Gianluigi Buttiglieri

Comprehensive study of ibuprofen and its metabolites in activated sludge batch experiments and aquatic environment

Even though Ibuprofen is one of the most studied pharmaceutical in the aquatic environment, there is still a lack of information about its fate and the generation of different transformation products along wastewater treatment plants (WWTPs). Ibuprofen biotransformation products can be generated by human metabolism or by microorganisms present in WWTPs and in natural waters, soils, and sediments, which increase the probability to find them in environment. In this work, the presence of ibuprofen and its main metabolites: ibuprofen carboxylic acid (CBX IBU), 2-hydroxylated ibuprofen (2-OH IBU) and 1-hydroxylated ibuprofen (1-OH IBU), was monitored quantitatively along the biodegradation processes occurring in different batch activated sludge (BAS) experiments under different working conditions. Total ibuprofen removal, achieved in almost all the experiments, was related in part to the formation of the metabolites mentioned. Another ibuprofen metabolite, 1,2-dihydroxy ibuprofen, was detected in BAS experiments for the first time. The metabolites 2-OH IBU and 1-OH IBU remained in solution at the end of ibuprofen biodegradation experiments whereas CBX IBU disappeared faster than hydroxylated metabolites. In addition, also the biodegradation of 1-OH IBU, 2-OH IBU and CBX IBU was evaluated in batch experiments: CBX IBU removal occurred at the highest rate followed by IBU, 2-OH IBU, and 1-OH IBU, which exhibited the lowest removal rate. Finally, Ibuprofen and ibuprofen metabolites were monitored in sewage and natural water samples, where they were found at higher levels than expected: the maximum concentration in influent wastewater samples were 13.74, 5.8, 38.4, 94.0μg/L for IBU, 1-OH IBU, CBX IBU and 2-OH IBU respectively; whereas maximum levels in effluent wastewater samples were 1.9, 1.4, 10.7, 5.9 μg/L for IBU, 1-OH IBU, CBX IBU and 2-OH IBU respectively. High levels of the compounds were also found in river samples, in particular for CBX IBU, which was detected up to 3.9 μg/L.

Pharmaceuticals occurrence in a WWTP with significant industrial contribution and its input into the river system

Occurrence and removal of 81 representative Pharmaceutical Active Compounds (PhACs) were assessed in a municipal WWTP located in a highly industrialized area, with partial water reuse after UV tertiary treatment and discharge to a Mediterranean river. Water monitoring was performed in an integrated way at different points in the WWTP and river along three seasons. Consistent differences between therapeutic classes were observed in terms of influent concentration, removal efficiencies and seasonal variation. Conventional (primary and secondary) treatment was unable to completely remove numerous compounds and UV-based tertiary treatment played a complementary role for some of them. Industrial activity influence was highlighted in terms of PhACs presence and seasonal distribution. Even if global WWTP effluent impact on the studied river appeared to be minor, PhACs resulted widespread pollutants in river waters. Contamination can be particularly critical in summer in water scarcity areas, when water flow decreases considerably.

Effects on activated sludge bacterial community exposed to sulfamethoxazole.

The bacterial community shift on a lab scale Sequencing Batch Reactor (SBR) fed with synthetic wastewater and exposed to 50μgL(-1) of sulfamethoxazole (SFX) for 2months was investigated in this study. The impact on biological nutrient removal performance and SFX removal efficiencies were also studied. Satisfactory biological nutrient removal was observed as regards to COD and Nitrogen. SFX removal efficiencies ranged between 20% and 50% throughout the experimental period, enhanced within the aerobic phases of the SBR cycle, with no evident signs of biomass acclimation. Nevertheless, denaturing gradient gel electrophoresis (DGGE) analysis showed significant variance leading to not only the fading, but also the emergence of new species in the bioreactor bacterial community after SFX dosage. According to the phylogenetic analysis, bacteria belonging to Betaproteobacteria and Gammaproteobacteria classes were the dominant species, among them, the Thiotrix spp. (Gammaproteobacteria) cell number increased due to its tolerance to the antibiotic. On the other hand, the classes Sphingobacteria, Actinobacteria, Chloroflexi and Chlorobi were found to be more vulnerable to the antibiotic load and disappeared. The sulphonamide resistance gene sulI was also quantified and discussed, as there are very few studies on bacterial resistance in lab-scale treatment reactors.

Removal of ibuprofen and its transformation products: experimental and simulation studies.

Pharmaceutically active compounds (PhACs) deserve attention because of their effect on ecosystems and human health, as well as their continuous introduction into the aquatic environment. Classification schemes are suggested to characterise their biological degradation, e.g., based on pseudo-first-order kinetics, but these schemes can vary significantly, presumably due to pharmaceutical loads, sludge characteristics and experimental conditions. Degradation data for PhAC transformation products (TPs) are largely lacking. The present work focuses not only on the biodegradation of the pharmaceutical compound ibuprofen but also on its best-known TPs (i.e., carboxyl ibuprofen and both hydroxyl ibuprofen isomers). Ibuprofen is one of the most commonly consumed PhACs and can be found in different environmental compartments. The experiment performed consisted of a set of aerated batch tests with different suspended solid and ibuprofen concentrations to determine the influence of these parameters on the calculated biodegradation constant (K(biol)). Sampling of the liquid phase at different scheduled times was assessed, removal efficiencies were calculated and pseudo-first-order kinetics were adjusted to obtain experimental K(biol) values for the parent compound and its TPs. The experimental data were successfully fitted to ASM-based models, with K(biol) values for the target compounds ranging from almost 1 to 17 L gSST(-1) d(-1), depending on the concentrations of the biomass and ibuprofen. This work provides innovative knowledge not only regarding the removal of TPs but also the formation kinetics of these TPs.

