Compounds In Industrial Wastewater Research Articles

Estimation of Measurement Uncertainty for Nonylphenol Compounds in Industrial Wastewater

This study focuses on quantifying the impact of various factors on nonylphenol analysis and identifying the key contributors affecting the analytical outcomes. We calculated the measurement uncertainty arising from the analysis process using GC-MS, aiming to pinpoint uncertainty sources, quantify them numerically and then calculated the overall uncertainty through uncertainty synthesis. The results revealed that factors such as calibration curve construction, internal standard injection, and reproducibility through repeated testing significantly influenced the synthetic standard uncertainty. Negligible effects were observed during processes, involving concentration and filling the standard volume post-purification, as well as during sample collection. The relative expanded uncertainty for nonylphenol concentration was within 4.6%. The uncertainty contributions from each step were as follows: sample collection, calibration curve construction, injection of internal standards, filling of the 1 mL standard volume, and reproducibility from repeated testing accounted for 0.0%, 92.7%, 4.0%, 0.1%, and 3.2% of the total uncertainty, respectively.

Determination of nine organic amine compounds in CO2 absorption liquid by hydrophilic interaction liquid chromatography-electrostatic field orbitrap high resolution mass spectrometry

Carbon dioxide (CO2) absorption and capture is an effective measure to achieve the "dual carbon" goal of carbon peak and carbon neutrality in China. Organic amine compounds are widely used in the industrial separation and recovery of CO2. Thus, the establishment of analytical methods for organic amine compounds is of great significance for the research and development of carbon capture and storage (CCS) technology and carbon capture, utilization and storage (CCUS) technology. In this study, a method was developed for the determination of nine organic amine compounds in CO2 absorption liquid by hydrophilic interaction liquid chromatography (HILIC)-electrostatic field orbitrap high resolution mass spectrometry. The sample was diluted with water and filtered through a 0.22 μm nylon membrane before sampling and analysis. An Accucore HILIC column (100 mm×2.1 mm, 2.6 μm) was used for separation at 30 ℃. Gradient elution was conducted using 90% acetonitrile aqueous solution containing 5 mmol/L ammonium formate and 0.1% formic acid as mobile phase A and 10% acetonitrile aqueous solution containing 5 mmol/L ammonium formate and 0.1% formic acid as mobile phase B. Determination was performed using an electrospray ion source (ESI) in the positive ion mode. The quantitative analysis was carried out by standard addition method. The chromatographic retention performance of different chromatographic columns and the influence of different mobile phases on the separation of the organic amine compounds were compared, and the method was validated. The results showed that the linear ranges of the nine organic amine compounds were 0.04-25000 ng/mL with the linear correlation coefficients (R2) greater than 0.9910. The limits of detection (LODs) of the method were in the range of 0.0004-0.0080 ng/mL, and the limits of quantification (LOQs) of the method were in the range of 0.0035-0.0400 ng/mL. The average recoveries of the method ranged from 85.30% to 104.26% with relative standard deviations (RSDs) of 0.04%-7.95% at the spiked levels of 1, 1.5 and 3 times sample concentration. The established method was applied to detect the absorption waste liquid of a cement plant, and nine organic amine compounds could be effectively detected. The stability of the actual sample was tested, and the RSDs were 0.10%-6.35% in 48 h at 4 ℃. The method is sensitive, rapid and accurate for the determination of the nine organic amine compounds in industrial waste water. It can provide reference for the detection of organic amine compounds, and provide strong technical support for the research and industrial application of CO2 capture technology.

Biodegradation of pharmaceutical compounds in industrial wastewater using biological treatment: a comprehensive overview

Biodegradation of pharmaceutical compounds in industrial wastewater using biological treatment: a comprehensive overview

Heterogeneous Catalytic and Non-Catalytic Supercritical Water Oxidation of Organic Pollutants in Industrial Wastewaters Effect of Operational Parameters

