Di-(2-ethylhexyl)phthalate in sewage sludge and post-treated sludge: quantitative determination by HRGC-MS and mass spectral characterization

Biodegradation of high di-(2-Ethylhexyl) phthalate (DEHP) concentration by food waste composting and its toxicity assessment using seed germination test

Di-(2-ethylhexyl) phthalate (DEHP), a plasticizer derived from phthalate ester, is used as an additive in industrial products such as plastics, paints, and medical devices. However, DEHP is known as an endocrine-disrupting chemical, causing cancers and adverse effects on human health. This study evaluated DEHP biodegradation efficiency via food waste composting during 35 days of incubation. At high DEHP concentrations (2167 mg kg^-1) in food waste compost mixture, the DEHP biodegradation efficiency was 99% after 35 days. The highest degradation efficiency was recorded at the thermophilic phase (day 3 - day 11) with the biodegradation rate reached 187 mg kg^-1 day^-1. DEHP was metabolized to dibutyl phthalate (DBP) and dimethyl phthalate (DMP) and would be oxidized to benzyl alcohol (BA) and mineralized into CO₂ and water via various metabolisms. Finally, the compost's quality with residual DEHP was evaluated using Brassica chinensis L. seeds via 96 h of germination tests. The compost (at day 35) with a trace amount of DEHP as the end product showed no significant effect on the germination rate of Brassica chinensis L. seeds (88%) compared to that without DEHP (94%), indicating that the compost can be reused as fertilizer in agricultural applications. These results provide an improved understanding of the DEHP biodegradation via food waste composting without bioaugmentation and hence facilitating its green remediation and conversion into value-added products. Nevertheless, further studies are needed on DEHP biodegradation in large-scale food waste composting or industrial applications.

Composting and green technologies for remediation of phthalate (PAE)-contaminated soil: Current status and future perspectives

Phthalate esters (PAEs) are hazardous organic compounds that are widely added to plastics to enhance their flexibility, temperature, and acidic tolerance. The increase in global consumption and the corresponding environmental pollution of PAEs has caused broad public concerns. As most PAEs accumulate in soil due to their high hydrophobicity, composting is a robust remediation technology for PAE-contaminated soil (efficiency 25%-100%), where microbial activity plays an important role. This review summarized the roles of the microbial community, biodegradation pathways, and specific enzymes involved in the PAE degradation. Also, other green technologies, including biochar adsorption, bioaugmentation, and phytoremediation, for PAE degradation were also presented, compared, and discussed. Composting combined with these technologies significantly enhanced removal efficiency; yet, the properties and roles of each bacterial strain in the degradation, upscaling, and economic feasibility should be clarified in future research.

Occurrence and dissipation mechanism of organic pollutants during the composting of sewage sludge: A critical review

Sewage sludge contains various classes of organic pollutants, limiting its land application. Sludge composting can effectively remove some organic pollutants. This review summarizesrecent researches on concentration changes and dissipation of different organic pollutants including persistent organic pollutants during sludge composting, and discusses their dissipation pathways and the current understanding on dissipation mechanism. Some organic pollutants like PAHs and phthalates were removed mainly through biodegradation or mineralization, and their dissipation percentages were higher than those of PCDD/Fs and PCBs. Nevertheless, some recalcitrant organic pollutants could be sequestrated in organic fractions of sludge mixtures, and their levels and ARG abundance even increased after sludge composting in some studies, posing potential risks for land application. This review demonstrated that microbial community and their corresponding degradation for organic pollutants were influenced by different pollutants, bulking agents, composting methods and processes. Further research perspectives on removing organic pollutants during sludge composting were highlighted.

