Performance of a novel multiple draft tubes airlift loop membrane bioreactor to treat ampicillin pharmaceutical wastewater under different temperatures

In this study, the performance and removal mechanisms of a novel lab-scale multiple draft tubes airlift loop membrane bioreactor (Mt-ALMBR) for treating high-strength ampicillin pharmaceutical wastewater under different temperatures (7 degrees C, 16 degrees C, 24 degrees C, 36 degrees C, 48 degrees C) were investigated. During 150 days operation, the optimal average chemical oxygen demand (COD) and ampicillin removal rates were 98.2 +/- 0.2% (36 degrees C) and 63.2 +/- 5.6% (7 degrees C), respectively. The main mechanisms of pollutants removal were membrane removal (7 similar to 16 degrees C) and bioreactor removal (16 - 48 degrees C). Adsorption and membrane rejection were main pathways at low temperature, as temperature increased, hydrolysis and biodegradation gradually occupied a dominant position. Meanwhile, the optimum temperature ranges for activated sludge microorganisms were 16 degrees C similar to 36 degrees C, the corresponding beta-lactamase at 36 degrees C was the highest activity value among all the set temperature values. Experimental results showed that temperature had a significant impact on the removal rate, the optimum temperature range was proposed to be at 24 similar to 36 degrees C. The half-life (t(1/2)) of ampicillin drastically decreased from 330.0 d to 2.1 d when the temperature was increased from 7 degrees C to 48 degrees C. And the maximum adsorption capacity K-f at the adsorption temperatures of 7, 16, 24, 36 and 48 degrees C was 0.1284, 0.2169, 0.0645, 0.1502 and 0.1524 mg/g, respectively. The values of Delta G degrees were all negative, proving that the adsorption process of the ampicillin belonged to a spontaneous physical adsorption. In addition, autoregressive integrated moving average (ARIMA) and mathematical fitting models were developed and well simulated the performance of Mt-ALMBR to treat the ampicillin wastewater. These results suggest that Mt-ALMBR holds great potential for application in ampicillin pharmaceutical wastewater treatment.