Chemosphere 104 (2014) 69–75
Contents lists available at ScienceDirect
Chemosphere journal homepage: www.elsevier.com/locate/chemosphere
Toxicity of nonylphenol diethoxylate in lab-scale anaerobic digesters Hande Bozkurt 1, F. Dilek Sanin ⇑ Department of Environmental Engineering, Middle East Technical University, 06800 Ankara, Turkey
h i g h l i g h t s NP compounds are among endocrine disrupting chemicals and present in WWTP sludge in high amounts. Their toxicity on anaerobic microorganisms is investigated. Sludge samples used in reactor construction were found to contain NP and NP1EO but no NP2EO. Methane production profiles did not show any significant toxic effect after NP2EO spike. The added NP2EO is completely degraded into NP1EO and NP in live reactors.
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Article history: Received 4 June 2013 Received in revised form 19 October 2013 Accepted 24 October 2013 Available online 21 November 2013 Keywords: Anaerobic digestion Anaerobic Toxicity Assay test Nonylphenol compounds NP2EO Sludge
a b s t r a c t Nonylphenol compounds have high commercial, industrial and domestic uses owing to their surface active properties. In addition to their toxic, carcinogenic and persistent characteristics; they have drawn the attention of scientists lately due to their endocrine disrupting properties. Their widespread use and disposal cause them to enter wastewater treatment systems at high concentrations. Since they are highly persistent and hydrophobic, they accumulate mostly on sludge. In this study using Anaerobic Toxicity Assay (ATA) tests, the toxicity of a model nonylphenol compound, nonylphenol diethoxylate (NP2EO), for anaerobic digestion of sludge was determined. The test bottles were dosed with NP2EO in acetone, with concentrations ranging from 1 mg L 1 to 30 mg L 1. During the tests, gas productions and compositions in terms of methane and carbon dioxide were monitored. To be able to judge about the fate, the target compounds were extracted from water and sludge and analyzed using GC/MS. The sludge samples used for assembling the reactors were found to contain NP and NP1EO but no NP2EO. After the assay was completed, all the NP2EO spiked into the live reactors was found to disappear. The increase seen in NP1EO and NP and further accumulation of NP in the system, indicated the conversion of NP2EO to these metabolites. On the other hand, no conversion was observed in abiotic reactors. Inhibition of NP2EO for anaerobic microorganisms was not observed throughout the tests considering the biogas production of the test reactors in comparison to the control reactors. Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction Non-ionic surfactants have a big share in the world’s surfactant market, with alkylphenols being the most widely used non-ionic surfactants. Nonylphenol (NP) compounds constitute about 80% of the alkylphenols, whereas the rest, 20%, being octylphenols. Due to their surface active properties NP compounds have high commercial, industrial and domestic uses. Industrial uses exist in tannery, textile, paper, detergent and personal care product industries (CEPA, 1999; Diaz and Ventura, 2002). Additionally, these chemicals are being used in many daily activities as ⇑ Corresponding author. Tel.: +90 312 210 2642; fax: +90 312 210 2646. E-mail address: [email protected] (F.D. Sanin). Current address: Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800 Lyngby, Denmark. 1
0045-6535/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.chemosphere.2013.10.059
deodorants, shampoos, skin care products, etc. (Diaz and Ventura, 2002). Knowing that these chemicals are produced and consumed at considerable rates, it will be correct to say that NP compounds will eventually end up in either domestic and industrial wastewater treatment plants or surface waters directly. NP compounds are considered strongly toxic and carcinogenic chemicals which would have adverse effects even with short term exposures (Cox, 1996). During short term exposures these chemicals result in respiratory diseases, vocal cord disorders, headache and skin and eye irritation. Moreover, the NP compounds are listed among the ‘‘endocrine disrupting chemicals’’ (EDCs). Endocrine disrupting substances are capable of mimicking natural hormones due to their similarity to them. As the name implies, they are capable of interfering with the endocrine system and prohibit its proper functioning. With their similarity to the estrogen hormone, NP compounds can create estrogenic effect on the body and result
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H. Bozkurt, F.D. Sanin / Chemosphere 104 (2014) 69–75
in serious health problems mainly related with the reproductive system (Warhurst, 1995; Ying et al., 2002; Birkett and Lester, 2003; Lintelmann et al., 2003). The observations in literature demonstrate the capacity of NP to interfere with various types of cells and organs, with different modes of action at concentrations as low as 0.01 mg d 1 (Colerangle and Roy, 1996). The reported mechanisms of NP toxicity to organisms are probably as a result of the interaction of NP with proteins, changing the shape and activity of enzymatic proteins and structural proteins. This causes changes in cell membrane permeability, as seen for nonionic surfactants (Scott-Fordsmand and Krogh, 2004). In addition, NP has been shown to be capable of interfering with the regulatory systems of different types of cells by several mechanisms which include capacity to trigger respiratory toxicity in cells (probably by changing the membrane permeability of the mitochondria) (Argese et al., 1994), alter the cell-cycle kinetics by conversion of immature structures to mature structures (Colerangle and Roy, 1996) and produce telemetric associations and chromosomal aberrations (Roy et al., 1998). These results indicate that the effects of NP are very diverse and unpredictable as a consequence of its ability to initiate numerous responses. In bacterial cells the major toxicity action seems to be due to increased cell membrane permeability. With industrial and domestic wastewater discharges, NP compounds end up in the wastewater treatment plants. Because the first degradation reactions are fast, concerns and studies are focused mainly on NP2EO, NP1EO and NP. In Canada, NP concentration was found to be 2.68–13.3 lg L 1 in untreated wastewater samples of textile industries (CEPA, 1999). In the wastewater samples of pulp and paper industries, NP1EO, NP2EO and NPnEO (n = 3–17) concentrations were measured as
Contents lists available at ScienceDirect
Chemosphere journal homepage: www.elsevier.com/locate/chemosphere
Toxicity of nonylphenol diethoxylate in lab-scale anaerobic digesters Hande Bozkurt 1, F. Dilek Sanin ⇑ Department of Environmental Engineering, Middle East Technical University, 06800 Ankara, Turkey
h i g h l i g h t s NP compounds are among endocrine disrupting chemicals and present in WWTP sludge in high amounts. Their toxicity on anaerobic microorganisms is investigated. Sludge samples used in reactor construction were found to contain NP and NP1EO but no NP2EO. Methane production profiles did not show any significant toxic effect after NP2EO spike. The added NP2EO is completely degraded into NP1EO and NP in live reactors.
