source:LASEN Environmental Protection release date:2025-12-12 Number of reads:75
Heavy metal pollution in industrial wastewater has become a core challenge in global water environmental management. Heavy metals such as cadmium, lead, and chromium pose persistent threats to ecosystems and human health due to their non-biodegradability, bioaccumulation potential, and high toxicity. In China, stringent regulations—including the Integrated Wastewater Discharge Standard (GB 8978-1996)—impose strict controls on 13 Category I pollutants, including total mercury, cadmium, and hexavalent chromium. These regulations require industrial facilities to treat wastewater at the workshop or production facility level to meet discharge limits for heavy metals at the milligram-per-liter (mg/L) level or lower.
Against this backdrop, developing effective and cost-efficient technologies for treating heavy metal-containing wastewater has become essential to achieving regulatory compliance and enabling resource recovery.
Membrane separation technology
Membrane separation technology, with its advantages of strong selectivity and simple operation, demonstrates unique value in the treatment process of heavy metal wastewater. The rejection rate of reverse osmosis membranes for divalent and higher-valence heavy metal ions exceeds 99%, and the treated water can be directly reused in production processes. Nanofiltration membranes can selectively retain specific heavy metal ions (such as copper and nickel), enabling fractional recovery. Electrodialysis technology achieves the separation of concentrated heavy metals and freshwater through the selective permeation of ion exchange membranes, and the concentrated solution can be further electrolyzed to recover metals. The core challenge of membrane technology lies in membrane fouling control, which requires extending membrane lifespan through regular cleaning, pretreatment optimization, and other measures.
Adsorption and Ion Exchange
Adsorption technology captures heavy metals through physical/chemical interactions with porous materials (such as activated carbon, zeolites) or functionalized materials (such as chelating resins, biomass adsorbents). Activated carbon can achieve an adsorption capacity of 50-100 mg/g for lead and cadmium, but its regeneration efficiency is relatively low. Chelating resins enable selective adsorption of heavy metals via specific functional groups (such as aminophosphonic and thiol groups) and can be reused after regeneration. Biomass adsorbents (such as chitosan and algae) utilize natural polymer structures to adsorb heavy metals, offering both environmental friendliness and cost-effectiveness. Ion exchange technology, on the other hand, replaces heavy metal ions in wastewater with exchangeable ions on the resin, making it suitable for treating low-concentration wastewater. However, the resin requires periodic regeneration using strong acids or bases.
Electrochemical methods
The electrochemical method directly removes or recovers heavy metals through electrode reactions. In the electrolysis process, under the action of direct current, heavy metal ions are reduced to elemental metals (such as copper and nickel) at the cathode, enabling resource utilization. The electrocoagulation method employs soluble electrodes (such as iron and aluminum) as anodes, generating flocculants through electrochemical dissolution to simultaneously remove heavy metals and suspended solids. Membrane electrolysis technology combines electrochemistry with membrane separation to achieve the concentration of heavy metals and the reuse of freshwater. The core advantages of the electrochemical method lie in its high treatment efficiency and high purity of metal recovery. However, the issue of energy consumption needs to be addressed by optimizing electrode materials and reaction conditions.
Achieving compliance with heavy metal discharge standards is not the final goal, but rather a systemic endeavor that spans the entire production process. At the source, process optimization is essential to reduce heavy metal usage—for example, electroplating enterprises can adopt cyanide-free plating technologies to fundamentally minimize pollutant generation. During production, intelligent equipment plays a critical role in process control and management.
With 15 years of hands-on experience in wastewater treatment, Lanshen Environmental Protection has helped over 500 chemical enterprises resolve a wide range of wastewater issues. Based on your specific needs, we can provide an integrated, one-stop solution covering chemical dosing optimization, biochemical system adjustment, process retrofitting, and engineering construction. If you require assistance, please click “Contact Us Now” in the top-right corner—we are committed to serving you!
Website:https://www.dglanshen.com/news_30/573.html
