Chromium-containing wastewater treatment system
The chromium-containing wastewater treatment system is a special technology and equipment for treating industrial wastewater containing chromium. It is mainly used to reduce the concentration of chromium in water to meet environmental protection standards. Chromium is a heavy metal that is widely present in wastewater from electroplating, leather, dyes and other industries. It has strong toxicity and environmental hazards. Therefore, it is particularly important to develop an effective sewage treatment system.
Characteristics of chromium-containing wastewater
Chromium-containing wastewater is usually divided into two forms:
Hexavalent chromium: Commonly found in electroplating and chemical industries, it is highly toxic and easily soluble in water.
Trivalent chromium: Relatively low toxicity, but its concentration still needs to be controlled to avoid environmental pollution.
Treatment methods
1. Physical method
Precipitation method: chromium is precipitated by adding flocculants to separate solid waste.
Membrane separation technology: ultrafiltration or nanofiltration membranes are used to remove chromium ions in water.
2. Chemical method
Reduction method: Use a reducing agent (such as sodium sulfite) to reduce hexavalent chromium to trivalent chromium, followed by precipitation treatment.
Neutralization method: chromium is precipitated by adjusting the pH value, usually combined with precipitation method.
3. Biological method
Biodegradation: chromium is converted into harmless substances by microorganisms. This method works better when treating low-concentration chromium-containing wastewater.
4. Comprehensive treatment technology
Modern sewage treatment systems often use a combination of multiple methods. For example, physical methods can be used to remove most of the suspended solids, and then chemical and biological methods can be used to further reduce the concentration of chromium in the water.
Treatment process
The following is a typical chromium-containing sewage treatment process:
Pretreatment: Remove large particles of suspended solids.
Chemical treatment: Add a reducing agent to convert hexavalent chromium into trivalent chromium.
Precipitation and separation: Chromium is precipitated in a sedimentation tank.
Biological treatment: Use activated sludge method or other biological treatment technologies to further degrade organic matter and residual metal ions.
Post-treatment and disinfection: Ensure that the effluent meets the discharge standards.
Conclusion
With the increasingly stringent environmental regulations, the effective treatment of chromium-containing wastewater has become particularly important. By rationally selecting and combining different treatment technologies, the chromium content in sewage can be effectively reduced, and water resources and the ecological environment can be protected. Enterprises should choose appropriate sewage treatment systems according to their actual conditions to achieve sustainable development goals.