Spinel cobalt ferrite-based porous activated carbon in conjunction with UV light irradiation for boosting peroxymonosulfate oxidation of bisphenol A.

Developing heterogeneous catalysts with high performance for peroxymonosulfate (PMS) activation to decontaminate organic pollutants from wastewater is of prominent importance. In this study, spinel cobalt ferrite (CoFe2O4) materials were coated on the surface of powdered activated carbon (CoFe2O4@PAC) via the facile co-precipitation method. The high specific surface area of PAC was beneficial for the adsorption of both bisphenol A (BP-A) and PMS molecules. The CoFe2O4@PAC-mediated PMS activation process under UV light could effectively eliminate 99.4% of the BP-A within 60 min of reaction. A significant synergy effect was attained between CoFe2O4 and PAC towards PMS activation and subsequent elimination of BP-A. Comparative tests demonstrated that the heterogeneous CoFe2O4@PAC catalyst had a better degradation performance in comparison with its components and homogeneous catalysts (Fe, Co, and, Fe + Co ions). The formed by-products and intermediates during BP-A decontamination were evaluated using LC/MS analysis, and then a possible degradation pathway was proposed. Moreover, the prepared catalyst exhibited excellent performance in recyclability with slight leaching amounts of Co and Fe ions. A TOC conversion of 38% was obtained after five consecutive reaction cycles. It can be concluded that the PMS photo-activation process via the CoFe2O4@PAC catalyst can be utilized as an effective and promising method for the degradation of organic contaminants from polluted-water resources.

Wastewater-based epidemiology approach: The learning lessons from COVID-19 pandemic and the development of novel guidelines for future pandemics.

Wastewater-based epidemiology (WBE) provides a comprehensive real-time framework of population attitude and health status. This approach is attracting the interest of medical community and health authorities to monitor the prevalence of a virus (such as the severe acute respiratory syndrome coronavirus 2, SARS-CoV-2) among a community. Indeed, WBE is currently fine-tuning as environmental surveillance tool for coronavirus disease 2019 (COVID-19) pandemic. After a bibliometric analysis conducted to discover the research trends in WBE field, this work aimed to side-by-side compare the conventional method based on clinical testing with WBE approach. Furthermore, novel guidelines were developed to apply the WBE approach to a pandemic. The growing interest on WBE approach for COVID-19 pandemic is demonstrated by looking at the sharp increase in scientific papers published in the last years and at the ongoing studies on viral quantification methods and analytical procedures. The side-by-side comparison highlighted the ability of WBE to identify the hot-spot areas faster than the conventional approach, reducing the costs (e.g., rational use of available resources) and the gatherings at medical centers. Contrary to clinical testing, WBE has the surveillance capacity for preventing the virus resurgence, including asymptomatic contribution, and ensuring the preservation of medical staff health by avoiding the exposure to the virus infection during clinical testing. As extensively reported, the time in collecting epidemiological data is crucial for establishing the prevention and mitigation measures that are essential for curbing a pandemic. The developed guidelines can help to build a WBE system useful to control any future pandemic.

Microwave regeneration of granular activated carbon saturated with PFAS.

This study investigated the regeneration of PFAS-saturated granular activated carbons (GACs) by microwave (MW) irradiation. Two commercially available GACs (bituminous coal based GAC [BCGAC] and lignite coal based GAC [LCGAC]) were saturated with perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) and then irradiated at different MW conditions (applied power = 125 - 500 W, irradiation time = 3 - 12 min). The performance of MW regeneration for PFOS- or PFOA-saturated GACs was assessed by evaluating the variation of GAC adsorption capacity (regeneration efficiency, RE) and weight loss percentage (WL). Moreover, the effect of MW irradiation on GAC textural properties (e.g., surface area and pore volume) was examined through N2 adsorption isotherms. Additionally, five successive adsorption/regeneration cycles were carried out at the MW operational condition that allowed to reach the target temperature (T>600°C) while minimizing the WL. Both GACs exhibited a strong ability to convert MW irradiation into a rapid temperature increase (~150°C min-1 at 500 W). The highest values of RE (>90%) for both PFOA- and PFOS-saturated GACs were obtained at MW irradiation conditions that employed short regeneration time (3 min) and optimal temperature. Indeed, the highest RE did not occur at the highest temperatures (>750°C) due to the damage of GAC porous structure, particularly for LCGAC. After five cycles, the observed values of RE (~65%) and a moderate weight loss (<7%) demonstrated the good performance of MW irradiation for regenerating PFOA- and PFOS-saturated BCGAC. The obtained findings pointed out that MW irradiation is a promising alternative regeneration technique for PFAS-saturated GAC.

