Concentrations Of Organic Contaminants Research Articles

Estimating wastewater emissions and environmental levels of typical organic contaminants based on regionalized modelling.

Organic contaminants (OCs) are released into the environment through effluent discharges from wastewater treatment plants (WWTP), posing risks to environment health. However, emissions from various source, particularly large-scale investigations across different industries, remain poorly understood. Based on both sampling and statistical data, this study estimates the emissions of 10 OCs, including perfluorooctane acid (PFOA), perfluorooctane sulfonate (PFOS), 4-nonylphenol (4-NP), 4-tert-octylphenol (4-t-OP), dibutyl phthalate (DBP), di-iso-butyl phthalate (DIBP), dimethyl phthalate (DMP), butyl benzyl phthalate (BBP), di(2-ethylhexyl) phthalate (DEHP), and bisphenol A (BPA), from the effluents of 160 factories across 8 industries, 541 municipal wastewater treatment plants (MWWTPs), and 8 waste treatment plants (WTPs) in the upper Yangtze River Basin. A level III fugacity multimedia model was used to assess the impacts of these emissions on local watersheds. Among the 8 industries, paper production was the largest contributor, accounting for over 80% of total OC emissions, which amounted to 89.1 kg/yr. The contributions of domestic and industrial sources were 91.5% and 8.5%, respectively, underscoring the predominance of domestic sources in the release of the 10 OCs. PFOA emerged as the most dominant compound, with total emissions amounting to 4464 kg/yr from domestic sources and 170 kg/yr from industrial sources. The predicted concentrations of OCs in the receiving rivers closely aligned with values reported in existing literature, differing by no more than one order of magnitude. To our knowledge, this is the first comprehensive report on emissions from various sources in the upper Yangtze River Basin.

Association of Hepatic Gene Expression with Chemical Concentrations in Wild-Collected Double-Crested Cormorant Embryos using an EcoToxChip Gene Array.

Contaminant monitoring programs use wild bird eggs, but determining whether measured concentrations elicit adverse effects relies on extrapolation from toxicity studies with avian model species. Here, we directly evaluated the relationships between whole embryo contaminant concentrations and mRNA expression in liver tissue of the double-crested cormorant (Nannopterum auritum). Eggs collected from three North American sites (one from Lake Erie and two from the Salish Sea) were artificially incubated until pipping. Hepatic mRNA was analyzed with an EcoToxChip quantitative polymerase chain reaction (qPCR) array containing 354 target genes. The remaining embryo was analyzed for mercury and 95 persistent organic contaminants. Lake Erie embryos had higher concentrations of most organic contaminants than those from the Salish Sea. Sparse partial least-squares regression analysis of contaminant and gene expression data indicated that chlorinated hydrocarbons, especially polychlorinated biphenyls (PCBs), were associated with variation in gene expression. Linear correlations revealed consistent pairwise associations between chlorinated contaminants and the expression of nine genes (seven genes with PCBs and two with β-hexachlorocyclohexane). Partial least-squares discriminant analysis identified embryos from the Lake Erie site accurately. Overall, gene expression in embryos from wild-collected eggs was associated with tissue contaminant concentrations, and thus, transcriptomic measurements may serve to identify individuals or populations affected biologically by contaminants.

Assessing human exposure to organic contaminants in fish: A modeling approach integrating chemical bioconcentration and food thermal processing

An increasing number of chemicals found in the environment potentially pose a threat to organisms such as fish. Models for risk assessment are vital resources that enable possible measurements of the hazards associated with chemical exposure. Traditional monitoring techniques and experimental procedures, however, are unable to keep up with the compounds that are becoming more and more implicated in environmental problems. Furthermore, a significant amount of data invariably results in inaccuracies. Here, we proposed an integrated approach that combines machine learning and fuzzy logic mathematical methods, assessing the risks associated with chemical exposure from contaminated fish with the least amount of data entry possible. We predicted the concentrations of organic contaminants in the environment, serving as a baseline for quantifying the fuzzy risks during household thermal processing of the fish. With a mean R2 value of 0.78, concentration of chemicals in the aquatic environment emerged as the most influential factor in predicting bioconcentration factors. Heptachlor, Endosulfan-sulfate, Endrin, and Endrin aldehyde are four high-risk pesticides throughout the entire processing process compared to others. The findings underscore the importance of considering processing methods and environmental factors in order to ensure food safety.