a r t i c l e
i n f o
Article history: Received 4 June 2013 Received in revised form 19 October 2013 Accepted 24 October 2013 Available online 21 November 2013 Keywords: Anaerobic digestion Anaerobic Toxicity Assay test Nonylphenol compounds NP2EO Sludge
a b s t r a c t Nonylphenol compounds have high commercial, industrial and domestic uses owing to their surface active properties. In addition to their toxic, carcinogenic and persistent characteristics; they have drawn the attention of scientists lately due to their endocrine disrupting properties. Their widespread use and disposal cause them to enter wastewater treatment systems at high concentrations. Since they are highly persistent and hydrophobic, they accumulate mostly on sludge. In this study using Anaerobic Toxicity Assay (ATA) tests, the toxicity of a model nonylphenol compound, nonylphenol diethoxylate (NP2EO), for anaerobic digestion of sludge was determined. The test bottles were dosed with NP2EO in acetone, with concentrations ranging from 1 mg L 1 to 30 mg L 1. During the tests, gas productions and compositions in terms of methane and carbon dioxide were monitored. To be able to judge about the fate, the target compounds were extracted from water and sludge and analyzed using GC/MS. The sludge samples used for assembling the reactors were found to contain NP and NP1EO but no NP2EO. After the assay was completed, all the NP2EO spiked into the live reactors was found to disappear. The increase seen in NP1EO and NP and further accumulation of NP in the system, indicated the conversion of NP2EO to these metabolites. On the other hand, no conversion was observed in abiotic reactors. Inhibition of NP2EO for anaerobic microorganisms was not observed throughout the tests considering the biogas production of the test reactors in comparison to the control reactors. Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction Non-ionic surfactants have a big share in the world’s surfactant market, with alkylphenols being the most widely used non-ionic surfactants. Nonylphenol (NP) compounds constitute about 80% of the alkylphenols, whereas the rest, 20%, being octylphenols. Due to their surface active properties NP compounds have high commercial, industrial and domestic uses. Industrial uses exist in tannery, textile, paper, detergent and personal care product industries (CEPA, 1999; Diaz and Ventura, 2002). Additionally, these chemicals are being used in many daily activities as ⇑ Corresponding author. Tel.: +90 312 210 2642; fax: +90 312 210 2646. E-mail address: [email protected] (F.D. Sanin). Current address: Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800 Lyngby, Denmark. 1
0045-6535/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.chemosphere.2013.10.059
deodorants, shampoos, skin care products, etc. (Diaz and Ventura, 2002). Knowing that these chemicals are produced and consumed at considerable rates, it will be correct to say that NP compounds will eventually end up in either domestic and industrial wastewater treatment plants or surface waters directly. NP compounds are considered strongly toxic and carcinogenic chemicals which would have adverse effects even with short term exposures (Cox, 1996). During short term exposures these chemicals result in respiratory diseases, vocal cord disorders, headache and skin and eye irritation. Moreover, the NP compounds are listed among the ‘‘endocrine disrupting chemicals’’ (EDCs). Endocrine disrupting substances are capable of mimicking natural hormones due to their similarity to them. As the name implies, they are capable of interfering with the endocrine system and prohibit its proper functioning. With their similarity to the estrogen hormone, NP compounds can create estrogenic effect on the body and result
70
H. Bozkurt, F.D. Sanin / Chemosphere 104 (2014) 69–75
in serious health problems mainly related with the reproductive system (Warhurst, 1995; Ying et al., 2002; Birkett and Lester, 2003; Lintelmann et al., 2003). The observations in literature demonstrate the capacity of NP to interfere with various types of cells and organs, with different modes of action at concentrations as low as 0.01 mg d 1 (Colerangle and Roy, 1996). The reported mechanisms of NP toxicity to organisms are probably as a result of the interaction of NP with proteins, changing the shape and activity of enzymatic proteins and structural proteins. This causes changes in cell membrane permeability, as seen for nonionic surfactants (Scott-Fordsmand and Krogh, 2004). In addition, NP has been shown to be capable of interfering with the regulatory systems of different types of cells by several mechanisms which include capacity to trigger respiratory toxicity in cells (probably by changing the membrane permeability of the mitochondria) (Argese et al., 1994), alter the cell-cycle kinetics by conversion of immature structures to mature structures (Colerangle and Roy, 1996) and produce telemetric associations and chromosomal aberrations (Roy et al., 1998). These results indicate that the effects of NP are very diverse and unpredictable as a consequence of its ability to initiate numerous responses. In bacterial cells the major toxicity action seems to be due to increased cell membrane permeability. With industrial and domestic wastewater discharges, NP compounds end up in the wastewater treatment plants. Because the first degradation reactions are fast, concerns and studies are focused mainly on NP2EO, NP1EO and NP. In Canada, NP concentration was found to be 2.68–13.3 lg L 1 in untreated wastewater samples of textile industries (CEPA, 1999). In the wastewater samples of pulp and paper industries, NP1EO, NP2EO and NPnEO (n = 3–17) concentrations were measured as