The Assessment of the Sewage and Sludge Contamination by Phthalate Acid Esters (PAEs) in Eastern Europe Countries

Phthalate acid esters (PAEs) are widely used as raw materials for industries that are well known for their environmental contamination and toxicological effects as “endocrine disruptors”. The determining of PAE contamination was based on analysis of dimethyl phthalate (DMP), diethyl phthalate (DEP), dipropyl phthalate (DPP), dibutyl phthalate (DBP), diisobutyl phthalate (DiBP), dicyclohexyl phthalate (DCHP) and di(2-ethylhexyl) phthalate (DEHP) in wastewater and sediment samples collected from city sewer systems of Lithuania and Poland, and Denmark for comparison. The potential PAE sources as well as their concentrations in the wastewater were analyzed and discussed. The intention of the study was to determine the level and key sources of pollution by phthalates in some Eastern European countries and to reveal the successful managerial actions to minimize PAEs taken by Denmark. Water and sludge samples were collected in 2019–2020 and analyzed by gas chromatography-mass spectrometry. The highest contamination with phthalates in Lithuania can be attributed to DEHP: up to 63% of total PAEs in water samples and up to 94% of total PAEs in sludge samples, which are primarily used as additive compounds to plastics but do not react with them and are gradually released into the environment. However, in water samples in Poland, the highest concentration belonged to DMP—up to 210 μg/L, while the share of DEHP reached 15 μg/L. The concentrations of priority phthalate esters in the water samples reached up to 159 μg/L (DEHP) in Lithuania and up to 1.2 μg/L (DEHP) in Denmark. The biggest DEHP concentrations obtained in the sediment samples were 95 mg/kg in Lithuania and up to 6.6 mg/kg in Denmark. The dominant compounds of PAEs in water samples of Lithuania were DEHP > DEP > DiBP > DBP > DMP. DPP and DCHP concentrations were less than 0.05 μg/L. However, the distribution of PAEs in the water samples from Poland was as follows: DMP > DEHP > DEP > DBP, and DiBP, as well as DPP and DCHP, concentrations were less than 0.05 μg/L. Further studies are recommended for adequate monitoring of phthalates in wastewater and sludge in order to reduce or/and predict phthalates’ potential risk to hydrobiots and human health.

Metagenomic analysis exploring microbial assemblages and functional genes potentially involved in di (2-ethylhexyl) phthalate degradation in soil

Widespread use of di (2-ethylhexyl) phthalate (DEHP) as a plasticizer has caused considerable soil pollution; however, little is known about indigenous microbial communities involved in its degradation in soil. In this study, metagenomic sequencing combined with metabolite determination was used to explore microorganisms and genes potentially involved in DEHP degradation in aerobic and anaerobic soils. The results showed that under both dryland aerobic and flooded anaerobic conditions, DEHP was initially hydrolyzed into mono (2-ethylhexyl) phthalate which was then hydrolyzed into phthalic acid; benzoic acid was the central intermediate during further metabolism steps. Bacteria were more responsive to DEHP presence than fungi/archaea, and potential degradative genes stimulated by DEHP were predominantly associated with bacteria, reflecting the dominant role of bacteria in DEHP degradation. Members of the Actinomycetales seemed to be the dominant degraders under aerobic conditions, while a number of phyla i.e. Gemmatimonadetes, Proteobacteria, Acidobacteria and Bacteroidetes appeared to be involved under anaerobic conditions. Interestingly, ~50% of esterase/lipase/cytochrome P450 genes enriched by DEHP under aerobic conditions were from Nocardioides, a bacterial genus that has not been previously directly linked to phthalate ester degradation. The results indicate that novel degraders may play an important role in DEHP degradation in natural soil environments. This study provides a better understanding of the phthalate ester biodegradation processes occurring in soil.

Di 2-ethylhexylphtalate in the aquatic and terrestrial environment: a critical review

Phthalates are being increasingly used as softeners-plasticizers to improve the plasticity and the flexibility of materials. Amongst the different plasticizers used, more attention is paid to di (2-ethylhexylphtalate) (DEHP), one of the most representative compounds as it exhibits predominant effects on environment and human health. Meanwhile, several questions related to its sources; toxicity, distribution and fate still remain unanswered. Most of the evidence until date suggests that DEHP is an omnipresent compound found in different ecological compartments and its higher hydrophobicity and low volatility have resulted in significant adsorption to solids matrix. In fact, there are important issues to be addressed with regard to the toxicity of this compound in both animals and humans, its behavior in different ecological systems, and the transformation products generated during different biological or advanced chemical treatments. This article presents detailed review of existing treatment schemes, research gaps and future trends related to DEHP.

