Behavior Of Micropollutants Research Articles

Contamination of water, soil, and plants by micropollutants from reclaimed wastewater and sludge from a wastewater treatment plant

Several studies have shown that plants can absorb various micropollutants. The behavior of micropollutants from wastewater treatment plant resources was comprehensively investigated in raised beds in which either a mixture of vegetables or maize was grown. The beds were either irrigated with treated wastewater or enriched with sewage sludge or composted sewage sludge. Over the year, samples of wastewater, water drained from the beds, soils and plants were analyzed. Of the seventy-five analyzed substances, fifty-four, thirty-three and twenty-seven were quantified in wastewater, sewage sludge, and composted sludge, respectively. Alarmingly, approximately 20 % of the compounds from wastewater were also detected in the solutions leached from the beds irrigated with wastewater (e.g., gabapentin, tramadol, sertraline, carbamazepine, its metabolites, and benzotriazoles). In addition, a gradual increase in the content of four substances (telmisartan, venlafaxine, carbamazepine, citalopram) was recorded in these beds. The compounds from both biosolids used for soil enrichment tended to remain in the soils (e.g., telmisartan, venlafaxine, sertraline, its metabolite, citalopram, and its metabolite). Only four compounds (sertraline and three benzotriazoles) leached from these beds. Uptake of some chemicals (e.g., gabapentin, tramadol, carbamazepine and its metabolite, and venlafaxine and its metabolite) and their accumulation in plant tissues was observed mainly in vegetables grown on beds irrigated with wastewater. However, daily consumption values for edible plant parts and individual compounds did not indicate a direct threat to human health. Results of this innovative study show possible risks associated with the use of these resources in agriculture. Of particular concern is the possible micropollutants percolation towards groundwater, including those for which high sorption and thus low mobility in the soil environment is expected, such as sertraline. Soil and crop contamination cannot be neglected either.

Behavior of Micropollutants in Polishing Units that Combine Sorption and Biodegradation Mechanisms to Improve the Quality of Activated Sludge Effluent

The current study evaluated the removal of six micropollutants (estrone (E1); 17β-estradiol (E2); 17α-ethynylestradiol (EE2); ibuprofen (IBP), diclofenac (DCF), and paracetamol (PCT)) from the final effluent of an activated sludge domestic sewage treatment plant using polishing filters. Four polishing filters were assembled as columns and filled with a mixture of sand and vermiculite, sand and charcoal, sand and granulated activated carbon (9:1 by volume), and sand only. The column filters were placed near the outlet of a full-scale activated sludge treatment plant and were fed with a treated effluent containing from 4.71 to 28.93 ng L-1 of the target compounds at a hydraulic loading rate (HLR) of 50 m3 m−2 day−1. Samples were collected periodically from the influent (biologically treated sewage) and effluent of the four columns and analyzed for estrogens, anti-inflammatories, and analgesic compounds. Liquid samples were submitted to a solid phase extraction (SPE) and analyzed by gas chromatography coupled with mass spectrometry after their derivatization. Among the compounds found, diclofenac was distinguished by the high occurrence of detection in the samples (85%) and higher mean concentration (~ 17 ng L−1). High removal efficiency (> 90%) of the estrogens was observed in the polishing systems studied, while for the other targets, the removal efficiency varied from 10 to 30%. The concentration values of some compounds were low, probably due to rainfall during the sampling period.

LC-HRMS Data Processing Strategy for Reliable Sample Comparison Exemplified by the Assessment of Water Treatment Processes.

The behavior of micropollutants in water treatment is an important aspect in terms of water quality. Nontarget screening by liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) offers the opportunity to comprehensively assess water treatment processes by comparing the signal heights of all detectable compounds before and after treatment. Without preselection of known target compounds, all accessible information is used to describe changes across processes and thus serves as a measure for the treatment efficiency. In this study, we introduce a novel LC-HRMS data processing strategy for the reliable classification of signals based on the observed fold changes. An approach for filtering detected features was developed and, after parameter adjustment, validated for its recall and precision. As proof of concept, the fate of 411 target compounds in a 0.1 μg/L standard mix was tracked throughout the data processing stages, where 406 targets were successfully recognized and retained during filtering. Potential pitfalls in signal classification were addressed. We found the recursive peak integration to be a key point for the reliable classification of signal changes across a process. For evaluating the repeatability, a combinatorial approach was conducted to verify the consistency of the final outcome using technical replicates of influent and effluent samples taken from an ozonation process during drinking water treatment. The results showed sufficient repeatability and thus emphasized the applicability of nontarget screening for the assessment of water treatment processes. The developed data processing strategies may be transferred to other research fields where sample comparisons are conducted.

Seasonality of temperatures and redox zonations during bank filtration – A modeling approach

Bank filtration (BF) is a common technique for supplying drinking water, using the ability of the infiltration zone and aquifer passage to attenuate or degrade undesired substances that infiltrate from surface waters to groundwater abstraction wells. Temporal and spatial changes of temperatures and redox conditions are often the controlling factors for the fate and behavior of micropollutants during subsurface passage and consequently for the extracted raw water quality. A 2-dimensional cross-sectional heat transport and multi-species reactive transport model was set up to simulate the seasonally varying temperatures and redox conditions on the infiltration path at a bank filtration site in Berlin, Germany. The calibrated model was able to capture the observed variations in O2 and NO3− when considering temperature dependence of the redox reaction kinetics. The observed Mn2+- and Fe2+-concentrations were not well replicated by the model, presumably due to mineral reactions that were not accounted for in the simulations. SO42− was found to behave conservative, i.e., the observed concentration could be well simulated without any reactions. The simulations reveal the transience of BF systems with regard to temperatures and redox conditions, which has important implications for the BF quality and should therefore be accounted for.

