Presentation on theme: "1 Laboratory of Analytical Chemistry, Department of Chemistry, University of Athens, Panepistimioupolis Zografou, Athens, Greece. 2 Wadsworth Center, New."— Presentation transcript:
1 Laboratory of Analytical Chemistry, Department of Chemistry, University of Athens, Panepistimioupolis Zografou, Athens, Greece. 2 Wadsworth Center, New York State, Department of Health, and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Albany, NY, USA. Alexandros G. Asimakopoulos 1,2, Kurunthachalam Kannan 2, Nikolaos S. Thomaidis 1
Benzotriazoles (BTRs) – Benzothiazoles (BTHs): Uses & Applications : BTHs contain the 1,3-benzothiazole skeleton in their structure. R: chemical group or atom Flame and corrosion inhibitors. Ultraviolet (UV) light stabilizers in plastics & antifogging agents. Found in pigments, dishwasher detergents, de-icing fluids. Corrosion inhibitors, are used as herbicides, slimicides, fungicides, photosensitizers. Constituents of azo dyes, de-icing fluids, drugs, food flavors, rubber. Some occur naturally in the environment, i.e., tobacco smoke and tea leaves. BTRs contain the 1,2,3-benzotriazole skeleton in their structure.
Target chemicals assessed in the WWTP BTRs : 1. 1H-benzotriazole (1H-BTR) 2. 1-hydroxy-benzotriazole (1-OH-BTR) 3. Tolyltriazole (TTR, a mixture of isomers of 4-methyl-1H-benzotriazole [4-Me-1H-BTR] and 5-methyl-1H-benzotriazole [5-Me-1H-BTR]) 4. Xylyltriazole (XTR, or 5,6-dimethyl-1H-benzotriazole [5,6-diMe-1H-BTR]) BTHs: 1. benzothiazole (BTH) 2. 2-hydroxy-benzothiazole (2-OH-BTH) 3. 2-methylthio-benzothiazole (2-Me-S-BTH) 4. 2-amino-benzothiazole (2-amino-BTH) BTRs: BTHs: Polar compounds. BTRs are weak bases. BTHs present both acidic and basic properties.
Schematic diagram of Treatment Process
Sample collection Wastewater and sludge samples were collected from a WWTP that serves a population of 3.700.000, in Athens. Samples were collected in April 2012; the average flow rate of sewage was approx. 743.000 m 3 /day, and the average production of dewatered sludge was approx. 112.000 kg/day. Influent and effluent samples (50 mL), primary sludge (5 mL), secondary sludge (20 mL), and mixed liquor samples from the bioreactors (20 mL) were immediately filtered after collection. All solid samples were stored at −20 °C until analysis. The filtered wastewater samples were acidified to pH 2.50±0.10, and stored in the dark at 4 °C until analysis.
Schematic diagram of the analytical method Evaporation to near-dryness with N2 gas, reconstituted in 1 mL CH3OH/ACN (1:1 v/v) Adjustment pH to 3.0±0.1 Filtration: pre-ashed GF/F filter SPE: Strata-X RP (200mg, 6cc) Conditioning: 10 mL CH3OH Equilibration: 10 mL acidified H 2 O Washing: 2×5 mL acidified H 2 O Elution: 10 mL CH 3 OH/ACN (1:1 v/v) Liquid samples: 50/20/5 mL Filtrate LC-ESI(+)MS/MS Supernatant dilution to 50 mL Centrifugation: 4000 rpm/10 min (×1,×2,×3) SLE: Vortex mixing for 1 min with 5 mL MeOH/Milli-Q water (1:1 v/v) (adjusted to pH 3.00±0.10). Sonication for 45 min (37 oC). Dried Sludge: 100 mg Filter
Occurrence in Sewage sludge. Target analytes Sewage Sludge (ng/g) D1/D2 1H-BTR81/84 1-OH-BTRND/ND TTR116/107 XTRND/ND BTH174/88 2-OH-BTH74/33 2-Me-S-BTH61/61 2-Amino-BTHND/ND y Removal by sorption onto sludge seems insignificant.
Distribution of BTRs and BTHs between aqueous phase and suspended solids in influent and effluent wastewater The presence of exocellular biopolymers on the surfaces of biosolids following secondary treatment creates favorable conditions for higher sorption onto particulates present in bioreactors and secondary sludge.
Solid-Liquid Distribution Coefficients, Log Kd of BTRs & BTHs Target Analytes Primary sludge Influent bioreactor Secondary sludge 1H-BTR0.581.652.46 TTR0.350.680.86 BTH0.321.992.17 2-OH-BTH0.722.112.43 2-Me-S-BTH1.28-* 2-Amino-BTH0.41-* * Concentrations were not detectable Both BTRs & BTHs have low affinity for primary sludge and this changed gradually in biosolids from the bioreactor and the secondary sludge. However, log Kd values were lower than 2.5.
Average Daily Loadings & Discharges
Summary (1/2) Biotransformation of some BTHs had been reported, and this contributes significantly to their removal during wastewater treatment. A similar mechanism is expected for BTRs. The removal efficiencies for BTHs calculated agree with the results from previous studies. The concentrations of 1H-BTR and TTR in sludge from Athens were similar to those reported previously. Only one study had reported BTH concentrations in sludge, where BTH, 2-Me-S-BTH and 2-OH-BTH were found approximately three times higher than the values reported here.
Summary (2/2) Based on the results of the influent and effluent wastewater samples, most of the target analytes were determined in all samples at concentrations similar to or lower than those reported for other WWTP samples. This is the first environmental study that analyzed the particulate matter of wastewater for these compounds. Distribution between aqueous phase and suspended solids in influent and effluent wastewater, and calculation of solid-liquid distribution coefficients were reported for the first time for these compounds.
This project was implemented under the Operational Program “Education and Lifelong Learning” and funded by the European Union (European Social Fund) and National Resources — THALIS. Acknowledgements