Activated soil filters for removal of biocides from contaminated run-off and waste-waters

Building facades can be equipped with biocides to prevent formation of algal, fungal and bacterial films. Thus run-off waters may contain these highly active compounds. In this study, the removal of several groups of biocides from contaminated waters by means of an activated soil filter was studied.A technical scale activated vertical soil filter (biofilter) with different layers (peat, sand and gravel), was planted with reed (Phragmites australis) and used to study the removal rates and fate of hydrophilic to moderate hydrophobic (log K_ow 1.8-4.4) biocides and biocide metabolites such as: Terbutryn, Cybutryn (Irgarol® 1051), Descyclopropyl-Cybutryn (Cybutryn and Terbutryn metabolite), Isoproturon, Diuron, and its metabolite Diuron-desmonomethyl, Benzo-isothiazolinone, n-Octyl-isothiazolinone, Dichloro-n-octylisothiazolinone and Iodocarbamate (Iodocarb). Three experiments were performed: the first one (36 d) under low flow conditions (61 L m⁻² d⁻¹) reached removal rates between 82% and 100%. The second one was performed to study high flow conditions: During this experiment, water was added as a pulse to the filter system with a hydraulic load of 255 L m⁻² within 5 min (retention time <1 h). During this experiment the removal rates of the compounds decreased drastically. For five compounds (Cybutryn, Descyclopropyl-Cybutryn, Diuron, Isoproturon, and Iodocarb) the removal dropped temporarily below 60%, while it was always above 70% for the others (Terbutryn, Benzo-isothiazolinone, n-Octyl-isothiazolinone, Dichloro-n-octylisothiazolinone). However, this removal is a considerable improvement compared to direct discharge into surface waters or infiltration into soil without appropriate removal. In the last experiment the removal efficiencies of the different layers were studied. Though the peat layer was responsible for most of the removal, the sand and gravel layers also contributed significantly for some compounds. All compounds are rather removed by degradation than by sorption.     

PCBs in sediments of the Great Lakes--distribution and trends, homolog and chlorine patterns, and in situ degradation

A region-wide data analysis on polychlorinated biphenyls (PCBs) in the sediment of the Great Lakes reveals a total accumulation of approximately 300 ± 50 tonnes, representing a >30% reduction from the 1980s. Evidence of in situ degradation of sediment PCB was found, with estimated t_1/2 of 11 and 17 years, at two open water locations in Lake Ontario. The relative abundance of heavy homologs as well as para-chlorines decreases with increasing depth, while the opposite is true for medium and light homologs and ortho-chlorines. In Lake Michigan, the vertical pattern features enrichment of heavier congeners and reduction of ortho-chlorines in deeper sediment layers, opposite to the trend in Lake Ontario. PCBs decrease log-linearly with increasing latitude and longitude. Air deposition of PCBs to lake sediment decreases at about 0.077 ng cm⁻² yr⁻¹ per degree latitude (N) for the geographic region extending from the Great Lakes to within the Arctic Circle.     

Solvent extraction for heavy crude oil removal from contaminated soils

A new strategy of heavy crude oil removal from contaminated soils was studied. The hexane-acetone solvent mixture was used to investigate the ability of solvent extraction technique for cleaning up soils under various extraction conditions. The mixtures of hexane and acetone (25 vol%) were demonstrated to be the most effective in removing petroleum hydrocarbons from contaminated soils and approx 90% of saturates, naphthene aromatics, polar aromatics, and 60% of nC₇-asphaltenes were removed. Kinetic experiments demonstrated that the equilibrium was reached in 5 min and the majority of the oil pollutants were removed within 0.5 min. The effect of the ratio between solvent and soil on the extraction efficiency was also studied and results showed that the efficiency would increase following the higher solvent soil ratio. Then the multistage continuous extraction was considered to enhance the removal efficiency of oil pollutants. Three stages crosscurrent and countercurrent solvent extraction with the solvent soil ratio 6:1 removed 97% oil contaminants from soil. Clearly the results showed that the mixed-solvent of hexane and acetone (25 vol%) with character of low-toxic, acceptable cost and high efficiency was promising in solvent extraction to remove heavy oil fractions as well as petroleum hydrocarbons from contaminated soils.     