Sustainable urban water management: Evaluating two pilot-scale advanced decentralized treatment systems for removal of organic contaminants of emerging concern in reclaimed groundwater

The rapid growth of population and the effects of climate change have placed unprecedented pressure on urban water supplies and pollution control. Consequently, it is essential to explore new local water resources in water-strained areas. To this end, this work focuses on evaluating pollutant removal effectiveness of decentralized treatment systems for groundwater reclamation. Two pilot-scale treatment trains, Treatment Line 1 (L1) and Treatment Line 2 (L2), which use membrane-free (with granulated activated carbon as the main process) or membrane-based (with reverse osmosis as the primary technology), were compared for their effectiveness in reducing concentrations of organic contaminants of emerging concern (CECs). Additionally, the effect of sodium hypochlorite addition for biofilm control on the contaminant removal performance was also examined. Results from the analysis of nearly 120 trace organic compounds (only 21 were detected in the raw water) showed that L2 significantly overperformed L1. Furthermore, the addition of a pre-chlorination step did not improve the removal performance. Regarding trace organic compounds, L1 without pre-chlorination averaged an overall good removal performance (94 ± 12%). However, Irbesartan, gemfibrozil and gabapentin showed moderate removals (50–90%) and Valsartan was poorly removed (<50%). After pre-chlorinating L1, the overall removal performance decreased (86 ± 20%). Nearly one third of the target contaminants showed moderate removal (50–90%), with Irbesartan and Valsartan exhibiting poor attenuations (<50%), highlighting that negatively-charged compounds were challenging to eliminate. In contrast, L2 exhibited very high removals (>99%) on all studied trace organic contaminants regardless of pre-chlorination. Our study also identified several indicator compounds to monitor CEC removal. Finally, considering the trade-offs between cost and final water use (non-potable), L1-based schemes with intermittent pre-chlorination could be the preferred implementation option. The results of this work will offer valuable insights into decentralized treatment systems, assisting decision-makers in choosing suitable approaches for sustainable urban water management.

Statistical analysis and optimization of mechanical-chemical electro-Fenton for organic contaminant degradation in refinery wastewater

Refinery wastewater (RWW) poses significant environmental challenges due to its high concentration of organic contaminants, necessitating effective treatment solutions. This study employs the mechanical design of the Electro-Fenton (EF) technique as a feasible alternative for treating RWW. The anode and cathode electrodes, made of stainless steel and iron, respectively, were utilized to conduct organic removal (OR) from RWW. To maximize performance, two metric optimization design techniques were examined: Box Behnken Design (BBD) and response surface methodology. The analysis of variance revealed a high coefficient of determination value (R2 = 0.9685), indicating a second-order provable relationship between the response and self-governing variables. Additional statistical analysis was performed to assess the validity and reliability of the suggested approach. A predictive regression model was developed based on unresolved values, demonstrating a high level of agreement with experimental values. This model identified the optimal equation for the empirical model to predict OR based on predetermined parameters. Based on the BBD, the percentage of OR reached 93.45 % at pH 3, temperature, and electrolysis time of 60 °C, and 30 minutes, respectively. The implications of this study suggest that the optimized Electro-Fenton technique could serve as a robust solution for addressing the environmental impact of RWW, contributing to sustainable wastewater management practices.

Fish Health Altered by Contaminants and Low Water Temperatures Compounded by Prolonged Regional Drought in the Lower Colorado River Basin, USA.

