In the treatment of metal-containing wastewater, PAM is often combined with inorganic flocculants such as polyaluminum sulfate and polyaluminum chloride to form a composite flocculant. The addition of PAM can cause the particles to form coarse alum flowers through adsorption bridging, thereby accelerating Settling to improve the flocculation effect.

      Chromium-containing wastewater: Chromium in the electroplating wastewater exists in the form of Cr3 + and Cr6 +, of which Cr6 + is 100 times more toxic than Cr3 +. It is irritating to the skin and can cause skin ulcers. Long-term intake can cause diseases such as sarcoma and squamous cell carcinoma. Therefore, the wastewater containing Cr6 + must be treated with reasonable treatment technology and recovery methods to meet the national wastewater discharge standards.

      Nickel-containing wastewater: A large amount of wastewater is generated during the nickel electrolysis process, and its composition is relatively complex. In addition to a small amount of mail extractant, oil and some particulate suspended matter, it also contains nickel, cobalt and copper and other metal ions. Discharging these waste waters without treatment will not only cause serious environmental pollution, but also lose metal resources. The combination of PAM and different inorganic flocculants has a good removal effect on nickel.

     Copper-containing wastewater: APAM is used in conjunction with other agents (such as sodium diethyldithiocarbamate) to effectively treat copper-containing electroplating wastewater. After the latter reacts with copper-containing waste water as an absorbent, the pH value is adjusted with sodium hydroxide, and then put into polyferric sulfate and APAM, and then clarified and discharged after flocculation.

     Calcium, magnesium and other hardness-producing wastewater: use APAM with some chemicals to treat hardness ions in the circulating cooling water of the power plant. APAM mainly plays a role in flocculation, greatly reducing the residence time of the clarifier.

     In the next section, we will expand the application of polyacrylamide in the treatment of organic wastewater.