Comparison of the new Cl2/O3/UV process with different ozone- and UV-based AOPs for wastewater treatment at pilot scale: Removal of pharmaceuticals and changes in fluorescing organic matter.

This work critically compared the removal of fluorescing PARAFAC components and selected pharmaceuticals (carbamazepine, fluoxetine, gemfibrozil, primidone, sulfamethoxazole, trimethoprim) from a tertiary wastewater effluent by different UV- and ozone-based advanced oxidation processes (AOPs) operated at pilot-scale. Investigated AOPs included UV/H2O2, UV/Cl2, O3, O3/UV, H2O2/O3/UV, and the new Cl2/O3/UV. AOPs comparison was accomplished using various ozone doses (0-9 mg/L), UV fluences (191-981 mJ/cm2) and radical promoter concentrations of Cl2 = 0.04 mM and H2O2 = 0.29 mM. Chlorine-based AOPs produced radical species that reacted more selectively with pharmaceuticals than radical species and oxidants generated by other AOPs. Tryptophan-like substances and humic-like fluorescing compounds were the most degraded components by all AOPs, which were better removed than microbial products and fulvic-like fluorescing substances. Removal of UV absorbance at 254 (UV254) nm was always low. Overall, chlorine-based AOPs were more effective to reduce fluorescence intensities than similar H2O2-based AOPs. The Cl2/O3/UV process was the most effective AOP to degrade all target micro-pollutants except primidone. On the other hand, the oxidation performance of pharmaceuticals by other ozone-based AOPs followed the order H2O2/O3/UV > O3/UV > O3. UV/Cl2 process outcompeted UV/H2O2 only for the removal of trimethoprim and sulfamethoxazole. Correlations between the removal of pharmaceuticals and spectroscopic indexes (PARAFAC components and UV254) had unique regression parameters for each compound, surrogate parameter and oxidation process. Particularly, a diverse PARAFAC component for each investigated AOP resulted to be the most sensitive surrogate parameter able to monitor small changes of pharmaceuticals removal.

Interpretation of the formation of unstable halogen-containing disinfection by-products based on the differential absorbance spectroscopy approach.

Concentrations of several toxic disinfection by-products (DBP), notably haloacetonitriles (e.g., trichloroacetonitrile, TCAN) and haloketones (e.g., di- and trichloropropanone, DCPN and TCPN, respectively) are affected by chlorination conditions and the inherent instability of these DBPs. In this study, effects of temperature, chlorine dose and reaction time on the formation of TCAN, DCPN and TCPN were interpreted using the approach of differential absorbance spectroscopy. Experimental data obtained for a wide range of water quality conditions demonstrate that in some cases the concentrations of some of the unstable DBPs increased rather than decreased at low temperatures and realistically long contact times. Despite the presence of pronounced changes of the kinetics of generation and degradation of these DBPs at varying temperatures and chlorine doses, their concentrations were strongly correlated with the concurrent changes of spectroscopic properties of DOM quantified via differential absorbance measurements at 272 nm (ΔA272). The maximum values of TCAN, DCPN and TCPN concentrations observed for the chlorination of eight different surface waters occur at the relative decreases of absorbance at 272 nm (defined as RΔA272) values of ca. 0.32 (±0.03), 0.24 (±0.05), and 0.42 (±0.03), respectively. The activation energies of degradation reactions of unstable DBPs were examined and the results indicate that TCAN and TCPN are caused by their hydrolysis with OH- while the degradation of DCPN is mainly caused by halogenation reaction with HOCl. These results in this study may be important for controlling the formation of unstable DBPs and further optimization of drinking water treatment.

Comparison of AOPs at pilot scale: Energy costs for micro-pollutants oxidation, disinfection by-products formation and pathogens inactivation.