Effects of biochar on the transformation and earthworm bioaccumulation of organic pollutants in soil.

Little is known about the effects of biochar on the fate and behavior of micropollutants in soil, especially in the presence of soil macrofauna. Using a 14C-tracer, we studied the fate of 2,4-dichlorophenol and phenanthrene, after 30 days in soil in the presence of a biochar (0-5%, dry weight) produced from China fir at 400 °C and/or the earthworm Metaphire guillelmi. Application of the biochar significantly reduced the degradation and mineralization of both pollutants and strongly increased the accumulation of their metabolites in soil. The earthworm had no significant effects on the degradation of parent molecules of the pollutants but it significantly reduced the mineralization of the pollutants independent of the presence of the biochar. Although at an application rate of <1% the biochar strongly sorbed both pollutants, it did not significantly decrease the bioaccumulation of free dichlorophenol and phenanthrene and their metabolites by the earthworm. Our results demonstrate the complex effects of biochar on the fate, transformation, and earthworm bioaccumulation of organic pollutants in soil. They show that biochar application may not be an appropriate strategy for treating soil contaminated with hydrophobic organic pollutants and underline the importance of soil-feeding earthworms in risk assessments of biochar effects on soil remediation.

Occurrence and loss over three years of 72 pharmaceuticals and personal care products from biosolids–soil mixtures in outdoor mesocosms

Municipal biosolids are in widespread use as additives to agricultural soils in the United States. Although it is well known that digested sewage sludge is laden with organic wastewater contaminants, the fate and behavior of micropollutants in biosolids-amended agricultural soils remain unclear. An outdoor mesocosm study was conducted in Baltimore, Maryland, to explore the fate of 72 pharmaceuticals and personal care products (PPCPs) over the course of three years in that were placed in plastic containers made from polyvinylchloride and kept exposed to ambient outdoor conditions. Of the 72 PPCPs tested for using EPA Method 1694, 15 were initially detected in the soil/biosolids mixtures at concentrations ranging from low parts-per-billion to parts-per-million levels. The antimicrobials triclocarban and triclosan showed the highest initial concentrations at 2715 and 1265 μg kg −1, respectively. Compounds showing no discernable loss over three years of monitoring included diphenhydramine, fluoxetine, thiabendazole and triclocarban. The following half-life estimates were obtained for compounds showing first-order loss rates: azithromycin (408–990 d) carbamazepine (462–533 d), ciprofloxacin (1155–3466 d), doxycycline (533–578 d), 4-epitetracycline (630 d), gemfibrozil (224–231 d), norfloxacin (990–1386 d), tetracycline (578 d), and triclosan (182–193 d). Consistent with other outdoor degradation studies, chemical half-lives determined empirically exceeded those reported from laboratory studies or predicted from fate models. Study results suggest that PPCPs shown in the laboratory to be readily biotransformable can persist in soils for extended periods of time when applied in biosolids. This study provides the first experimental data on the persistence in biosolids-amended soils for ciprofloxacin, diphenhydramine, doxycycline, 4-epitetracycline, gemfibrozil, miconazole, norfloxacin, ofloxacin, and thiabendazole.

The role of NOM fouling for the retention of estradiol and ibuprofen during ultrafiltration

The impact of membrane fouling by natural organic matter (NOM) on the behavior of micropollutants during ultrafiltration (UF) was investigated. Batch experiments with radioactively labeled estradiol and ibuprofen in the presence of NOM model compounds (alginate, Nordic aquatic and Aldrich humic acid) were performed using a hydrophilic and a hydrophobic membrane. The results indicate that the impact of the NOM fractions studied on micropollutant retention correlated with the fouling mechanism of the individual NOM fractions. NOM substances of high molecular weight such as alginate and Aldrich HA that foul the membrane by pore blocking and cake/gel formation had a greater impact than the Nordic aquatic humic acid of lower molecular weight. The effect of cake formation was attributed partly to micropollutant-NOM partitioning and subsequent NOM retention and partly to the effect of the fouling layer itself acting as a kind of second membrane. Fouling by NOM cake/gel formation led to a significantly increased retention of estradiol, whereas the impact of fouling on ibuprofen retention was negligible due to significantly lower log K oc values of ibuprofen compared to estradiol. Moreover, NOM adsorption on the membrane can lower the adsorption of hydrophobic micropollutants. Membrane adsorption of estradiol was in the order of mg/m 2 and was largely reversible with caustic solutions. The results of this study may prove useful for predicting the mass flow of micropollutants in UF applications.

Behaviour of Micropollutants in Soils Amended with River Cleaning out Sludge in Northern France

Thisstudyis aimed at determining the fate of some heavy metals and hydrocarbons in soils amended with sludge from river cleaning out. Northern France has been chosen for the experiment because it is a heavily industrialized region where contamination by micropollutants has been very acute for many years. Several French laboratories are associated in this joint project which is partly sponsored by the Ministry of Environment and Artois-Picardie Water Agency. The parcel of land studied has a surface area of 100m2. It has been instrumented with Chamberland candles in order to get water for micropollutants analysis, tensiometers and a neutronic probe so as to collect informations on the hydric state of the soil. Once instrumented the parcel has been spread with sludge from river cleaning out. The main objective is to obtain an estimation of the fluxes of micropollutants and to evaluate the respective proportions of infiltration and drainage. A lab study based on lysimeters is carried out together with the field study. The field study will last at least 2 years while the lab study will be going on for a year.