Measurement method of suspended solids: gravimetric method

1. Measurement method of suspended solids: gravimetric method

2. Measuring method principle

Filter the water sample with a 0.45μm filter membrane, leave it on the filter material and dry it at 103-105°C to a constant weight solid, and obtain the suspended solids content after drying at 103-105°C.

3. Preparation before experiment

3.1, Oven

3.2 Analytical balance

3.3. Dryer

3.4. The filter membrane has a pore size of 0.45 μm and a diameter of 45-60 mm.

3.5, glass funnel

3.6. Vacuum pump

3.7 Weighing bottle with an inner diameter of 30-50 mm

3.8, toothless flat mouth tweezers

3.9, distilled water or water of equivalent purity

4. Assay steps

4.1 Put the filter membrane in a weighing bottle with tweezers without teeth, open the bottle cap, move it into an oven (103-105°C) and dry it for 2 hours, then take it out and cool it to room temperature in a desiccator, and weigh it. Repeat drying, cooling, and weighing until constant weight (the difference between the two weighings is not more than 0.5mg).

4.2 Shake the water sample after removing suspended solids, measure 100ml of a well-mixed sample and filter it with suction. Let all the water pass through the filter membrane. Then wash three times with 10ml of distilled water each time, and continue suction filtration to remove traces of water. If the sample contains oil, use 10ml of petroleum ether to wash the residue twice.

4.3 After stopping the suction filtration, carefully take out the filter membrane loaded with SS and place it in the weighing bottle with the original constant weight, move it into an oven and dry it at 103-105°C for 2 hours, then move it into a desiccator, let it cool to room temperature, and weigh it , repeatedly drying, cooling, and weighing until the weight difference between the two weighings is ≤ 0.4mg. the

5. Calculate:

Suspended solids (mg/L) = [(A-B)× 1000× 1000]/V

In the formula: A——suspended solid + filter membrane and weighing bottle weight (g)

B——Membrane and weighing bottle weight (g)

V——water sample volume

6.1 Applicable scope of the method This method is suitable for the determination of suspended solids in wastewater.

6.2 Precision (repeatability):

Repeatability: The same analyst in the laboratory samples 7 samples of the same concentration level, and the relative standard deviation (RSD) of the obtained results is used to express the precision; RSD≤5% meets the requirements.