Influence of Chironomus riparius (Diptera, Chironomidae) and Tubifex tubifex (Annelida, Oligochaeta) on oxygen uptake by sediments. Consequences of uranium contamination

The diffusive oxygen uptake (DOU) of sediments inhabited by Chironomus riparius and Tubifex tubifex was investigated using a planar oxygen optode device, and complemented by measurements of bioturbation activity. Additional experiments were performed within contaminated sediments to assess the impact of uranium on these processes. After 72 h, the two invertebrate species significantly increased the DOU of sediments (13-14%), and no temporal variation occurred afterwards. Within contaminated sediments, it was already 24% higher before the introduction of the organisms, suggesting that uranium modified the sediment biogeochemistry. Although the two species firstly reacted by avoidance of contaminated sediment, they finally colonized it. Their bioturbation activity was reduced but, for T. tubifex, it remained sufficient to induce a release of uranium to the water column and an increase of the DOU (53%). These results highlight the necessity of further investigations to take into account the interactions between bioturbation, microbial metabolism and pollutants.     

Bioremediation of tributyltin contaminated sediment: degradation enhancement and improvement of bioavailability to promote treatment processes

Bioremediation of tributyltin (TBT) contaminated sediment was studied and degradation enhancement and improvement of bioavailability were also investigated. In TBT spiked sediment, the half-life of TBT in the control sample, representing natural attenuation, was 578 d indicating its persistence. In the stimulated sample (pH 7.5, aeration and incubated at 28 °C), the half-life was significantly reduced to 11 d. Further stimulation by nutrient addition (succinate, glycerol and l-arginine) or inoculation with Enterobacter cloacae (∼10⁷ viable cells g⁻¹ of sediment) resulted in half-life reduction to 9 and 10 d, respectively. In non-spiked sediment, the indigenous microorganisms were able to degrade aged TBT, but the extended period of contamination decreased the degradation efficiency. To improve bioavailability, addition of surfactant, adjustment of salinity and sonication were studied. The highest percentage solubilisation of TBT in water was obtained by adjusting salinity to 20 psu, which increased the solubility of TBT from 13% to 33%. Half-lives after bioavailability was improved were 5, 4 and 4 d for stimulation, stimulation w/nutrient addition and stimulation w/inoculation, respectively. However, natural attenuation in the control sample was not enhanced. The results show that providing suitable conditions is important in enhancing TBT biodegradation, and bioavailability improvement additionally increased the rate and degraded amount of TBT. Unfortunately, nutrient addition and inoculation of the degrader did not enhance the degradation appreciably.     

Application of the comet assay and detection of DNA damage in haemocytes of medicinal leech affected by aluminium pollution: A case study

This report describes an investigation of genotoxic effects in medicinal leech (Hirudo verbana) exposed to water and sediment of Lake Njivice (Krk Island, Croatia) contaminated by aluminium compounds. The levels of primary DNA damage in leech haemocytes and loss of DNA integrity caused by acute and chronic exposure to contaminated water and sediment were investigated using the alkaline comet assay. Genotoxic effects induced by acute exposure to contaminants were evaluated on leech haemocytes and blood cells of fish and mouse treated ex vivo. The effects of chronic exposure were assessed on haemocytes sampled from an animal kept under laboratory conditions on contaminated water and sediment for 180 days. The results indicate the DNA damaging potential of aluminium compounds present in an excess amount in tested samples.     

Long-term dynamics of the atrazine mineralization potential in surface and subsurface soil in an agricultural field as a response to atrazine applications

The dynamics of the atrazine mineralization potential in agricultural soil was studied in two soil layers (topsoil and at 35-45 cm depth) in a 3 years field trial to examine the long term response of atrazine mineralizing soil populations to atrazine application and intermittent periods without atrazine and the effect of manure treatment on those processes. In topsoil samples, ¹⁴C-atrazine mineralization lag times decreased after atrazine application and increased with increasing time after atrazine application, suggesting that atrazine application resulted into the proliferation of atrazine mineralizing microbial populations which decayed when atrazine application stopped. Decay rates appeared however much slower than growth rates. Atrazine application also resulted into the increase of the atrazine mineralization potential in deeper layers which was explained by the growth on leached atrazine as measured in soil leachates recovered from that depth. However, no decay was observed during intermittent periods without atrazine application in the deeper soil layer. atzA and trzN gene quantification confirmed partly the growth and decay of the atrazine degrading populations in the soil and suggested that especially trzN bearing populations are the dominant atrazine degrading populations in both topsoil and deeper soil. Manure treatment only improved the atrazine mineralization rate in deeper soil layers. Our results point to the importance of the atrazine application history on a field and suggests that the long term survival of atrazine degrading populations after atrazine application enables them to rapidly proliferate once atrazine is again applied.     

