C2–C8 NMHCs over the Eastern Mediterranean: Seasonal variation and impact on regional oxidation chemistry

More than 2500 measurements of C₂–C₈ non-methane hydrocarbons (NMHCs) have been conducted at Finokalia sampling station on the island of Crete over a thirty-month period (September 2003–February 2006), to investigate the factors controlling NMHC levels and estimate their role in the oxidizing capacity of the Eastern Mediterranean atmosphere. Atmospheric concentrations of NMHCs range from below the detection limit (5 pptv) to a few ppbv and present a hydroxyl radical (OH) driven seasonal pattern with lower values during summer. The diel variability was also influenced by the reaction of the NMHC with the OH radical, exhibiting a nighttime maximum and a midday or early afternoon minimum. Long-lived compounds demonstrate higher concentrations under the influence of the northern sector (European continent), indicating that besides chemistry, transport significantly contributes to NMHCs levels in the area. Based on the observed NMHCs diurnal cycles, mean OH radical levels of 3.5 × 10⁶ molecules cm⁻³ have been derived for May–October period.     

Identification of new ozonation disinfection byproducts of 17β-estradiol and estrone in water

Estrogens are a class of micro-pollutants found in water at low concentrations (in the ng L⁻¹ range), but often sufficient to exert estrogenic effects due to their high estrogenic potency. Disinfection of waters containing estrogens through oxidative processes has been shown to lead to the formation of disinfection byproducts, which may also be estrogenic. The present work investigates the formation of disinfection byproducts of 17β-estradiol (E2) and estrone (E1) in the treatment of water with ozone. Experiments have been carried out at two different concentrations of the estrogens in ground water (100 ng L⁻¹ and 100 μg L⁻¹) and at varying ozone dosages (0-30 mg L⁻¹). Detection of the estrogens and their disinfection byproducts in the water samples has been performed by means of ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with a triple quadrupole (QqQ) and a quadrupole-time of flight (QqTOF) instrument. Both E2 and E1 have been found to form two main byproducts, with molecular mass (MM) 288 and 278 in the case of E2, and 286 and 276 in the case of E1, following presumably the same reaction pathways. The E2 byproduct with MM 288 has been identified as 10epsilon-17beta-dihydroxy-1,4-estradieno-3-one (DEO), in agreement with previously published results. The molecular structures and the formation pathways of the other three newly identified byproducts have been suggested. These byproducts have been found to be formed at both high and low concentrations of the estrogens and to be persistent even after application of high ozone dosages.     

Copper mobilization affected by weather conditions in a stormwater detention system receiving runoff waters from vineyard soils (Champagne, France)

Copper, a priority substance on the EU-Water Framework Directive list, is widely used to protect grapevines against fungus diseases. Many vineyards being located on steep slopes, large amounts of Cu could be discharged in downstream systems by runoff water. The efficiency of stormwater detention basins to retain copper in a vineyard catchment was estimated. Suspended solids, dissolved (Cu_diss) and total Cu (Cu_tot) concentrations were monitored in runoff water, upstream, into and downstream from a detention pond. Mean Cu_tot concentrations in entering water was 53.6 μg/L whereas it never exceeded 2.4 μg/L in seepage. Cu_tot concentrations in basin water (>100 μg/L in 24% of the samples) exceeded LC₅₀ values for several aquatic animals. Copper was principally sequestered by reduced compounds in the basin sediments (2/3 of Cu_tot). Metal sequestration was reversible since sediment resuspension resulted in Cu remobilization. Wind velocity controlled resuspension, explained 70% of Cu_diss variability and could help predicting Cu mobilization.     

Lactate oxidation in pyrite suspension: a Fenton-like process in situ generating H2O2

Pyrite is a common mineral at many mining sites. In this study, the mineral pyrite was studied as a Fenton-like reagent for environmental concerns. We selected lactate as a model target molecule to evaluate the Fenton-like catalytic efficiency of pyrite upon organic oxidation. A complete set of control experiments in both aerobic and anaerobic atmospheres unequivocally established that the pyrite in aqueous solution could spontaneously in situ generate OH and H₂O₂, serving as a Fenton-like reagent to catalyze the oxidation of lactate to pyruvate with no need for additional H₂O₂. We called it the pyrite-only Fenton-like (PF) reagent. Monitoring concentration changes of lactate and pyruvate with the time indicated that the pyrite mediated the favorable pyruvate formation at pH 4.5, 60 °C, under air atmosphere. The PF reaction could be stimulated by visible light illumination. Under the optimum conditions, up to 50% of lactate was degraded within 10 d. The results suggest that pyrite and its Fenton-like processes may be potentially practical in wastewater treatment.     

Decomposition and oxidation of sodium 3,5,6-trichloropyridin-2-ol in sub- and supercritical water

Sodium 3,5,6-trichloropyridin-2-ol (STCP) is a necessary precursor compound for the production of chlorpyrifos and triclopyr, which are extensively used as pesticide and herbicide, respectively. In the process of STCP production, however, large amount of wastewater containing STCP is discharged, which causes increasingly environmental concerns. Therefore, it is of great significance to develop a rapid and effective method for the disposal of containing STCP contaminants. In this work, the thermal decomposition of STCP in sub- and supercritical water was investigated using a continuous tubular reactor. While STCP was stable below 280 °C, it could be effectively decomposed at elevated temperature. FT-IR spectra of the decomposition products indicated that the pyridine ring structure in the STCP molecule was stable even at temperatures up to 400 °C. The decomposition reaction was mainly caused by the substitution of Cl groups in the STCP molecule with OH groups, resulting in polyhydroxylated pyridines as the major decomposition product. Moreover, high pressure favored the substitution reaction. To completely decompose STCP into non-toxic or low toxic compounds, supercritical water oxidation (SCWO) was employed to evaluate the oxidation of STCP using H₂O₂ as an oxidant. It was found that STCP could be completely oxidized to H₂O, CO₂ and corresponding inorganic ammonium salts with an oxidation rate of 99%.     

