How to measure moisture content in the wastewater? – OHAUS

In recent years, the environmental problems, including global warming, air/water pollution etc., has drawn extensive attention from the international community.

Why do we need to measure the moisture content in wastewater?

In recent years, the environmental problems, including global warming, air/water pollution etc., has drawn extensive attention from the international community. Multiple governments have enacted laws and regulations to protect our environment.In the area of water pollution control, municipal wastewater treatment is an important aspect. Generally, the wastewater goes through wastewater treatment process and produces sludge, a semi-solid slurry. The sludge is then dewatered before disposed in a landfill site. A fast moisture content determination is critical in wastewater treatment process in two perspectives.

On one hand, the quality of sludge needs to comply with the regulations. The moisture content requirement of the sludge after dewatering is clearly defined in the regulations. For instance, in Chinese national standard, the sludge moisture content needs to be below 80%. Disposing sludge with >80% moisture content could face serious administrative penalty.

On the other hand, the cost of wastewater treatment is directly linked with the solid weight. For a plant dewatering 2000m² of sludge, a -0.5% solid weight change could potentially save tens of thousands of dollars in flocculants cost annually.

Therefore, it is crucial to accurately measure moisture content in wastewater and sludge.

How to measure the moisture content in wastewater?

The standard method to measure the moisture content in wastewater is the oven method, lasting at least a couple of hours. However, with a moisture analyzer, it takes only 5-20mins. Even better, no calculation of moisture content based on wet and dry weight is needed.
To ensure an accurate measurement of moisture content in wastewater, two things we need to extra attention to. Firstly, the wastewater is a liquid substance with suspended solids. A good sample preparation process is critical. Secondly, a powerful moisture analyzer, which can provide accurate and repeatable test results, is also a key factor.


Sample Preparation

1. Sample collection

A sample is collected from the wastewater tank. The sample needs to be representative.

2. Sample preparation3-(1).jpgAfter sample is collected, carefully mix the sample until its homogeneous state before placing it on a sample pan.

Use a pipette to extract the most representative sample from the middle of the beaker.

3. Sample placement onto the glass fiber4.png

When we place the liquid sample onto the pan, it tend to generate drop shape on the pan because of the surface tension of liquid. This prevents the moisture evacuation and lead to a slow measuring process.

A glass fiber pad is recommended. By using it, the surface tension is reduced and overall surface area is increased and this ensures a faster measurement process and a repeatable result.

5.jpgMoisture analyzer

A good sample preparation is only part of a success moisture analysis. A reliable moisture analyzer is another a key factor. The customer chooses Ohaus MB120 for their process, because its ability to produce accurate, repeatable and fast test results.
Ohaus MB120 offers a halogen heating system with the highest drying temperature of 230°C. This enables an efficient dry process. Moreover, Ohaus MB120 features a readability of 0.01% and repeatability of 0.015%, which ensures accurate and repeatable test results. Furthermore, the full color touch screen on Ohaus MB120 displays detailed information, which enables a very simple and easy man machine interaction.

In summary, Ohaus MB120 with good sample preparation provides quick, easy and reliable moisture analysis. The accurate moisture content greatly contribute to the cost saving and efficient operation of wastewater treatment facilities.