Federico G.A. Vagliasindi

Low-temperature thermal desorption of diesel polluted soil: Influence of temperature and soil texture on contaminant removal kinetics

Five soil size aggregate fractions, corresponding to coarse (500-840 μm), medium (200-350 μm), fine (75-200 μm) sand, silt (10-75 μm) and clay (<4 μm), were artificially contaminated with diesel, and thermally treated using a laboratory scale apparatus to investigate the effect of soil texture on contaminant adsorption and removal. Ex situ thermal process was simulated using helium as the carrier gas at a flow rate of 1.5 L min(-1), different temperatures (100-300 °C) and different treatment times (5-30 min). The amount of contaminant adsorbed on the soil and the residual amount after thermal treatment was determined by gas chromatography. Results showed that adsorption phenomena and desorption efficiency were affected by the soil texture and that temperature and time of treatment were key factors in remedial process. A temperature of 175 °C is sufficient to remedy diesel polluted sandy and silty soils, whereas a higher temperature (250 °C) is needed for clays. Thermal desorption of diesel polluted soil was shown to be governed by first-order kinetics. Results are of practical interest and may be used in scaling-up and designing desorption systems for preliminary cost and optimal condition assessment.

Use of fluorescence EEM to monitor the removal of emerging contaminants in full scale wastewater treatment plants

This study investigated the applicability of different techniques for fluorescence excitation/emission matrices data interpretations, including peak-picking method, fluorescence regional integration and PARAFAC modelling, to act as surrogates in predicting emerging trace organic compounds (ETOrCs) removal during conventional wastewater treatments that usually comprise primary and secondary treatments. Results showed that fluorescence indexes developed using alternative methodologies but indicative of a same dissolved organic matter component resulted in similar predictions of the removal of the target compounds. The peak index defined by the excitation/emission wavelength positions (λex/λem) 225/290nm and related to aromatic proteins and tyrosine-like fluorescence was determined to be a particularly suitable surrogate for monitoring ETOrCs that had very high removal rates (average removal >70%) (i.e., triclosan, caffeine and ibuprofen). The peak index defined by λex/λem=245/440nm and the PARAFAC component with wavelength of the maxima λex/λem=245, 350/450, both identified as humic-like fluorescence, were found remarkably well correlated with ETOrCs such as atenolol, naproxen and gemfibrozil that were moderately removed (51-70% average removal). Finally, the PARAFAC component with wavelength of the maxima λex/λem=<240, 315/380 identified as microbial humic-like fluorescence was the only index correlated with the removal of the antibiotic trimethoprim (average removal 68%).

Modeling bromide effects on yields and speciation of dihaloacetonitriles formed in chlorinated drinking water

This study examined effects of bromide on yields and speciation of dihaloacetonitrile (DHAN) species that included dichloro-, bromochloro- and dibromoacetonitriles generated in chlorinated water. Experimental data obtained using two water sources, varying concentrations and characters of Natural Organic Matter (NOM), bromide concentrations, reaction times, chlorine doses, temperatures and pHs were interpreted using a semi-phenomenological model that assumed the presence of three kinetically distinct sites in NOM (denoted as sites S1, S2 and S3) and the occurrence of sequential incorporation of bromine and chlorine into them. One site was found to react very fast with the chlorine and bromine but its contribution in the DHAN generation was very low. The site with the highest contribution to the yield of DHAN (>70%) has the lowest reaction rates. The model introduced dimensionless coefficients (denoted as φ1(DHAN), φ2(DHAN) and φ3(DHAN)) applicable to the initial DHAN generation sites and their monochlorinated and monobrominated products, respectively. These parameters were used to quantify the kinetic preference to bromine incorporation over that of chlorine. Values of these coefficients optimized for DHAN formation were indicative of the strongly preferential incorporation of bromine into the engaged NOM sites. The same set of φ(i)(DHAN) coefficients could be used to model the speciation of DHAN released from their kinetically different precursors. The dimensionless speciation coefficients φ(i)(DHAN) were determined to be site specific and dependent on the NOM content and character as well as pH. The presented model of DHAN formation and speciation can help quantify in more detail the generation of DHAN and provide more insight necessary for further assessment of their potential health effects.

