Sensors are the foundation of water treatment control systems. They are what originally convert physical parameters from equipment and processes into digital information that machines and people can use. Put simply, water treatment plant control without sensors is a non-starter. Period. To understand what can be monitored, controlled, or automated in a water treatment plant, many are asking the question: What types of sensors are used in water treatment control plants?
This article explores the types of sensors operators use today in the average wastewater treatment plant with a specific focus on the following components:
Types of sensors used for water quality in wastewater treatment
Water quality is the business of water treatment plants, but it’s not just the final product that water treatment operators care about. Water quality must be measured and controlled throughout the entire treatment process. That’s where water quality sensors come in.
Water quality is a critical parameter in many wastewater treatment processes.
These are the types of sensors most commonly used to measure water quality in wastewater treatment.
Measure how acidic or alkaline water is
Oxidation-reduction potential (ORP) sensors
Measure the ability to oxidize or reduce a substance
Measure water clarity
Total suspended solids (TSS) sensors
Measure the amount of silt, sediment, and substances suspended in water
Dissolved oxygen (DO) sensors
Measure oxygen levels dissolved in water
Chemical oxygen demand (COD) sensors
Measure oxygen levels in water for use in chemical treatment reactions
Biological oxygen demand (BOD) sensors
Measure oxygen levels in water for use by bacteria in treatment processes
Ultraviolet (UV) detection sections
Measure the absorption of light as a corollary for the presence of organic matter
Substance detection sections
Measure the presence of molecules such as nitrogen, phosphorous, and chlorine
Each of these sensors is used in various processes within water treatment plant controls to monitor water quality during each process.
Process controls instrumentation in wastewater treatment
Process controls instrumentation is a critical element of any wastewater treatment plant control system. As the name implies, process controls instrumentation in wastewater treatment monitors parameters of the particular treatment processes. “Process” in this context means the fluid dynamics process whereby water gets transported through vessels, pumps, and pipes for different treatment phases. Process instrumentation is crucial for calculating system efficiency and for assuring that necessary treatment processes can occur. Put simply, process instrumentation lets people know if water isn’t getting where it needs to go on time and at a reasonable cost.
Process controls instrumentation involves measuring level, temperature, pressure, and flow.
The core sensors used in process controls instrumentation for wastewater treatment are:
Measure levels of water, other liquids, and solids in various holding tanks
Measure pressures in piping and pressure vessels
Measure water temperature, equipment temperatures, and other temperatures
Measure the flow rates of water and additives through piping
Each of these can describe a critical variable that helps water treatment plant control operators monitor and maintain dynamic fluid properties, keeping wastewater treatment schedules on track.
Types of sensors used to monitor water pump diagnostics
Without pumps, liquids don’t move. If pumps go offline, wastewater treatment plants lose the capacity to treat water, which means raw sewage discharges into surface water, at best, and people get sick, at worst.
Other types of wastewater treatment plant control sensors
In addition to sensors used for water quality, process controls instrumentation, and pump diagnostics, sensors are used to monitor various other processes in wastewater treatment. This can include electrical and power systems, backup generator systems, safety systems, and more. Here are some example sensors in other wastewater treatment plant controls processes.
Electrical Substations and Systems
Wastewater treatment plants consume a lot of power, and not just from pumps. Electricity is critical to keeping water treatment plants online. Here are some of the sensors used to monitor electrical systems in water treatment plants:
Measure current consumed at the electrical panel
Load balancing diagnostic sensors
Measure diagnostics of load balancing equipment
Measure diagnostics of capacitor banks
Power conditioning sensors
Measure diagnostics of power conditioning equipment
Backup diesel generators should be constantly monitored to ensure they come online when needed.
These are the types of sensors used to monitor backup generators at wastewater treatment plants:
Fuel level sensors
Measure the level of diesel in generator fuel tanks
Annunciator panel sensors
Connect to generator panels to monitor warnings, faults, and shutdown codes
Measure the oil pressure in the generator engine sump and the coolant pressure
Measure oil temperature and coolant temperature
Battery voltage sensors
Measures the voltage of the battery that powers the panel when the generator is offline
Automatic transfer switch sensors
Measures the status of the automatic transfer switch that transfers power from grid to generator
Safety System Sensors
Safety is critical to water treatment plants. In general, sensors (and remote monitoring systems) help water treatment plants operate more safely by eliminating the need to put people in risky places just to record process parameters. Additionally, these types of sensors can be used to ensure safety in wastewater treatment plants:
Hydrogen Sulfide (H2S) sensors
Measure the presence of H2S gas, a toxic byproduct of decomposition in sewage
Emergency gas scrubber sensors
Measure the effectiveness and readiness of emergency toxic gas scrubbers
Connect your sensors to remote monitoring
Sensors in wastewater treatment plants are only valuable when they are connected to a system that monitors, controls, and automates wastewater treatment plants to ensure safety, maximize treatment rates, and reduce costs.
Many operators find value in connecting their wastewater treatment plant controls sensors to a remote monitoring system. This can lead to less downtime, lower incident rates, and faster time to insights that increase overall treatment efficiency.
Ready to connect to the things that matter to your business?
Remote asset monitoring creates a more efficient workforce, pushes down your operating costs, and drives data driven business outcomes. Learn how WellAware can help you achieve your digital transformation goals.