Competitive adsorption and transport of phthalate esters in the clay layer of JiangHan plain, China

This study aimed to investigate the adsorption behavior of phthalate esters (PAEs) in the clay layer of JiangHan Plain, China, so as to make better understanding about the source and control of PAEs in groundwater. Adsorption kinetics, isotherms, and miscible displacement experiments were conducted, and different models were used to simulate the experiment data. Results showed that the adsorption kinetics followed pseudo-second-order model. The kinetic parameters showed quantitative relationships with straight and branched chain carbon numbers of PAEs. These relationships were simulated and carefully discussed. The adsorption isotherms followed linear model better. And partition coefficient (Kd) increased with the carbon chain length of PAEs. Miscible displacement experiments showed that DEHP could not flow out of the column in 100d. HYDRUS-1D and two-site sorption model (linear, first order nonequilibrium adsorption) were used for the simulation of the breakthrough and transport curves of DMP, DEP, DBP, and DiBP. Results showed that the dispersion coefficients (D) and partition coefficient (Kd(')) increased with the carbon chain length. About 10% DBP and DiBP and 1% DMP and DEP were absorbed on the type-1 sites. DMP and DEP were much easier to transfer into the type-2 sites than DBP and DiBP. DBP and DiBP might aggregate in micro-pores of the sorbent. Retardation coefficient and Damkohler number were also calculated and discussed. It was proved that clay layer is an important retarder for PAEs downward transport. However, it can be passed through if the time is sufficient.

Direct competitive immunosorbent assay for detection of MEHP in human urine

Di-(2-ethylhexyl) phthalate (DEHP) is the most commonly used plasticizer for flexible polyvinyl chloride (PVC), which is also known as one of the environmental endocrine disruptors with the reproductive, developmental and embryonic toxicity after entering human body. Mono-2-ethylhexyl phthalate (MEHP) is one of the most complicate metabolites from DEHP in vivo and responsible for many toxic effects of DEHP. In order to evaluate human exposure to DEHP, a direct competitive enzyme-linked immunosorbent (dcELISA) based on monoclonal antibody (mAb) was developed to detect MEHP. A hybridoma cell line 4B9 secreting mAb against MEHP was prepared, and the horseradish peroxidase (HRP) labeled antigen as a probe in the dcELISA was made. After optimization of ELISA reaction conditions, the standard curve with a linear range from 0.56 to 1000 ng mL(-1) and a detection limit of 0.39 ng mL(-1) was established. The cross-reactivities of anti-MEHP mAb to other ten phthalate esters were less than 5% except for mono-methylphthalate (MME). The average recoveries of MEHP from distilled water and negative human urine were both between 87.4% and 94.72% with coefficient of variation (CV) less than 5%. Here, the ELISA method on detecting MEHP was successfully established and applied to real urine sample analyses and the results were confirmed by HPLC. Furthermore, it was indicated that the immunoassay was reliable and suitable for monitoring MEHP.

Chlortetracycline degradation by photocatalytic ozonation in the aqueous phase: mineralization and the effects on biodegradability

Chlortetracycline (CTC) is a hazardous material in aquatic environments. This study was focused on optimization of photocatalytic ozonation processes for removal of CTC from wastewater at pH 2.2 and 7.0. In this study, the tested processes for CTC removal were arranged from the least efficient to the most efficient as: UV, UV/TiO2, O3, O3/UV and O3/UV/TiO2. Ozonation efficiency was due to ozone affinity for electron-rich sites on the CTC molecule. In the O3/UV and O3/UV/TiO2 processes, efficiency was increased by the photolysis of CTC and generation of *OH. At pH 7.0, all the processes were more efficient for CTC degradation than at pH 2.2 due to CTC speciation, ozone decay to *OH and the attractions between ionized CTC and TiO2 particles. UV/O3 at pH 7.0 showed an additive effect while other combination processes showed a synergistic effect that resulted in higher rates of reactions than the sums of individual reaction rates. The TOC removal ranged from 8% to 41% after one hour of reaction, with the above-mentioned order of efficiency. The biodegradability increased rapidly during the early minutes of the reaction. A reaction time of 10-15 min was sufficient for near maximum biodegradability, making these processes good pretreatments for the biological processes.

