Presentation on theme: "Benzotriazoles & benzothiazoles"— Presentation transcript:
1Benzotriazoles & benzothiazoles in a WWTP in Greece: Occurrence and removal efficienciesAlexandros G. Asimakopoulos1,2,Kurunthachalam Kannan2, Nikolaos S. Thomaidis11Laboratory of Analytical Chemistry, Department of Chemistry,University of Athens, Panepistimioupolis Zografou, Athens,Greece.2Wadsworth Center, New York State, Department of Health,and Department of Environmental Health Sciences, Schoolof Public Health, State University of New York at Albany,Albany, NY, USA.
2Benzotriazoles (BTRs) – Benzothiazoles (BTHs): Uses & Applications BTRs contain the 1,2,3-benzotriazole skeleton in their structure.:Flame and corrosion inhibitors.Ultraviolet (UV) light stabilizers in plastics & antifogging agents.Found in pigments, dishwasher detergents, de-icing fluids.R: chemical group or atomBTHs contain the 1,3-benzothiazole skeleton in their structure.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 high production volume chemicals (> 9000 tons only in the U.S.)R: chemical group or atom
3Target chemicals assessed in the WWTP BTRs:BTHs:BTRs :1H-benzotriazole(1H-BTR)hydroxy-benzotriazole(1-OH-BTR)3. Tolyltriazole(TTR, a mixture of isomers of4-methyl-1H-benzotriazole [4-Me-1H-BTR]and 5-methyl-1H-benzotriazole [5-Me-1H-BTR])Xylyltriazole(XTR, or 5,6-dimethyl-1H-benzotriazole[5,6-diMe-1H-BTR])BTHs:benzothiazole(BTH)2. 2-hydroxy-benzothiazole(2-OH-BTH)2-methylthio-benzothiazole(2-Me-S-BTH)2-amino-benzothiazole(2-amino-BTH)Polar compounds.BTRs are weak bases.BTHs present both acidic and basic properties.
5Sample collectionWastewater and sludge samples were collected from a WWTP that serves a population of , in Athens.Samples were collected in April 2012; the average flow rate of sewage was approx m3/day, and the average production of dewatered sludge was approx 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.The filtered wastewater samples were acidified to pH 2.50±0.10, and stored in the dark at 4 °C until analysis.All solid samples were stored at −20 °C until analysis.
6Schematic 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±0.1Filtration: pre-ashed GF/F filterSPE: Strata-X RP (200mg, 6cc)Conditioning: 10 mL CH3OHEquilibration: 10 mL acidified H2OWashing: 2×5 mL acidified H2OElution: 10 mL CH3OH/ACN (1:1 v/v)Liquid samples: 50/20/5 mLSupernatant dilution to 50 mLCentrifugation: 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 mgFilterFiltrate3 DIAFANEIA THA LEEI PROVLIMATALC-ESI(+)MS/MS
8Occurrence in primary and secondary sludge & influent bioreactor samples .TargetanalytesPrimary sludge(grab samples)Influent bioreactorSecondary sludgeDissolved phase(ng/L)D1/ D2Particulate matter (ng/g)Dissolved phase (ng/L)Particulate matter(ng/g)1H-BTR2621/451417/10141/12538/39531/66527/261-OH-BTR173/NDND/ND31/35TTR27109/21088316/716123/463922/714964/638323/32XTR1/ND1/1BTH10543/14010<41/<41ND/172ND/<41288/ND<41.3/ND2-OH-BTH11545/30224102/93207/10235/44175/21621/292-Me-S-BTH1250/188726/3329/2125/282-Amino-BTH108/248<34/<34<34/NDA major portion is biotransformed during the activated sludge treatment process.
9Occurrence in Sewage sludge Target analytesSewage Sludge (ng/g)D1/D21H-BTR81/841-OH-BTRND/NDTTR116/107XTRBTH174/882-OH-BTH74/332-Me-S-BTH61/612-Amino-BTH.Removal by sorption onto sludge seems insignificant.
10Distribution of BTRs and BTHs between aqueous phase and suspended solids in influent and effluent wastewaterThe 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.
11Solid-Liquid Distribution Coefficients, Log Kd of BTRs & BTHs TargetAnalytesPrimarysludgeInfluentbioreactorSecondary1H-BTR0.581.652.46TTR0.350.680.86BTH0.321.992.172-OH-BTH0.722.112.432-Me-S-BTH1.28-*2-Amino-BTH0.41*Concentrations were not detectableBoth 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.
13Summary (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.a principle of toxicology, expressed by Paracelsus13
14Summary (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.a principle of toxicology, expressed by Paracelsus
15AcknowledgementsThis project was implemented under the Operational Program “Education and Lifelong Learning” and funded by the European Union (European Social Fund) and National Resources — THALIS.