What are the difficulties in treating complex electroplating wastewater?

In recent years, due to the new progress in surface treatment technology, it has been widely used in electroplating and chemical plating. The use of a large number of complexing agents has led to a new trend in electroplating wastewater. Not only has the discharge of wastewater changed greatly, but the types of complexing agents are also increasing, and the composition of wastewater is becoming increasingly complex.

Complex heavy metal wastewater has always been a difficult and hot issue in the field of environmental protection due to the variety of metal types and difficulty in treatment. Compared with free heavy metal ions, complex heavy metals no longer exist in the form of a single heavy metal ion, but form stable chelates with substances such as citric acid, EDTA, tartaric acid, ammonia, etc. For example, in the nickel plating process, medium strength or weak chelating agents are generally used, with hydroxyl carboxylic acid being more commonly used.

Heavy metal ions and chelating agents form stable chelates, which are not easy to form hydroxide or sulfide precipitates. Therefore, traditional chemical precipitation methods cannot effectively remove heavy metal ions from wastewater, making removal more difficult. Therefore, a comprehensive comparison was made between existing treatment technologies for complex heavy metal wastewater, and induction and summary were made, hoping to provide reference for the optimization selection of complex electroplating wastewater treatment technology schemes and the in-depth development of treatment technology research.

Chemical, physical, and biochemical methods have their own advantages when used to treat complex electroplating wastewater, but they also have some shortcomings in practical applications.

The chemical precipitation method has simple equipment and convenient operation, but it is expensive and produces a large amount of sludge; The oxidation method requires a large amount of oxidation and high pharmaceutical costs; The ferrite method produces a large amount of mud;

The adsorption method should consider the regeneration and renewal of the adsorbent;
The ion exchange method also needs to consider the frequent regeneration of ion exchange resins.

So a single method for treating complex heavy metal wastewater is not the best choice, and the optimized combination of multiple methods should have greater development prospects for the treatment of complex heavy metal wastewater.