Wastewater level sensor occupies a large proportion in sewage treatment applications. It is used in almost all aspects of sewage treatment. In sewage treatment, the level of waste water, sludge, chemical solutions, etc. needs to be measured. Sewage lift station and wastewater treatment plant often use radar, ultrasonic, pressure sensor, etc. To monitor the liquid level.

In the sewage treatment system using automatic control. The wastewater level sensor is used to measure the liquid level. Many also involve the start and stop of interlocking pumps and the opening and closing of control valves in automatic control.

The following combined process analysis, the selection of wastewater level sensor.

Wastewater Level Sensor for Septic Tank-Sewage Holding Tank

Featured Wastewater Level Sensors

Selection of Level Sensors for Wastewater Treatment

Sewage treatment projects involve the measurement of various process parameters such as liquid level (difference), flow, pressure, temperature, concentration (including PH, dissolved oxygen, etc.), turbidity and so on.

Because the process of sewage treatment involves many occasions that need to measure the liquid level. Also because of the characteristics of the process of sewage treatment itself. In the selection process, it is necessary to select a suitable level gauge according to the characteristics of each process and medium. It will have a great impact on the accuracy, reliability and stability of process measurement and economic life.

It is recommended to choose a level gauge with high accuracy, low maintenance, and long service life as far as possible when the budget permits. The liquid level measurement and control of the entire sewage treatment can be operated reliably, stably and safely.

Pay attention to the following points when selecting Level Sensor

  • Measurement object. Such as the physical and chemical properties of the measured medium. As well as working pressure and temperature, installation conditions, the speed of liquid level changes, etc.;
  • The sensor must be able to measure sewage. The acid, alkali and small particles in the sewage have no influence on its measurement accuracy and life.
  • The sensor has high measurement accuracy, easy to install and easy to adjust.
  • The Level Sensor display is intuitive and has analog output and alarm output functions.
  • Measurement and control requirements. Such as measuring range. Measurement (or control) accuracy. On-site instructions, remote instructions. The interface with the computer. Safe anti-corrosion. Reliability and ease of construction.

Wastewater Level Sensors Types

In sewage treatment, the level of waste water, sludge, chemical solutions, etc. needs to be measured. In the sewage treatment system using automatic control. The Level Sensor is used to measure liquid level. Many also involve the start and stop of interlocking pumps and the opening and closing of control valves in automatic control.

Compared with other types of measuring instruments, there are many types of level gauges suitable for sewage treatment projects. There are two types of contact and non-contact measurement.

All of the above must be considered. Pay attention to the physical and chemical properties of different measured liquids according to different types of Level Sensors.

The following will analyze the selection of the sewage treatment Level Sensor according to the combined process.

Magnetic flap Level Sensor works according to the principle of buoyancy and magnetic coupling.

When the liquid level in the measured container rises and falls. The float in the main pipe of the level gauge also rises and falls.

Magnetic flap Level Sensor

The permanent magnetic steel in the float is transferred to the field indicator through magnetic coupling. The red and white turning columns are driven to turn over 180.

When the liquid level rises. The turning column turns from white to red.
When the liquid level drops, the turning column turns from red to white.

The red and white boundary of the indicator is the actual height of the medium liquid level in the container, so as to realize the indication of the liquid level.


  1. The structure is simple. The display is clear. The reading is intuitive. Especially suitable for on-site display.
  2. There are few openings in the equipment. Generally, a magnetic flap level gauge with remote output is used. It can be monitored on site and remotely.
  3. According to the condition of the medium. For example, the medium that is easy to be fouled and clogged. The main pipe needs to be cleaned regularly to remove the sediment in the pipe. To ensure the accuracy of the measurement. In the sewage treatment process. Magnetic flap Level Sensor is often used in chemical dissolving tanks. Liquid level measurement of acid tank\alkali tank, etc.

The static pressure type liquid level measurement method is based on the principle that the static pressure of the liquid column is proportional to the height of the liquid column.

The liquid level measurement is achieved by measuring the static pressure generated by the height of the liquid column.

Differential pressure Level Sensor is used when the liquid level in the container changes. The static pressure generated by the liquid column also works according to the principle of change.

