Treatability studies in real contaminated soils are essential to predict the feasibility of microbial consortium augmentation for field-scale bioremediation of contaminated sites. In this study, the biodegradation of a mixture of seven PAHs in a manufactured gas plant (MGP) soil contaminated with 3967 mg kg⁻¹ of total PAHs using novel acid-, metal-tolerant, N-fixing, P-solubilizing, and biosurfactant-producing LMW and HMW PAH-degrading bacterial combinations as inoculums was compared in slurry- and solid-phase microcosms over natural attenuation. Bioaugmentation of 5 % of bacterial consortia A and N in slurry- and solid-phase systems enhanced 4.6–5.7 and 9.3–10.7 % of total PAH degradation, respectively, over natural attenuation. Occurrence of 62.7–88 % of PAH biodegradation during natural attenuation in soil and slurry illustrated the accelerated rate of intrinsic metabolic activity of the autochthonous microbial community in the selected MGP soil. Monitoring of the total microbial activity and population of PAH degraders revealed that the observed biodegradation trend in MGP soil resulted from microbial mineralization. In the slurry, higher biodegradation rate constant (k) and lower half-life values (t ₁/₂) was observed during bioaugmentation with consortium N, highlighting the use of bioaugmentation in bioslurries/bioreactor to achieve rapid and efficient bioremediation compared to that of a static solid system. In general, natural attenuation was on par with bioaugmentation. Hence, depending on the type of soil, natural attenuation might outweigh bioaugmentation and a careful investigation using laboratory treatability studies are highly recommended before the upscale of a developed bioremediation strategy to field level.

The content and speciation of heavy metals can fundamentally affect the hydrolysis of sludge. This research study investigates the migration and transformation rule of heavy metals during the hydrolysis process by measuring the content of exchangeables (F1), bound to carbonates (F2), bound to Fe-Mn oxides (F3), bound to organic matter (F4), and residuals (F5) under different periods of time undergoing hydrolysis. The results show that the hydrolysis process generally stabilized Cu, Zn, Mn, Ni, Pb, Cr, and As by transforming the unstable states into structurally stable states. Such transformations and stabilization were primarily caused by the changes in local metal ion environment and bonding structure, oxidation of sulfides, pyrolyzation of organic matter, and evaporation of resulting volatile materials. An X-ray diffractometry (XRD) of the residuals conducted after hydrolysis indicated that hydrolysis did have a significant influence on the transportation and transformation of heavy metals.

This study investigates the importance of the organic matter characteristics of several organic amendments (i.e., buffalo manure, food and kitchen waste, fruit and vegetables waste, and activated sewage sludge) and their influence in the bioremediation of a polycyclic aromatic hydrocarbons (PAH)-contaminated soil. The removal of low molecular weights (LMW) and high molecular weights (HMW) PAHs was monitored in four bioremediation reactors and used as an indicator of the role of organic amendments in contaminant removal. The total initial concentration of LMW PAHs was 234 mg kg⁻¹ soil (dry weight), while the amount for HMW PAHs was 422 mg kg⁻¹ soil (dry weight). Monitoring of operational parameters and chemical analysis was performed during 20 weeks. The concentrations of LMW PAH residues in soil were significantly lower in reactors that displayed a mesophilic phase, i.e., 11 and 15 %, compared to reactors that displayed a thermophilic phase, i.e., 29 and 31 %. Residual HMW PAHs were up to five times higher compared to residual LMW PAHs, depending on the reactor. This demonstrated that the amount of added organic matter and macronutrients such as nitrogen and phosphorus, the biochemical organic compound classes (mostly soluble fraction and proteins), and the operational temperature are important factors affecting the overall efficiency of bioremediation. On that basis, this study shows that characterization of biochemical families could contribute to a better understanding of the effects of organic amendments and clarify their different efficiency during a bioremediation process of PAH-contaminated soil.

Embryonic and early postembryonic development of the cuttlefish Sepia officinalis (a cephalopod mollusk) occurs in coastal waters, an environment subject to considerable pressure from xenobiotic pollutants such as pharmaceutical residues. Given the role of serotonin in brain development and its interaction with neurodevelopmental functions, this study focused on fluoxetine (FLX), a selective serotonin reuptake inhibitor (SSRI, antidepressant). The goal was to determine the effects of subchronic waterborne FLX exposure (1 and 10 μg L⁻¹) during the last 15 days of embryonic development on neurochemical, neurodevelopmental, behavioral, and immunological endpoints at hatching. Our results showed for the first time that organic contaminants, such as FLX, could pass through the eggshell during embryonic development, leading to a substantial accumulation of this molecule in hatchlings. We also found that FLX embryonic exposure (1 and 10 μg L⁻¹) (1) modulated dopaminergic but not serotonergic neurotransmission, (2) decreased cell proliferation in key brain structures for cognitive and visual processing, (3) did not induce a conspicuous change in camouflage quality, and (4) decreased lysozyme activity. In the long term, these alterations observed during a critical period of development may impair complex behaviors of the juvenile cuttlefish and thus lead to a decrease in their survival. Finally, we suggest a different mode of action by FLX between vertebrate and non-vertebrate species and raise questions regarding the vulnerability of early life stages of cuttlefish to the pharmaceutical contamination found in coastal waters.