This work reports supercritical water oxidation (SCWO) of organic pollutants in industrial wastewater in the absence and presence of catalysts. To increase the efficiency of the oxidation process, the SCWO of organic compounds in industrial wastewater was performed in the presence of various iron- and manganese-containing heterogeneous catalysts (Fe-Ac, Fe-OH, and Mn-Al). The catalytic and non-catalytic SCWO of organic compounds in wastewater from PJSC “Nizhnekamskneftekhim”, generated from the epoxidation of propylene with ethylbenzene hydroperoxide in the process of producing propylene oxide and styrene (PO/SM), was performed. The effect of operational parameters (temperature, pressure, residence time, type of catalysts, oxygen excess ratio, etc.) on the efficiency of the process of oxidation of organic compounds in the wastewater was studied. SCWO was studied in a flow reactor with induction heating under different temperatures (between 673.15 and 873.15 K) and at a pressure of 22.5 MPa. The reaction time ranged from 1.8 to 4.83 min. Compressed air was used as an oxidizing agent (oxidant) with an oxidant ratio of two to four. A pseudo-first-order model expressed the kinetics of the SCWO processes, and the rate constants were evaluated. In the present work, in order to optimize the operation parameters of the SCWO process, we used the thermodynamic properties of near- and supercritical water by taking into account the asymmetric behavior of the liquid–vapor coexistence curve.

Recent Advances in the Development of Novel Iron–Copper Bimetallic Photo Fenton Catalysts

Advanced oxidation processes (AOPs) have been postulated as viable, innovative, and efficient technologies for the removal of pollutants from water bodies. Among AOPs, photo-Fenton processes have been shown to be effective for the degradation of various types of organic compounds in industrial wastewater. Monometallic iron catalysts are limited in practical applications due to their low catalytic activity, poor stability, and recyclability. On the other hand, the development of catalysts based on copper oxides has become a current research topic due to their advantages such as strong light absorption, high mobility of charge carriers, low environmental toxicity, long-term stability, and low production cost. For these reasons, great efforts have been made to improve the practical applications of heterogeneous catalysts, and the bimetallic iron–copper materials have become a focus of research. In this context, this review focuses on the compilation of the most relevant studies on the recent progress in the application of bimetallic iron–copper materials in heterogeneous photo–Fenton-like reactions for the degradation of pollutants in wastewater. Special attention is paid to the removal efficiencies obtained and the reaction mechanisms involved in the photo–Fenton treatments with the different catalysts.

BTEXS Removal From Aqueous Phase by MCM-41 Green Synthesis Using Rice Husk Silica

Large volumes of contaminated industrial wastewater have caused growing concern among researchers and environmentalists. Benzene, toluene, ethylbenzene, xylene, and styrene (BTEXS) cyclic hydrocarbons in industrial effluents are often completely stable to biodegradation and must be treated before disposal. In this context, using adsorption processes is a potential alternative for treating a wide range of organic pollutants, especially aromatic compounds in industrial wastewater. This study investigated the preparation of MCM-41 from silica; extracted from rice husk ash; MCM-41 was green synthesized to evaluate the effect of mesoporous used in BTEXS removal of an aqueous medium using the Taguchi method. The aqueous solution contains cyclic hydrocarbons was synthetically prepred based on real industrial effluent in concentrations of 50, 100, and 150 mg/l using MCM-41 catalysts, in doses of 0.1, 0.5, and 1g, at different pH values. In the present study, the optimum results obtained by Taguchi method analysis were pH =11, for duration of 60 minutes, the concentration of cyclic hydrocarbon solution BTEXS 100 mg/l, and nanoparticle dose of 0.5 g. The maximum BTEXS removal of 77.36% was achieved by the use of hydrogen peroxide.

Janus mesoporous wood-based membrane for simultaneous oil/water separation, aromatic dyes removal, and seawater desalination

