Suspended Solids Analyzer | TSS Monitor | Suspended Solids Meter (2023)




How do you measure from low NTU all the way up to 8% solids? By using the SoliSense®from Pi. Using patented optical technology the self-cleaning, simple to use, low drift suspended solids sensor from Pi is a cost-effective way of measuring the solids in a range of applications including all those associated with municipal wastewater plants and municipal water plants such as mixed liquor suspended solids (MLSS), return activated sludge (RAS), plant inlet and plant outlet, centrate, filter backwash and other monitoring requirements. Because of its patented technology that allows it to measure such a large range in a single sensor, the SoliSense® has integrated self-cleaning for a long maintenance intervals with calibration checking as little as once per year. Installation can be dipping into a tank or inserting into a pipe.

SoliSense® Suspended Solids Meter 3D View


  • From 2 NTU to 8% Solids
  • Displays in NTU, mg/l, g/l or % solids –flexible
  • AutoClean optical sensor – months without maintenance
  • Stable and reliable– excellent process control
  • Suitable for all potable, waste and process waters
  • Up to 12 months between maintenance
  • Up to 12 months between calibration

The patented technology in the SoliSense® means that a single sensor can cover a very large range. This means that you don’t need to have so many different sensors across a water treatment works (WTW) or wastewater treatment works (WWTW). This in turn means;

  • Less spares – need to be held across one or more plants
  • No requirement to know the range before ordering –easier purchasing
  • One online suspended solids analyzer can be an:
    • MLSS meter
    • TSS meter
    • Online total suspended solids meter
    • Online effluent monitor
    • Online inlet monitor
    • Online ‘in process’ suspended solids analyzer

The SoliSense® has been designed to be suitable for all suspended solids monitoring applications in both water treatment works and wastewater works including:

  • Inlet monitoring(turbidity 2-4,000 NTU)
  • Effluent monitoring(suspended solids 0-1,000 mg/l)
  • Online suspended solids analyzer
  • Online RAS meter(Return Activated Sludge)
  • Online MLSS meter(Mixed Liquor Suspended Solids)
  • Online WAS meter(Waste Activated Sludge)
  • Thickened sludge– Online total suspended solids meter
  • Centrate– Online total suspended solids meter
  • Filtrate– Online total suspended solids meter
  • Backwash water – For control of filter backwashing on a water treatment plant
  • Wastewater effluent – Online total suspended solids meter
  • Wastewater influent – Online total suspended solids meter
(Video) Portable Suspended Solids Sensor Calibration

The SoliSense® suspended solids sensor can come with several installation options including;

  • Dip –where the sensor is mounted on the end of a pole that dips it into a tank or open body of water
  • Insertion – where the sensor is inserted into a pipe through a special ball valve that allows the sensor to be removed while still under pressure
  • Flow cell – where the sensor is mounted in a specialist flow cell and the sample flows through it.

To learn more please scroll down and download the brochure or contact us to discuss the best option for your application.

Each sensor has an LED light source that emits in the infra-red and has a working lifetime of 15 years. Each suspended solids sensor has two detectors.

The light emitted is detected by the emitter detector. That light then goes through the sapphire optical windows and into the sample. With refraction and reflection, some light comes back into the sensor to the detector, which is at 120 degrees to the emitted light, and the ratio of the emitted light to the received light is proportional to the suspended solids in the sample. By varying the amount of light that is outputting the sensor can correct for effects introduced by, for example, the optical properties of the windows or aging optics or drifting electronics (all electronics drift). It is this technique that has been patented and provides for the stability and range of the SoliSense®.

The electronics provide a fully scalable output allowing the SoliSense® to measure any part, or the whole, of the scale. The sensor probe comes equipped with the capability of having a water jet regularly sweep over the optical lenses keeping them clean. If you have an application that ranges from low NTU all the way to %age solids then the SoliSense®is certainly the suspended solids monitor for you! With up to 5 calibration points you can accurately monitor your process across a wide range of sample concentrations.

The probes are constructed of 316 stainless steel with sapphire optical windows, so can withstand demanding operating environments.

