality.
A unit process that allows solids to settle out of water by gravity.
Combined accuracy measures (precision and trueness)
Metrics for precision and repeatability measurements
Parent class for synchronization methods to align data from multiple sources to common time intervals
Process by which nitrate is deoxidized to nitrogen gas and nitrogen oxides.
Process by which ammonia is oxidized to nitrite and subsequently nitrate.
A core membrane separation process for desalination and advanced purification.
A device used to increase the solids concentration of a slurry
Instances of Thickener must have the Thickening process.
A filtration method that uses biological processes to remove contaminants.
A unit process that utilizes biological activity for water treatment.
A unit process that uses chemicals or other methods to kill or inactivate harmful microorganisms in water.
Parent class for interpolation methods to estimate values between known data points
Aerobic suspended-growth biological treatment
Parent class for error and uncertainty measurements
The most generic process for separation of any two constituents.
Base class for all chemicals used in wastewater treatment
The `hasMeasurementRange` relation is used to link to a numerical `Property` whose value indicates the maximum or minimum that can physically be measured, e.g. by a sensor.
Parent class for aggregation functions that combine multiple data points
A unit process that removes smaller particles from water by passing it through a filter.
EnumerationKind for aggregation semantics carried by a property, such as total, mean, maximum, or minimum.
An equipment used to remove impurities from liquids or gases
Instances of Filter must have the Filtration process.
A unit process that involves the addition of chemicals to water to achieve a desired effect.
A tank used for reaction or biological/chemical treatment processes
A reactor may have recirculation or return connection points
The `hasNumericRange` relation is used to link to a numerical `Property` whose value indicates the span between the minimum and maximum measured values.
If present, `hasAggregation` associates a quantifiable property with one aggregation semantics such as total, mean, maximum, or minimum.
The `hasVariableRange` relation is used to link to a numerical `Property` whose value indicates the maximum or minimum for the measured variable during normal operation.
A unit process that relies on physical forces to separate or treat water.
This property is used to associate a water treatment process with a piece of equipment.