The goal of this study was to assess health of male Common Carp (carp, Cyprinus carpio) at four sites with a wide range in environmental organic contaminant (EOC) concentrations and water temperatures in Lake Mead National Recreation Area NV/AZ, US, and the potential influence of regional drought. Histological and reproductive biomarkers were measured in 17-30 carp at four sites and 130 EOCs in water per site were analyzed using passive samplers in 2010. Wide ranges among sites were noted in total EOC concentrations (>10Xs) and water temperature/degree days (10Xs). In 2007/08, total polychlorinated biphenyls (tPCBs) in fish whole bodies from Willow Beach (WB) in the free-flowing Colorado River below Hoover Dam were clearly higher than at the other sites. This was most likely due to longer exposures in colder water (12-14 °C) and fish there having the longest lifespan (up to 54 years) for carp reported in the Colorado River Basin. Calculated estrogenicity in water exceeded long-term, environmentally safe criteria of 0.1-0.4 ng/L by one to three orders of magnitude at all sites except the reference site. Low ecological screening values for four contaminants of emerging concern (CEC) in water were exceeded for one CEC in the reference site, two in WB and Las Vegas Bay and three in the most contaminated site LVW. Fish health biomarkers in WB carp had 25% lower liver glycogen, 10Xs higher testicular pigmented cell aggregates and higher sperm abnormalities than the reference site. Sperm from LVW fish also had significantly higher fragmentation of DNA, lower motility and testis had lower percent of spermatozoa, all of which can impair reproduction. Projections from a 3D water quality model performed for WB showed that EOC concentrations due to prolonged regional drought and reduced water levels could increase as high as 135%. Water temperatures by late 21st century are predicted to rise between 0.7 and 2.1 °C that could increase eutrophication, algal blooms, spread disease and decrease dissolved oxygen over 5%.

Efficient electrochemical removal of ammoniacal nitrogen from livestock wastewater: The role of the electrode material

Wastewater from livestock farms contains high concentrations of suspended solids, organic contaminants, and nitrogen compounds, such as ammoniacal nitrogen. Discharging livestock effluents into water bodies without appropriate treatment leads to severe environmental pollution. Compared to conventional treatment methods, electrochemical oxidation exhibits higher nitrogen removal efficiencies. In the present work, the electrochemical removal of ammoniacal nitrogen from real livestock wastewater was investigated through a lab-scale reactor. Preliminary experiments were carried out to investigate the effects of different anode materials, including boron-doped diamond and iridium/ruthenium-coated titanium, on the total nitrogen removal efficiency using synthetic wastewater. Boron-doped diamond, a well-known non-active electrode, allowed to obtain 63.7 ± 1.21 % of total nitrogen degradation efficiency. However, the iridium/ruthenium-coated titanium electrode, belonging to the class of active anodes, showed a higher performance, achieving 78.8 ± 0.76 % contaminant degradation. Coupling iridium/ruthenium-coated titanium anode with a stainless-steel cathode improved the performance of the system, achieving even 96.2 ± 2.73 % of total nitrogen removal. The optimized cell configuration was used to treat livestock wastewater, resulting in the degradation of 67.0 ± 2.25 % of total nitrogen and 37.3 ± 0.68 % of total organic carbon when sodium chloride was added. At the end of the process, the ammonium content was completely removed, and only 17.7 ± 0.51 % of the initial nitrogen turned into nitrate. The results show that the proposed system is a promising approach to treating livestock wastewater by coupling high contaminant removal efficiencies with low operational costs. Anyway, further studies on process optimization with an emphasis on power requirements and electrode costs need to be carried out.

Electrochemical Hydrogen Peroxide Generation and Activation Using a Dual-Cathode Flow-Through Treatment System: Enhanced Selectivity for Contaminant Removal by Electrostatic Repulsion.

To oxidize trace concentrations of organic contaminants under conditions relevant to surface- and groundwater, air-diffusion cathodes were coupled to stainless-steel cathodes that convert atmospheric O2 into hydrogen peroxide (H2O2), which then was activated to produce hydroxyl radicals (·OH). By separating H2O2 generation from its activation and employing a flow-through electrode consisting of stainless-steel fibers, the two processes could be operated efficiently in a manner that overcame mass-transfer limitations for O2, H2O2, and trace organic contaminants. The flexibility resulting from separate control of the two processes made it possible to avoid both the accumulation of excess H2O2 and the energy losses that take place after H2O2 has been depleted. The decrease in treatment efficacy occurring in the presence of natural organic matter was substantially lower than that typically observed in homogeneous advanced oxidation processes. Experiments conducted with ionized and neutral compounds indicated that electrostatic repulsion prevented negatively charged ·OH scavengers from interfering with the oxidation of neutral contaminants. Energy consumption by the dual-cathode system was lower than values reported for other technologies intended for small-scale drinking water treatment systems. The coordinated operation of these two cathodes has the potential to provide a practical, inexpensive way for point-of-use drinking water treatment.