By using two detectors in a single probe it is possible to:

  • Measure turbidity from 2 NTU to 4,000 NTU
  • Measure solids from 0.001 to 80 g/l (8% solids) – Sludge
  • Measure solids from 0.001 to 500 g/l (50% solids)– Silicates

Focus Ons are a series of short articles distributed by email providing technical information regarding instrumentation, process measurement in potable, waste, process and pool waters. If you would like to join the mailing list, pleasecontact us.

>> SoliSense<sup>®</sup> for TSS Monitoring

>> Probe Fouling

Total Suspended Solids Measurement – SoliSense®Article592kB
Measurement of Suspended SolidsTechnical Note742kB
SoliSense® for TSS MonitoringTechnical Note753kB
SoliSense® Mounting OptionsTechnical Note686kB
Probe FoulingTechnical Note459kB


Suspended solids are particles suspended in water. They occur naturally and can be seen for example in rivers after a rainfall event when the river appears ‘muddy’.

Treating water and wastewater has two main focuses: the removal of organics and particles, and then disinfection. Having information about the level of suspended solids can be invaluable in informing treatment processes (such as tracking changes in suspended solids in raw water entering a drinking water plant or monitoring the efficacy wastewater at the outlet), and so these kinds of sensors are very common in many industries and applications.

Suspended solids are generally measured in mg/l. Sometimes, if they are present in large amounts, a percentage is used or g/l.

Suspended solids and turbidity are measured differently, but they are related. Suspended solids measurements are based on the mass of solids present in a certain volume of water (mg/l), whereas turbidity is measuring how ‘cloudy’ it is in NTU. A common conversion used is 1mg/l = 2 NTU, but different suspended materials can have a different relationship.

The qualities of the process water and the solids to be measured will affect the effective maximum level that can be measured. For a ‘clean’ application (such as silica in clean water), we could expect to be able to measure up to 50% solids (500,000 mg/l) reliably. On the opposite side of the spectrum, black sludge in a wastewater plant may have a reliable limit as low as 5% (50,000 mg/l). Experience shows that in most wastewater works the upper limit is around 8% solids (80,000 mg/l).

The SoliSense® has integrated temperature compensation as standard, and so changes in temperature will have a negligible effect upon the sensor. However, the SoliSense® is a rugged stainless steel sensor of significant mass; it can take time for the SoliSense® to reach thermal equilibrium, so rapid changes in temperature (>2°C per 10 min) could have an effect upon the reading.

"The Pi products provide excellent value for money and represent the best municipal drinking water analyzers available."

John Clark

Chemtrac - Atlanta

"The support from Pi and its partners is superb. They go above and beyond to ensure that, not only is their equipment perfect but that the process is working great too. Five Stars!"

Anthony Glitto

Equip Solutions - Illinois, USA

"Going from ORP control to amperometric chlorine sensor control has undoubtedly improved the pool water immensely!"

Chris Tedeschi

Link Automation - USA
(Video) How to Monitor Suspended Solids using Pi's Suspended Solids Meter - Measurements - SoliSense

"We've been using these analyzers since 2008. They're easy to use and very stable. Calibration and maintenance is quick and simple."

Lloyd Gruginski

Chehalis WTP - Chehalis, WA

"We at Scottish Water have been using the excellent Pi LabSense 3 and portable UV254 instruments in the field for optimizing our Water Treatment processes for some years now. We find them easy to use and invaluable for detecting and resolving issues in a timely, efficient and effective manner. Two great pieces of kit!”

Paul Weir

Scottish Water - UK

"I want to thank you and all at Process Instruments for all the assistance, information and handholding during the year. The help that was so freely given was very much appreciated. Can you please extend my appreciation to all at Pi and let me wish you all a happy, safe and wonderful Christmas and I look forward to working with you again in 2021."

Michael Bailey

Wexford Co. Co. - Ireland

"Excellent level of support and always so much more prompt than a lot of our suppliers."

Phill Tuxford

Detectronic - UK

"The plant can’t produce good quality water without the CoagSense."

