distillation, purification, and by-product recovery processes of coking and coal gas production. It contains volatile phenols, polycyclic aromatic hydrocarbons, and heterocyclic compounds such as oxygen, sulfur, and nitrogen. It is a type of industrial organic wastewater with high CODcr, high phenol value, high ammonia nitrogen, and is difficult to treat.
2. There are three main sources of coking wastewater:
(1) Residual ammonia water, which is generated during coal dry distillation and coal gas cooling. Its volume accounts for more than half of the total coking wastewater and is the main source.
(2) Wastewater generated during coal gas purification, such as final cooling water from coal gas and crude benzene separation water.
(3) Wastewater generated during the refining processes of tar and crude benzene, and in other situations.
3. The easily degradable organic compounds in coking wastewater are mainly phenolic compounds and benzene compounds. Arsenol, naphthalene, furan, and imidazoles are degradable organic compounds. Recalcitrant organic compounds mainly include arsenic, carbazole, biphenyl, and terphenyl. The quality of coking wastewater varies greatly depending on the process flow and production operation methods of each plant.
4. The characteristics of coking plant wastewater are as follows: CODcr 3000-3800 mg/L, phenol 600-900 mg/L, cyanide 10 mg/L, oil 50-70 mg/L, and ammonia around 300 mg/L. If CODcr is calculated at 3500 mg/L and ammonia at 280 mg/L, then each ton of coke can produce at least 0.65 kg CODcr and 0.05 kg ammonia. With a national coke production of 70 million tons, this translates to 45,500 tons of CODcr and 3,500 tons of ammonia annually. If this wastewater is not treated, it will cause significant environmental pollution.
5. Coking wastewater mainly includes coal washing wastewater, coke quenching wastewater, ammonia stripping wastewater, tar processing wastewater, coal gas final cooling circulating water, crude benzene separation water, refined benzene separation water, ammonium sulfate wastewater, and other wastewater.