This study aims to evaluate extensively the inhibition of six PCB (polychlorinated biphenyls) congeners in batch reactors under fermentative-methanogenic condition. The reactors with anaerobic sludge were fed with mineral medium, co-substrates (ethanol and sodium formate), and five PCB concentrations. The maximum methane production (MMP) in the reactor without PCB (RC), with 0.5 (R0.5), 1.5 (R1.5), 3.0 (R3.0), 4.5 (R4.5), and 6.0 mg/L (R6.0) of PCB, was 654.83, 193.08, 111.65, 104.60, 96.67, and 79.50 μmolCH₄/gTVS, respectively. The methane inhibition for the reactors R0.5, R1.5, R3.0, R4.5, and R6.0 were 70, 83, 84, 85, and 88 %, respectively. The concentration that causes 50 % of inhibition (IC₅₀) for PCB was 0.03 mg/L. The inhibition results present two different profiles according to the concentration range. The concentration range of 0.5 to 3.0 mg/L of PCB inhibited the acetoclastic microorganisms and the concentration of 4.5 to 6.0 mg/L inhibited both methanogenic and acidogenic population. The acidogenic populations were less sensitive to the PCB than the methanogenic. Lower methane production and organic matter removal were verified in all reactors with PCB compared to RC, without PCB. The microbial community highlighted lower diversity index for reactors with higher PCB concentration. In the reactors with PCB, the populations of bacteria domain were more susceptible to composition changes than the archaea domain. The inhibitory effect of PCB is concentration-dependent and affected differently the populations of organisms in the reactor. Moreover, the range of 4.5 to 6.0 mg/L of PCB severely inhibited the anaerobic community.

This study investigated the effects of various soil conditions, including drying-rewetting, nitrogen deposition, and temperature rise, on the quantities and the composition of dissolved organic matter leached from forest and wetland soils. A set of forest and wetland soils with and without the nitrogen deposition were incubated in the growth chambers under three different temperatures. The moisture contents were kept constant, except for two-week drying intervals. Comparisons between the original and the treated samples revealed that drying-rewetting was a crucial environmental factor driving changes in the amount of dissolved organic carbon (DOC). The DOC was also notably increased by the nitrogen deposition to the dry forest soil and was affected by the temperature of the dry wetland soil. A parallel factor (PARAFAC) analysis identified three sub-fractions of the fluorescent dissolved organic matter (FDOM) from the fluorescence excitation–emission matrices (EEMs), and their compositions depended on drying-rewetting. The data as a whole, including the DOC and PARAFAC components and other optical indices, were possibly explained by the two main variables, which were closely related with the PARAFAC components and DOC based on principal component analysis (PCA). Our results suggested that the DOC and PARAFAC component information could provide a comprehensive interpretation of the changes in the soil-leached DOM in response to the different environmental conditions.

To analyze the daytime and phenological variations of canopy O₃ and CO₂ uptake of winter wheat, the canopy fluxes of wheat plants were measured using a chamber system with four different O₃ levels (0, 40, 80, and 120 nmol mol⁻¹) being applied. During the daytime (7:30–18:00 hours), canopy fluxes usually peaked around noon in early growing stages, while a generally decreasing trend from morning to afternoon was observed in the later stages. O₃ and CO₂ fluxes were positively and negatively correlated with O₃ concentration, respectively. Significant differences were observed in O₃ fluxes but CO₂ fluxes among O₃ treatments. Photosynthetically active radiation (PAR) and vapor pressure deficit (VPD) could affect canopy gas uptake in opposite ways. On the phenological timescale, both O₃ and CO₂ fluxes followed the variation of leaf area index (LAI) with the maximum occurring simultaneously at the booting stage. The daytime mean fluxes varied from −10.6 to −17.2 nmol m⁻² s⁻¹ for O₃ and from −5.9 to −19.6 μmol m⁻² s⁻¹ for CO₂. Quantitatively important O₃ deposition (−3.1∼−11.6 nmol m⁻² s⁻¹) was also observed at night with the ratios being about 40∼70 % relative to the daytime O₃ fluxes for most measuring days, which indicates a significant contribution from non-stomatal components to canopy O₃ removal. This study confirms that environmental variables and plant phenology are important factors in regulating canopy O₃ and CO₂ uptake. O₃ exposure (≤120 nmol mol⁻¹) could not significantly affect the CO₂ uptake of wheat canopy in a short time (ca. 10 min).