Quantifying the formation of nitrogen-containing disinfection by-products in chlorinated water using absorbance and fluorescence indexes

Among known but unregulated disinfection by-products (DBPs), several nitrogenous species (N-DBPs) have been found in drinking waters. While concentrations of N-DBP are much lower than those of trihalomethanes (THMs) and haloacetic acids (HAAs), their potential toxicity is higher. In this study the relationships between the formation of N-DBPs and the changes in NOM caused by the chlorination of raw Ancipa water quantified by the use of differential absorbance and fluorescence indexes were investigated. Very strong relationships were found between selected N-DBPs (i.e. trichloronitromethane and dichloroacetonitrile) and the proposed spectroscopic indexes that were previously developed to quantify the changes in natural organic matter (NOM) during chlorination at varying reaction conditions (chlorine dose, reaction time and temperature) and the generation of DBPs. Obtained results clearly indicate that the changes in NOM absorbance and fluorescence are fundamental descriptors of the formation of both commonly controlled halogenated DBPs and N-DBPs. This approach may be suitable for real time monitoring of emerging N-DBPs and for studying their formation pathways.

Monitoring the Behavior of Emerging Contaminants in Wastewater-Impacted Rivers Based on the Use of Fluorescence Excitation Emission Matrixes (EEM)

This study investigated the applicability of fluorescence indexes based on the interpretation of excitation emission matrices (EEMs) by PARAFAC analysis and by selecting fluorescence intensities at a priori defined excitation/emission pairs as surrogates for monitoring the behavior of emerging organic compounds (EOCs) in two catchment basins impacted by wastewater discharges. Relevant EOC and EEM data were obtained for a 90 km stretch of the Simeto River, the main river in Sicily, and the smaller San Leonardo River, which was investigated for a 17 km stretch. The use of fluorescence indexes developed by these two different approaches resulted in similar observations. Changes of the fluorescence indexes that correspond to a group of humic-like fluorescing species were determined to be highly correlated with the concentrations of recalcitrant contaminants such as sucralose, sulfamethoxazole and carbamazepine, which are typical wastewater markers in river water. Changes of the fluorescence indexes related to tyrosine-like substances were well correlated with the concentrations of ibuprofen and caffeine, anthropogenic indicators of untreated wastewater discharges. Chemical oxygen demand and dissolved organic carbon concentrations were correlated with humic-like fluorescence indexes. The observed correlations were site-specific and characterized by different regression parameters for every collection event. Caffeine and carbamazepine showed correlations with florescence indexes in the San Leonardo River and in the alluvial plain stretch of the Simeto River, whereas sucralose, sulfamethoxazole and ibuprofen have always been well correlated in all the investigated river stretches. However, when data of different collection events from river stretches where correlations were observed were combined, good linear correlations were obtained for data sets generated via the normalization of the measured concentrations by the average value for the corresponding collection event. These results show that fluorescence based indexes can be used to monitor the behavior of some trace organic contaminants in wastewater impacted rivers and to track wastewater discharges in streams and rivers.

Stabilisation/solidification of Radionuclides Polluted Soils: a Novel Analytical Approach for the Assessment of the γ-radiation Shielding Capacity

Soil contamination caused by γ-radiation emitter radionuclides is a serious problem worldwide. Cementbased Stabilisation/solidification (S/S) could represent an optimal choice to treat radionuclides polluted soils due to the possibility to shield the γ-radiation emitted by contaminant. In order to better planning the treatment procedures, a novel analytical approach has been developed and applied in order to assess the γ-radiation shielding (γRS) of cylindrical S/S treated bodies taking into account the shielding properties of materials used in S/S treatment, all the parameters related to nuclear processes involved and the interaction between radiation and matter. Calculations were compared with γRS values obtained by bench-scale experimental activities. For experiments a soil spiked by thorium oxide (ThO2) was stabilised/solidified using different binder mixture of Portland cement and barite aggregates at different soil:binder ratios and tested for its γ-radiation shielding properties. Results obtained showed that the presence of the barite aggregates mixed with cement gives a significant containment of the γ-radiation possibly representing an optimal choice to S/S treat low level radionuclides polluted soil. Furthermore, a good correspondence between analytical and experimental data was observed making the proposed analytical approach a potential suitable tool to great simplify the estimation of γ-radiation shielding properties of several binders-materials-radionuclides S/S systems.