This work evaluated different advanced oxidation processes (AOPs) operated at pilot-scale as tertiary treatment of municipal wastewater in terms of energy efficiency, disinfection by-products formation and pathogens inactivation. Investigated AOPs included UV/H2O2, UV/Cl2, O3, O3/UV, H2O2/O3/UV, Cl2/O3/UV. AOPs were operated using various ozone doses (1.5-9 mg L-1), and UV fluences (191-981 mJ cm-2). Electrical energy costs necessary for the oxidation of contaminants of emerging concern (CEC) (i.e., carbamazepine, fluoxetine, gemfibrozil, primidone, sulfamethoxazole, trimethoprim) were calculated using the electrical energy per order (EEO) parameter. Ozonation resulted by far the most energy efficient process, whereas UV/H2O2 and UV/Cl2 showed the highest energy costs. Energy costs for AOPs based on the combination of UV and ozone were in the order O3/UV ≈ Cl2/O3/UV > H2O2/O3/UV, and they were significantly lower than energy costs of UV/H2O2 and UV/Cl2 processes. Cl2/O3/UV increased bromate formation, O3/UV and O3 had same levels of bromate formation, whereas H2O2/O3/UV did not form bromate. In addition, UV photolysis resulted an effective treatment for NDMA mitigation even in combination with ozone and chlorine in AOP technologies. Ozonation (doses of 1.5-6 mg L-1) was the least effective process to inactivate somatic coliphages, total coliform, escherichia coli, and enterococci. UV irradiation was able to completely inactivate somatic coliphages, total coliform, escherichia coli at low fluence (191 mJ cm-2), whereas enterococci were UV resistant. AOPs that utilized UV irradiation were the most effective processes for wastewater disinfection resulting in a complete inactivation of selected indicator organisms by low ozone dose (1.5 mg L-1) and UV fluence (191-465 mJ cm-2).

Remediation of petrol hydrocarbon-contaminated marine sediments by thermal desorption.

In this study, a hydrocarbon-contaminated marine sediment was treated applying ex-situ thermal desorption (ESTD) at bench-scale. Temperatures up to 280 °C and heating times (t) in the 5-30 min range were investigated. Results revealed that temperatures in the range 200-280 °C led to Total Petrol Hydrocarbon (TPH)-removal efficiency (RE) from 75 to 85% (t = 10 min). The maximum RE of 89% was obtained at 200 °C for 30 min. However, a shorter remediation time of 5 min (or lower temperatures of 160 and 180 °C with longer times) is needed to reach the TPH standard limit. Data also demonstrated the selectivity of the treatment in TPH fraction removal. The modelling of the TPH removal kinetics and desorption isotherm jointly with activation energy calculation (>30 kJ mol-1) indicated that ESTD process is quite unfavorable for marine sediments. This is due to the fact that ESTD is regulated by chemisorption processes and occurred in two distinct TPH removal phases: evaporation and boiling vaporization. This depends on the strong affinity of the TPH with the fine sediment particles, as well as on the high initial water, salinity, organic matter and sulfides content. However, the comparison between alternative processes has shown that ESTD is the most feasible treatment process for TPH-contaminated marine sediment remediation. Obtained results also add relevant information that can be used as a basis for future scaling-up investigations of ESTD for hydrocarbon-contaminated marine sediments.

Microwave based regenerating permeable reactive barriers (MW-PRBs): Proof of concept and application for Cs removal.

The present study evaluates the concept of permeable reactive barrier (PRB) coupled with microwaves (MWs) as in situ-regenerating technology with focus on Cs-contaminated water. Experimental and modelling results data from batch and column tests were carried out, evaluating several chemical-physical and environmental parameters. Main results showed a very rapid increase in GAC temperature during MW irradiation up to ∼680 °C. This highlights the GAC strong ability to transform MW power into heat due to GAC excellent dielectric properties (ε' = 13.8). Physical characterization revealed that GAC pore volume and specific surface area change with the number of regeneration cycles. GAC regeneration efficiency variation reflects this behaviour with a maximum value of ∼112% (5th cycle). The final GAC weight loss of ∼7% further demonstrates GAC life span preservation during MW irradiation. Results from column tests confirms that GAC can be regenerated by MW also in dynamic condition, due to sublimation/vaporization and vapour stripping Cs removal mechanisms and that the regeneration effectiveness is time-dependent. The breakthrough curve shape confirms significant benefits from MW irradiation. Overall, obtained finding demonstrated the feasibility of the proposed concept, also providing essential data to guide its scaling-up application.

