The main applications of nanofiltration water treatment equipment in sewage treatment are as follows:

1. Softening:

Membrane softening water mainly uses the selective permeability of nanofiltration membranes for ions of different valence states to soften water. While removing hardness, membrane softening can also remove turbidity, chromaticity and organic matter, and its effluent water quality is significantly better than other softening processes. Moreover, membrane softening has the advantages of no need for regeneration, no pollution, simple operation, and less land occupation, and has obvious social and economic benefits.

Membrane softening is very common in the United States. In the past 10 years, new softening water plants in Florida have adopted membrane softening to replace conventional lime softening and ion exchange processes. In recent years, with the continuous improvement of nanofiltration performance and the continuous decline in the price of nanofiltration membrane components, membrane softening has been superior to or close to conventional methods in terms of investment, operation, and maintenance.

2. Used to remove organic matter in water:

In addition to softening, nanofiltration membranes are mostly used for decolorization, removal of natural and synthetic organic matter (such as pesticides), trihalomethanes, disinfection byproducts (trihalomethanes and haloacetic acids) and their precursors and volatile organic matter in drinking water treatment, to ensure the biological stability of drinking water, etc.

3. Removal of trihalomethanes:

Studies have shown that nanofiltration membranes can remove most of the toxic and harmful organic matter and Ames mutagens in water, making the mutagenicity ratio MR values ​​of TA98 and TA100 strains less than 2 at each test dose, and the Ames test results are negative. Further research will examine the interception characteristics of nanofiltration technology for endocrine disrupting substances in drinking water to provide a basis for safe drinking water.

4. Removal of disinfection byproducts and their precursors:

Disinfection byproducts mainly include trihalomethanes (THMs), haloacetic acids (HAAs) and possible trichloroacetaldehyde hydroxide (CH). Foreign scientific and technological workers have conducted extensive research in this regard. The average retention rates of nanofiltration membranes for the precursors of these three disinfection byproducts are 97%, 94% and 86% respectively. By selecting appropriate nanofiltration membranes, the quality of drinking water can meet higher standards for safe drinking water quality.

5. Removal of volatile organic compounds (VOCs):

It has a high removal rate for trace volatile organic compounds in drinking water.

6. Application in piped drinking water:

Nanofiltration can intercept ions with a valence of more than two and other particles, and only water molecules and some monovalent ions (such as sodium, potassium, and chloride ions) are passed through. Nanofiltration can be used to produce direct drinking water, and a certain amount of ions are still retained in the effluent, and the treatment cost can be reduced.