for Water Quality Monitoring

Multiparameter Sonde / Meter Definition & Method

The main objects of water quality monitoring are surface water and water pollution sources, and the water quality monitoring items include two kinds: mandatory testing and selective testing.

For key monitoring stations, the monitoring items of water resources such as rivers, reservoirs, lakes and domestic water sources include more than 20 water quality parameters.

Such as pH, temperature, dissolved oxygen, turbidity, high ferocity index, conductivity, five-day biochemical oxygen demand, total organic carbon, ammonia nitrogen, cyanide, chlorophyll a, total number of fine bacteria, coliform bacteria, etc.

In actual detection, different water bodies often have different requirements.

Temperature, conductivity, pH value, turbidity, dissolved oxygen, these five water quality parameters are comprehensive indicators that appear as required items.

These five indicators can fully reflect the current situation of water quality and predict the development trend of water quality, which is an essential scientific basis for water quality monitoring.

Multiparameter Sonde Definition

At present, most of the water quality monitoring instruments are independent instruments, such as turbidity meter, pH meter, conductivity meter, dissolved oxygen meter, etc.

Their installation and maintenance are complex. High integration will be the development trend in the future.

In this chapter, we will focus on multiparameter sondes.

What is Multiparameter Sonde / Meter?

It is a compact sonde or sensor which could monitor temperature, pH value, turbidity, conductivity and dissolved oxygen in one instrument.

This equipment is unified for power supply and communication, which will greatly simplify the electrical structure.

At the same time, due to the high integration, the installation space of the instrument is reduced to the greatest extent, and the portability of the installation is also improved.

It reflects the quality of the water sample, forecasts the development trend of water quality, and provides scientific basis for the planning, development, management, utilization and prevention of water pollution.

CHAPTER 2:

Multiparameter Sond Measurement Method

In this paper, It will mainly introduce the types of monitoring elements and the detection principle of each element.

This will help us better understand the composition of multiparameter sonde.

Principle of Temperature Measurement
There are many kinds of temperature sensors, which use thermocouple and resistance.
Among the commonly used thermal resistances, the measurement accuracy of platinum thermal resistance is the highest, and it has a very stable resistance temperature relationship.
Compared with thermocouple, it has the following advantages:
1 The accuracy is high, and the error of temperature sensor is the least
2 Large measurement range
3 The fluctuation is relatively small. When the temperature fluctuation is small, it can achieve the accuracy and repeatability of 0.1 ℃.
Ph Measurement Principle
It is the pH composite electrode that completes the conversion between the pH value of the solution to be tested and the corresponding electrical signal, according to the change of the pH degree of the solution to be tested.
According to this principle, the pH complex electrode can convert the pH value into electrical signal for acquisition and processing.
Principle of Turbidity Measurement
Instrument analysis is the most commonly used method for accurate measurement of turbidity. Its principle is to use the transmission or scattering of light to convert the transmission or scattering light into electrical signal through photoelectric sensor, and then to collect and process the electrical signal to obtain the turbidity value.
According to different measuring principles, turbidity measurement methods can be divided into:
1 Transmission method
The principle of transmission method is to obtain the turbidity value by measuring the intensity of transmitted light. With the change of turbidity, the transmission light intensity will also change accordingly. The change law between them is in accordance with Bill Lambert’s law, that is to say, when the turbidity becomes larger, the transmission light intensity will decay exponentially.
2 Transmission light scattering light comparative measurement method
The principle of transmission light scattering light comparative measurement is to measure the ratio of scattering light and transmission light to obtain the turbidity value.
3. Scattering method.
The principle of scattering method is to obtain the turbidity value by measuring the intensity of scattered light. Scattering refers to the phenomenon that light will deviate from the incident direction and spread around when it is injected into the material with uneven lumps.
The scattering measurement method has many advantages, such as wide measurement range, high linearity, and it is very suitable for the occasion with large turbidity value.
Principle of Conductivity Measurement
The common methods of conductivity detection are electromagnetic measurement, electrode measurement and ultrasonic measurement.
However, the measurement range of electromagnetic conductivity method is too narrow, so it can only be used in the solution with high conductivity. Ultrasonic measurement method is rarely used in practical application, and electrode conductivity method is the most used in conductivity measurement.
The theoretical basis of the electrode type conductivity method is the conductivity principle of the electrolyte. The conductivity can be calculated indirectly by the resistance measurement method.
Principle of Dissolved Oxygen Measurement
The methods commonly used in the detection of dissolved oxygen include iodimetry, fluorescence quenching and polarographic electrode.
Iodimetry is one of the basic methods of dissolved oxygen detection stipulated by the national standard. It adopts pure chemical method, so it has the disadvantages of too complicated measurement process, only suitable for professional operation and too long detection process, which is not suitable for online measurement of dissolved oxygen. In addition, when using iodimetry for measurement, there must be a sampling process in advance, which can not directly detect the water sample, otherwise it will cause secondary pollution ;
Fluorescence quenching method is based on the theory of fluorescence quenching effect, that is, when the fluorescent substance is excited by the outside world, there will be an electrical signal, and oxygen molecules will have an obstacle effect on this process. Therefore, by detecting the electrical signal generated in this process, the concentration of oxygen molecules can be indirectly calculated
The fluorescence extraction method has good photochemical stability, no delay and high measurement accuracy. It is suitable for online measurement of dissolved oxygen and is applied in some occasions with high requirements.
At present, the most widely used dissolved oxygen measurement method is polarographic electrode method.
When a constant voltage is applied between the two poles, electrons flow from the cathode to the anode to generate a diffusion current. At a certain temperature, the diffusion current is proportional to the concentration of dissolved oxygen. A quantitative relationship between the current and the concentration of dissolved oxygen is established. The instrument automatically converts the reading of the galvanometer into the concentration of dissolved oxygen to display the value of dissolved oxygen.