Sorption and desorption of carbamazepine, naproxen and triclosan in a soil irrigated with raw wastewater: estimation of the sorption parameters by considering the initial mass of the compounds in the soil

The amphipod Hyalella azteca was exposed for 28 d to different combinations of Zn contaminated sediment and food. Sediment exposure (+clean food) resulted in increased Zn body burdens, increased mortality and decreased body mass when the molar concentrations of simultaneously extracted Zn were greater than the molar concentration of Acid Volatile Sulfide (SEM_Zn-AVS > 0), suggesting that dissolved Zn was a dominant route of exposure. No adverse effect was noted in the foodexposure (+clean sediment), suggesting selective feeding or regulation. Combined exposure (sediment + food) significantly increased adverse effects in comparison with sediment exposure, indicating contribution of dietary Zn to toxicity and bioaccumulation. The observed enhanced toxicity also supports the assumption on the presence of an avoidance/selective feeding reaction of the amphipods in the single sediment or food exposures. During 14 d post-exposure in clean medium, the organisms from the same combined exposure history received two feeding regimes, i.e. clean food and Zn spiked food. Elevated Zn bioaccumulation and reduced reproduction were noted in amphipods that were offered Zn spiked food compared to the respective organisms that were fed clean food. This was explained by the failure of avoidance/selective feeding behavior in the absence of an alternative food source (sediment), forcing the amphipods to take up Zn while feeding. Increasing Zn body burdens rejected the assumption that Zn uptake from food was regulated by H. azteca. Our results show that the selective feeding behavior should be accounted for when assessing ecological effects of Zn or other contaminants, especially when contaminated food is a potential exposure route.     

Uncertainty analysis using a fugacity-based multimedia mass-balance model: Application of the updated EQC model to decamethylcyclopentasiloxane (D5)

The EQuilibrium Criterion (EQC) model developed and published in 1996 was recently revised to include improved treatment of input partitioning and reactivity data, temperature dependence and an easier sensitivity and uncertainty analysis. This New EQC model was used to evaluate the multimedia, fugacity-based fate of decamethylcyclopentasiloxane (D5; CAS No. 541-02-6) in the environment over a temperature range of 1–25 °C. In addition, Monte Carlo uncertainty analysis was used to quantitatively determine the influence of temperature and input partitioning and reactivity data on the behavior of D5 under various emission scenarios. Results indicated that emission mode was the most influential factor determining the fate and distribution of D5 in the model environment. When emitted to air and soil, D5 partitioned to and remained in the air compartment where rates of removal from degradation and advection processes were relatively rapid. In contrast, D5 emitted to water resulted in a substantial mass fraction of D5 being accumulated in the sediment compartment, where rates of removal from degradation and advection processes were slow. The mass distributions and fate of D5 in the model environment were strongly influenced by multiple input parameters, including temperature, the mode of emission (especially emission rate to water), K_OC and half-life in air. As temperature decreased from 25 °C to 1 °C, K_OC and half-life in air became increasingly more influential such that the mass distribution of D5 increased in air and decreased in sediment, resulting in decreased overall persistence.     

Adsorption and breakdown of penicillin antibiotic in the presence of titanium oxide nanoparticles in water

The fate and transport of antibiotics in natural water systems is controlled in part by interactions with nanometer (10⁻⁹ m) metal oxide particles. Experiments were performed by mixing solutions of ampicillin (AMP), a common, penicillin-class human and veterinary antibiotic, with 25 nm-TiO₂ (anatase) nanoparticles at different pH conditions. Both sorption and degradation of AMP were observed in the AMP-nanoparticle solutions. For AMP concentrations from ∼3 μM to 2.9 mM the overall AMP removal from solution can be described by linear isotherms with removal coefficients (K_r) of 3028 (±267) L kg⁻¹ at pH 2, 11,533 (±823) L kg⁻¹ at pH 4, 12,712 (±672) L kg⁻¹ at pH 6, and 1941 (±342) L kg⁻¹ at pH 8. Mass spectral analysis of AMP solutions after removal of the solid nanoparticles yielded ions that indicate the presence of peniclloic acid, penilloic acid and related de-ammoniated by-products as possible compounds resulting from the degradation of AMP at the TiO₂ surface.     