The static pressure type Level Sensor measures the liquid level by measuring the static pressure generated by the liquid level height.

According to P=pgh,
And the density of the liquid P.
The acceleration of gravity g is known.
As long as the pressure P is measured, the liquid level h can be calculated.

One kind of pressure instrument used for liquid level measurement is Submersible Level Sensor.

That is, put the liquid level measuring instrument into the medium of the liquid level to be measured. As the liquid level changes. Pressure detection elements such as diffused silicon in the pressure transmitter convert the static pressure into a resistance signal for liquid level detection. Submersible Level Sensor can be directly put into the measured medium.

Features of Submersible Level Sensor.

  • The structure is simple. Adopt solid structure. No moving parts.
  • It is quite convenient to install and use. long lasting.
  • The measurement range is relatively wide. It can measure from water and oil to phases with higher viscosity, etc.
  • It is not affected by blistering, deposition, and electrical durability of the measured medium. No material fatigue and wear. Insensitive to vibration and shock.
  • The price is cheap. The reliability is relatively high.
  • When installing, pay attention to choosing a place where the fluid is relatively stable and the fluctuation is small. if
  • It is inevitable to avoid the impact of water flow, and when friction and vibration, it is necessary to install an isolation tube. Reduce the impact of water flow. Ensure the accuracy and stability of the measurement.
  • Install the plunger type liquid level timer. It is best to be 100mm to 200mm away from the bottom of the tank or tank. In order to reduce the sedimentation of silt and medium at the bottom of the tank or tank, which affects the accuracy of the measurement.
  • In an environment with poor water quality. Especially when the medium has a lot of suspended solids and impurities. Allow
  • Easy to block the pressure tapping hole. Affect measurement accuracy. The level gauge needs to be cleaned regularly and the pressure tapping hole should be cleared. To ensure the accuracy and stability of the measurement.

The pressure type Level Sensor is suitable for use in processes with better water quality. For example, the supernatant collection tank, filter tank. Clear pool, drain pool and SBR pool. By installing isolation pipes to avoid impurities in the sludge at the bottom of the pool, it can also be used in the thickening tank with stirring.

Float Level Sensors - Single and Multipoint

Float level sensor is a kind of continuous liquid level measurement sensor. Also called float level switch, float level gauge, float level transmitter.

Float level sensors are continuous level sensors. It can display the liquid level percentage, 4~20mA current and liquid level value on the spot. Output the switching value signal to conduct liquid Bit switch control. Low-cost. Single-point or multi- point measurement and control optional.

  1. It is suitable for the liquid level measurement of the liquid medium in the container except for the on-site display. It can also be equipped with remote transmitter, liquid level controller and other functions.
  2. The display is intuitive and eye-catching. The display direction can be changed according to user requirements.
  3. Large measuring range. Not limited by the height of the container.
  4. The display component is completely isolated from the measured medium. Therefore, the sealing is good and reliable.
  5. Simple structure, easy installation and easy maintenance.
  6. Corrosion resistance and explosion-proof.

Ultrasonic Level Sensor is a non-contact meter that uses the principle of echo ranging.

The echo ranging principle is also called the travel time or propagation time measurement principle.

It emits energy waves through a device that can emit energy waves (usually pulse signals). The energy wave is reflected by an obstacle. The reflected signal is received by a receiving device.

Determine the level change according to the time difference of the energy wave movement process. The energy wave signal is processed by the electronic device, and finally converted into an electrical signal related to the level.

The level gauge that uses ultrasonic waves as energy waves is the Ultrasonic Level Sensor.

Ultrasound uses gas (in most cases, air is used as the propagation medium. Changes in air pressure (vacuum), temperature, humidity, and airflow will change the propagation speed of ultrasonic waves.

Features of Ultrasonic Level Sensor

  • Ultrasonic Level Sensor can achieve non-contact measurement. Stable and reliable operation: Ultrasonic Level Sensor is installed above the silo and liquid tank. It does not directly touch the material, which overcomes the disadvantages of other models of Ultrasonic Level Sensor that directly touch the material.
  • The range that can be measured is large. Liquid, block, powder level can be measured.
  • It can measure continuously at fixed points. And can conveniently provide remote measurement and remote control measurement signals.
  • The installation is simple and convenient. And no security protection is required.