Uptake of di-(2-ethylhexyl) phthalate of vegetables from plastic film greenhouses

Uptake of di-(2-ethylhexyl) phthalate (DEHP) of nine vegetables including potherb mustard, bok choy, celery, spinach, cabbage, leaf of tube, lettuce, garlic, and edible amaranth in plastic film greenhouses with different plastic films, film thickness, greenhouse age, and greenhouse height was studied. The results showed that the higher the DEHP content of film, the thicker the film, the lower the height of the greenhouse, and the younger the age of the greenhouse were, the higher the DEHP concentration of vegetables was. The results afford significant information for production of safe vegetables with low level DEHP contamination.

Review of 'emerging' organic contaminants in biosolids and assessment of international research priorities for the agricultural use of biosolids

A broad spectrum of organic chemicals is essential to modern society. Once discharged from industrial, domestic and urban sources into the urban wastewater collection system they may transfer to the residual solids during wastewater treatment and assessment of their significance and implications for beneficial recycling of the treated sewage sludge biosolids is required. Research on organic contaminants (OCs) in biosolids has been undertaken for over thirty years and the increasing body of evidence demonstrates that the majority of compounds studied do not place human health at risk when biosolids are recycled to farmland. However, there are 143,000 chemicals registered in the European Union for industrial use and all could be potentially found in biosolids. Therefore, a literature review of 'emerging' OCs in biosolids has been conducted for a selection of chemicals of potential concern for land application based upon human toxicity, evidence of adverse effects on the environment and endocrine disruption. To identify monitoring and research priorities the selected chemicals were ranked using an assessment matrix approach. Compounds were evaluated based upon environmental persistence, human toxicity, evidence of bioaccumulation in humans and the environment, evidence of ecotoxicity and the number and quality of studies focussed on the contaminant internationally. The identified chemicals of concern were ranked in decreasing order of priority: perfluorinated chemicals (PFOS, PFOA); polychlorinated alkanes (PCAs), polychlorinated naphthalenes (PCNs); organotins (OTs), polybrominated diphenyl ethers (PBDEs), triclosan (TCS), triclocarban (TCC); benzothiazoles; antibiotics and pharmaceuticals; synthetic musks; bisphenol A, quaternary ammonium compounds (QACs), steroids; phthalate acid esters (PAEs) and polydimethylsiloxanes (PDMSs). A number of issues were identified and recommendations for the prioritisation of further research and monitoring of 'emerging' OCs for the agricultural use of biosolids are provided. In particular, a number of 'emerging' OCs (PFOS, PFOA and PCAs) were identified for priority attention that are environmentally persistent and potentially toxic with unique chemical properties, or are present in large concentrations in sludge, that make it theoretically possible for them to enter human and ecological food-chains from biosolids-amended soil.

Fate of endocrine-active compounds during municipal biosolids treatment: a review

For two decades, the fates of endocrine-disrupting compounds (EDCs) across various wastewater treatment processes have been studied using chemical and in vitro bioassay measurements. In comparison, little work has been conducted to track the fates of EDCs during municipal biosolids stabilization, particularly using bioassay approaches. This leads to knowledge gaps with respect to understanding which single or combined biosolid treatments facilitate EDC removal, and what the total endocrine-active potency of treated biosolids might be. These unknowns in turn heighten public opposition and distrust of biosolids reuse applications. This review aims to summarize what is currently known regarding EDC removal during commonly used full-scale biosolids treatment processes and highlights analytical challenges that are relevant when in vitro bioassays and chemical analyses are applied to biosolids samples.

