Handling phenolic wastewater from coke ovens and by-product plants In integrated steelworks, how is phenolic water from coke ovens/by-product recovery commonly managed to minimise pollution and conserve resources?

Introduction / Context:
Coke oven and by-product recovery operations generate phenolic wastewater containing phenols, cyanides, ammonia, thiocyanates, and suspended matter. This stream is environmentally hazardous and requires careful management. Plants aim to reduce fresh water intake and pollutant discharge by treating and reusing water within the process loop wherever feasible.

Given Data / Assumptions:

• Phenolic water originates from gas cooling, tar separation, and by-product recovery steps.
• Compliance requires minimising untreated discharge and preventing toxic releases to natural waters.
• On-site treatment and reuse are available.

Concept / Approach:
An effective practice is to treat the contaminated water (e.g., oil/tar removal, ammonia stripping, suspended solids removal, and further polishing) and recycle it back to process services such as coke oven gas cooling. This reduces river discharge, limits phenolic load to the environment, and lowers fresh water demand. Using such water for coke quenching is generally undesirable due to air emission of phenolic vapours. Direct discharge is unacceptable without adequate treatment.

Step-by-Step Solution:

Verification / Alternative check:
Typical flowsheets for integrated steel plants show internal loops where treated water is reused for gas cooling, with biological treatment applied to remove phenols before any final discharge.

Why Other Options Are Wrong:

Common Pitfalls:
Relying only on simple filtration; phenolic removal typically needs stripping/biological steps. Always verify with local discharge norms.

Final Answer:
filtration and recycling for cooling coke oven gas.