Directional transport of liquid is crucial for many applications including seawater desalination , oil/water separation, fog collection, membrane distillation and so forth. Particularly, Janus wood membranes, with asymmetric special wetting property on two sides, and mechanically robust bio-based substrate with ample pores and open nano-/micro-channels, present enticing opportunities to address this challenge. In this study, we report a Janus mesoporous wood-based membrane demonstrating the capabilities for simultaneous oil/water separation, aromatic dyes removal, and seawater desalination. Thanks to the inner driving force arising from the asymmetric special wettability, unique wood microchannels for the transpiration of trees, and the synergistic effect of PPy and Ag/AgCl NPs anchored to wood matrix, Janus mesoporous wood-based membrane would promote the desired transport without any external energy input for high-efficiency seawater desalination and switchable oil/water separation. Meanwhile, the aromatic dyes and other organic compounds in industrial wastewater or polluted seawater would get more opportunities to contact with the anchored Ag/AgCl NPs during flowing through the wood microchannels. Above advantages endow the Janus mesoporous wood-based membrane with excellent pollutant degradation efficiency (MB: 86.4 %, RhB: 91.9 %), high solar conversion efficiency (95.33 %), outstanding separation efficiency towards oil-in-water emulsion (∼99.51 %), remarkable oil adsorption capacity (∼8 times of its own weight), and great antibacterial efficiencies (E. coli: 99.87 %, S. aureus: 99.78 %, B. subtilis: 99.96 %). Results also show that this Janus mesoporous wood-based membrane has the satisfactory resistance to acid and base, robust mechanical structure, good recycling stability, high salinity tolerance and remarkable self-desalting capability. This study represents a new avenue for fabrication and design of Janus wood-based photothermal materials, and certainly will contribute to alleviating the global water and energy shortage issue. Asymmetric special wettability, unique wood microchannels, and the synergistic effect of PPy and Ag/AgCl NPs anchored to wood matrix endow the as-presented Janus mesoporous wood-based membrane with excellent aromatic dyes degradation efficiency (MB-86.4 %, RhB-91.9 %), high solar conversion efficiency (95.33 %), outstanding separation efficiency towards O/W emulsion (∼99.51 %), remarkable oil adsorption capacity (∼8 times of its own weight), great antibacterial efficiencies (E. coli-99.87 %, S. aureus-99.78 %, B. subtilis-99.96 %), and remarkable salinity tolerance. It certainly will contribute to alleviating the global water and energy shortage issue. • Mechanically robust wood membrane with asymmetric special wettability, ample pores and open microchannels was fabricated. • Janus wood membrane can simultaneously complete oil/water separation, aromatic dyes removal, and seawater desalination. • PPy/Ag/AgCl NPs endow the wood with excellent MB/RhB degradation efficiency, and high solar conversion efficiency (95.33 %). • It has oil/water separation efficiency (99.51 %), oil adsorption capacity (∼8 times), and antibacterial efficiency (99.96 %). • Such Janus mesoporous wood-based membrane will contribute to alleviating the global water and energy shortage issue.

Effective heterogeneous catalysis of micro-size H3PMo6W6O40@rht-MOF-1 for degradation of phenolic compounds under molecular oxygen

Since the huge damage to human health and the survival of animals and plants was caused by phenol and its derivatives, it is impending to develop efficient and durable heterogeneous catalysts of catalytic wet air oxidation (CWAO) for eliminating these phenolic compounds. The heterogeneous system POMs@rht-MOF-1 H3PMo12−xWxO40@rht-MOF-1 (1, x = 3; 2, x = 6; 3, x = 9) and the micro-size complex 2 (denoted by 2 (1 µm) have been designed and synthesized. FT-IR, PXRD, TGA, N2 adsorption-desorption isotherms and XPS were applied to characterize their structures. Upon complex 2 (1 µm) is employed as catalysts for degradation of phenol under molecular oxygen (O2) as oxidant, the catalytic degradation efficiency and TOC reduction up to 95 % and 91 % under optimized condition, respectively. The catalyst 2 (1 µm) could be reused 7 times with negligible reduction. An apparent Arrhenius activation energy of 33.13 KJ/mol and TOF value of 0.3325 (min−1) for phenol were obtained. When catalyst 2 (1 µm) is applied to catalyze mixed phenolic compounds, the degradation efficiency of 85 % is afforded. Furthermore, the catalyzed degradation reaction mechanism is verified via EPR analysis. This method affords an effective path for preparing heterogeneous catalysts and applying in removing the phenolic compounds in industrial wastewater.

Comparison of Fenton and Photo-Fenton Processes for Removal of Organic Pollutants from Tanneries, Department of Quindío, Colombia

The wastewater produced by tanneries has many recalcitrant and toxic organic pollutants that do not meet the current environmental standard and are very dangerous for humans and biota. Therefore, there is an urgent challenge in developing robust oxidation processes guaranteeing their organic elimination to preserve water quality. Fenton and photo-Fenton techniques, which are part of advanced oxidation processes, are currently very innovative and effective for the decontamination of polluting organic agents and recalcitrant compounds in industrial wastewater. In this context, this research aimed to apply the reagents Fenton (Fe+2/H2O2) and photo-Fenton (Fe+2/H2O2 + uv) in contaminated waters from tanneries in the Department of Quindío, Colombia. For this, solutions of 1L of raw water extracted from the tanneries were prepared by adjusting the pH to 4.0. Then, Fenton’s reagent was added and stirred for 2 hours at 150 rpm. Later these same solutions were exposed to ultraviolet light at 269 nm for 2 hours to perform the photo-Fenton process. The results indicated that better decontamination of these effluents was obtained with the photo-Fenton process, although the differences between the two reagents were not statistically significant (p > 0.05). However, we found a decrease in water turbidity, chemical oxygen demand (COD), total organic carbon (TOC), and color, in a higher percentage with photo-Fenton (92%), which makes these techniques sustainable to improve the environment and the quality of life of people who live around these industries. In addition, the advanced oxidation processes are very economical when implemented since, in the photo-Fenton case, solar energy, a type of renewable energy, is used. It should also be noted that they are very efficient techniques when removing organic contaminants for the tannery industries since these have been reported as one of the most polluting industries in the world. Therefore, these processes are recommended for the effective decontamination of organic residues in the effluents produced by the tanning processes.

