Design of Wastewater Treatment Plant for Phenol Removal
- Industry / Organization: Iron and Steel Industry (Coke Oven By-product Plant)
- Project Type: Wastewater treatment plant design and process simulation
- Geographical Context: India (reference to integrated steel plants regulated by CPCB)
- Process Overview: Treatment of phenolrich wastewater using supercritical CO₂ extraction, simulated using CHEMCAD® process simulator
Challenge
Chicago Bridge & Iron’s (CB&I) Process Engineering Division Gasification System was tasked with developing the design for a gasification system serving an LNG off-loading terminal. An innovative and energy efficient approach was taken utilizing waste heat from a nearby power plant. A key criterion in the design was to insure the new, interconnecting system did not compromise the mechanical integrity or operation of the plant cooling system.
Solution
A wastewater treatment plant was theoretically designed and simulated using the CHEMCAD® process simulator, focusing on the removal of phenol via supercritical CO₂ extraction. The process employs counter-current extraction where supercritical CO₂ selectively removes phenol from wastewater. The extracted phenol is subsequently separated and recovered through a distillation column, while CO₂ is depressurized, separated, recompressed, and recycled within the system. The PSRK (Peng–Soave–Redlich–Kwong) thermodynamic model was selected to accurately predict phase behavior under supercritical conditions. Comprehensive equipment modeling included pumps, compressors, heat exchangers, valves, extractors, separators, and a distillation column.
Results
Simulation results demonstrated that nearly all phenol present in the wastewater feed stream was removed. Approximately 7.8 kmol/h of phenol entering the system was recovered, with treated water containing almost zero phenol concentration. The effluent quality met and exceeded CPCB discharge standards. The simulation also successfully converged material and energy balances, validated phase envelopes, and provided detailed sizing data for critical equipment such as the distillation column.