Chemical precipitation method for heavy metal wastewater

Precipitation by means of chemical process for wastewater laden with heavy metals
Presently, the chemical precipitation method stands as the most prevalent treatment methodology for wastewater containing low concentrations of heavy metals. This method entails the introduction of chemical agents into wastewater, thereby transforming heavy metals into heavy metal compounds via chemical reactions for precipitation.
Treatment of wastewater contaminated with heavy metals
Neutralization precipitation method
By incorporating neutralizing agents such as composite alkali into the wastewater, the pH level of the wastewater can be adjusted to attain the natural precipitation threshold of heavy metals in water, subsequently precipitating in the water.
Coagulation sedimentation method
By introducing coagulants such as calcium salts, aluminum salts, and iron salts into wastewater, they undergo coagulation and precipitation reactions with heavy metals present in the wastewater, yielding heavy metal precipitates. These heavy metals are subsequently isolated from the water through precipitation separation.
Sulfide precipitation method
By incorporating sulfide precipitants such as sodium sulfide into wastewater laden with heavy metals, it forms sulfide precipitates with heavy metal ions in the water. However, owing to the fact that sodium sulfide is a hazardous chemical and is subject to numerous regional and usage constraints, its application is becoming increasingly uncommon.
In the chemical precipitation method, due to the subpar treatment efficacy of the preceding traditional methods, there exist certain shortcomings in the treatment outcomes and sludge volume. An increasing number of individuals are adopting the heavy metal chelation method, which involves the addition of heavy metal removal agents to wastewater laden with heavy metals to induce chelation reactions with heavy metal ions in the wastewater, forming dense insoluble precipitates, and subsequently significantly enhancing the sedimentation rate and removal rate through net capture of flocs.