An experimental investigation was carried out by IRSA on the treatment of a pharmaceutical wastewater stream obtained from the industrial production of the antibacterial nalidixic acid. Membrane bioreactor (MBR) followed by an oxidation step (specifically ozonation or UV/H2O2) as well as the integration of MBR and oxidation were investigated. The reported results reflect two main experimental activities: (i) the optimization of both the single processes and the integrated MBR-ozonation with a synthetic wastewater whose composition simulating the real industrial stream; (ii) the comparison of two different integrated processes (MBR-ozonation and MBR-UV/H2O2) for the treatment of the real wastewater. In the first set of experiments the membrane bioreactor was initially acclimated to the synthetic wastewater, then ozonation was inserted in the recirculation stream of the biological reactor. Separate tests of ozonation and UV/H2O2 application to the MBR effluent were carried out in order to investigate the formation of nalidixic acid by-products. Then, two tests with the integrated MBR-ozonation were performed, separated by a sufficient period for re-acclimatization of the biological system to the initial conditions. Ozone dosages of 68.7 and 206 mg L-1 were provided in the two tests of integrated MBR-ozonation. The system was continuously monitored in terms of gross parameters for the evaluation of process performance, and detailed chemical analyses were carried out in order to assess the fate of the main antibacterial compound and the formation/degradation of its by-products. The minimization of most of the identified by-products was better achieved with the integration of MBR with ozonation than using the conventional treatment configuration, i.e. polishing after biological oxidation by MBR. Moreover, the MBR biomass was characterized during the different experimental phases both in terms of respirometric activity, microbiology (FISH), and protein expression. In the second group of tests, after acclimatization of the MBR bacterial consortia to the real nalidixic acid wastewater, a first experiment with integrated MBR-ozonation and a second one with integrated MBR- UV/H2O2 were performed. Comparison with the conventional treatment configuration, i.e. oxidation polishing after MBR was always performed. The procedure adopted with the real wastewater was similar to the one tested with the synthetic stream. So the two experiments with the integrated processes were separated by a sufficient period for re-acclimatization of the biological system to the initial conditions. Moreover, also in this case separate ozonation and UV/H2O2 application to the effluent of the MBR fed on the real wastewater were carried out for investigating by-product formation. In the case of real industrial wastewater, other organic compounds were also identified and their fate during the employed treatment systems was investigated. As in the previous set of experiments the processes were closely monitored through conventional parameters and more specific chemical analyses. The system's biology was also monitored by measuring respirometric activity, and the main composition of bacterial consortia was investigated with FISH. Standard toxicity tests with bioluminescent bacteria (Microtox) were also performed in order to compare the real wastewater with the effluent of the different treatment phases (MBR, MBR-ozonation, MBR-UV/H2O2). Results showed the effectiveness of both the integrated MBR-ozonation and MBR-UV/H2O2 configurations in terms of nalidixic acid and by-products removal showing a synergistic effect of the chemical oxidation step placed in the recirculation stream of the biological system. The possibility of limiting the doses of chemical oxidants to those required for improving the biodegradability of recalcitrant compounds, allowing the biological system to remove the resulting by-products, was confirmed as the main advantage of the integrated configuration with respect to the use of chemical oxidation as a pre- or post-treatment. In the case of nalidixic acid this was successfully achieved with both the integrated system configurations tested.
Progetto FP6 INNOWATECH, Deliverable D 2.12 Report on the application of integrated MBR/AOP process to pharmaceutical wastewater
G Mascolo;A Pollice;C Salerno;
2009
Abstract
An experimental investigation was carried out by IRSA on the treatment of a pharmaceutical wastewater stream obtained from the industrial production of the antibacterial nalidixic acid. Membrane bioreactor (MBR) followed by an oxidation step (specifically ozonation or UV/H2O2) as well as the integration of MBR and oxidation were investigated. The reported results reflect two main experimental activities: (i) the optimization of both the single processes and the integrated MBR-ozonation with a synthetic wastewater whose composition simulating the real industrial stream; (ii) the comparison of two different integrated processes (MBR-ozonation and MBR-UV/H2O2) for the treatment of the real wastewater. In the first set of experiments the membrane bioreactor was initially acclimated to the synthetic wastewater, then ozonation was inserted in the recirculation stream of the biological reactor. Separate tests of ozonation and UV/H2O2 application to the MBR effluent were carried out in order to investigate the formation of nalidixic acid by-products. Then, two tests with the integrated MBR-ozonation were performed, separated by a sufficient period for re-acclimatization of the biological system to the initial conditions. Ozone dosages of 68.7 and 206 mg L-1 were provided in the two tests of integrated MBR-ozonation. The system was continuously monitored in terms of gross parameters for the evaluation of process performance, and detailed chemical analyses were carried out in order to assess the fate of the main antibacterial compound and the formation/degradation of its by-products. The minimization of most of the identified by-products was better achieved with the integration of MBR with ozonation than using the conventional treatment configuration, i.e. polishing after biological oxidation by MBR. Moreover, the MBR biomass was characterized during the different experimental phases both in terms of respirometric activity, microbiology (FISH), and protein expression. In the second group of tests, after acclimatization of the MBR bacterial consortia to the real nalidixic acid wastewater, a first experiment with integrated MBR-ozonation and a second one with integrated MBR- UV/H2O2 were performed. Comparison with the conventional treatment configuration, i.e. oxidation polishing after MBR was always performed. The procedure adopted with the real wastewater was similar to the one tested with the synthetic stream. So the two experiments with the integrated processes were separated by a sufficient period for re-acclimatization of the biological system to the initial conditions. Moreover, also in this case separate ozonation and UV/H2O2 application to the effluent of the MBR fed on the real wastewater were carried out for investigating by-product formation. In the case of real industrial wastewater, other organic compounds were also identified and their fate during the employed treatment systems was investigated. As in the previous set of experiments the processes were closely monitored through conventional parameters and more specific chemical analyses. The system's biology was also monitored by measuring respirometric activity, and the main composition of bacterial consortia was investigated with FISH. Standard toxicity tests with bioluminescent bacteria (Microtox) were also performed in order to compare the real wastewater with the effluent of the different treatment phases (MBR, MBR-ozonation, MBR-UV/H2O2). Results showed the effectiveness of both the integrated MBR-ozonation and MBR-UV/H2O2 configurations in terms of nalidixic acid and by-products removal showing a synergistic effect of the chemical oxidation step placed in the recirculation stream of the biological system. The possibility of limiting the doses of chemical oxidants to those required for improving the biodegradability of recalcitrant compounds, allowing the biological system to remove the resulting by-products, was confirmed as the main advantage of the integrated configuration with respect to the use of chemical oxidation as a pre- or post-treatment. In the case of nalidixic acid this was successfully achieved with both the integrated system configurations tested.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