Exploring the potential of applying proteomics for tracking bisphenol A and nonylphenol degradation in activated sludge

A significant percentage of bisphenol A and nonylphenol removal in municipal wastewater treatment plants relies on biodegradation. Nonetheless, incomplete information is available concerning their degradation pathways performed by microbial communities in activated sludge systems. Hydroquinone dioxygenase (HQDO) is a specific degradation marker enzyme, involved in bisphenol A and nonylphenol biodegradation, and it can be produced by axenic cultures of the bacterium Sphingomonas sp. strain TTNP3. Proteomics, a technique based on the analysis of microbial community proteins, was applied to this strain. The bacterium proteome map was obtained and a HQDO subunit was successfully identified. Additionally, the reliability of the applied proteomics protocol was evaluated in activated sludge samples. Proteins belonging to Sphingomonas were searched at decreasing biomass ratios, i.e. serially diluting the bacterium in activated sludge. The protein patterns were compared and Sphingomonas proteins were discriminated against the ones from sludge itself on 2D-gels. The detection limit of the applied protocol was defined as 10(-3) g TTNP3 g(-1) total suspended solids (TSSs). The results proved that proteomics can be a promising methodology to assess the presence of specific enzymes in activated sludge samples, however improvements of its sensitivity are still needed.

Knowledge-based control module for start-up of flat sheet MBRs

In start-up periods low MLSS concentration may lead to fouling phenomena and uncommon frequency of chemical cleanings using membrane bioreactors. A knowledge-based control module for the optimisation of start-up procedures in membrane bioreactors is presented and validated in this paper. The main objective of the control module is to accelerate the growth of MLSS and the achievement of the design flux while minimising the fouling phenomenon during start-up periods. The module was validated in a pilot-scale membrane bioreactor with the University of Cape Town configuration and submerged flat sheet microfiltration membranes. The knowledge of the control system was represented as a decision tree before being implemented. A fully satisfactory start-up, both for the filtration and the biological phase, was obtained in 20 days, saving time and preserving the membrane integrity.

Unraveling the potential of a combined nitritation-anammox biomass towards the biodegradation of pharmaceutically active compounds

In the past few years, anaerobic ammonium oxidation-based processes have attracted a lot of attention for their implementation at the mainstream line of wastewater treatment plants, due to the possibility of leading to energy autarky if combined with anaerobic digestion. However, little is known about the potential degradation of micropollutants by the microbial groups responsible of these processes and the few results available are inconclusive. This study aimed to assess the degradation capability of biomass withdrawn from a combined nitritation/anaerobic ammonium oxidation (combined N/A) pilot plant towards five pharmaceutically active compounds (ibuprofen, sulfamethoxazole, metoprolol, venlafaxine and carbamazepine). Batch experiments were performed under different conditions by selectively activating or inhibiting different microbial groups: i) regular combined N/A operation, ii) aerobic (optimal for nitrifying bacteria), iii) aerobic with allylthiourea (an inhibitor of ammonia monooxygenase, enzyme of ammonia oxidizing bacteria), iv) anoxic (optimal for anaerobic ammonium oxidizing bacteria), v) aerobic with acetate (optimal for heterotrophic bacteria) and vi) anoxic with acetate (optimal for heterotrophic denitrifying bacteria). Ibuprofen was the most biodegradable compound being significantly degraded (49-100%) under any condition except heterotrophic denitrification. Sulfamethoxazole, exhibited the highest removal (70%) under optimal conditions for nitrifying bacteria but in the rest of the experiments anoxic conditions were found to be slightly more favorable (up to 58%). For metoprolol the highest performance was obtained under anoxic conditions favoring anammox bacteria (62%). Finally, carbamazepine and venlafaxine were hardly removed (≤10% in the majority of cases). Taken together, these results suggest the specificity of different microbial groups that in combination with alternating operational parameters can lead to enhanced removal of some micropollutants.

Proteomics reliability for micropollutants degradation insight into activated sludge systems

Little information is available on pharmaceutical trace compounds degradation pathways in wastewater. The potential of the proteomics approach has been evaluated to extract information on activated sludge microbial metabolism in degrading a trace concentration of a pharmaceutical compound (ibuprofen). Ibuprofen is one of the most consumed pharmaceuticals, measured in wastewater at very high concentrations and, despite its high removal rates, found in different environmental compartments. Aerated and completely mixed activated sludge batch tests were spiked with ibuprofen at 10 and 1,000 μg L(-1). Ibuprofen concentrations were determined in the liquid phase: 100% removal was observed and the kinetics were estimated. The solid phase was sampled for proteomics purposes. The first objective was to apply proteomics to evaluate protein profile variations in a complex matrix such as activated sludge. The second objective was to determine, at different ibuprofen concentrations, which proteins followed pre-defined trends. No newly expressed proteins were found. Nonetheless, the obtained results suggest that proteomics itself is a promising methodology to be applied in this field. Statistical and comparative studies analyses provided, in fact, useful information on biological reproducibility and permitted us to detect 62 proteins following coherent and plausible expected trends in terms of presence and intensity change.

Development of an algorithm for air-scour optimization in membrane bioreactors

Abstract Membrane Bioreactors are used in an increasing number of wastewater treatment facilities because of their compactness and efficiency in solid-liquid separation. In this paper the development of an air-scour control algorithm based upon short term and long term membranes permeability evolution is presented. An open loop calibration and partial validation was carried out in a semi-industrial scale pilot plant where manual changes in air-scour flow had been previously carried out. The control system was successfully tested in closed loop in an industrial scale pilot plant, defining a maximum daily air-scour decrease or increase of 6% of the air-scour recommended by membranes suppliers. A maximum air-scour saving of 20%, calculated in terms of air flow saved, was achieved without interfering with the biological nutrient removal and without any apparent long term effect.