Mechanisms associated with the separation of phenols from complex coexisting systems

Phenols are recognized as one of the major hazardous organic compounds in industrial wastewater. However, the effects of the coexisting substances on the elimination of the phenolic pollutants were less explored. Herein, we have systematically evaluated the adsorption processes of hydroquinone with respect to three adsorbents in acid, salt, and homolog systems. Our results demonstrated that low concentrations of coexisting acids could benefit the adsorption process with a maximum promotion rate of 143.4% (Qe from 74.3 to 180.9 mg/g), while high concentration of lactic acid resulted in considerable inhibition to St-DVB-nitro with a maximum inhibitory rate to 72.8% (Qe=20.2 mg/g). The coexisting salts exhibited a potentiation effect with a maximum promotion efficiency of 105.9% (Qe=153.0 mg/g). Competitive binding to adsorption sites could be observed in homolog coexisting system, where p-nitrophenol served as the dominant adsorbent and the hydroquinone adsorption capacity were only maintained at 45.4% (Qe=33.7 mg/g). On basis of the coexisting and preloading systems study, KCl could increase the force of mass transfer by salting-out effect and cation synergistic effect to promote the adsorption. Meanwhile, preloading experiments confirmed the competitive occupation effect of lactic acid and p-nitrophenol on the adsorption site, and the more hydrophobic p-nitrophenol could even desorbed hydroquinone (desorption rate 19.5–22.2%). This work on the interactions among phenols, coexisting factors and solid interfaces will guide the actual phenols wastewater treatment.

Development of a Polyphenol Oxidase Biosensor from Corn Tassel Extract for Determination of Phenolic Compounds in Industrial Waste Water

Development of a Polyphenol Oxidase Biosensor from Corn Tassel Extract for Determination of Phenolic Compounds in Industrial Waste Water

Enhancing electronic metal support interaction (EMSI) over Pt/TiO2 for efficient catalytic wet air oxidation of phenol in wastewater

Phenol is one of the major hazardous organic compounds in industrial wastewater. In this work, a highly active Pt/TiO2 catalyst for catalytic wet air oxidation (CWAO) of phenol was obtained by supporting pre-synthesized Pt on TiO2. During the followed hydrogen reduction, strong hydrogen spillover occurred without the migration of TiO2 onto Pt. The reduced support then enhanced the electron transfer from TiO2 to Pt, increasing the percentage of partially negative Pt (Ptδ-), which has been confirmed by XPS. The strong EMSI made the obtained catalyst far more active than Pt/TiO2 prepared by impregnation method. The electron-enriched Pt/TiO2 achieved total organic carbon (TOC) conversion of 88.8% and TOF 149 h−1 at 100 °C and 2 MPa O2, while conventional Pt/TiO2 gave TOC conversion of 39.5% and TOF 41 h−1 for CWAO of phenol. Our work indicates that the enhancement of EMSI between metal and support can be an effective approach to develop highly active catalysts for phenol treatment.

Effects of inorganic ions on the transfer of weak organic acids and their salts in electrodialysis process

Electrodialysis has been considered to be a competitive technology in the treatment and reclamation of organic saline wastewater. As a kind of typical compounds in industrial wastewater, the mass transfer property of organic electrolyte were important to the operation of the treatment process and product quality. The benzoic acid/sodium benzoate and citric acid/sodium citrate in the electrodialysis process and diffusion process were investigated in this paper. The effects of cations (Na+, K+, Mg2+, Ca2+) and anions (Cl- and SO42-) were discussed. The mass transfer of organic acids and their salts through the ion exchange membrane has two forms: electromigration and diffusion, both of which were affected by the degree of ionization, molecular size and molecular structure. The contribution of electromigration was found to be predominant over that of diffusion as a current is applied. The influence of inorganic ions mainly includes dehydration of organic matter and water content of the membrane. These opposite effects play different roles in the mass transfer of organic acids and their salts through the ion exchange membrane with and without current. It was also shown that the existence of organic acids and their salts had little effect on the mass transfer properties of inorganic salts.

