LAUSR

Abstract The growth of industries and population is accompanied by the introduction of emerging chemical pollutants such as pharmaceutical compounds into natural water sources. The purification of these pollutants is essential to protect the environment and promote community health. The present study aims to investigate the removal of acetaminophen (ACT), one of the most widely used pharmaceutical compounds, and chemical oxygen demand (COD) through a completely environmentally friendly biological method, namely cyclic biological reactor (CBR). This process is performed using high-load synthetic pharmaceutical wastewater on a laboratory scale. During the study the effect of cycle time, hydraulic retention time (HRT), ACT and COD concentration, and temperature on reactor performance are inspected. Finally, the performances of two CBR and sequencing batch reactor (SBR) are compared. Financial analysis, analysis of variance (ANOVA), and nonlinear regression are applied to study the influence of cycle time and concentration of ACT and COD on CBR performance. Two cubic models have been developed for the effect of cycle and concentration on ACT and COD removal efficiencies using design expert software. The models are utilized to calculate the optimum operating conditions. At 18-h cycle and 500 mg/L ACT and 7600 mg/L COD concentrations, the models show 98 % and 95 % removal efficiencies for ACT and COD, respectively. Results showed that CBR is an economically proper process to treat various types of wastewaters thanks to its low-space occupation, easy operation, low-energy consumption, and, high efficiency. It can also be used to upgrade old treatment plants in the future.