Monitoring NDMA precursors throughout membrane-based advanced wastewater treatment processes by organic matter fluorescence.

This study investigates the potential of fluorescence excitation/emission matrices (EEM) measurement as a tool to predict N-Nitrosodimethylamine (NDMA) formation in water reuse applications. In particular, samples from a pilot-scale membrane biological reactor (MBR) followed by nanofiltration (NF) advanced water treatment plant, are used for the study. Concentrations of both, specific NDMA precursors and NDMA formation potential (FP) are correlated with different EEM peaks. The specific precursors investigated are: erythromycin, azithromycin, clarithromycin, venlafaxine, o-desmethylvenlafaxine, ranitidine and citalopram, while the NDMA FP is conventionally measured by the NDMA formation potential test. EEM peaks investigated are obtained by fluorescence regional integration as well as by the peak picking method generating I1, I2, I3, I4, and I5 peaks. Results showed that protein-like materials are correlated with the bulk NDMA FP and specific NDMA precursors. Additionally, selected fluorescence peaks such as I1, I2 and I4 are strongly correlated with NDMA precursors throughout the MBR-NF pilot plant. The removal of NDMA precursors and EEM peaks also correlated well (R2 > 0.8). This data shows that fluorescence EEM can be a promising tool to monitor the concentration of NDMA precursors and their removal in water reuse application.

Field technical applicability and cost analysis for microwave based regenerating permeable reactive barriers (MW-PRBs) operating in Cs-contaminated groundwater treatment.

The present study tests the potentiality of a novel microwave based regenerating permeable reactive barrier (MW-PRB) system as combined treatment for Cs-contaminated groundwater. Granular activated carbon (GAC) was selected as adsorptive materials in batch and column MW-regeneration experiments. Experimental and modeling data were elaborated for technical and economic considerations in order to assess the MW-PRB feasibility jointly with essential information regarding its real field applicability. Batch experiments investigated the effects of 10 adsorption-MW regeneration cycles under different MW irradiation conditions (applied electric field = 200-460 V m-1; irradiation times = 1-15 min) by assessing GAC variation properties in term of regeneration yield (δ), specific area and weight loss (WL) variation. Column tests were carried using a dedicated setup essentially including a column filled with GAC implanted in a MW oven cavity (MW electric field of 385 V m-1, irradiation times 5-15 min). Lab-scale results shown the ability of MW in Cs removal from GAC as demonstrated by regeneration yield (δ = 79-110%) and WL (6.78% for 10 cycles) values. This was confirmed in dynamic conditions by data from MW-column tests highlighting the highest Cs removal of ~80% when the maximum regeneration time was applied. Residual Cs concentration in breakthrough curves fitted well with the proposed Yoon and Nelson model (R2 = ~0.97). Results from techno-economic analysis revealed the MW-PRB viability and its advantages also in comparison with conventional PRB systems, demonstrating the concept of combined MW-PRB treatment. Saved cost obtained demonstrated in fact the potential cost effectiveness of MW-PRB system and, consequently, the implementation of novel approach is encouraged. Calculated PRB longevity vs groundwater velocity curves are useful in order to predict long-term PRB performance and the response of the remediation activities, as well as for guiding the design and the scaling-up of MW-PRB treatment.

Inner filter effect, suspended solids and nitrite/nitrate interferences in fluorescence measurements of wastewater organic matter.