Removal of carotene-like colored compounds by liquid-liquid extraction during polycyclic aromatic hydrocarbons analysis of plant tissue

Plants contain a wide variety of chemicals, some of which may have similar chromatographic behavior to polycyclic aromatic hydrocarbons (PAHs). During solid phase extraction (SPE) with Si-gel for instance, the co-elution of carotene-like colored compounds with PAHs has been observed. In this paper, liquid–liquid extraction was applied for the separation and subsequent analysis of PAHs from plant extracts. PAHs containing 2–6 rings, which include naphthalene, phenanthrene, pyrene, benzo[a]pyrene and benzo[ghi]perylene, were used as representative target chemicals. Carotene-like compounds extracted from Komatsuna (Brassica campestris) shoot by acetone followed by Si-gel treatment were incorporated as undesired components in the model matrix. Results showed the feasibility of employing either acetonitrile or 2% (w/v) KOH–methanol as solvents for high PAHs recovery and low extraction of colored fraction. For acetonitrile, 86.9–93.5% of each PAH could be recovered after three extraction cycles (relative standard deviation, RSD < 1.6%) with only about 10% co-extraction of colored fraction. For 2% KOH–methanol, PAHs recoveries ranging from 79.3% to 83.1% after five cycles (RSD < 1.5%) were achieved while the percent extraction of colored fraction was also low at 10%. The relatively higher selectivity of the solvents for PAHs over the colored fraction as well as the solubility of the matrix solution in the solvent may have contributed to these results. On this basis, liquid–liquid extraction is very useful for the pre-treatment of plant extracts for PAHs analysis.     

Field-scale operation of methane biofiltration systems to mitigate point source methane emissions

Methane biofiltration (MBF) is a novel low-cost technique for reducing low volume point source emissions of methane (CH₄). MBF uses a granular medium, such as soil or compost, to support the growth of methanotrophic bacteria responsible for converting CH₄ to carbon dioxide (CO₂) and water (H₂O). A field research program was undertaken to evaluate the potential to treat low volume point source engineered CH₄ emissions using an MBF at a natural gas monitoring station. A new comprehensive three-dimensional numerical model was developed incorporating advection-diffusive flow of gas, biological reactions and heat and moisture flow. The one-dimensional version of this model was used as a guiding tool for designing and operating the MBF. The long-term monitoring results of the field MBF are also presented. The field MBF operated with no control of precipitation, evaporation, and temperature, provided more than 80% of CH₄ oxidation throughout spring, summer, and fall seasons. The numerical model was able to predict the CH₄ oxidation behavior of the field MBF with high accuracy. The numerical model simulations are presented for estimating CH₄ oxidation efficiencies under various operating conditions, including different filter bed depths and CH₄ flux rates. The field observations as well as numerical model simulations indicated that the long-term performance of MBFs is strongly dependent on environmental factors, such as ambient temperature and precipitation.     

Effect of Fenton pretreatment on anaerobic digestion of olive mill wastewater and olive mill solid waste in mesophilic conditions

The olive mill waste (OMW) generated from olive oil extraction process constitutes a major environmental concern owing to its high organic and mineral matters and acidic pH. Anaerobic digestion (AD) is a main treatment for reducing the organic matter and toxic substances contained in OMW and generating at the same time, energy in the form of biogas. AD of OMW that contains lignocellulose is limited by the rate of hydrolysis due to their recalcitrant structure. This study is devoted to the effect of Fenton process (FP) pretreatment on olive mill wastewater (OMSW) /olive mill solid waste (OMWW) co-digestion to improve their digestibility and in this way the biogas production. The FP pretreatment was performed in batch mode at 25°C, various H₂O₂/[Fe²⁺] ratios (100–1200), catalyst concentration ([Fe²⁺]) ranging from 0.25 to 2 mM, reaction time varying from 30 to150 min, and different pH (3–11). The best performance was obtained with H₂O₂/[Fe²⁺] = 1000, [Fe²⁺] = 1.5 mM, 120 min, and pH 3. Biochemical methane potential (BMP) tests conducted in batch wise digester and at mesophilic conditions (37 °C) showed that cumulative biogas and methane production were higher without FP treatment, and correspond to 699 and 416 mL/g VS, respectively. However, pre-treated OMSW results into an increase of 24% of methane yield. After 30 days of AD, the methane yield was 63%, 54%, and 48%, respectively, for OMSW treated without iron precipitation, with iron precipitation and untreated OMSW sample.     

阴极氧还原产电生物可渗透反应栅的研究Ⅱ.酸蚀处理对不锈钢丝电极性能的影响

不锈钢毛虽然用作阴极氧还原产电生物反应栅（CORE—PRB）的电极材料虽然有很多优点，但是反应电流较小。尝试对不锈钢毛进行酸蚀处理后用作电极材料，并分别研究比较了4种不同电极组合的产电反应性能。酸蚀处理显著提高不锈钢毛阳极的反应性能，并对提高不锈钢毛阴极的反应性能有一定作用。酸蚀的作用主要是使不锈钢毛表面变得粗糙，有利于提高电极表面积和材料的生物亲和性。虽然生物产电反应对COD降解的直接贡献不到10％，但是不同电极组合下COD的去除率与它们生物产电反应的贡献率呈现高度正相关性。