Critical evaluation of municipal solid waste composting and potential compost markets

Mechanical biological treatment (MBT) of mixed waste streams is becoming increasingly popular as a method for treating municipal solid waste (MSW). Whilst this process can separate many recyclates from mixed waste, the resultant organic residue can contain high levels of heavy metals and physical and biological contaminants. This review assesses the potential end uses and sustainable markets for this organic residue. Critical evaluation reveals that the best option for using this organic resource is in land remediation and restoration schemes. For example, application of MSW-derived composts at acidic heavy metal contaminated sites has ameliorated soil pollution with minimal risk. We conclude that although MSW-derived composts are of low value, they still represent a valuable resource particularly for use in post-industrial environments. A holistic view should be taken when regulating the use of such composts, taking into account the specific situation of application and the environmental pitfalls of alternative disposal routes.

Phthalate removal throughout wastewater treatment plant: case study of Marne Aval station (France)

The fate of six phthalates: dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DnBP), butyl benzyl phthalate (BBP), bis (2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP) was investigated throughout wastewater treatment processes in the wastewater treatment plant (WWTP) of Marne Aval (France). That plant treats wastewater from a highly populated area and was used as a pilot station for development of nitrification processes. In wastewater, at each step of treatment, DEHP was always the major compound (9 to 44 microg L(-1)), followed by DEP (1.6 to 25 microg L(-1)). Other phthalates averaged 1 microg L(-1) and DnOP remained close to the detection limit in nearly all cases. In sludge, the prevailing compound was also DEHP (72 microg g(-1)) which is consistent with its tendency to get sorbed upon suspended matter (SM). DnOP came in third, in relation with its resistance to biodegradation. For the studied period, the removal efficiency of DEHP from wastewater was about 78%. That removal seemed to proceed rather from particle settling than from biodegradation. A highly significant correlation (p<0.001) was found between DEHP and SM concentrations throughout treatment processes. The other compounds: DMP, DEP, DnBP and BBP, displayed satisfactory efficiencies ranging from 68 to over 96% for the lighter ones obviously more easily degraded. Under rainy periods, the plant discharge impact upon Marne River quality in terms of phthalate fluxes, appeared to be minor as compared to the amount brought by the storm overflows in the same area. Downstream of the WWTP discharge, DEHP concentration remained under the European norm for surface water (NQE: 1.3 microg L(-1)). Our study documents the behaviour of phthalate esters throughout a WWTP which treatment device is used by 55% of the WWTP in the river Seine basin.

On the fate of LAS, NPEOs and DEHP in municipal sewage sludge during composting

The fate of hydrophobic xenobiotic pollutants such as linear alkylbenzene sulfonates (LAS), nonylphenol ethoxylates (NPEO) and di-ethyl-hexyl phthalate (DEHP) during sewage sludge composting was addressed in this work. The experiments were conducted in a fully automated in-vessel autothermal composting system which was fed with a mixture of primary and secondary sludge and manure. The mixture composition was determined to achieve satisfactory humidity, C/N ratio and free air space (FAS). The effect of various parameters, such as the initial xenobiotic concentration, the presence of multiple xenobiotic compounds and the temperature of composting material sustained during the process on the xenobiotics biodegradation kinetics was investigated. It was generally established that significant xenobiotic reduction is achievable through composting under all conditions tested. According to the obtained results, the presence of LAS, NPEO and DEHP even at higher concentrations was not inhibitory to the bioprocess. However, the presence of multiple xenobiotic compounds such as NPEO, NP and DEHP in the sludge can influence LAS removal during LAS composting.

Phytotoxic effects of sewage sludge extracts on the germination of three plant species

