Semipermeable membrane device (SPMD) for monitoring PCDD and PCDF levels from a paper mill effluent in the Androscoggin River, Maine, USA

Identification of organic pollutants with potential ecological and health risks in aquatic environments: Progress and challenges

Thousands of organic pollutants are intentionally and unintentionally discharged into water bodies, adversely affecting the ecological environment and human health. Screening for organic pollutants that pose a potential risk in aquatic environments is essential for risk management. This review evaluates the processes, methods, and technologies used to screen such pollutants in the aquatic environment and discuss their advantages and disadvantages, in addition to the challenges and knowledge gaps in this field. Combining non-target screening, target screening, and suspect screening is often effective for compiling a list of potential risk compounds and enables the quantitative analysis of these compounds. Sample preparation technologies and pollutant detection technologies considerably affect the results of pollutant screening. The limited amount of chemical and toxicological information contained in databases hinders the screening of organic pollutants with potential risk. Machine learning, high-throughput methods, and other technologies will increase the accuracy and convenience of screening for high-risk pollutants. This review provides an important reference for screening these compounds in aquatic environments and can be used in future pollutant screening and risk management.

Survey of bioavailable PCDDs, PCDFs, dioxin-like PCBs, and PBBs in air, water, and sediment media using semipermeable membrane devices (SPMDs) deployed in the Hartbeespoort Dam area, South Africa

A survey of bioavailable polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like PCBs (dl-PCBs), and polybrominated biphenyls (PBBs) from ambient air, water and sediment was performed in the Hartbeespoort Dam area in South Africa, a region where data on highly toxic Stockholm Convention persistent organic pollutants (POPs) is scanty. The sampling was designed to simulate POP bioaccumulation in benthic and aquatic dwelling organisms as well as ambient air for estimation of ecological risk. The objective was to survey the spatiotemporal distribution and fate of bioavailable priority persistent organic compounds in the Hartbeespoort Dam in summer, autumn and winter seasons and to validate the utility of a comprehensive two-dimensional gas chromatography-time of flight mass spectrometry (GCxGC-TOF) method for PCDD/F, PCB, and PBB analysis. The highest detection rates for bioavailable priority POPs were for PCB 77 and PCB 126 which were detected in 15 and 16 of the 22 samples, though the majority of the detections were < LOQ for PCB 77. Overall, PCB 126, PBB 10 and PBB 49 recorded the highest quantified bioavailable concentrations per site in SPMDs deployed in the Hartbeespoort Dam. The SPMDs deployed in air at the Magalies River site in winter recorded the highest toxic equivalency quotient (TEQ) of 29.77 pg TEQ SPMD^-1. The highest TEQs recorded for SPMDs deployed in the sediment phase were 10.2, 3.3, and 3.2 pg TEQ SPMD^-1, recorded at the Harbour site in summer, Dam wall in summer and Harbour in winter respectively. In water, SPMDs deployed at the Crocodile River site recorded the highest TEQ of 0.81 pg TEQ SPMD^-1 in summer. TEQ data shows that air carries significant bioavailable dl-toxicity compared to the water phase, and sediment generally carries the highest dl-toxicity. Detection rates for bioavailable PBBs were generally very low, with < 3 detections being quantified above the LOQ for the majority of the sites. Statistical analysis of TEQs computed at all sites, using AVOVA shows that the dispersion of TEQs in the Hartbeespoort Dam is largely homogenous as the differences between the TEQs were insignificant (p > 0.05).

Synthesis and evaluation of Fe3O4-impregnated activated carbon for dioxin removal

