Treatment of sodium nitrate wastewater from a precious metal enterprise in Wenjiang District, Sichuan Province
Sodium nitrate wastewater evaporation treatment project
The organic matter of high salinity organic wastewater varies greatly according to the production process, and the types and chemical properties of the organic matter are quite different.The salt substances are mostly Cl-, SO42-, Na+, Ca2+ ,etc. If it is directly discharged, it has a great impact on the environment; and it is difficult to handle in the biochemical treatment process. These ions are essential nutrients for microbial growth, which can promote enzyme reaction and maintain membrane balance and regulate osmotic pressure.However,if these ion concentrations are too high, it will inhibit and toxic the microorganisms. High salt concentration, high osmotic pressure will cause dehydration of microbial cells and protoplast separation; salting out reduces dehydrogenase activity; high chloride ion has toxic effect on bacteria; High salt concentration and increased density of wastewater will let the the active mud to float and drain, which seriously affects the purification effect of the biological treatment system.
For high salt water, it mainly comes from the following aspects:
1. High-salt wastewater from chemical production processes;
2. From chemical wastewater treatment;
3. High-salt wastewater from freshwater recycling process.
For sodium nitrate high salt water, the solubility of the material is high, and the boiling point is higher in the case of saturated solubility.The physical properties of the data are as follows:
Sodium nitrate solubility
|
Item |
Maximum dissolved mass / g in 100g water at the following temperatures |
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|
0 |
10 |
20 |
25 |
30 |
40 |
50 |
60 |
70 |
80 |
90 |
100 |
|
|
Sodium nitrate |
72.7 |
79.9 |
87.6 |
91.6 |
96.1 |
105 |
114 |
125 |
|
149 |
|
176 |
Sodium nitrate boiling point
|
Item |
Boiling point / ℃ of the solution at the following concentrations (g / 100g water) |
||||||
|
10 |
25 |
40.7 |
50 |
75 |
100 |
222 |
|
|
Sodium nitrate |
101.1 |
102.7 |
|
105.2 |
107.6 |
110.1 |
126 |
Project
|
No |
Item |
Introduction |
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|
1 |
Name |
Treatment of sodium nitrate wastewater from a precious metal enterprise in Wenjiang District, Sichuan Province |
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|
2 |
Address |
Sichuan Chengdu |
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|
3 |
Treatment of wastewater industry |
Precious metal smelting |
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|
4 |
Capacity |
5Ton/hour |
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|
5 |
Process Technology |
Raw water - preheating system - MVR evaporation concentration - single effect evaporation - cold crystallization system |
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|
6 |
Process introduction |
The project is a mixed wastewater treatment project containing sodium sulfate, sodium chloride and sodium nitrate. The former stage is treated by MVR evaporation. During this process, sodium sulfate and sodium chloride are concentrated to supersaturation.Sodium sulfate and sodium chloride are separated by thermal crystallization.For the enriched sodium nitrate, it is further concentrated by single-effect evaporation.After that,cold crystallization is carried out to ensure stable operation of the system. |
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|
7 |
Photos |
Inlet water |
Evaporation water |
Salt discharge |
