Characteristics and Treatment Methods for Cyanide-Containing Wastewater
1. Main Characteristics
Cyanide-containing wastewater primarily originates from industries such as electroplating, gas production, coking, metallurgy, metal processing, chemical fiber, plastics, pesticides, and chemical manufacturing. This type of wastewater is highly toxic and exhibits instability in water, facilitating its decomposition. Both inorganic and organic cyanides are extremely toxic substances, capable of causing acute poisoning in humans upon ingestion. The lethal dose for humans is 0.18g for cyanide and 0.12g for potassium cyanide. In aquatic environments, cyanide concentrations of 0.04–0.1 mg/L are lethal to fish.
Treatment Methods:
Process modifications should be prioritized to reduce or eliminate the discharge of cyanide-containing wastewater. For example, the adoption of cyanide-free electroplating can entirely eliminate cyanide discharge from electroplating workshops. Wastewater with high cyanide concentrations should be treated for resource recovery, while wastewater with low cyanide levels must undergo purification before discharge. Recovery methods include acidification-aeration, alkaline absorption, and steam desorption. Treatment methods such as alkaline chlorination, electrolytic oxidation, pressurized hydrolysis, biochemical treatment, bio-iron process, ferrous sulfate method, and air stripping are also employed. Among these, alkaline chlorination is the most widely applied.
Characteristics and Treatment Methods for Phenol-Containing Wastewater
1. Main Characteristics
Phenol-containing wastewater primarily originates from industrial sectors such as coking plants, gas plants, petrochemical plants, and insulating material manufacturers, as well as processes including petroleum cracking for ethylene production, synthetic phenol manufacturing, polyamide fiber synthesis, dye production, pesticide formulation, and phenolic resin synthesis. This wastewater contains phenolic compounds, which are protoplasmic toxins capable of coagulating proteins.
Treatment Methods:
Common treatment approaches include physical adsorption, chemical steam dephenolization, solvent extraction, chemical oxidation, activated sludge process, biofilm treatment, and biological contact oxidation.