Tolerance, uptake and removal of nitrobenzene by a newly-found remediation species Mirabilis jalapa L

The growth, photosynthesis rate, and ultrastructure of Mirabilis jalapa L. as a newly-found remediation species under stress of nitrobenzene (NB) and its uptake and removal of NB by the plants were investigated. The results showed that M. jalapa plants could endure contaminated soils by lower than 10.0 mg NB kg⁻¹ because there was no decrease in the total length of the plant roots, the maximum length of the hypocotyle, the length of the first seminal root, the height of the shoots and the dry biomass of the seedlings as well as the photosynthesis rate of the plants compared with those in the control. In particular, the growth of the plants could be significantly (P < 0.01) enhanced by 0.1 mg NB kg⁻¹ under unautoclaved and autoclaved soils. Ultrastructural observations on leaf cells of the plants found that these cells had smooth, clean and continuous cell membranes and cell walls, indicating that there was no obvious damage by NB in comparison with those in the control. Although the absorption of NB in shoots and roots of M. jalapa was weak, plant-promoted biodegradation of NB was considerable and the dominant contribution in the removal of NB from contaminated soils, suggesting the feasibility of M. jalapa applied to phytoremediation of NB contaminated soils.     

Fate and transport of carbamazepine in soil aquifer treatment (SAT) infiltration basin soils

The transport and fate of the pharmaceutical carbamazepine (CBZ) were investigated in the Dan Region Reclamation Project (SHAFDAN), Tel-Aviv, Israel. Soil samples were taken from seven subsections of soil profiles (150 cm) in infiltration basins of a soil aquifer treatment (SAT) system. The transport characteristics were studied from the release dynamics of soil-resident CBZ and, subsequently, from applying a pulse input of wastewater containing CBZ. In addition, a monitoring study was performed to evaluate the fate of CBZ after the SAT. Results of this study indicate adsorption, and consequently retardation, in CBZ transport through the top soil layer (0-5 cm) and to a lesser extent in the second layer (5-25 cm), but not in deeper soil layers (25-150 cm). The soluble and adsorbed fractions of CBZ obtained from the two upper soil layers comprised 45% of the total CBZ content in the entire soil profile. This behavior correlated to the higher organic matter content observed in the upper soil layers (0-25 cm). It is therefore deduced that when accounting for the full flow path of CBZ through the vadose zone to the groundwater region, the overall transport of CBZ in the SAT system is essentially conservative. The monitoring study revealed that the average concentration of CBZ decreased from 1094 ± 166 ng L⁻¹ in the recharged wastewater to 560 ± 175 ng L⁻¹ after the SAT. This reduction is explained by dilution of the recharged wastewater with resident groundwater, which may occur as it flows to active reclamation wells.     

Effects of black carbon on bioturbation-induced benthic fluxes of polychlorinated biphenyls

It is unknown whether carbonaceous geosorbents, such as black carbon (BC) affect bioturbation by benthic invertebrates, thereby possibly affecting sediment-water exchange of sediment-bound contaminants. Here, we assess the effects of oil soot on polychlorinated biphenyl (PCB) mass transfer from sediment to overlying water, for sediments with and without tubificid oligochaeta as bioturbators. PCB levels were so low that toxicity to the oligochaeta played no role, whereas soot levels and binding affinity of PCBs to soot were so low that pore water PCB concentrations were not significantly affected by binding of PCBs to soot. This setup left direct effects of BC on bioturbation activity as the only explanation for any observed effects on mass transfer. Mass transfer coefficients (K_L) for benthic boundary layer transport were measured by a novel flux method using Empore™ disks as a sink for PCBs in the overlying water. For the PCBs studied (logK_ow 5.2-8.2), K_L values ranged from 0.2 to 2 cm × d⁻¹ in systems without tubificids. Systems with tubificids showed K_L values that were a factor of 10-25 higher. However, in the presence of oil soot, tubificids did not cause an increase in mass transfer coefficients. This suggests that at BC levels as encountered under field conditions, the mechanism for reduction of sediment-water transfer of contaminants may be twofold: (a) reduced mass transfer due to strong binding of the contaminants to BC, and (b) reduced mass transfer of contaminants due to a decrease in bioturbation activity.     