Research of the process of biological wastewater treatment under conditions of uneven load of the treatment system

The main purpose of the article is to develop a multifactorial model for rapid assessment of the efficiency of biological wastewater treatment reactors. A mathematical model of the process of biological wastewater treatment has been developed based on: changes in the concentration of organic contaminants in the bioreactor over time, taking into account the uneven flow of wastewater to the treatment plant, the process of substrate entering the bioreactor (different amounts may enter at different times). The software implementation of the proposed algorithm for solving the corresponding model problem in Python is carried out. The results of computer experiments on the study of the efficiency of wastewater treatment in biological treatment reactors for different operating conditions of facilities are presented. In particular, such processes were considered with taking into account the unevenness of the load, because the maximum cleaning loads are in the morning and in the evening. The task was solved to simulate a real situation and show how cleaning takes place at the maximum load at a certain time of the day. The results obtained will be useful for calculations in the design of biological treatment facilities or in the reconstruction of existing bioreactors for their prospective operation under new operating conditions.

Determining buffering capacity of polydimethylsiloxane-based passive dosing for hydrophobic organic compounds in large-volume bioassays

Polydimethylsiloxane (PDMS) is the most widely used material for passive dosing. However, the ability of PDMS to maintain constant water concentrations of chemicals in large-volume bioassays was insufficiently investigated. In this study, we proposed a kinetic-based method to determine the buffering capacity of PDMS for maintaining constant water concentrations of hydrophobic organic contaminants (HOCs) in large-volume bioassays. A good correlation between log Kow and PDMS-water partitioning coefficients (log KPW) was observed for HOCs with log Kow values ranging from 3.30 to 7.42. For low-molecular-weight HOCs, volatile loss was identified as the primary cause of unstable water concentrations in passive dosing systems. Slow desorption from PDMS resulted in a reduction of water concentrations for high-molecular-weight HOCs. The volume ratio of PDMS to water (RV) was the key factor controlling buffering capacity. As such, buffering capacity was defined as the minimum RV required to maintain 90% of the initial water concentration and was determined to be 0.0076–0.032 for six representative HOCs. Finally, passive dosing with an RV of 0.014 was validated to effectively maintain water concentrations of phenanthrene in 2-L and 96-h toxicity tests with adult mosquitofish. By determining buffering capacity of PDMS, this study recommended specific RV values for cost-efficient implementation of passive dosing approaches in aquatic toxicology, particularly in large-volume bioassays.

Persistent Trace Organic Contaminants Are Transformed Rapidly under Sulfate- and Fe(III)-Reducing Conditions in a Nature-Based Subsurface Water Treatment System.

Subsurface treatment systems, such as constructed wetlands, riverbank filtration systems, and managed aquifer recharge systems, offer a low-cost means of removing trace organic contaminants from treated municipal wastewater. To assess the processes through which trace organic contaminants are removed in subsurface treatment systems, pharmaceuticals and several major metabolites were measured in porewater, sediment, and plants within a horizontal levee (i.e., a subsurface flow wetland that receives treated municipal wastewater). Concentrations of trace organic contaminants in each wetland compartment rapidly declined along the flow path. Mass balance calculations, analysis of transformation products, microcosm experiments, and one-dimensional transport modeling demonstrated that more than 60% of the contaminant removal could be attributed to transformation. Monitoring of the system with and without nitrate in the wetland inflow indicated that relatively biodegradable trace organic contaminants, such as acyclovir and metoprolol, were rapidly transformed under both operating conditions. Trace organic contaminants that are normally persistent in biological treatment systems (e.g., sulfamethoxazole and carbamazepine) were removed only when Fe(III)- and sulfate-reducing conditions were observed. Minor structural modifications to trace organic contaminants (e.g., hydroxylation) altered the pathways and extents of trace organic contaminant transformation under different redox conditions. These findings indicate that subsurface treatment systems can be designed to remove both labile and persistent trace organic contaminants via transformation if they are designed and operated in a manner that results in sulfate-and Fe(III)-reducing conditions.