The antenna of the radar sensor emits electromagnetic wave signals in the form of beams. The emission wave is being measured
The surface of the material is reflected. The reflected echo signal is still received by the antenna.

Every point in the transmitted and reflected beams is collected by ultrasonic sampling.

The signal is processed by the intelligent processor to get the distance between the medium and the probe. It is sent to the terminal display for display, alarm, operation, etc.

The distance D from the surface of the material is proportional to the time travel T of the pulse:


Where C is the speed of light and E is known due to the distance of the empty tank. Then the level L is: L=E-D

Features of Radar Level Sensor:

  • Radar Level Sensor adopts integrated design. There are no moving parts. There is no mechanical wear. Long service life.
  • Due to the characteristics of electromagnetic waves, it is not affected by the environment. Therefore, its measurement applications are relatively wide. The probe of Radar Level Sensor has no contact with the surface of the medium. It is a non-contact measurement. It can accurately and quickly measure different media. The probe is hardly affected by temperature, pressure, gas, etc. It can change greatly under bad working conditions. Use in occasions where the ultrasonic level gauges such as water vapor, steam, and foam are not competent.
  • Radar Level Sensor is also suitable for use in occasions where there is a stirrer and the liquid level changes impermanently.
  • Radar Level Sensor is relatively expensive, but it can be applied to almost every process level control process of sewage treatment.

About Water Level Sensor Types and how they work. OMEGA Engineering has a good introduction video. Let’s take a look.

Ultrasonic Septic Tank Sensor

Septic tank ultrasonic level meter is used as an instrument to intelligently detect the height of the septic tank. Played a vital role in the maintenance of public toilets.

In the previous toilet maintenance, the manure trucks were cleaned regularly and fixedly. Doing so will inevitably cause some waste of resources.

Install septic tank ultrasonic level gauges in public toilets. The liquid level of the manure tank can be monitored in real time. It will automatically alarm when it reaches a certain height. The transmission system is connected to the control center. The front calls the police and the rear supports.

This can greatly save manpower and material resources. It is of great significance for energy saving, environmental protection and resource saving.

Septic tank ultrasonic level meter needs to be equipped with automatic alarm device or SMS alarm device. Ultrasonic module with 485 communication is used for liquid level monitoring. And through multiple communication modules with 485, the liquid level is monitored uniformly by the unified terminal system. This can not only display in real time. It is also possible to remind the user management personnel through a text message reminder or terminal alarm device when the septic tank is almost full.

Septic Tank Alarm Float Switch

The float level switch is specially used for liquid level detection of various medium and small normal pressure and pressure liquid storage tanks, remote transmission of on-site indicator signals, and liquid level alarm. It can be applied to various sanitary, toxic, corrosive media and explosive gas dangerous places. There are also many types of installation. Suitable for various forms of containers.

External Tank Level Indicator

The external tank level indicator is a new type of non-intrusive ultrasonic level measurement system. This is a real non-invasive, non-contact measurement method.

Just install the measuring probe on the outer wall of the bottom of the tank or container. The reflection and transmission characteristics of ultrasonic waves are used to realize the measurement of the liquid level inside the storage tank.

The calculated liquid level value is displayed locally, and a remote signal is output. The meter can output the measurement result to the control system through 4-20 mA analog signal, HART, RS-485 and other interfaces. At the same time, data can also be sent to the Internet via wireless transmission via WIFI, GPRS and NBIOT.

When the ultrasonic wave emitted by the probe propagates to the inner wall of the bottom of the container. The first reflected echo is generated due to the change of the propagation medium. After that, the ultrasonic wave continues to propagate in the measured liquid medium. When propagating to the gas-liquid interface, the propagation medium changes again. Produce a second reflection echo.

Assume that the time difference between the first reflected echo and the second reflected echo is T. According to the propagation speed c of the ultrasonic wave in the measured liquid. The liquid level value L =c*T/2 can be obtained in the container.

