Treatment of organic wastewater by ozone in a continuous rotating solid foam stirrer tank

Abstract

The work herein employed a novel rotating solid foam stirrer tank (RSFST) under continuous operation in attempt to intensify ozone-liquid mass transfer rate and possibly enhance treatment of organic wastewater. P-nitrophenol (PNP) and acid red B (ARB) were separately used to simulate phenolic and dye wastewater. Results show that the removal efficiency of PNP and ARB dye increased with increasing rotational speed and gas flow rate but decreased with increasing liquid flow rate and initial wastewater concentration. The highest removal efficiency of PNP and ARB was attained at pH of 11 and 7, respectively. Ozone utilization efficiency increased with increasing stirring speed, liquid flow rate, initial wastewater concentration and pH but decreased with increasing gas flow rate. The treatment efficiency of organic wastewater in the RSFST reactor is superior to that of many other reactors (rotating packed bed and bubble column, etc.). Correlations to predict the removal efficiency of the organics were developed and the deviation between the experimental and predicted values is within 15%, indicating that the correlations can be used to predict the removal efficiency of PNP and ARB by ozone in RSFST. The study provides a scientific reference for development of a new high-efficiency ozone oxidation reactor.