Anatomy of the organic carbon in an industrial wastewater: Implications of particle size distribution, respirometry and process modelling

This study evaluated the fate of chemical oxygen demand (COD) fractions of an organized industrial district effluent treated with pilot membrane bioreactor (MBR) system. A series of respirometric analyses were performed on raw wastewater together with 450 nm, 100 kDa and 1 kDa filtered samples obtained from particle size distribution (PSD) experiments. The PSD analysis revealed that more than 300 mg/L of the influent COD accumulated in the lowest size range (<2 nm), accounting for 49–52 % of the total COD. The bulk (64 %) of the influent COD consisted of soluble hydrolysable COD (SH1). The hydrolysis rates for SH1 (0.80–1.28 1/day) were slightly below the levels suggested for domestic wastewaters, indicating the presence of inhibitory compounds in industrial wastewaters. The COD removal efficiency of MBR pilot was found as 85 %; however, 43 % of effluent COD (106 mg/L) still included rapidly hydrolysable organics in the size bracket of 5–30 nm. In this respect, the COD fractions for activated sludge process models used for MBR applications require a new-insight to correctly reflect organic matter balances in the treatment system.

Application of a Solid Ceramic Membrane for Monitoring Volatile Organic Compounds in Industrial Wastewater.

A large quantity of volatile organic compounds (VOCs) can be released into water environments from oil spills and chemical exposure accidents. A recently developed solid ceramic dosimeter (SCD) could be used for long-term measuring of low VOCs concentrations in water. However, calibration and field testing of these SCDs have thus been far insufficient to apply for VOCs monitoring in a water environment in a chemical industrial area. We conducted laboratory calibration experiments and stability tests of the SCD. The mass accumulation of 14 target VOCs from 2 to 100 μg/L was increased linearly with time in the sampler. The absorption rate of the VOCs was related to Henry’s law constant. The average diffusion coefficient of the 14 VOCs in the SCD wall was 1.02 × 10−9 m2/s. The SCD was utilized in a petrochemical plant complex in South Korea with an industrial wastewater reservoir. After a total of 7 days of deployment, chloroform, ethylbenzene, and toluene were detected by both passive sampling and grab sampling at the same VOC concentrations.

Determination of phenolic compounds in industrial wastewaters by gas chromatography after extraction and preconcentration by microextraction procedure

&lt;p&gt;This paper presents an efficient, simple, and fast method for the derivatization, extraction, and preconcentration of several phenolic compounds (phenol, o–, m– and p–cresol, 4–chlorophenol, and 2–nitrophenol) from wastewater samples and analysis of those samples by gas chromatography–flame ionization detection. In this method, initially the phenolic compounds are derivatized with acetic anhydride in an alkaline pH. In the following, the derivatized analytes are extracted into mL–volume of acetonitrile during homogeneous liquid–liquid extraction and further enrichment of the analytes are accomplished by their extraction into µL–volume of 1,1,2–trichloroethane through dispersive liquid–liquid microextraction step. Effective parameters controlling the performance of the proposed method such as type and volume of derivatization agent and catalyst, type and volume of extraction/disperser solvent in homogeneous liquid–liquid extraction, and type and volume of extraction solvent and salt addition in dispersive liquid–liquid microextraction are optimized. Under optimum conditions linear range of the proposed method was obtained 0.7–4000 µg L–1. Limits of detection and quantification were in the ranges of 0.07–0.20 and 0.23–0.70 µg L–1, respectively. Enrichment factors and extraction recoveries were ranged from 220 to 440 and 44 to 88%, respectively.&lt;/p&gt;&#x0D;

Identification of unknowns in industrial wastewater using offline 2D chromatography and non-target screening

Industrial wastewater is characterised by a complex composition of trace organic compounds (TrOC) in a difficult matrix. The identification of unknown pollutants is of high interest. On the one hand to ensure protection of the environment by elucidating contaminations and on the other hand to protect the biological treatment step in the wastewater treatment plant (WWTP). Due to the high variability of the matrix, the identification of compounds of interest is very time consuming and often unsuccessful. To overcome this limitation, a prioritisation method was developed to identify so called ‘known unknowns’, i.e. compounds frequently detected but not identified, as prioritised compounds in industrial wastewater. The method based on an offline two-dimensional (offline 2D) liquid chromatography (LC) approach with ultra violet (UV) detection in the first and high-resolution mass spectrometry (HRMS) in the second dimension. As a proof of concept, an identification process of one ‘known unknown’ is described. The compound was identified as a dichlorodinitrophenol isomer by retention time in two dimensions, UV spectrum, exact mass, mass fragmentation and 1H- NMR. As prioritisation method, the offline 2D LC in combination with non-target analysis provides a powerful workflow to determine tentative structures of unknown organic compounds in industrial wastewater.