In this study, it was assessed the effectiveness to correct for inner filter effect (IFE) the fluorescence spectra of several wastewaters (i.e., primary, secondary and tertiary wastewater effluents) and wastewater-impacted surface waters using a common method based on UV absorbance measurements. In samples of secondary/tertiary wastewater effluents and surface waters, IFE was severe at excitation wavelengths <240 nm, and it was low (4-11%) at excitation wavelengths >340 nm. On the contrary, IFE has always been significant in primary wastewater effluents. After IFE correction, linear relationship was observed between fluorescence and absorbance in dilution series across the full excitation-emission matrix (EEM), although some distortions were still present. Particularly, experimental data showed the presence of static/dynamic quenching of fluorescence due to nitrite/nitrate, which cannot be corrected by IFE correction methods. Indeed, after addition of different nitrate/nitrite concentrations in wastewater (3-40 mg/L as N), the estimated static/dynamic quenching error (QE) after IFE correction was often >20% for tyrosine and tryptophan-like fluorescence measured at excitation <240 nm. However, the QE was low (<5-10%) for fluorescence measured at excitation >240 nm. Overall, the QE increased with the increase of nitrite/nitrate concentration in wastewater. Total suspended solids (TSS) (i.e., particulate organic matter) in water produced intense fluorescence peaks in the tyrosine-like and tryptophan-like region of EEM, and TSS increased the absorbance values at all the excitation wavelengths of the UV-visible absorption spectra in unfiltered samples compared to 0.7 µm filtered samples. On the contrary, tertiary effluents employing full scale sand filtration (TSS < 2-4 mg/l) had similar UV absorbance and fluorescence spectra to 0.7 µm filtered samples. Finally, it was observed that uncorrected fluorescence intensities in the humic-like region of EEM were similar in both filtered and unfiltered samples, and it was independent of TSS concentration, dilution factor and water quality.

Data on the effects of filters, storage conditions, and chlorination in fluorescence and absorbance wastewater measurements.

Data presented in this data article show artifacts (bias and error) that influence fluorescence measurement of dissolved organic matter (DOM) due to samples handling and storage. Data show interferences in fluorescence measurements related to filtration of water by different filter materials, including 0.7 µm glass microfiber filter, 0.45 µm polyvinylidene fluoride (PVDF) membrane, 0.45 µm cellulose nitrate membrane, and 0.45 µm polyethersulfone (PES) syringe filter. Data show also changes of several fluorescence indexes and UV absorbance measurements of wastewater organic matter respect to time under different storage conditions. Particularly, spectroscopic data were acquired using 0.7 µm filtered and unfiltered wastewater samples stored at different temperatures (i.e, room temperature, 4 °C, -20 °C) over a testing period of 21 days. Finally, data show the effect of chlorine disinfection (doses of 0.5-8 mg/L) in fluorescence measurements accomplished in samples from two secondary wastewater effluents. Data of this article are related to the publication "M. Sgroi, E. Gagliano, F.G.A. Vagliasindi, P. Roccaro, Absorbance and EEM fluorescence of wastewater: effects of filters, storage conditions, and chlorination, Chemosphere, 243, 2020, 125292 [1]". Raw data are available in a public repository (https://doi.org/10.17632/pf86xs7ybk.1).

Removal of poly- and perfluoroalkyl substances (PFAS) from water by adsorption: Role of PFAS chain length, effect of organic matter and challenges in adsorbent regeneration.

Poly- and perfluoroalkyl substances (PFAS) are a wide group of environmentally persistent organic compounds of industrial origin, which are of great concern due to their harmful impact on human health and ecosystems. Amongst long-chain PFAS, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are the most detected in the aquatic environment, even though their use has been limited by recent regulations. Recently, more attention has been posed on the short-chain compounds, due to their use as an alternative to long-chain ones, and to their high mobility in the water bodies. Therefore, short-chain PFAS have been increasingly detected in the environmental compartments. The main process investigated and implemented for PFAS removal is adsorption. However, to date, most adsorption studies have focused on synthetic water. The main objective of this article is to provide a critical review of the recent peer-reviewed studies on the removal of long- and short-chain PFAS by adsorption. Specific objectives are to review 1) the performance of different adsorbents for both long- and short-chain PFAS, 2) the effect of organic matter, and 3) the adsorbent regeneration techniques. Strong anion-exchange resins seem to better remove both long- and short-chain PFAS. However, the adsorption capacity of short-chain PFAS is lower than that observed for long-chain PFAS. Therefore, short-chain PFAS removal is more challenging. Furthermore, the effect of organic matter on PFAS adsorption in water or wastewater under real environmental conditions is overlooked. In most studies high PFAS levels have been often investigated without organic matter presence. The rapid breakthrough of PFAS is also a limiting factor and the regeneration of PFAS exhausted adsorbents is very challenging and needs more research.

Data on the inner filter effect, suspended solids and nitrate interferences in fluorescence measurements of wastewater organic matter.