In order to evaluate the ability of three types of extracts to explain the ecotoxicological risk of treated municipal sewage sludges, the OECD 208A germination test was applied using three plants (Lolium perenne L., Brassica rapa L., and Trifolium pratense L.). Three equivalent batches of sludge, remained as dewatered sludge, composted with plant remains and thermally dried, from an anaerobic waste water treatment plant were separated. Samples from these three batches were extracted in water, methanol, and dichloromethane. Plant bioassays were performed and the Germination Index (GI) for the three plants was evaluated once after a period of 10 days. Germination in extracts was always lower than the respective controls. The germination in composted sludge (GI 40.9-86.2) was higher than the dewatered (GI 2.9-45.8), or thermally dried sludges (GI 24.6-64.4). A comparison of the germination between types of extracts showed differences for dewatered sludge with the three plants, where the water and methanol extracts had significantly lower germination than the dichloromethane extract. A higher half maximal effective concentration (EC50) in composted extracts was established, mainly in the water extract (EC50 431-490 g kg(-1)). On the contrary, the germination was strongly inhibited in the water extract of the dewatered sludge (EC50 14 g kg(-1)). The germination was positively correlated with the degree of organic matter stability of the parent sludge, and an inverse correlation was detected for total nitrogen, hydrolysable nitrogen and ammonium content. It is concluded that the phytotoxic effect of the water extract is more closely related to hydrophilic substances rather than lipophilic ones, and care must be taken with dewatered sludge application, especially with their aqueous eluates. Results obtained in this work show the suitability of the use of sludge extracts in ecotoxic assays and emphasize the relevance of sewage sludge stabilization by post-treatment processes.

Degradation kinetics of di-(2-ethylhexyl) phthalate (DEHP) and organic matter of sewage sludge during composting

The potential degradation of di-(2-ethylhexyl) phthalate (DEHP) and organic matter of sewage sludge by composting was investigated using laboratory reactor at different operating conditions (E-1, E-2 and E-3). In all conditions, single stage thermophilic phase was observed within 2 days and almost, 60% of DEHP was degraded under this phase. At the end of composting, total DEHP degradation of more than 85% was observed in all conditions and total carbon reduction was 11.8% in E-1, 7.6% in E-2 and 10.8% in E-3. Similar trend was observed in the degradation of total nitrogen. The reduction of volatile solids (VS) in the composting reactors was 5.4% in E-1 (18 days), 5.5% in E-2 (12 days) and 4.3% in E-3 (18 days). The degradation kinetics of DEHP in thermophilic phase (including initial mesophilic phase) and the phase there after were determined by first order and fractional power kinetics, respectively. The significance of experimental parameters in DEHP degradation was assessed by Pearson correlation approach. Elevated temperature produced during composting was effective for the rapid degradation of DEHP from sewage sludge compared to mesophilic treatment.

Ozonation catalyzed by homogeneous and heterogeneous catalysts for degradation of DEHP in aqueous phase

Di-(2-ethyl hexyl) phthalate (DEHP), a recalcitrant and an endocrine disrupting chemical, was studied for its removal from wastewater by advanced oxidation process. The effects of pH, transition metal ions, and granular activated carbon (GAC) were investigated. Removal of DEHP increased with increase in pH and among metal ions Cr(III) was found to be the most active catalyst to remove DEHP. In the case of GAC, original carbon (G0) and GAC pre-ozonated in gas phase for 10 min (G10) were tested as catalysts in catalytic ozonation and found G0 to be more active than G10. This is because, during pre-ozonation, basic groups like chromene, pyrones and also graphene layers were oxidized to acidic surface oxygen groups. These basic surface groups are reported to be active catalytic centres for ozone decomposition into .OH which is a strong oxidant. According to kinetic manipulations, DEHP degradation rate constant due to .OH was affected by the catalyst while that due to direct ozonation is same in all cases with or without catalyst. G0 was doped with chromia gels (G0/CrA) to combine the benefits of homogeneous and heterogeneous catalysis. G0/CrA showed lower catalytic efficiency than that of only G0. This might be because of changes in surface structure of GAC caused by doping of chromia gel and changes in chemical nature of Cr(III) during formation of gel. A good correlation was found between the rate constants of ozone decay and DEHP degradation (R2=0.96). This correlation confirms that ozone decomposition into .OH is a critical factor for the activity of a catalyst during ozonation.