CHAPTER 3:

Monitoring Parameter Influence

This chapter introduces the advantages and disadvantages of each detection method.

	Advantages
Temperature	There is a close relationship between water temperature and physical and chemical properties of water. The solubility of dissolved gases (such as carbon dioxide, oxygen, etc.) in water, the activities of microorganisms and aquatic organisms, biochemical reaction speed, salinity and pH value will change with the change of water temperature. Water temperature is a necessary item in water quality testing, and it is also a very important index in water quality evaluation.
Ph	PH value is the negative logarithm of the concentration of hydrogen ion in solution, which is one of the most commonly used water quality indicators. The pH value of natural water mostly ranges from 6 to 9; the pH value of daily drinking water is required to be controlled between 6.5 and 8.5; in order to prevent corrosion of metal equipment and pipelines, the pH value of some industrial water must be strictly controlled between 7.0 and 8.5. PH value plays an important role in biochemical treatment and water quality assessment.
Turbidity	Turbidity is a reflection of the obstruction degree of suspended matter in water to the light passing through. Water with high turbidity will look very turbid, while water with low turbidity will look very clear. The main substances causing turbidity are small particles, such as sludge, microorganism, organic matter and clay. The turbidity of water can objectively reflect the degree of pollution of the tested water body by silt, microorganism, organic matter, clay and other small particles. Therefore, turbidity is a very important water quality index, in the water quality index of people’s living water and various industries.
Conductivity	There are many alkalis, inorganic acids and salts in water, which exist in the form of ions, all of which make the aqueous solution have conductivity. The more salts dissolved in water, the greater the conductivity. Therefore, the total concentration of ions in the effluent can be calculated by measuring the conductivity, which is a very important indicator for the purity of water. If the conductivity is very small, it means that there is less salt in the water, which means that the water is purer, and vice versa. In addition to the amount of ions in water, the type of ions can also affect the conductivity of water. In the practical application of water quality detection, conductivity is a necessary item, which is a very important index.
Dissolved Oxygen	Dissolved Oxygen (DO) refers to the oxygen existing in molecular state in water. There are many dissolved oxygen in rivers, lakes and oceans. It is essential for the survival of aquatic organisms. Some reducing substances (such as ferrous ion, sulfur ion and sulfite) in water will consume dissolved oxygen to some extent, and bacteria in water will also consume them. Therefore, the dissolved oxygen value has a good indication for the degree of water pollution, which is a key indicator for the detection of water quality. The higher the content of dissolved oxygen in the water indicates the better the water quality. The dissolved oxygen in the water without any pollution is close to the saturation value under the same temperature and pressure. With the deterioration of water pollution, the dissolved oxygen in the water will be reduced accordingly. For dissolved oxygen detection in waterworks, food processing, sewage treatment plants, medical departments, environmental supervision departments and aquaculture and other fields has a very great guidance and significance.