Polychlorinated dibenzo-p-dioxins and -furans (PCDD/PCDFs) are highly toxic organic pollutants in soils and sediments which persist over timescales that extend from decades to centuries. There is a growing need to develop effective technologies for remediating PCDD/Fs-contaminated soils and sediments to protect human and ecosystem health. The use of sorbent amendments to sequester PCDD/Fs has emerged as one promising technology. A synthesis method is described here to create a magnetic activated carbon composite (AC-Fe₃O₄) for dioxin removal and sampling that could be recovered from soils using magnetic separation. Six AC-Fe₃O₄ composites were evaluated (five granular ACs (GACs) and one fine-textured powder AC(PAC)) for their magnetization and ability to sequester dibenzo-p-dioxin (DD). Both GAC/PAC and GAC/PAC-Fe₃O₄ composites effectively removed DD from aqueous solution. The sorption affinity of DD for GAC-Fe₃O₄ was slightly reduced compared to GAC alone, which is attributed to the blocking of sorption sites. The magnetization of a GAC-Fe₃O₄ composite reached 5.38 emu/g based on SQUID results, allowing the adsorbent to be easily separated from aqueous solution using an external magnetic field. Similarly, a fine-textured PAC-Fe₃O₄ composite was synthesized with a magnetization of 9.3 emu/g.

Removal of the organic content from a bleached kraft pulp mill effluent by a treatment with silica-alginate-fungi biocomposites

This study attempts a treatment strategy of a bleached kraft pulp mill effluent with Rhizopus oryzae or Pleurotus sajor caju encapsulated on silica-alginate (biocomposite of silica-alginate-fungi, with the purpose of reducing its potential impact in the environment. Active (alive) or inactive (death by sterilization) Rhizopus oryzae or Pleurotus sajor caju was encapsulated in alginate beads. Five beads containing active and inactive fungus were placed in a mold and filled with silica hydrogel (biocomposites). The biocomposites were added to batch reactors containing the bleached kraft pulp mill effluent. The treatment of bleached kraft pulp mill effluent by active and inactive biocomposites was performed throughout 29 days at 28°C. The efficiency of treatment was evaluated by measuring the removal of organic compounds, chemical oxygen demand and the relative absorbance ratio over time. Both fungi species showed potential for removal of organic compounds, colour and chemical oxygen demand. Maximum values of reduction in terms of colour (56%), chemical oxygen demand (65%) and organic compounds (72-79%) were attained after 29 days of treatment of bleached kraft pulp mill effluent by active Rhizopus oryzae biocomposites. The immobilization of fungi, the need for low fungal biomass, and the possibility of reutlization of the biocomposites clearly demonstrate the industrial and environmental interest in bleached kraft pulp mill effluent treatment by silica-alginate-fungi biocomposites.

Estimating pesticide sampling rates by the polar organic chemical integrative sampler (POCIS) in the presence of natural organic matter and varying hydrodynamic conditions

The polar organic chemical integrative sampler (POCIS) was calibrated to monitor pesticides in water under controlled laboratory conditions. The effect of natural organic matter (NOM) on the sampling rates (R(s)) was evaluated in microcosms containing <0.1-5 mg L(-1) of total organic carbon (TOC). The effect of hydrodynamics was studied by comparing R(s) values measured in stirred (SBE) and quiescent (QBE) batch experiments and a flow-through system (FTS). The level of NOM in the water used in these experiments had no effect on the magnitude of the pesticide sampling rates (p > 0.05). However, flow velocity and turbulence significantly increased the sampling rates of the pesticides in the FTS and SBE compared to the QBE (p < 0.001). The calibration data generated can be used to derive pesticide concentrations in water from POCIS deployed in stagnant and turbulent environmental systems without correction for NOM.

The analysis of dioxins and related compounds

The analysis of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, polychlorinated biphenyls, and other related compounds requires complex sample preparation and analytical procedures using highly sensitive and selective state-of-the-art instrumentation to meet very stringent data quality objectives. The analytical procedures (extraction, sample preparation), instrumentation (chromatographic separation and detection by mass spectrometry) and screening techniques for the determination of dioxins, furans, dioxin-like polychlorinated biphenyls and related compounds with a focus on new approaches and alternate techniques to standard regulatory methods are reviewed.

