What is the difference between turbidity and sludge concentration？

What is the difference between turbidity and sludge concentration？

With the process of urbanization, the treatment load of sewage treatment plants continues to increase, and the sludge concentration becomes higher and higher, making turbidity a very difficult problem.

Sludge concentration meters and turbidity meters are important instruments widely used in the fields of sewage treatment and environmental monitoring to quickly and accurately measure the concentration of substances in water.

What's the difference between them?

1 What is turbidity test for? What is sludge concentration test for?

Turbidity is a key indicator of water clarity, often utilized to assess water quality. It quantifies the cloudiness of water, with higher turbidity readings indicating greater opacity due to increased suspended particles. These particles, including silt, algae, plankton, and sewage, scatter and absorb light rather than allowing it to pass through the water directly.

The measurement principle of turbidity involves assessing the light scattered by suspended particles in water, a process influenced by factors like particle size, shape, composition, and surface characteristics. Essentially, an uptick in turbidity signals a rise in suspended particles per unit volume of water.

Turbidity meters are instruments employed to gauge the concentration of particulate matter in a liquid, such as suspended or dissolved solids in water.

Similarly, sludge concentration meters measure particulate matter concentration in sludge, including sludge particle concentration or total solid content.

Mixed liquor suspended solids concentration, or mixed liquor sludge concentration, denotes the level of suspended solids in the mixed liquor resulting from blending sewage and activated sludge in an aeration tank, representing the volume of activated sludge in the tank.

This concentration indirectly reflects the quantity of microorganisms within the mixed liquid. To uphold the purification efficiency of the aeration tank, maintaining a specific sludge concentration is imperative. Typically, for the activated sludge

2 What is normal turbidity unit sludge concentration unit?

Turbidity measurements are commonly expressed in nephelometric turbidity units (NTU) or formazine turbidity units (FNU). Although often used interchangeably, these units differ as they reflect the method of turbidity measurement employed.

NTU denotes Nephelometric Turbidity Unit, indicating that the instrument measures light scattered by the sample at a 90-degree angle to the incident light.

FNU represents formazine scattered light units and also signifies measurement of light scattered by the sample at a 90-degree angle to the incident light.

However, NTU measurements stem from a beam of white light as per US EPA 180.1, while FNU measures turbidity using an infrared light source in compliance with the European Drinking Water Protocol ISO 7027.

Turbidimeters function by projecting a beam of light into a water sample and gauging the intensity of scattered light at a specific angle. When suspended particles are present in water, they scatter light, and the scattered light's intensity correlates with the concentration of suspended particles. A turbidity meter translates the measured scattered light intensity into turbidity units (NTU), thereby indicating the sample's turbidity level.

Hence, NTU serves as a relative unit of measurement, expressing the intensity of light scattering due to suspended particles in a water sample, rather than an absolute measure. Typically, higher NTU values indicate greater suspended particles in the water and consequently higher turbidity.

MLSS (Mixed Liquor Suspended Solids) units are mainly measured in milligrams per liter (mg/L), but for activated sludge, it's primarily in grams per liter (g/L), equivalent to kilograms per cubic meter (kg/m³).

MLSS represents the concentration of suspended solids in mixed liquor, i.e., sludge concentration, encompassing total suspended solid mass in sewage treatment system mixed liquor. It's pivotal for evaluating microorganism total and suspended solid system load and concentration.

Daxin's sludge concentration meter operates similarly to a turbidity meter, utilizing light scattering characteristics to swiftly and accurately measure solid particle concentration in sludge water.

3 Turbidity range of water，Sludge concentration range of water

Typical Turbidity values:

l EPA drinking water standards (conventional filtration): <0.3 NTU in 95% of samples; never higher than 1 NTU

l Treated water: 0 to 1 NTU

l Fresh water, >21.5 in. visibility: <10 NTU

l Fresh water, 2.5 in. visibility: 240 NTU

l Short-term stress to aquatic life: >10 NTU

l Unsafe level for most aquatic life: >100 NTU

Typical Sludge concentration values:

l Drinking Water: Less than 1 mg/L.

l Wastewater Treatment: Typically 2,000 to 5,000 mg/L.

l Industrial Wastewater: Can vary widely, depending on the industry and pollutants present.

l Natural Water Bodies: Generally low under normal conditions, but can increase in polluted or sediment-rich areas.

4 How do you measure turbidity and sludge concentration?

I'd like to introduce you to the turbidity meter and sludge concentration meter manufactured by Dongguan Daxin Electronics Company.

Turbidity Meter:

Our turbidity meter utilizes a unique approach, measuring the ratio of scattered light to transmitted light rather than relying solely on scattered light. This innovative method enhances the accuracy and reliability of the turbidity sensor while simplifying maintenance and increasing resistance to contamination.

Sludge Concentration Meter:

In sewage, suspended particle concentrations can be exceptionally high. Traditional turbidity meters often struggle to provide accurate readings due to significant blockage of incident and scattered light by these particles. To address this challenge, our sludge concentration meter employs a 30-degree scattered light measurement approach. Additionally, our sensor features a cutting-edge nano-anti-fouling coating on its optical surface, ensuring maintenance-free operation for up to two months.