CHAPTER 4:

Multiparameter Sondes Applications

Multiparameter Sondes can be seen in a lot water quality projects. They can be found in every corner of our lives and play a huge role.

Water quality inspection of rivers and lakes
Industrial and mining enterprises, detection of urban sewage discharge
Water quality monitoring of petrochemical, chemical, power generation, pharmaceutical, food, electronic, water plant, etc
Water quality inspection of urban parks
Smart city water quality detection

CHAPTER 5:

Find More About Multiparameter Sondes

Multiparameter Sonde is already a trend in our current life. I hope the audience can learn more from other aspects. Including Wikimedia/Patent/Video and so on.

WikiPedia

Water quality
Water quality refers to the chemical, physical, biological, and radiological characteristics of water.^[1] It is a measure of the condition of water relative to the requirements of one or more biotic species, or to any human need or purpose.^[2] It is most frequently used by reference to a set of standards against which compliance, generally achieved through treatment of the water, can be assessed. The most common standards used to assess water quality relate to health of ecosystems, safety of human contact, and drinking water.
Guidelines for drinking-water quality
This fourth edition of the World Health Organization’s Guidelines for Drinking-water Quality builds on over 50 years of guidance by WHO on drinking-water quality, which has formed an authoritative basis for the setting of national regulations and standards for water safety in support of public health.
It is the product of significant revisions to clarify and elaborate on ways of implementing its recommendations of contextual hazard identification and risk management, through the establishment of health-based targets, catchment-to-consumer water safety plans and independent surveillance.

Patents

US10302616B2:Submersible multi-parameter sonde having a high sensor form factor sensor
Abstract
Provided are multi-parameter sonde systems having a unique form-factor, wherein the plurality of sensors are arranged in a tight-fit configuration. This provides a single distal sensing surface and minimal separation distance between adjacent sensors. The sensors may be pie shaped with an interlocking feature to tightly hold the sensors together, with a sensor guard disposed over the outer surface of the interlocked sensors. Sensor-guards disclosed herein may have an integrated sensor storage and sensor guard configuration, thereby avoiding a need for a separate storage cup and that are configured to minimize unwanted biological growth. Also provided are uniquely shaped individual sensors having interlocking features to hold several sensors together in a sonde.
InventorElijah Lyle Scott Steven Collin Sewell Duane B. McKee
Current Assignee In-Situ Inc
EP3218694A1:Compact sensor for measuring turbidity or fluorescence in a fluid sample
Abstract
Provided are turbidometers and fluorometers having a unique form-factor to accommodate a number of optical components in a confined geometry. This provides the ability to compensate for change in light intensity from an optical source even in a closed-loop manner. The ability to package reference and signal detectors, along with a relatively large diameter LED light source in a confined geometry is particularly suited for applications requiring small-diameter sensors, such as multi-parameter sonde devices having a total diameter that is in the sub-two inch range.
Other languagesGerman French
InventorNathan T. Baltz Steven Collin Sewell
Current Assignee In-Situ Inc
US10365097B2:Sonde having orientation compensation for improved depth determination
Abstract
Provided herein are sondes having a pressure sensor that is separated from active sensing portions of the other sonde sensor or sensors by a longitudinal distance along the sonde. The pressure sensor may be positioned in the base portion of the sonde, with removable sensors connected thereto with a sensor plane at a distal end of the sensors that measures any number of parameters associated with the liquid in which the sonde is immersed. An orientation sensor positioned in the base portion determines an orientation angle of the sonde that, in combination with the depth determined at the pressure sensor location by the pressure sensor, provides the ability to determine the actual depth of the sensor plane, irrespective of orientation angle. Accordingly, improved depth measurement is achieved, without having to confine placement of the pressure sensor at the sensor plane.
InventorAshley Steinbach Duane B. McKee
Current Assignee In-Situ Inc
US20170254752A1:Optical nitrate sensor for multiparameter water quality measurement
Abstract
An optical nitrate sensor features a signal processor or signal processing module configured to: receive signaling containing information about a measurement (M) of UV optical absorbance of nitrate dissolved in water of a UV light that is generated by a UV LED centered at 229 nm and that traverses a confined volume of the water within a prescribed region of a sensor body, and also about a reference sample (R) of a portion of the UV light not traversing the confined volume of the water; and determine corresponding signaling containing information about the concentration of nitrate dissolved in the water, based upon the signaling received.
InventorChristopher John PALASSIS Miguel A. ROJO
Current Assignee YSI Inc