Biodegradation of 4-aminobenzenesulfonate by Ralstonia sp. PBA and Hydrogenophaga sp. PBC isolated from textile wastewater treatment plant

A co-culture consisting of Hydrogenophaga sp. PBC and Ralstonia sp. PBA, isolated from textile wastewater treatment plant could tolerate up to 100 mM 4-aminobenzenesulfonate (4-ABS) and utilize it as sole carbon, nitrogen and sulfur source under aerobic condition. The biodegradation of 4-ABS resulted in the release of nitrogen and sulfur in the form of ammonium and sulfate respectively. Ninety-eight percent removal of chemical oxygen demand attributed to 20 mM of 4-ABS in cell-free supernatant could be achieved after 118 h. Effective biodegradation of 4-ABS occurred at pH ranging from 6 to 8. During batch culture with 4-ABS as sole carbon and nitrogen source, the ratio of strain PBA to PBC was dynamic and a critical concentration of strain PBA has to be reached in order to enable effective biodegradation of 4-ABS. Haldane inhibition model was used to fit the degradation rate at different initial concentrations and the parameters μ_max, K_s and K_i were determined to be 0.13 h⁻¹, 1.3 mM and 42 mM respectively. HPLC analyses revealed traced accumulation of 4-sulfocatechol and at least four unidentified metabolites during biodegradation. This is the first study to report on the characterization of 4-ABS-degrading bacterial consortium that was isolated from textile wastewater treatment plant.     

Effect of coplanar PCB concentration on dechlorinating microbial communities and dechlorination in estuarine sediments

The effect of concentration of coplanar PCB on the dechlorinating microbial community and dechlorination were investigated in anoxic estuarine sediment collected from Er-Jen River and enriched with 10 and 50 mg L⁻¹ of 3,4,4′,5-tetrachlorobiphenyl, 3,3′,4,4′,5-pentachlorobiphenyl, and 3,3′,4,4′,5,5′-hexachlorobipheny. Dechlorination rates were similar in the cultures enriched with 10 and 50 mg L⁻¹ of 3,4,4′,5-tetrachlorobiphenyl, whereas significantly higher dechlorination rates were observed in cultures enriched with 10 mg L⁻¹ of 3,3′,4,4′,5-pentachlorobiphenyl. No dechlorination was observed in sediment slurries enriched with 3,3′,4,4′,5,5′-hexachlorobipheny. Para dechlorination occurred prior to meta dechlorination during reductive dechlorination of 3,4,4′,5-tetrachlorobiphenyl and 3,3′,4,4′,5-pentachlorobiphenyl. GC-MS and denaturing gradient gel electrophoresis (DGGE) were used to detect dechlorination products and dechlorinating microorganisms in the enriched sediment cultures during the process of degradation. Two Chloroflexi phylotypes observed in DGGE were responsible for para and meta dechlorination respectively. Phylotype Cp-1 has 98% similarity to uncultured bacterium N5-12. Phylotype Cm-1 has 99% similarity to uncultured dechlorinating bacterium m1 or SF1 belonging to the ο-17/DF-1 group of PCB-dechlorinating bacteria.     

Partitioning behaviour of perfluorinated alkyl contaminants between water, sediment and fish in the Orge River (nearby Paris, France)

This paper reports on the partitioning behaviour of 15 perfluorinated compounds (PFCs), including C₄-C₁₀ sulfonates and C₅-C₁₄ carboxylic acids, between water, sediment and fish (European chub, Leuciscus cephalus) in the Orge River (nearby Paris). Total PFC levels were 73.0 ± 3.0 ng L⁻¹ in water and 8.4 ± 0.5 ng g⁻¹ in sediment. They were in the range 43.1-4997.2 ng g⁻¹ in fish, in which PFC tissue distribution followed the order plasma > liver > gills > gonads > muscle. Sediment-water distribution coefficients (log K_d) and bioaccumulation factors (log BAF) were in the range 0.8-4.3 and 0.9-6.7, respectively. Both distribution coefficients positively correlated with perfluoroalkyl chain length. Field-based biota-sediment accumulation factors (BSAFs) are also reported, for the first time for PFCs other than perfluorooctane sulfonate. log BSAF ranged between −1.3 and 1.5 and was negatively correlated with the perfluoroalkyl chain length in the case of carboxylic acids.     

Comparative bioremediation potential of four rhizospheric microbial species against lindane

Four microbial species (Kocuria rhizophila, Microbacterium resistens, Staphylococcus equorum and Staphylococcus cohnii subspecies urealyticus) were isolated from the rhizospheric zone of selected plants growing in a lindane contaminated environment and acclimatized in lindane spiked media (5-100 μg mL⁻¹). The isolated species were inoculated with soil containing 5, 50 and 100 mg kg⁻¹ of lindane and incubated at room temperature. Soil samples were collected periodically to evaluate the microbial dissipation kinetics, dissipation rate, residual lindane concentration and microbial biomass carbon (MBC). There was a marked difference (p < 0.05) in the MBC content and lindane dissipation rate of microbial isolates cultured in three different lindane concentrations. Further, the dissipation rate tended to decrease with increasing lindane concentrations. After 45 d, the residual lindane concentrations in three different spiked soils were reduced to 0%, 41% and 33%, respectively. Among the four species, S. cohnii subspecies urealyticus exhibited maximum dissipation (41.65 mg kg⁻¹) and can be exploited for the in situ remediation of low to medium level lindane contaminated soils.     