The 2′,7′-dichlorofluorescin (DCFH) assay is widely used to measure particle-bound reactive oxygen species (ROS), which are considered as a major contributor leading to the adverse health effects upon exposure to atmospheric particulate matter. DCFH, a non-fluorescent substance that can be oxidized to highly fluorescent dichlorofluorescein (DCF) in the presence of horseradish peroxidase (HRP), is usually used as a probe for ROS determination due to its response to diverse and relevant oxidant species. However, there is limited literature that reports the effects of different experimental conditions in the performance of this assay. In our work, various experimental conditions, such as pH value, incubation temperature, reagent concentration and stability, reaction time, linearity range, and extraction method, were examined and optimized as a pilot study for developing an online system for atmospheric ROS measurement. The results showed that pH value, reagent concentration, and extraction method significantly affect the performance of DCFH assay, while incubation at a specified temperature (37 °C) did not increase the oxidization extent of DCFH. After optimization, some practical samples were measured using different experimental parameters to check the performance of the optimized assay. The comparisons of these measurements showed that optimization can greatly improve the detection limit and reproducibility of the DCFH assay, which can then be employed to better the accuracy of offline and online ROS measurement.

Photolysis or photocatalysis may provide a process for mitigating ecological risks of naphthenic acids (NAs) contained in energy-derived waters such as refinery effluents and process waters. If effective, fixed-film TiO₂ photocatalysis of NAs could decrease operational expenses as well as capital costs for water treatment. The overall objective of this study was to measure rates and extents of photolysis and photocatalytic degradation of commercial NAs using bench-scale fixed-film TiO₂ and confirm changes in NA concentrations using sensitive vertebrate (fish = Pimephales promelas) and invertebrate (Daphnia magna) species. Specific objectives were to (1) measure rates and extents of degradation of commercial (Fluka) NAs throughout an 8-h duration of natural sunlight (“photolysis”) and natural sunlight in the presence of fixed-film TiO₂ (“photocatalysis”) and (2) measure changes in toxicity in terms of mortality with sentinel fish and microinvertebrate species. Bench-scale chambers using thin-film TiO₂ irradiated with natural sunlight were used to measure photocatalysis, and HPLC was used to quantify NAs. After 4 h in photocatalysis treatments, >92 % decline was observed with an average removal rate of 15.5 mg/L/h and half-life of 2 h. After 5 h of photocatalysis, there was no measurable NA toxicity for fish (P. promelas) or microinvertebrates (D. magna). Photocatalytic degradation achieved efficacious rates and extents of removal of Fluka NAs and eliminated acute toxicity to sentinel aquatic organisms, indicating the potential for application of this technology for mitigating ecological risks. Coupled with existing treatment processes (i.e., aerobic biodegradation), photocatalysis can augment rates and extents of NA removal from impacted waters.

Present technologies for wastewater treatment do not sufficiently address the increasing pollution situation of receiving water bodies, especially with the growing use of personal care products and pharmaceuticals (PPCP) in the private household and health sector. The relevance of addressing this problem of organic pollutants was taken into account by the Directive 2013/39/EU that introduced (i) the quality evaluation of aquatic compartments, (ii) the polluter pays principle, (iii) the need for innovative and affordable wastewater treatment technologies, and (iv) the identification of pollution causes including a list of principal compounds to be monitored. In addition, a watch list of 10 other substances was recently defined by Decision 2015/495 on March 20, 2015. This list contains, among several recalcitrant chemicals, the painkiller diclofenac and the hormones 17β-estradiol and 17α-ethinylestradiol. Although some modern approaches for their removal exist, such as advanced oxidation processes (AOPs), retrofitting most wastewater treatment plants with AOPs will not be acceptable as consistent investment at reasonable operational cost. Additionally, by-product and transformation product formation has to be considered. The same is true for membrane-based technologies (nanofiltration, reversed osmosis) despite of the incredible progress that has been made during recent years, because these systems lead to higher operation costs (mainly due to higher energy consumption) so that the majority of communities will not easily accept them. Advanced technologies in wastewater treatment like membrane bioreactors (MBR) that integrate biological degradation of organic matter with membrane filtration have proven a more complete elimination of emerging pollutants in a rather cost- and labor-intensive technology. Still, most of the presently applied methods are incapable of removing critical compounds completely. In this opinion paper, the state of the art of European WWTPs is reflected, and capacities of single methods are described. Furthermore, the need for analytical standards, risk assessment, and economic planning is stressed. The survey results in the conclusion that combinations of different conventional and advanced technologies including biological and plant-based strategies seem to be most promising to solve the burning problem of polluting our environment with hazardous emerging xenobiotics.