Facile Fabrication of Uniform MFe₂O₄ (M = Co, Ni, Cu) Hollow Spheres and Their Recyclable Superior Catalytic Activity Towards 4-Nitrophenol Reduction.

We have developed a facile, efficient, economic, and green method to fabricate uniform MFe2O4 (M Co, Ni, Cu) hollow spheres by using polyacrylamide (PAM) as an additive agent. The as-obtained three types of hollow ferrites are employed to catalyze the reductive transformation of nitrophenols to aminophenols, which exhibit excellent catalytic activity. The kinetics of the catalytic reaction follows the quasi-first order reaction and its rate constant (kapp) values for CoFe2O4, NiFe2O4 and CuFe2O4 are calculated to be 1.62, 11.74 and 37.28 min-1, respectively. These data are higher than those former reports which using similar reactions catalyzed by different nanocatalysts. Among the three catalysts, NiFe2O4 and CuFe2O4 can be successfully reused for at least six consecutive cycles and have a stable conversion efficiency of about 100%, while CoFe2O4 is catalytically inactive after three cycles. The superiority of the catalytic reduction of NiFe2O4 and CuFe2O4 may be due to their soft magnetic properties as well as their better separation efficiency of the electron-hole pairs. Thus it is expected that these two recyclable hollow ferrites will be used commercially in the treatment of aromatic nitro compounds in industrial wastewater.

Photocatalytic degradation properties of α-Fe 2 O 3 nanoparticles for dibutyl phthalate in aqueous solution system

The phthalate ester compounds in industrial wastewater, as kinds of environmental toxic organic pollutants, may interfere with the body's endocrine system, resulting in great harm to humans. In this work, the photocatalytic degradation properties of dibutyl phthalate (DBP) were investigated using α-Fe2O3 nanoparticles and H2O2 in aqueous solution system. The optimal parameters and mechanism of degradation were discussed by changing the morphology and usage amount of catalysts, the dosage of H2O2, pH value and the initial concentration of DBP. Hollow α-Fe2O3 nanoparticles showed the highest degradation efficiency when 30 mg of catalyst and 50 µl of H2O2 were used in the DBP solution with the initial concentration of 13 mg l−1 at pH = 6.5. When the reaction time was 90 min, DBP was degraded 93% for the above optimal parameters. The photocatalytic degradation mechanism of DBP was studied by the gas chromatography–mass spectrometry technique. The result showed that the main degradation intermediates of DBP were ortho-phthalate monobutyl ester, methyl benzoic acid, benzoic acid, benzaldehyde, and heptyl aldehyde when the reaction time was 2 h. DBP and its intermediates were almost completely degraded to CO2 and H2O in 12 h in the α-Fe2O3/ H2O2/UV system.

Removal of dimethylphenols and ammonium in laboratory-scale horizontal subsurface flow constructed wetlands.

Phenolic compounds in industrial wastewaters are toxic pollutants and pose a threat to public health and ecosystems. More recently, focus is being directed toward combining the treatment of these compounds with a cost-effective and environmentally sound technology. The removal efficiency of dimethylphenol and ammonium nitrogen was studied, for the first time, in three different laboratory-scale horizontal subsurface flow constructed wetlands planted with Juncus effusus. Two of the wetlands used were filled with gravel. One of these was planted and the second left without vegetation. The third wetland was a hydroponic system. It was found that the removal efficiencies of dimethylphenol was dependent on the inflow loading of the contaminant and was higher in the planted systems. Both planted systems yielded 99% removal efficiency up to loads of 240mg/d, compared to only 73% for the unplanted constructed wetland. Factors and processes such as redox dynamics, methanogenesis, reduction of ammonium and low nitrate and nitrite concentrations imply simultaneous aerobic and anaerobic dimethylphenol transformations. A significant surplus of organic carbon was detected in the planted wetlands, which may originate from intermediates of the dimethylphenol transformation processes and/or organic plant root exudates. The present study demonstrates that horizontal subsurface flow constructed wetlands are a promising alternative system for the treatment of effluents contaminated with dimethylphenol isomers.