Optimal design of a high atom utilization and sustainable process for the treatment of crude phenol separation wastewater

The wastewater generated by crude phenol separation (CPS) process contains complex pollutants such as oil, phenolic compounds, and sodium sulfate. The environment will be seriously destroyed if the wastewater is discharged without proper treatment. In order to dispose crude phenol separation process wastewater (CPSW) effectively, this paper proposes an integration system that combines the source exploration of CPS and the optimum design of CPSW treatment. The CPS process is first simulated to obtain the composition of CPSW and then optimized to improve its atomic utilization. A treatment process is then designed after CPS process simulation, which is divided into two parts: the extraction of phenol and the electrolysis of sodium sulfate. A novel phenol extraction process is proposed, in which the wastewater is separated into oil and aqueous phases according to density difference. As phenolic compounds exist in both two phases after separation, pyrazole and methyl n-butyl ketone (MBK) are used to extract phenol from the oil and aqueous phase, respectively. After that, a heat integration is explored for the extraction process to reduce the energy consumption. A control scheme is also established by supplementing necessary controllers. These controllers make the process get back to smooth operation quickly in the face of +10% disturbances of feed flow, which is verified by dynamic simulation. Finally, the sodium sulfate in CPSW is specifically disposed by electrolysis based on experimental results. The obtained sodium hydroxide and sulfuric acid solutions are recycled to CPS process for the further improvement of atom utilization.

Automated summary

This paper proposes an integration system combining the source exploration of CPS and the optimum design of CPSW treatment. By simulating and optimizing the CPS process, a novel phenol extraction method and sodium sulfate electrolysis treatment process are designed to effectively dispose of CPSW and reduce energy consumption.