Data presented in this article show the extent of the inner filter effect (IFE) in fluorescence measurements of wastewater and wastewater-impacted surface water samples. Particularly, data show the effectiveness of a commonly used method for IFE correction based on UV absorbance measurement to reinstate the linearity of the relationship between fluorescence intensities and absorbance values. Data report also the effect of nitrates in fluorescence measurements of wastewater samples. Finally, data presented in this work show the effect of total suspended solids (TSS) in the UV absorbance and fluorescence measurements of different waters. Particularly, data describe the TSS effect in fluorescence intensities acquired at different pairs of excitation-emission wavelengths, and in waters with different TSS concentration. Data of this article are related to the publication "M. Sgroi, E. Gagliano, F.G.A. Vagliasindi, P. Roccaro, Inner filter effect, suspended solids and nitrite/nitrate interferences in fluorescence measurements of wastewater organic matter, Sci. Total Environ., In press" [1]. Raw data are available in a public repository (https://doi.org/10.17632/4zss49jycj.1).

Absorbance and EEM fluorescence of wastewater: Effects of filters, storage conditions, and chlorination.

Aim of this study was to delineate sample handling procedures for accurate fluorescence and UV absorbance measurements of wastewater organic matter. Investigations were performed using different wastewater qualities, including primary, secondary and tertiary wastewater effluents, and a wastewater-impacted surface water. Filtration by 0.7 µm glass microfiber filter, 0.45 µm polyvinylidene fluoride (PVDF) membrane, 0.45 µm cellulose nitrate membrane, and 0.45 µm polyethersulfone (PES) syringe filter released manufacture impurities in water that affected fluorescence measurements. However, pre-washing of filter by Milli-Q water was able to eliminate these interferences. Different storage conditions were tested, including storage of filtered and unfiltered samples under different temperatures (25 °C, 4 °C, -20 °C). According to the obtained results, the best practice of wastewater samples preservation was sample filtration at 0.7/0.45 µm immediately after collection followed by storage at 4 °C. However, the time of storage that assured changes of these spectroscopic measurements that do not exceed the 10% of the original value was dependent on water quality and selected wavelengths (i.e., selected fluorescing organic matter component). As a general rule, it is advisable to perform fluorescence and UV absorbance measurements as soon as possible after collection avoiding storage times of filtered water longer than 2 days. Finally, addition of chlorine doses typical for wastewater disinfection mainly affected tryptophan-like components, where changes that exceed the 10% of the fluorescence intensity measured in the unchlorinated sample were observed even at very low doses (≥1 mg/L). On the contrary, tyrosine-like and humic-like components showed changes <10% at chlorine doses of 0.5-5 mg/L.

Comparison of the yields of mono-, Di- and tri-chlorinated HAAs and THMs in chlorination and chloramination based on experimental and quantum-chemical data.

Thermodynamic and kinetic aspects of the formation of trihalomethanes and haloacetic acids determined based on the quantum chemical (QC) simulations were compared in this study with the experimental data generated using the differential spectroscopy approach in chlorination and chloramination. The ratios of the slopes of the correlations between -DlnA350 values and individual DBPs concentrations (SNH2Cl/SHOCl) were observed to be linearly correlated with the ratios of the Gibbs free energies (ΔGNH2Cl/ΔGHOCl) of the corresponding reactions of chloramine and chlorine with acetaldehyde which was used as a model DBP precursor in QC simulations. Further QC examination of the kinetics of chlorination and chloramination of the model compound acetoacetic acid showed that the activation energy of reactions between monochloramine that directly participates in substitution reactions to form mono-, di and tri-halogenated intermediates are 2-3 times higher than those of HOCl formed via the hydrolysis monochloramine. This result confirms that the interactions of chloramine with NOM and ensuing DBP formation are primarily mediated by the free chlorine released as a result of the hydrolysis of monochloramine while direct halogenation of NOM by monochloramine is likely to provide a small contribution to DBP formation.

Degradation of root exudates in closed hydroponic systems using UV/H2O2: Kinetic investigation, reaction pathways and cost analysis.

