Through their release of effluents, conventional wastewater treatment plants (WWTPs) represent a major pollution point sources for pharmaceutically active compounds (PhACs) in water bodies. The combination of a biological activated carbon (BAC) filter coupled with an ultrafiltration (UF) unit was evaluated as an advanced treatment for PhACs removal at pilot scale. The BAC-UF pilot plant was monitored for one year. The biological activity of the biofilm that developed on the granular activated carbon (GAC) particles and the contribution of this biofilm to the overall removal of PhACs were evaluated. Two different phases were observed during the long-term monitoring of PhACs removal. During the first 9200 bed volumes (BV; i.e., before GAC saturation), 89, 78, 83 and 79% of beta-blockers, psychiatric drugs, antibiotics and a mix of other therapeutic groups were removed, respectively. The second phase was characterized by deterioration of the overall performances during the period between 9200 and 13,800 BV. To quantify the respective contribution of adsorption and biodegradation, a lab-scale setup was operated for four months and highlighted the essential role played by GAC in biofiltration units. Physical adsorption was indeed the main removal mechanism. Nevertheless, a significant contribution due to biological activity was detected for some PhACs. The biofilm contributed to the removal of 22, 25, 30, 32 and 35% of ciprofloxacin, bezafibrate, ofloxacin, azithromycin and sulfamethoxazole, respectively.
Microbacterium sp. strain BR1 is a bacterial strain that recently received attention for its capability to mineralize sulfamethoxazole (SMX) and other sulfonamides. In this study, the survival of Microbacterium sp. in municipal sludge waters was tested in batch experiments to explore optimal process conditions. Inoculation of Microbacterium sp. was subsequently performed in a pilot membrane bioreactor (MBR) operated in two configurations: treating full-scale MBR permeate (post-treatment) and treating raw municipal wastewater. SMX removal by Microbacterium sp. could not be proved in any of the configurations, except for SMX concentrations far higher than the ones normally found in municipal wastewater. By use of molecular tools (fluorescence in situ hybridization analysis) a low capability to survive in activated sludge systems was assessed. After inoculation, Microbacterium sp. was reduced to a small fraction of the viable biomass. The observed growth rate appeared to be many times lower than the one of typical activated sludge micro-organisms. Possibilities of application in full-scale municipal wastewater treatment are scarce.
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