Mick Murphy

Wexford Co. Co. - Ireland

"We started using Process Instruments 10 years ago and they worked so well that when we were looking at expanding, Process Instruments were our "go to" company."

Rebecca - Pool Manager

Woodland Spa - Burnley, UK

"We've been installing pools and spa controllers from Pi for more than 10 years and they just are the best on the market."

Dr. Lester Symmonds

Pool Sentry - UK

"We've used the CRIUS® with chlorine, pH and conductivity sensors for several years and confirm quality, performance and reliability has been wholly satisfactory to date."

David Kerr

Karis Technical Services Ltd. - UK

"We in ECM ECO Monitoring can only recommend Process Instruments products and services to all other potential clients.They have very complex portfolio of products for water quality monitoring in various types of industries, friendly attitude, very quick delivery time and prompt reaction to all our needs and inquires.Our clients especially appreciate the particle counters and sizers allowing identification of drinking water treatment problems. The Streaming Current Monitors are a great tool for optimisation of expensive chemicals.”


ECM ECO Monitoring - Slovakia

"Simply the best turbidity available."

John Clark

Chemtrac - Atlanta, GA

"In 2019, we purchased 29 particle counters which were installed in our water plants. So far, their performance has been perfect."

Li Yongjun

Jinan Hongquan Water Company - China
(Video) Testing result reading--Portable Suspended Solids Analyzer LH-XZ03

"We have installed hundreds of ozone analyzers from Pi over the years. They are just accurate, reliable and require low maintenance."

Jiao Tumei

Qingdao Guolin Environmental Technology Co., Ltd., - China

"Over the last few years we've purchased chlorine and turbidity analyzers from Chemtrac and with routine calibration the probes measure the chlorine and turbidity without any issue. We are very happy with this product and would highly recommend them."

Daniel "Buck" Owen

Ocoee Utility District - Ocoee TN

“Servicing customers is much more than just solving problems or addressing complaints and Pi does that very competently with technical and quick efforts providing a good experience."

Clovis Tuchapski

Buckman - Latin America

"Pi's technical team has enabled us to be one step ahead of our competitors by adding value to our projects thanks to their fast and excellent support from the moment you first reach out.

Ibrahim Kaplin

Thermomed - Turkey

"The Streaming Current Monitor from Pi is the best SCM I have ever used. The analyser responds quickly and has many powerful functions, which helps me save a lot of money."

Ye Yancong

Xiamen Xishan Water Plant - China

“Process Instruments has a broad range of high quality and user-friendly solutions for water-industry problems. The short lead times and great customer support make Pi a reliable partner.”

Péter Szabó


"Process Instruments UK always have a high level of customer service. All our interactions with Pi have exceeded our expectations. It is always a pleasure working with you.”

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Izasa Scientific - Spain

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Allpronix - South Africa

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(Video) Total Suspended Solids (TSS) Demonstration

Suspended Solids Meter Downloads



(Video) TSG 2087S Online TSS Suspended Solid Meter BOQU Instrument


How do you measure suspended solids? ›

You can accurately calculate total suspended solids in wastewater by using a TSS sensor or monitor. These devices measure water in the region of 1,000 mg/L – 8% solids, indicating the presence of suspended solids in water.

What instrument is used to measure total suspended solids? ›

The readings were measured using a multimeter. The linear correlation coefficient between the estimated total suspended solids and measured TSS was very high and the root mean square error was low.

What is a TSS meter? ›

What is it? TSS and TDS measure the amount of particulate matter (tiny pieces of things) floating in water. In lakes and rivers this can include particles from algae, other organic matter, silt and clay, and other inorganic substances (such as minerals, salts and metals).

Which sensors measure suspended solids in water? ›

Memosens sensor for suspended solids and turbidity measurement in water, wastewater and utilities.

How do you accurately measure solids? ›

The three most common methods for measuring solid ingredients are by cups, weight, and (for smaller amounts) teaspoons. Many commercial recipes, particularly for baking, give measurements by weight.

