Background:
If you've ever seen a river turn cloudy after a heavy rain, or noticed particles in your water after utility maintenance, you probably already know that measuring particles and solids is critical to assessing your water quality profile. When measuring water quality for solids, it is key to understand that solids exist in many physical forms and that different measurement principles can provide different types of information. Parameters such as turbidity, total suspended solids (TSS) and total dissolved solids (TDS) provide information based on the size, distribution and type of particles present in the solution. In this blog, our team of YSI experts will clarify the difference between each parameter, the measurements they provide, and provide turbidity transmitter recommendations for your job!
What is Turbidity?
Turbidity is an optical parameter defined most narrowly as the transparency of a medium. Turbidity can be measured in two ways: by nephelometric or nephelometric methods. In both methods, light (of known intensity) passes through the medium and is detected and recorded. Nephelometric methods measure the degree to which light is scattered, while nephelometric methods quantify the degree to which light decays. Results obtained from both techniques are now reported in Nephelometric Turbidity Units (NTU) or Formazin Nephelometric Units (FNU). More specifically, NTU is a unit of measurement commonly used to express turbidity readings captured using white light at a 90-degree detection angle (EPA 180.1 compliant) and FNU when using 860 nm light with a 90-degree detection angle (ISO 7027 compliant) Light (Near Infrared) is often used when capturing readings.
The role of turbidity transmitter
Turbidity transmitters primarily monitor turbidity to determine water clarity. Highly turbid water is opaque and is often colloquially described as cloudy or cloudy. This cloudy quality of highly turbid water is directly related to the large number of particles dispersed in the water. In this sense, turbidity and TSS are related, but despite their similarities, it is important not to confuse the two. Turbidity can be used to indicate changes in the concentration of TSS in water, but does not provide a specific measurement of these solids. Likewise, turbidity is purely a measure of relative transparency.
Although it is an optical parameter, the usefulness and utility of turbidity measurement cannot be overemphasized. Turbidity is one of the easiest and least costly ways to determine the health of a water source. Suspended particles can enter water bodies in a number of ways; discharge, erosion, runoff, algal blooms, or agitated sediment are just a few potential causes of high turbidity. These reasons all have an impact on the water body, and elevated TSS levels in turbid water lead to higher water temperatures, lower dissolved oxygen levels, and reduced photosynthesis levels—leading to underwater vegetation death, further reductions in dissolved oxygen levels, and disruption of ecosystem food chains. Among other things, erosion and runoff can increase the amount of pollutants in water bodies, harmful algal blooms.
How do labs measure turbidity?
Traditional methods of determining the TDS and TSS of a solution are performed in a laboratory setting and include filtration, evaporation, and gravimetric analysis of the total mass of solids. The laboratory procedure for measuring TDS involves passing a known volume of water through a filter of specified pore size and weighing the residue after the filtrate has evaporated. On the other hand, laboratory methods for determining TSS involve drying and weighing the mass of solids captured on the filter during the filtration step. While these gravimetric methods can produce highly accurate results, the time required to collect samples, send samples to a laboratory for processing, and receive results can be lengthy and especially inconvenient when sampling at multiple locations.
Turbidity Measurement Problems
Over the years, turbidity has had a reputation for delivering varied results, largely due to the number of various platforms available on the market. Particle size, shape, distribution throughout the water sample, morphology and color also have an impact on the accuracy of turbidity measurements. Regardless of the cause, turbidity measurements do suffer from a range of possible disturbances. These disturbances can cause positive or negative bias. Negative bias, or results appearing lower than their true value, occurs most often in samples with NTU values above 1, and the margin of error becomes more significant at values even larger than that. Positive turbidity interferences are most likely to be found in samples with very low turbidity values (readings below 0.1 NTU),
JXCT's Portable Turbidity meter
Turbidity detector are one of the intelligent online chemical analysis instruments. It can continuously monitor data through the transmission output and connect the recorder to realize remote monitoring and recording. It can also be connected to the RS485 interface through the MODBUS-RTU protocol for easy connection Enter the computer to realize monitoring and recording.