Videos

Aqua TROLL 600 Multiparameter Sonde

CHAPTER 6:

How To Buy Multiparameter Sonde

The factories of smart sensors are all over the world. How can we choose the most suitable one?

When you come to this page, ZWQ500 Multi-Parameter Water Quality Meter has appeared in front of you.

I believe that when you finish reading the introduction below, you will make the right purchase decision.

Model	ZWQ500
Measure Items	Measuring Principle	Measure Range	Measure Accuracy	Response Time
Temperature	RTD	-30-130℃	±0.1℃	N/A
pH	Glass Electrode	0-14pH	±0.1pH	<15s
Conductivity	Graphite Electrode	0-200000μS/cm	±1%	<15s
Dissolved Oxygen	Fluorescence	0-20mg/L	±0.1mg/L	<45s
Turbidity	Scattering	0-4000NTU	±5%	<30s
Interface	RS485 (Modbus RTU)
Dimension	D75mm×L423mm
Operation Environment	0-60℃ 0-6bar
Power	DC12V/24V Solar

Learn More Request A Quote

CHAPTER 7:

Future of Multiparameter Sondes

As described above, Multiparameter Sondes monitoring method will become more and more convenient in the future.

It will become an indispensable part of our life.

Detection efficiency: the pre manual detection method takes a long time, and has the influence of secondary pollution. In the future, the detection technology must be the combination of multiple technologies to greatly improve the detection efficiency.
Maintainability: at present, there are too many manual detection processes, even with instrument detection, regular intervention by personnel is also required. In the future, with the development of AI technology, maintainability will be reduced through Internet of things technology, Including chemical oxygen demand calculation.
Real time online: compared with the timeliness of manual detection, detection is relatively backward. Through the development of Internet of things technology and 5g, the online real-time monitoring should be the main direction of Multiparameter Sondes.
Detection principle: compared with reagent detection, optical detection is a future development direction. Compared with single band detection, there are still some errors. The detection efficiency can be greatly improved by means of multi spectrum detection.
Higher integration: more sensors will be integrated to monitor more water quality parameters. Monitoring is more efficient.

CHAPTER 8:

Multiparameter Sondes FAQs

Here are some common questions about Multiparameter Sondes. We will update them regularly through customer feedback.

I hope you can find the answers here. If you have more questions, please email to us.

What is Multiparameter Sonde / Meter?

It is a compact sonde or sensor which could monitor temperature, pH value, turbidity, conductivity and dissolved oxygen in one instrument.

Is the type of water quality detected by the multiparameter sonde fixed?

Of course not, it mainly detects five main water quality indicators, and can also expand other water quality parameters according to environmental requirements.