Comparison of solid-phase and eluate assays to gauge the ecotoxicological risk of organic wastes on soil organisms

Development of methodologies to assess the safety of reusing polluted organic wastes in soil is a priority in Europe. In this study, and coupled with chemical analysis, seven organic wastes were subjected to different aquatic and soil bioassays. Tests were carried out with solid-phase waste and three different waste eluates (water, methanol, and dichloromethane). Solid-phase assays were indicated as the most suitable for waste testing not only in terms of relevance for real situations, but also because toxicity in eluates was generally not representative of the chronic effects in solid-phase. No general correlations were found between toxicity and waste pollutant burden, neither in solid-phase nor in eluate assays, showing the inability of chemical methods to predict the ecotoxicological risks of wastes. On the contrary, several physicochemical parameters reflecting the degree of low organic matter stability in wastes were the main contributors to the acute toxicity seen in collembolans and daphnids.

Plasticizers and their degradation products in the process streams of a large urban physicochemical sewage treatment plant

The plasticizers bis (2-ethylhexyl) phthalate (BEHP), bis (2-ethylhexyl) terephthalate (BEHTP) and bis (2-ethylhexyl) adipate (BEHA) were found in significant quantities in the influents, process streams, treated effluent and solid residues of a large physicochemical treatment plant in Montreal, Canada. Of these plasticizers, BEHA was the most abundant in the influent but most was removed during primary treatment. Evidence indicated that significant biodegradation occurred within the sewers and during treatment resulting in the formation of three biodegradation products that had been reported in earlier laboratory studies; namely, 2-ethylhexanol, 2-ethylhexanal and 2-ethylhexanoic acid. Significantly greater concentrations of 2-ethylhexanal were found in process streams than had been reported in earlier laboratory work. This was attributed to the fact that there were fewer opportunities for losses of this volatile compound over the course of wastewater treatment. The plasticizers were removed from the aqueous phase to varying degrees during treatment, with most ending up in the solid residues. All three metabolites and the parent plasticizers were observed in the effluent and most were found in the solids that were analyzed. Results suggest that the treatment plant does not effectively remove plasticizers from the influent and represents a significant source of these compounds and their degradation products in the environment.

Simultaneous sonication-assisted extraction, and determination by gas chromatography–mass spectrometry, of di-(2-ethylhexyl)phthalate, nonylphenol, nonylphenol ethoxylates and polychlorinated biphenyls in sludge from wastewater treatment plants

Di-(2-ethyl-hexyl)phthalate (DEHP), nonylphenol, nonylphenol mono- and diethoxylates (NPEs) and polychlorinated biphenyls (PCBs) are organic pollutants in sewage sludge which have to be monitored in the European Union according to a future Sludge Directive. In the present work, an analytical method for the simultaneous extraction and determination of DEHP, NPEs and PCBs is proposed for the routine analysis of these compounds in sludge from wastewater treatment plants. All the compounds were simultaneously extracted by sonication with hexane and analysed by gas chromatography-mass spectrometry (GC-MS) in electronic impact mode. Recoveries achieved were 105% for DEHP, 61.4-88.6% for NPEs and 55.8-108.3% for PCBs with relative standard deviation bellow 10%. Limits of quantification were 65 microg kg(-1) for DEHP, from 630 to 2504 microg kg(-1) for NPEs and from 5.4 to 10.6 microg kg(-1) for PCBs in dried sludge. The applicability of the proposed method was evaluated by the determination of these compounds in sludge from wastewater treatment plants in Seville (South Spain).

Behavior of di(2-ethylhexyl) phthalate discharged from domestic waste water into aquatic environment

The behavior of di(2-ethylhexyl) phthalate (DEHP) discharged from domestic waste water into river water, sediment and submerged aquatic vegetation was investigated. The concentrations of DEHP were found to be between 8-25 microg L(-1) in river water, 1,000-2,000 microg kg(-1) in sediment and less than 20-2,000 microg kg(-1) in submerged aquatic vegetation. The experiments performed in laboratory were on the biodegradation of DEHP in water and sediment, and also adsorption equilibrium of DEHP between water and sediment. The results obtained from the investigations made it clear that the high enrichment of DEHP from water to sediment was caused from not only its high adsorptive potential but also slow degradation in sediment.