Effects of tertiary treatment by fungi on organic compounds in a kraft pulp mill effluent

BACKGROUND, AIM AND SCOPE

Pulp and paper mills generate a plethora of pollutants depending upon the type of pulping process. Efforts to mitigate the environmental impact of such effluents have been made by developing more effective biological treatment systems in terms of biochemical oxygen demand, chemical oxygen demand, colour and lignin content. This study is the first that reports an evaluation of the effects of a tertiary treatment by fungi (Pleurotus sajor caju, Trametes versicolor and Phanerochaete chrysosporium and Rhizopus oryzae) on individual organic compounds of a Eucalyptus globulus bleached kraft pulp and paper mill final effluent after secondary treatment (final effluent).

MATERIAL AND METHODS

The tertiary treatment with P. sajor caju, T. versicolor and P. chrysosporium and R. oryzae was performed in batch reactors, which were inoculated with separate fungi species and monitored throughout the incubation period. Samples from effluent after secondary and after tertiary treatment with fungi were analysed for both absorbance and organic compounds. The samples were extracted for organic compounds using solid-phase extraction (SPE) and analysed by gas chromatography-mass spectrometry (GC/MS). The efficiencies of the SPE procedure was evaluated by recovery tests.

RESULTS

A total of 38 compounds (carboxylic acids, fatty alcohols, phenolic compounds and sterols) were identified and quantified in the E. globulus bleached kraft pulp mill final effluent after secondary treatment. Recoveries from the extraction procedure were between 98.2% and 99.9%. The four fungi species showed an adequate capacity to remove organic compounds and colour. Tertiary treatment with R. oryzae was able to remove 99% of organic compounds and to reduce absorbance on 47% (270 nm) and 74% (465 nm). P. sajor caju, T. versicolor and P. chrysosporium were able to remove 97%, 92% and 99% of organic compounds, respectively, and reduce 18% (270 nm) to 77% (465 nm), 39% (270 nm) to 58% (465 nm) and 31% (270 nm) to 10% (465 nm) of absorbance, respectively.

DISCUSSION

The wide variety of organic compounds found in the final effluent must be due to the degradation of E. globulus wood in pulp and paper mill. The concentrations of organic compounds in the final effluent of E. globulus bleached kraft pulp mill were in residual levels maybe due to the secondary treatment. The recovery tests showed the effectiveness of the extraction procedure, and no losses of analyte were suspected in the analytical determinations. Lignin derivatives such as vanilic acid, syringic acid, guaiacol, syringol and phloroglucinol were totally removed by R. oryzae, but the 47% absorbance reduction obtained at 270 nm suggests that these species were not able to complete degradation of lignin macromolecular compounds.

CONCLUSIONS

The organic compounds (carboxylic acids, fatty alcohols, phenolic compounds and sterols) were removed more efficiently by tertiary treatment with R. oryzae or P. chrysosporium, followed by P. sajor caju and T. versicolor. Regarding the removal of both colour and organic compounds, the tertiary treatment with R. oryzae was the most efficient.

RECOMMENDATIONS AND PERSPECTIVES

In order to reduce the deleterious impacts of paper mill effluents, efforts have been made to develop more effective advanced tertiary treatments. This study may serve as a basis of characterisation, in terms of organic compounds of E. globulus bleached kraft pulp mill final effluent after secondary treatment and as an effort to understand the effects of tertiary treatments with fungi on low concentrations of organic compounds from biological secondary treatment.

Spectroscopic changes on fulvic acids from a kraft pulp mill effluent caused by sun irradiation

Large volumes of wastewater with a high organic load are generated by the pulp and paper industry that negatively affect the quality of receiving waters. The main waste products in the pulp mill effluents are lignin derived macromolecular compounds, which are similar to natural humic substances and very resistant to wastewater treatments. Fulvic acids (FA) represent the higher percentage of these humic substances and it was observed that solar irradiation modify their properties. Several analytic tools, namely, UV-Visible, molecular fluorescence and FTIR spectroscopies, were used to assess the effect of solar exposition on fulvic acids from a kraft pulp mill effluent. It may be concluded that sun irradiation may alter to a high extent the physicochemical properties of macromolecular organic matter, namely fulvic acids, released by kraft pulp mill effluents. After solar exposition, the aromaticity decreases, the aliphatic structures become more oxygenated, and the fulvic acids from the pulp mill effluent remaining in solution are more similar to aquatic fulvic acids from non polluted sites.