A robust procedure for the determination of 16 US EPA PAHs in both aqueous (e.g. wastewaters, industrial discharges, treated effluents) and solid samples (e.g. suspended solids and sludge) from a wastewater treatment plant (WWTP) is presented. Recovery experiments using different percentages of organic modifier, sorbents and eluting solvent mixtures were carried out in Milli-Q water (1000 mL) spiked with a mixture of the PAH analytes (100 ng/L of each analyte). The solid phase extraction (SPE) procedures applied to spiked waste water samples (1000 mL; 100 ng/L spiking level) permitted simultaneous recovery of all the 16PAHs with yields >70% (6-13% RSD). SPE clean up procedures applied to sewage and stabilized sludge extracts, showed percent recoveries in the range 73-92% (7-13% RSD) and 71-89% (7-12% RSD), respectively. The methods were used for the determination of PAHs in aqueous and solid samples from the WWTP of Fusina (Venice, Italy). Mean concentrations, as the sum of the 16PAHs in aqueous and suspended solid samples, were found to be approx. in the 1.12-4.62 microg/L range. Sewage and stabilized sludge samples contained mean PAH concentrations, as sum of 16 compounds, in the concentration range of 1.44-1.26 mg/kg, respectively. Extraction and clean up procedures for sludge samples were validated using EPA certified reference material IRM-104 (CRM No. 912). Instrumental analyses were performed by coupling HPLC with UV-diode array detection (UV-DAD) and fluorescence detection (FLD).

Biomass-derived levulinic acid (LA) is an excellent substrate to obtain high-value esters that can be used as second-generation biofuels and biofuel additives. The present study focuses on the identification and definition of the key parameters crucial for the development of chemically and environmentally efficient protocols operating in continuous-flow for the preparation of structurally diverse alkyl levulinates via the esterification of LA. We have focused on the use of solid acid catalysts consisting of sulfonated cation exchange resins and considered different aliphatic alcohols to prepare levulinates 3 and 11-17 regioselectively, and in good to high yields (50-92%). Direct correlations between several reaction parameters and catalyst activity have been investigated and discussed to set proper flow reactors that allow minimal waste production during the workup procedure, enabling Environmental factor (E-factor) values as low as ca. 0.3, full recoverability and reusability of the catalysts, and the production of levulinates up to ca. 5 gxh −1 scale.

This study addresses the issue of whether it is possible to accurately predict the removal efficiencies of metals of environmental concern (i.e., Al, Ag, As, B, Ba, Cd, Cr, Fe, Mn, Hg, Ni, Pb, Cu, V, and Zn) in a wastewater treatment plant. The plant in question (at Fusina, Venice, Italy) is fed by mixed wastes from municipal and industrial sources (∼300 000 equivalent inhabitants) and discharges the treated effluent into the Venice lagoon. The year-long sampling campaign (2001−2002) yielded a substantial amount of analytical data and relatively wide ranges of concentrations of metals in the influent samples, which made it possible to study the removal efficiencies by plotting the terms (inlet concentration − outlet concentration) vs (inlet concentration) for each metal investigated. The data in the plots were fitted using the linear regression model Y = BX. The slope rates (terms B), which were estimated by the least-squares method, have been adopted as the removal efficiencies, and they can be considered as constants in the concentration ranges recorded in this work. The relative abundance of metals in the raw wastewaters feeding Fusina WWTP followed the order Al > Fe > B > Zn > Ba > Mn > Cu > Pb > Hg = Ni > Cr = As > V > Ag > Cd, while in the effluent the order was Fe > Al > Zn > Mn > Ba > Ni > Cu > Pb > Cr > Ag > As > Hg = V > Cd. The removal percentages (%) of the metals were Al = 92 ± 1; Ag = 94 ± 1; As = 76 ± 3; B = n.d.; Ba = 85 ± 2; Cd = 85 ± 2; Cr = 87 ± 1; Fe = 90 ± 1; Mn = 61 ± 2; Hg = 93 ± 1; Ni = 50 ± 3; Pb = 92 ± 1; Cu = 93 ± 1; V = 74 ± 2; and Zn = 75 ± 3.

Syntrophy and interspecies electron transfer among different microbial groups occurs in anaerobic digestion, and many papers recently reported their positive effect on biogas and methane production. In this paper, we present the results on the effect of conductive material, i.e., graphene, PAC and biochar addition in 3.5 L batch experiments, analyzing the biogas production curve. A peculiar curve pattern occurred in the presence of conductive materials. Compared to the respective controls, the addition of graphene produced a biogas surplus of 33%, PAC 20% and biochar 8%. Microbial community molecular analysis showed that syntrophic microorganisms present in the inoculum were stimulated by the conductive material addition. Graphene also appears to promote an interspecies electron transfer between Geobacter sp. and ca. Methanofastidiosum. This paper contributes to the understanding of the DIET-related microbial community dynamic in the presence of graphene and PAC, which could be exploited to optimize biogas and methane production in real-scale applications.

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