Environmental Assessment of Soil and Groundwater Pollution by BTEX Leaching in Valencia Region (Spain)

The impact of hydrocarbon spills in the unsaturated zone is a significant environmental concern, particularly in locations where contamination arises from leaks in underground fuel storage tanks (USTs). This paper presents the outcomes achieved through the utilization of VLEACH, a finite-difference numerical model, to assess the concentrations of organic contaminants in the solid, liquid, and gas phases within the vadose zone. Additionally, it evaluates the mass transfer of pollutants to the aquifer as part of an environmental assessment for the placement of a forthcoming service station. The study encompasses an analysis of 18 scenarios under realistic conditions based on actual field data. These scenarios were constructed, taking into account various factors, including the nature of the leak (one-time or permanent), the depth of the phreatic level, and the soil conditions and properties. The results highlight the potential environmental consequences of a permanent leak as compared to those resulting from a specific accident. The findings further emphasize the substantial influence of soil moisture on transport phenomena within the vadose zone. Variations in soil moisture significantly alter hydraulic conductivity, impact magnitudes, transport velocities, and even the predominant transport mechanism. Consequently, precise delineation of soil moisture becomes a crucial parameter in such simulations. Additionally, it has been observed that each component of BTEX (benzene, toluene, ethylbenzene, and xylene) experiences varying transport velocities through the vadose zone. Benzene, having a greater propensity to concentrate in the liquid and gas phases, exhibits the swiftest movement through the vadose zone. The detection of benzene in aquifers can serve as an indicator of the potential future arrival of the remaining BTEX compounds.

Landfill leachate treatment using fungi and fungal enzymes: a review.

Landfill leachate raises a huge risk to human health and the environment as it contains a high concentration of organic and inorganic contaminants, heavy metals, ammonia, and refractory substances. Among leachate treatment techniques, the biological methods are more environmentally benign and less expensive than the physical-chemical treatment methods. Over the last few years, fungal-based treatment processes have become popular due to their ability to produce powerful oxidative enzymes like peroxidases and laccases. Fungi have shown better removal efficiency in terms of color, ammonia, and COD. However, their use in the treatment of leachate is relatively recent and still needs to be investigated. This review article assesses the potential of fungi and fungal-derived enzymes in treating landfill leachate. The review also compares different enzymes involved in the fungal catabolism of organic pollutants and the enzyme degradation mechanisms. The effect of parameters like pH, temperature, contact time, dosage variation, heavy metals and ammonia are discussed. The paper also explores the reactor configuration used in the fungal treatment and the techniques used to improve leachate treatment efficacy, like pretreatment and fungi immobilisation. Finally, the review summarises the limitations and the future direction of work required to adapt the fungal application for leachate treatment on a large scale.

Geochemical and Geospatial Distribution of Organic Contaminants in the Flood Plain of Ekpetiama, Niger Delta Region of Nigeria

This study investigated the geochemical and geospatial distribution of organic contaminants in the floodplain water and sediments of Ekpetiama in the Niger Delta Region of Nigeria. This study is necessary because there are limited data on the level of organic contamination in this section of the Niger Delta Region of Nigeria. The extinction of planktons in Ekpetiama became a source of concern to the residents. This concern is because this section of the coastal plain provides fisher folks with livelihood. So, there was a need to track the source of contamination in this part of the Niger Delta region. Previous studies have suggested a high level of Total Petroleum Hydrocarbon and Total Hydrocarbon Content as possible sources of reduced dissolved oxygen in similar deltaic terrain. A total of 10 water and 10 sediment samples were collected and analyzed in triplicate at an interval of 100 m in the flood plain. A particle size analyzer was used to perform particle size analyses of air-dried sediments. The American Public Health Association method (APHA) was used to do the chemical analysis of the water samples. Here, a liquid-liquid extraction procedure was performed on sediment samples using 30 mL of Dichloromethane (DCM) as the extracting agent. The results were subjected to statistical validation. The mean grain size ranged from 2.37-4.83, kurtosis (1.94-0.49), and skewness (-0.8-0.71). The contaminant indicators (pH, biochemical oxygen demand, chemical oxygen demand, dissolved oxygen and Total Organic Carbon) point to the presence of organic contamination of the flood plain. The results indicated a total petroleum hydrocarbon range of 0.47-0.87 ppm in water and 0.69-0.96 ppm in sediments and a total hydrocarbon content range of 1.10-2.80 ppm in water and 2.56-3.90 ppm in sediment# samples. The results were above the permitted limits of the World Health Organisation. The source of ecological damage is the abnormal concentrations of organic contaminants in the flood plain. These results significantly caused ecosystem damage and human health effects in the food chain. This study provides information to the National Oil Spill Detection and Response Agency for a cleanup process.

