Phenol Cyanide Wastewater Treatment Process

In order to effectively remove CODCr and ammonia nitrogen from wastewater and ensure that the effluent quality meets national discharge standards, biological denitrification technology has emerged as a new and efficient technology in phenol cyanide wastewater treatment processes. Biological denitrification is the application of nitrification and denitrification reactions, which are two organic components of biological denitrification.

Step 1: First, add sodium hypochlorite to the phenol cyanide wastewater. Sodium hypochlorite is an effective method for removing cyanide ions and their compounds from wastewater. Under appropriate pH control, add NaClO solution to the wastewater to oxidize CN - to CO2 and N2. The reaction is as follows:

CN-+ClO-+H2O→CNCl+2OH-

CNCl+2OH-→CNO-+Cl-+H2O

2CNO-+3ClO-→CO2↑+N2↑+3Cl-+CO32-

Sodium hypochlorite is a strong oxidant that can remove most of the organic compounds in phenol cyanide wastewater, reducing the difficulty of subsequent biochemical treatment;

Step 2: Add ferrous sulfate to the phenol cyanide wastewater after a period of reaction in the first step, allowing excess sodium hypochlorite to synergistically react with ferrous sulfate, producing highly oxidizing free radicals that decompose organic matter in the wastewater, reducing the COD of phenol cyanide wastewater from around 4000mg/L to below 800mg/L;

Step 3: Use a dual membrane method of ultrafiltration membrane and reverse osmosis membrane to treat the phenol cyanide wastewater treated in the second step, so as to convert the wastewater into clear and concentrated solutions, and make the COD of the clear water less than 10mg/L, and the effluent concentration meet the requirements of the "Water Quality Standards for Recycled Water for Circulating Cooling Water (HG/T3923-2007)";

Step 4: The concentrated solution generated in Step 3 is further subjected to biochemical treatment and partially used as quenching water, while the remaining concentrated solution is further treated with flocculants for further separation and precipitation before being discharged.

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