Qualitative screening of reused nutrient solution (RNS) displays the presence of several organic acids. In this study, the degradation by UV/H2O2 of three of those organic acids (benzoic (BA), phthalic acid (PhA) and succinic acid (SA)) present in RNS was investigated. The results indicated that (i) the degradation rate of BA was faster than that of PhA and SA and (ii) by increasing the contact time the degradation of all acids was improved. For example, the removal of BA increased from 83% and 91% when increasing the contact time from 90 min to 270 min in the presence of 50 mg L-1 and UV. A maximum COD (30%) and UV254 (68%) removal were obtained when 200 mg L-1 H2O2 was applied for 90 min. No significant change was observed in terms of parameters such as PO43- and NO3- while electrical conductivity (EC) and pH were slightly changed during the oxidation process. Pseudo- first -order represented well the experimental data for the degradation of the selected organic acids in RNS (particularly for BA and PhA), exhibiting high linear correlation coefficients (R2 ≥ 0.96). Moreover, the results showed that the decomposition of organic acids was significantly influenced in the presence of inorganic ions in RNS. GC-MS analysis revealed the presence of several intermediate products during the oxidation process and the primary reaction pathway of benzoic acid was accordingly proposed. Finally, a bench scale cost investigation showed that low concentration H2O2 (50 mg L-1) in longer time (270 min) is more cost effective than high concentration H2O2 (200 mg L-1) in a shorter time (90 min).

Modeling emerging contaminants breakthrough in packed bed adsorption columns by UV absorbance and fluorescing components of dissolved organic matter.

This study investigated, using rapid small-scale column testing, the breakthrough of dissolved organic matter (DOM) and eleven emerging organic contaminants (EOCs) during granular activated carbon (GAC) filtration of different water qualities, including wastewater, surface water and synthetic water (riverine organic matter dissolved in deionized water). Fluorescing organic matter was better adsorbed than UV absorbance at 254 nm (UV254) and dissolved organic carbon (DOC) in all tested water. Furthermore, highest adsorption of DOM (in terms of DOC, UV254 and fluorescence) was observed during wastewater filtration. UV absorbing DOM had fast and similar breakthrough in surface water and synthetic water, whereas fluorescence breakthrough was very rapid only in synthetic water. PARAFAC modeling showed that different fluorescing components were differently adsorbed during GAC process. Particularly, fluorescing components with maxima intensity at higher excitation wavelengths, which are corresponding to humic-like fluorescence substances, were better removed than other components in all waters. As opposed to DOM, EOCs were better adsorbed during synthetic water filtration, whereas the fastest EOCs breakthrough was observed during filtration of wastewater, which was the water that determined the highest carbon fouling. Exception was represented by long-chained perfluoroalkylated substances (i.e., PFOA, PFDA and PFOS). Indeed, adsorption of these compounds resulted independent of water quality. In this study was also investigated the applicability of UV254 and fluorescing PARAFAC components to act as surrogates in predicting EOCs removal by GAC in different water matrices. Empirical linear correlation for the investigated EOCs were determined with UV254 and fluorescing components in all water qualities. However, fluorescence measurements resulted more sensitive than UV254 to predict EOC breakthrough during GAC adsorption. When the data from all water qualities was combined, good correlations between the microbial humic-like PARAFAC component and EOC removals were still observed and they resulted independent of water quality if considering only real water matrices (wastewater and surface water). On the contrary, correlations between EOC removals and UV254 removals were independent of water quality when combining data of surface waters and synthetic water, but a different correlation model was needed to predict EOCs breakthrough in wastewater.

Indoor release of asbestiform fibers from naturally contaminated water and related health risk.

This study investigates the occurrence of airborne asbestiform fibers released in indoor ambient due to the use of asbestos naturally contaminated water. Some experiments employed a laboratory physical model using an ultrasonic humidifier charged with contaminated groundwater. Other experiments were carried out at full scale to assess the release of asbestiform fibers during showering. Obtained results show that the concentration of the airborne asbestiform fibers released in the bathroom during showering is higher than the limit value set by the European and Italian Regulations, while the concentration of fibers released by the humidifier is much lower. However, it is noteworthy that the use of the humidifier at high exposure time results in similar health risk. Strong correlations were found between the concentration of the airborne asbestiform fibers and a novel surrogate parameter (i.e. the exposure-specific-water-consumption). These correlations can be used to monitor the asbestiform fibers concentration at varying operating conditions and therefore, to control the resulting health risk.

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.