Geochemical and Geospatial Distribution of Organic Contaminants in the Flood Plain of Ekpetiama, Niger Delta Region of Nigeria

This study investigated the geochemical and geospatial distribution of organic contaminants in the floodplain water and sediments of Ekpetiama in the Niger Delta Region of Nigeria. This study is necessary because there are limited data on the level of organic contamination in this section of the Niger Delta Region of Nigeria. The extinction of planktons in Ekpetiama became a source of concern to the residents. This concern is because this section of the coastal plain provides fisher folks with livelihood. So, there was a need to track the source of contamination in this part of the Niger Delta region. Previous studies have suggested a high level of Total Petroleum Hydrocarbon and Total Hydrocarbon Content as possible sources of reduced dissolved oxygen in similar deltaic terrain. A total of 10 water and 10 sediment samples were collected and analyzed in triplicate at an interval of 100 m in the flood plain. A particle size analyzer was used to perform particle size analyses of air-dried sediments. The American Public Health Association method (APHA) was used to do the chemical analysis of the water samples. Here, a liquid-liquid extraction procedure was performed on sediment samples using 30 mL of Dichloromethane (DCM) as the extracting agent. The results were subjected to statistical validation. The mean grain size ranged from 2.37-4.83, kurtosis (1.94-0.49), and skewness (-0.8-0.71). The contaminant indicators (pH, biochemical oxygen demand, chemical oxygen demand, dissolved oxygen and Total Organic Carbon) point to the presence of organic contamination of the flood plain. The results indicated a total petroleum hydrocarbon range of 0.47-0.87 ppm in water and 0.69-0.96 ppm in sediments and a total hydrocarbon content range of 1.10-2.80 ppm in water and 2.56-3.90 ppm in sediment# samples. The results were above the permitted limits of the World Health Organisation. The source of ecological damage is the abnormal concentrations of organic contaminants in the flood plain. These results significantly caused ecosystem damage and human health effects in the food chain. This study provides information to the National Oil Spill Detection and Response Agency for a cleanup process.

CuMn2O4/Mn2O3 micro composites: Sol- gel synthesis in the presence of sucrose and investigation of their photocatalytic properties

The treatment of effluents using adsorption of pollution of solvent is a necessary aspect of research. The use of photocatalysts for this purpose has received much attention from researchers. In current research, the micro composites based on copper manganese oxides were synthesized through sol–gel method and used as photocatalyst. The uniformity, structure, shape, and size of the products are affected by metal salt type, fuel type, annealing temperature and time. The metal nitrate salts, sucrose, 850 ˚C and 2 h were selected as optimum precursors, fuel, annealing temperature and time, respectively. XRD indicated the successful formation of CMO/MO MCs in the presence of sucrose after annealing at 850 ˚C for 2 h. VSM showed a ferromagnetic behavior with a coercivity of 970.56 Oe. To investigation of the photocatalytic properties of CMO/MO MCs, several factors, including different organic contaminants, organic contaminant concentrations, and micro composite dosages were scrutinized to achieve the best efficiency. The photocatalytic tests indicated that micro composites can degrade RBBR in high values. For example, when 0.03 g of micro composite was used with 10 ppm RBBR under visible irradiation for 90 min, 79.18% of RBBR was destroyed. The hydroxyl radicals and holes were found to be active agents implicated in the degradation of RBBR by the scavenger's test. The recycle test unveiled that micro composites are so stable and after six cycles, the photocatalyst efficiency decreased by 12% for RBBR.

Removal efficiency and energy consumption optimisation for carbamazepine degradation in wastewater by electrohydraulic discharge.

The treatment of recalcitrant emerging pollutants is a major concern in wastewater treatment. The purpose of this study was the optimisation of emerging recalcitrant pollutant degradation using carbamazepine as a representative pollutant. Investigations of the carbamazepine degradation in wastewater was carried out by manipulating discharge current, air flow rate, and initial concentration to maximise removal efficiency and minimise energy consumption. The study utilised a three factor at two levels factorial design with randomised central runs. Discharge current, air flow rate, and initial concentration were the independent variables while to removal efficiency and minimise energy consumption were the response variables. ANOVA analysis was performed on the data. Discharge current, air flow rate, and initial concentration significantly impacted the removal efficiency to different degrees. However, for energy consumption, only current and air flow rate were the significant variables. The highest removal efficiency obtained was 93% ± 4% for 10 and 40 mg/L initial carbamazepine concentration after 10 minutes of plasma treatment at a current of 0.45 A and no air flow rate. The reactor demonstrated the capability to treat high cyclic organic chemical contaminant concentration in wastewater with possible applications in pre-concentrated wastewater remediation. However, there is still room for reactor design optimisation. One key area of focus is reducing treatment cost, which may be achieved theoretically, pending further experimental investigation, by introducing an alternating current power supply which can reduce energy consumption by 50-60%.

