Efficient removal of norfloxacin by biological aerated filters: Effect of zeolite modification and analysis of microbial communities

Zeolites are inexpensive materials with a versatile range of uses. In this study, a biological aerated filter (BAF) with a zeolite as the filler was proposed for the first time to simultaneously remove norfloxacin (NOR), ammonium, and nitrate. To investigate the effect of zeolite modification on the BAF performance, a natural zeolite (NZ) was separately modified with (i) HCl, (ii) CeCl3 , and (iii) both HCl and CeCl3. First, the adsorption kinetics of NOR by the different modified zeolites was analyzed. The NZ, HCl-modified zeolite (HZ), and CeCl3 -HCl-modified zeolite (Ce@HZ) removed more than 90 % of NOR within 240 min. Subsequently, they were separately used as fillers for three BAFs to simultaneously remove NOR, COD, ammonium and nitrate. The removal efficiencies of COD and NOR were all higher than 90 % and 99.9 %, respectively. Meanwhile, HCl and HCl-CeCl3 modification enhanced the removal efficiency of ammonium and nitrate, respectively. Lastly, 16S rRNA sequencing was used to analyze the microbial communities in the BAFs. The results showed that Proteobacteria were dominant, and the species richness was the highest when HZ was used as the filler. The specific surface area of HZ was found to be nearly four times that of NZ. After modification with HCl and CeCl3, the zeta potential of NZ changed from -22.4 mV to 5.4 mV. The cost-effective modification process described here may offer insight into improved techniques for the removal of emerging pollutants for drinking water pre-treatment and deep sewage treatment.

Automated summary

Zeolites were used as fillers in a biological aerated filter (BAF) for simultaneous removal of norfloxacin, ammonium, and nitrate. Modified zeolites with HCl and HCl-CeCl3 demonstrated over 90% removal of norfloxacin within 240 minutes. The BAFs with modified zeolites also exhibited high removal efficiencies for COD, ammonium, and nitrate.