How do you measure total solids? ›

Total solids are measured by weighing the amount of solids present in a known volume of sample. This is done by weighing a beaker, filling it with a known volume, evaporating the water in an oven and completely drying the residue, and then weighing the beaker with the residue.

What method is used to measure TDS? ›

The two principal methods of measuring total dissolved solids are gravimetric analysis and conductivity. Gravimetric methods are the most accurate and involve evaporating the liquid solvent and measuring the mass of residues left.

How is TSS measured in a lab? ›

Summary of test method

A well-mixed, measured volume of a water sample is filtered through a pre-weighed glass fiber filter. The filter is heated to constant mass at 104 ± 1º C and then weighed. The mass increase divided by the water volume filtered is equal to the TSS in mg/L.

Can you measure TSS in the field? ›

The TSS concentration of a solution can be determined using sensor technology to measure turbidity levels in the field and calculate TSS based off a correlation to the true TSS value determined via laboratory analysis.

Why is TSS measured? ›

Excess suspended solids can damage an aquatic ecosystem. TSS analysis provides data that can be used to make routine environmental management decisions but does not provide detailed geological information.

Which sensors are used for water quality monitoring? ›

TOC Sensor - Total organic carbon (TOC) is an important parameter for water quality analysis. It is used as a direct indicator and a surrogate for many water quality purposes. There are two different TOC measurement devices available on the market: TOC analyzers and TOC sensors.

What sensor can be used for wastewater monitoring? ›

Gas sensors can be used as a safety device in the water purification process. The gas sensors receive input signals in chemical, physical, and biological stimulus and convert them into electrical signals. The gas sensors can be installed in different wastewater treatment processes.

What type of sensor is used when controlling the level of solids in a bin? ›

Level sensors use various technologies to measure the level of solids in a silo or bins. The amount of material on hand is calculated using data such as the size of the storage vessel, the distance to the material, and the bulk density.

What unit is used to measure solid? ›

The units generally used for solids and liquids are g/mL, for gases g/L. The density values of some solids, liquids and gases near room temperature are listed below (Table 1).

What is the standard unit for measuring solid? ›

Volume of a solid is measured in "cubic units".

What are 2 ways to measure a solid object? ›

The volume of a solid object can be measured in two ways:
  • For regular-shaped objects: Measure the dimensions (length, width, and height).
  • For irregular objects: Submerge the object in water and measure the volume of the displaced water using a graduated cylinder.

How can I check my TDS without meter? ›

#2. How To Check TDS Using Filter Paper & A Scale?
  1. A clean & sanitized glass container.
  2. Water sample for TDS determination.
  3. Filter paper or Layers of Cotton.
  4. Evaporating dish.
  5. A sterile stirring stick.
  6. A pipette to take 50ml water sample.
  7. A weighing machine or scale.
Aug 23, 2021

Can conductivity meter measure TDS? ›

In fact, conductivity meters are used to estimate the TDS in a substance.

What is a safe level of TDS in water? ›

1. What is the best TDS level for drinking water? Ans: Generally, the TDS level between 50-150 is considered as the most suitable and acceptable. Ans: If the TDS level is about 1000 PPM, it is unsafe and unfit for human consumption.

What is reporting limit for TSS? ›

The Laboratory is not required to analyze a Method Detection Limit for TSS analysis. A Reporting Limit is used and is based on a minimum residue of 1 mg/L. A 500-mL sample has a reporting limit of 2 mg/L.

How do you measure total suspended particles? ›

A water sample is filtered through a pre-weighed glass fiber filter, capturing the solids larger than 2 um. Then, the filter is dried in an oven to remove remaining water and weighed again. The weight difference over the sample volume provides the TSS concentration in mg/L.

What is TSS in refractometer? ›

The destructive method of TSS measurement is usually performed by refractometer. The measurement is done by dripping the liquid fruit extract on the detector. TSS value is expressed by %Brix, the value displayed is based on ratio of the speed of light in vacuum and speed of light through the sample.

What is difference between TDS and TSS? ›

TSS is measured by weighing the dried material on the filter. TDS is defined as the portion of organic and inorganic solids passing through the same filter (Rice et al.