Sensor with enhanced performance based on photonic crystal with a defect layer

We propose an improved structure of an optical biosensor based on a photonic crystal with a defect layer, which can detect the concentration of organic contaminants in water by defect mode shift. We investigated 4 types of defective photonic crystals with different arrangements of layers inside the perfect photonic crystals and their impact on the performance of the sensor. The sensitivity and amplitude of defect mode were examined as a function of defect layer thickness. Also, the peculiarities of edge modes in the presence of defect layer were investigated. Finally, we obtained a characteristic equation to determine the wavelengths of defect modes for an arbitrary 1D photonic crystal with an isotropic defect inside.

Characterization of an airborne organic contaminant sensor based on microfibers with sol–gel film

Introduction: Based on microfibers with sol–gel film, this study focuses on developing an organic contaminant sensing device to monitor airborne organic contamination in high-power laser facilities.Methods: The device heightened the sensitivity to the external environment with the nano-structure of sol–gel on the microfiber surface. The relationship between the additional laser transmission power loss caused by contaminants and the filling rate of the porosity of the film was discussed. In addition, we obtained the relationship between the additional loss and the refractive index of the microstructure.Results: The experimental results indicated that employing microfibers with microstructure coating could significantly improve sensing sensitivity to airborne organic contaminants. The precision of sensing surface contaminants can reach ng/cm2. When the concentration of organic contaminants is lower than 7.5%, the adsorption process of the microstructure coating is dominated by single-molecule adsorption, and the additional loss increases exponentially with increasing concentration, while the sensing limit is 70 ppm. When the concentration of organic contaminants exceeds 7.5%, the adsorption process of the surface microstructure coating is dominated by multimolecular adsorption. Therefore, the additional loss is exponentially related to the concentration of airborne organic contaminants, while the sensing limit is 10 ppm.Discussion: The study explored the adsorption mechanism of the sol–gel film to airborne organic contaminants at different concentrations. The Langmuir monolayer adsorption isotherm model and the Freundlich multi-molecular layer adsorption isotherm model was adopted to analyze and verify the experimental results, which suggested that the experimental results agree well with the simulation results. This work can be considered for in situ monitoring of airborne concentration contaminants and the transmittance of optics with the sol–gel film, and it also provides a new research method for in situ monitoring of airborne organic contaminants in the vacuum environment.

A green method for the determination of illicit drugs in wastewater and surface waters-based on a semi-automated liquid-liquid microextraction device

Liquid-phase microextraction (LPME) is a simple, low-cost, and eco-friendly technique that enables the detection of trace concentrations of organic contaminants in water samples. In this work, a novel customized microextraction device was developed for the LPME extraction and preconcentration of nine illicit drugs in surface water and influent and effluent wastewater samples, followed by analysis by GC–MS without derivatization. The customized device was semi-automated by coupling it with a peristaltic pump to perform the collection of the upper layer of the organic phase. The extraction parameters affecting the LPME efficiency were optimized. The optimized conditions were: 100 µL of a toluene/DCM/EtAc mixture as extractor solvent; 30min of extraction time under vortex agitation (500rpm) and a solution pH of 11.6. The limits of detection and quantification ranged from 10.5ng L−1 (ethylone) to 22.0ng L−1 (methylone), and from 34.9ng L−1 to 73.3ng L−1 for these same compounds, respectively. The enrichment factors ranged from 39.7 (MDMA) to 117 (cocaethylene) and the relative recoveries ranged from 80.4% (N-ethylpentylone) to 120% (cocaine and cocaine-d3). The method was applied to real surface water, effluent, and influent wastewater samples collected in Salvador City, Bahia, Brazil. Cocaine was the main drug detected and quantified in wastewater samples, and its concentration ranged from 312ng L−1 to 1,847ng L−1. Finally, the AGREE metrics were applied to verify the greenness of the proposed method, and an overall score of 0.56 was achieved, which was considered environmentally friendly.