Isolation, identification and characterization of Bacillus amyloliquefaciens BZ-6, a bacterial isolate for enhancing oil recovery from oily sludge

Over 100 biosurfactant-producing microorganisms were isolated from oily sludge and petroleum-contaminated soil from Shengli oil field in north China. Sixteen of the bacterial isolates produced biosurfactants and reduced the surface tension of the growth medium from 71 to <30 mN m⁻¹ after 72 h of growth. These bacteria were used to treat oily sludge and the recovery efficiencies of oil from oily sludge were determined. The oil recovery efficiencies of different isolates ranged from 39% to 88%. Bacterial isolate BZ-6 was found to be the most efficient strain and the three phases (oil, water and sediment) were separated automatically after the sludge was treated with the culture medium of BZ-6. Based on morphological, physiological characteristics and molecular identification, isolate BZ-6 was identified as Bacillus amyloliquefaciens. The biosurfactant produced by isolate BZ-6 was purified and analyzed by high performance liquid chromatography-electrospray ionization tandem mass spectrometry. There were four ion peaks representing four different fengycin A homologues.     

Toxicity and metabolism of copper pyrithione and its degradation product, 2,2'-dipyridyldisulfide in a marine polychaete

We conducted acute toxicity tests and sediment toxicity tests for copper pyrithione (CuPT) and a metal pyrithione degradation product, 2,2′-dipyridyldisulfide [(PS)₂], using a marine polychaete Perinereis nuntia. The acute toxicity tests yielded 14-d LC₅₀ concentrations for CuPT and (PS)₂ of 0.06 mg L⁻¹ and 7.9 mg L⁻¹, respectively. Sediment toxicity tests resulted in 14-d LC₅₀ concentrations for CuPT and (PS)₂ of 1.1 mg kg⁻¹ dry wt. and 14 mg kg⁻¹ dry wt., respectively. In addition to mortality, sediment avoidance behavior and decreases in animal growth rate were observed; growth rate was the most susceptible endpoint in the sediment toxicity tests of both toxicants. Thus, we propose lowest observed effect concentrations of 0.3 mg kg⁻¹ dry wt. and 0.2 mg kg⁻¹ dry wt. for CuPT and (PS)₂, respectively, and no observed effect concentrations of 0.1 mg kg⁻¹ dry wt. for both CuPT and (PS)₂. The difference in the toxicity values between CuPT and (PS)₂ observed in the acute toxicity test was greater than the difference in these values in the sediment toxicity test, and we attribute this to (PS)₂ being more hydrophilic than CuPT. In addition to the toxicity tests, we analyzed conjugation activity of several polychaete enzymes to the toxicants and marked activity of palmitoyl coenzyme-A:biocides acyltransferase and UDP-glucuronosyl transferase was observed.     

Removal capacity and pathways of phenolic endocrine disruptors in an estuarine wetland of natural reed bed

Phenolic compounds are partly known as endocrine disruptors with various harmful effects including feminization and carcinogenesis at very low concentrations. Consequently, the pathways and removal of these compounds in natural and artificial sewage treatment systems such as wetlands have received wide concern. In this paper, a natural reed bed wetland with an area of 695 ha located in the Liaohe River estuary in Northeast China was employed as a demonstration site to study the retention and removal efficiency of phenolic compounds including 4-nonylphenol (4-NP), bisphenol A (BPA), 4-t-octylphenol (4-t-OP), and 2,4-dichlorophenol (DCP), and to evaluate their purification capacity via water and mass balance analyses during an irrigation period from May 9 to September 8, 2009. The results showed that the phenolic compounds could be retained in the wetland system and removed through various processes. On average, 27.5% of phenolic compounds could be retained by the wetland substrate during the initial three-day irrigation period with a retention capacity order of 4-t-OP > 4-NP > BPA > DCP. During the following 120 d irrigation period, the phenolic compounds could be efficiently removed with an average percentage of 91.6%. It is estimated that 1.76 kg d⁻¹ of phenolic compounds could be removed by the Liaohe River estuarine wetland (∼8 × 10⁴ ha). The reed bed wetland system therefore provides a feasible mitigation option for phenolic pollutants in sewage and wastewater.