What are the three types of parameters to be considered for water quality monitoring? ›

There are three types of water quality parameters physical, chemical, and biological [8, 9].

How do you monitor water quality parameters? ›

Water quality can be measured by collecting water samples for laboratory analysis or by using probes which can record data at a single point in time, or logged at regular intervals over an extended period. The Department of Water uses water quality information to underpin decisions about water resource management.

What are the different types of water sensors? ›

Water sensors can come in many variations that include ultrasonic sensors, pressure transducers, bubblers, and float sensors.

Which sensor is used for monitoring? ›

Vibration sensors are the most commonly used sensors when monitoring rotating machinery. They are often credited for sensing the mechanical degradation of equipment components two months or so in advance of a failure, as shown in Figure 1.

Which sensor is used for process monitoring? ›

Ultrasound Sensors for Process Monitoring in Injection Moulding.

Which flow measuring meter is used in waste water treatment plants? ›

Thermal mass flow meters are ideal for monitoring the flow to each segment of the aeration tank. As energy costs increase, wastewater treatment plants have begun to control the air flow to the different parts of the aeration basin to obtain the desired dissolved oxygen (DO) content.

Which radar sensor for continuous level measurement of bulk solids? ›

The radar level sensor VEGAPULS 67 is used for cost-effective level measurement of bulk solids. It delivers continuously reliable measurement data on the levels of bulk solids in silos up to 15 m high as well as in crushers or small containers.

What is a solid state sensor? ›

A solid-state sensor is designed in such a way that the measurand, the physical property to be sensed, exploits a physical phenomenon within the sensor structure. This physical phenomenon leads to an electrical response that can be detected and magnified with electronics.

Which type of detector uses electromagnetic waves to measure the level of solids? ›

Ultrasonic level sensors are an excellent choice for solids level measurement, especially in comparison with radar level sensors.

How is suspended load measured? ›

Both streamflow and sediment concentration are continually changing. Streamflow is measured by making a discharge measurement. Suspended sediment, the kind of sediment that is moved in the water itself, is measured by collecting bottles of water and sending them to a lab to determine the concentration.

How are suspended solids in water measured? ›

In case you weren't sure, Suspended Solids is simply a density measurement used to describe exactly how much waste sludge and particles are in the water, and is measured in milligrams per litre (mg/l), grams per litre (g/l) or percentage solid (%). 1000mg/l = 1g/l = 0.1%.

How do you measure a suspended solid in water? ›

A water sample is filtered through a pre-weighed glass fiber filter, capturing the solids larger than 2 um. Then, the filter is dried in an oven to remove remaining water and weighed again. The weight difference over the sample volume provides the TSS concentration in mg/L.

Why is it important to measure suspended solids? ›

Total suspended solids are a significant factor in observing water clarity 3. The more solids present in the water, the less clear the water will be. Some sediment will settle to the bottom of a body of water, while others remain suspended.

How do you calculate suspended sediment load? ›

Determine total suspended-sediment discharge (in tons for the period of interest by multiplying the mean daily suspended-sediment discharge (from step h) by the total number of days in the period.

What equipment is used to measure sediment size? ›

Optical Laser diffraction point sensors (LISST)

Various Optical Laser diffraction instruments (LISST) are commercially available to measure the particle size and concentration of suspended sediments.

How is suspension sedimentation volume measured? ›

Sedimentation of a suspension is generally assessed by a jar test, during which a suspension is allowed to settle and the height of the clear liquid (supernatant)-suspension interface is measured as a function of the settling time.

What is the detection limit for TSS? ›

The determination of total suspended solids in chemical plant effluent. This method is limited to the determination of TSS in water samples collected from natural bodies of water containing TSS of < 20,000 mg/L. The desired detection limit for this method is 0.5 mg/L for a 1-L sample.

What test is a measure of the suspended solids in a water sample? ›

Gravimetric analysis is the most common method of measuring total suspended solids in water.


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5. Total Suspended Solid (TSS) Analyser - Quick Setup and Connections | Model - Tethys
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