The advantage of this liquid level measurement method is that there is no need to open holes or install flanges for the container to be tested. The internal liquid level information can be obtained directly from the outside of the container. The non-intrusive liquid level measurement is truly realized.

Marine Holding Tank Level Indicator

Portable ultrasonic liquid level indicator is best choice for tanks or pipes level measurement. It is designed to measure the presence or absence of liquid at a certain height position in a tank or in pipelines. Non-contact ultrasonic detection technology. SI-ML works perfect for detection of dangerous toxic or corrosive liquids. Under ordinary conditions, the maximum wall thickness of measurable containers is 30mm. The product is suitable for the detection of various types of liquids. Liquids are non-crystalline or other particulate matter. For example CO2 Tank. Thanks to non-contact detection technology, this level indicator is ideal for detecting hazardous toxic or corrosive liquids.

How to Measure Ground Water Level ?

Dynamic monitoring of groundwater level:

It is advisable to use existing water wells, natural outcrops of groundwater, or drilling and exploratory wells in the project. When the borehole is easy to be blocked, a filter can be installed in the borehole for monitoring.

SI-PCM260 Deep Well Water Level Sensor

Deep Well water level sensor is to apply Hydrostatic Level Sensor to deep well. Well water level sensor submerged in deep well work together with submersible water pump. Range within 300m ~ 1000m.

The groundwater level online monitoring system is widely used in underground water deep well water level measurement, mine water level gauge deep well measurement, and geothermal well water level measurement.

The groundwater level online monitoring system is based on the principle of hydrostatic pressure in which the pressure is proportional to the water depth. The water pressure sensitive integrated components are used as the sensor probe of the deep well water level measuring instrument.

When the sensor probe is fixed at a certain measuring point underwater. The height of the water column pressure above the measuring point plus the height of the point. The water level (the distance from the water surface to the wellhead) can be measured indirectly. The direct measurement is above the sensor probe The actual height of the liquid level in the deep well.


The FOGRod is a wastewater level sensor manufactured by Wastewater Level. Unlike most level sensors it has no moving parts, sensors or electronics in the wet well.

The FOGRod hangs in a wet well much like a float switch or ultrasonic transducer and connects to a Level Indicator Transducer (LIT) which mounts in your control panel. The LIT has 10 relays that correspond to 10 contacts on the FOGRod.


We can install a liquid level sensor or liquid level alarm in the water storage tank.
Through the display of liquid level value or alarm of high and low liquid level. We can know when the tank is full.

Ultrasonic externally attached oil level sensor uses the principle of ultrasonic echo ranging. The sensor is installed outside the bottom of the fuel tank and sends out an ultrasonic signal from the bottom, which is reflected by the oil surface, and then calculates the height of the liquid level according to time and speed. At the same time, combined with digital signal processing technology, it overcomes the influence of the container wall and realizes high-precision non-contact measurement of the liquid level in the container, which can meet the requirements of industrial applications in terms of application.

Including water dispensers, water heaters, toilets, humidifiers, etc., and other atomizers, coffee machines, beverage machines, electric steamers and other household appliances, medical and commercial machines, etc., all have water tanks inside.

Many machines cannot directly see the liquid level of the internal water tank. Therefore, a liquid level sensor is needed to detect the liquid level. Generally, detecting low liquid level can give a signal alarm when it is detected that there is almost no water. When a high liquid level is detected, a signal is given to prevent liquid overflow.

Water level sensors work by using sensor probes to indicate water levels in a storage tank. These probes send information back to the control panel to trigger an alarm or indicator. As mentioned above, the control panel can be programmed to automatically turn on your pump to refill the water again.

Tank level sensors monitor the level of liquids, pellets, powders, and other similar products in tanks and process systems. Available sensors include contact, non-contact and submersible sensors, as well as float and rotating paddle level switches.

Sino-Inst offers over 50 Wastewater Level Sensors/Systems for Sewage-Wastewater. About 50% of these are Radar level meters, 40% is magnetic level sensor.

A wide variety of Wastewater Level Sensors for Sewage-Wastewater options are available to you, such as free samples, paid samples.

Sino-Inst is a globally recognized supplier and manufacturer of Wastewater Level Sensor/System for Sewage-Wastewater instrumentation, located in China.

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