Removal of chlortetracycline in membrane biofilm reactor based on hydrogen and oxygen

SUMMARY Removal of Chlortetracycline in Membrane Biofilm Reactor Based on Hydrogen and Oxygen Antibiotics are pharmaceutical chemical group used in human and animal therapeutic purposes. Because of the widespread use of the antibiotics, they are an important micropollutant group. Commonly found in wastewater and receiving environment. They should be removed from the water because of their negative impact on the aquatic environments even at micro levels. In this study, simultaneous removal of chlortetracycline (CTC) and nitrate in membrane biofilm reactors (MBfRs) based on hydrogen (H2-MBfR) and oxygen (O2-MBfR) have been studied. For this purpose; effects of the hydraulic retention time (HRT) and partial pressure of H2 and O2 on the removal were investigated and under these conditions the degredation products such as (ECTC, ACTC and EACTC) were monitored. In addition, surface loadings and removal fluxes of pollutants were calculated for both reactors by considering the surface area of the membrane used in the system. H2 as an electron donor and NO3-N as a primary and CTC as a secondary electron acceptors were used in H2-MBfR, while O2 as an electron acceptor, NH4-N as a primary and CTC as a secondary electron donors were used in O2-MBfR. H2-MBfR receiving approximately 20-25 mg-N/l as NO3-N and 0.4-0.5 mg-CTC/l were operated under different HRTs, and H2 pressures. O2-MBfR receiving approximately 20-25 mg-N/l as NH4-N and 0.1-0.4 mg-CTC/l were operated under different HRTs in the range of 2.5-18 h, and O2 pressures in the range of 2-6 psi. The results showed that H2-MBfR accomplished successfully the degradation of CTC and it reached to CTC removal of 96 % at 5 h of HRT and 2 psi of H2 gas pressure, while 70 % CTC could be removed at 18 h of HRT and 6 psi of O2 gas pressure in O2-MBfR. In addition, polluting gas equivalent flux in both systems is also calculated. 0.357 solid H2 equivalent of each NO3-N flux, NH4-N flux of 4.57 times the O2 equivalent again addressed concurrently with nitrogen pollutants CTC the gas equivalent flux determined and in H2 MBfR CTC flow rate of 0178 times each equivalent flux of H2 and O2 flux 1.86 times the rate of CTC - MBfR O2 equivalent is calculated flux. Concentrations of the ECTC, ACTC and EACTC under the investigated conditions were found to be 28, 6 and 1 ppb for H2-MBfR and 7, 4 and 1 ppb for O2-MBfR. Surface fluxes and removal fluxes of CTC and NO3-N in H2-MBfR were calculated to be 185.04, 8280 and 71.64, 2520 mg/m2.g, respectively. Same fluxes of CTC and NH4-N in O2-MBfR were found to be 14.51, 1612.8 and 3.72, 1566 mg/m2.g, respectively. Keywords: MBfR, CTC, Flux, Degradation Products, Nitrification, Denitrification