N-Nitrosodimethylamine (NDMA) and its precursors in water and wastewater: A review on formation and removal

This review summarizes major findings over the last decade related to N-Nitrosodimethylamine (NDMA) in water and wastewater. In particular, the review is focused on the removal of NDMA and of its precursors by conventional and advanced water and wastewater treatment processes. New information regarding formation mechanisms and precursors are discussed as well. NDMA precursors are generally of anthropogenic origin and their main source in water have been recognized to be wastewater discharges. Chloramination is the most common process that results in formation of NDMA during water and wastewater treatment. However, ozonation of wastewater or highly contaminated surface water can also generate significant levels of NDMA. Thus, NDMA formation control and remediation has become of increasing interest, particularly during treatment of wastewater-impacted water and during potable reuse application. NDMA formation has also been associated with the use of quaternary amine-based coagulants and anion exchange resins. UV photolysis with UV fluence far higher than typical disinfection doses is generally considered the most efficient technology for NDMA mitigation. However, recent studies on the optimization of biological processes offer a potentially lower-energy solution. Options for NDMA control include attenuation of precursor materials through physical removal, biological treatment, and/or deactivation by application of oxidants. Nevertheless, NDMA precursor identification and removal can be challenging and additional research and optimization is needed. As municipal wastewater becomes increasingly used as a source water for drinking, NDMA formation and mitigation strategies will become increasingly more important. The following review provides a summary of the most recent information available.

Development of a performance threshold approach for identifying the management options for stabilisation/solidification of lead polluted soils

AbstractTwo soils spiked with lead at different rates were stabilised/solidified using Portland cement and fly ash at different soil:binder ratios, and tested for their setting time, unconfined compressive strength, leachability and durability. A performance threshold approach was used in order to identify optimal management options for the products of the S/S treatment. Results show that soil texture, percentage of binders and lead concentration play an important part in the treatment, significantly influencing the performance of the resulting products in terms of curing, compressive strength and durability. Pb soil concentrations higher than 15000 mg kg−1 were found to heavily reduce the applicability of the treatment requiring the maximum amount of binder in order to satisfy the performance criteria. The performance of sandy soils was shown to be limited by setting time and UCS features due to the retardation of the hydration reactions and also by its leaching behaviour, whereas for silt-clayey soils t...

Performance study and influence of radiation emission energy and soil contamination level on γ-radiation shielding of stabilised/solidified radionuclide-polluted soils

This work focuses on the stabilisation/solidification (S/S) of radionuclide-polluted soils at different (232)Th levels using Portland cement alone and with barite aggregates. The potential of S/S was assessed applying a full testing protocol and calculating γ-radiation shielding (γRS) index, that included the measurement of soil radioactivity before and after the S/S as a function of the emission energy and soil contamination level. The results indicate that setting processes are strongly dependent on the contaminant concentration, and for contamination level higher than 5%, setting time values longer than 72 h. The addition of barite aggregates to the cement gout leads to a slight improvement of the S/S performance in terms of durability and contaminant leaching but reduces the mechanical resistance of the treated soils samples. Barite addition also causes an increase in the γ-rays shielding properties of the S/S treatment up to about 20%. Gamma-ray measurements show that γRS strongly depends on the energy, and that the radioactivity with the contamination level was governed by a linear trend, while, γRS index does not depend on the radionuclide concentration. Results allow the calculated γRS values and those available from other experiments to be applied to hazard radioactive soil contaminations.

Effectiveness of water saving devices and educational programs in urban buildings

In this study different water saving measures (structural and non-structural) were implemented in different urban buildings. A monitoring program of water consumption was carried out to verify and compare the effectiveness of high-efficiency plumbing fixtures and educational programs in different types of buildings (two residential houses, two Middle Schools and two Sport Centres) located in a drought experienced region (Sicily, Italy). In all cases, relevant water conservation percentages were achieved with prominent values in public buildings. The highest water conservation (up to 60%) was observed in two Middle Schools, where a large amount of water was wasted. Overall, the structural measures led to high water conservation, while the educational programs did not always improve the water saving effectiveness. These results highlight that in some urban areas the awareness of water conservation is not well established and large volumes of water are wasted, especially in public buildings, due to faulty plumbing fixtures. Governments and Environmental Agencies should promote with more effort water saving measures in order to support green building policy and global sustainability.Ferrous catalyzed persulfate oxidation of dissolved aniline was investigated in aqueous systems under a variety of ferrous ion concentrations and temperature. Result showed that the addition of ferrous ions accelerated the degradation of aniline by persulfate. For the thermally activated persulfate oxidation experiment, the optimum persulfate/aniline concentration ratio at 30˚C was at 5.4 mM or 20/1. This ratio gave the highest aniline removal of 45%. For the ferrous ion catalyzed persulfate oxidation experiment, there was marginal difference in the result for the various ferrous ion/oxidant molar ratios. Thus, another series of experiment was conducted to determine the optimum ratio and a ferrous ion/persulfate molar ratio of 1.25/1 showed the highest removal efficiency.