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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.

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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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A calibrated ASM 2d model of a full scale MBR is modified as to include the soluble microbial products (SMPs) fractions and study their dynamics in full scale. Batch tests were conducted to estimate the SMP kinetics. The biomass associated products (BAPs) kinetics were estimated with results in tune with previous experiments. The utilization associated products (UAP) kinetics estimation was instead complicated by two aspects which regularly occur when spiking readily biodegradable COD: storage phenomena (not accountable in ASM 2d); the non-uniformity between the polysaccharide fraction, easily biodegradable, and the protein fraction, which proved to be refractory to biodegradation. The procedure for UAP kinetics estimation would thus require further analysis. UAPs were found in full scale markedly predominant compared to the BAPs. The data analysis revealed that the membrane rejection mechanism was identified as SMP loading rate dependent, emphasizing the need of a more careful consideration towards this parameter when working in a dynamic environment. The work discusses the feasibility of the SMP extension studies in dynamic conditions. Fine tuning of the membrane rejection factor, the necessity of more frequent sampling, and experimental determination of the additional kinetics SMP parameters become necessary and burdensome adaptations of the ASM calibrations. However both nutrients removal, sludge production and energy consumption modelling were not improved by including the SMP fraction in the modelling. SMPs did not correlate with fouling rates in this full scale MBR, indicating a strong drawback, since the main drive for these models is thus not accomplished.

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