1. Benzotriazoles & benzothiazoles
in a WWTP in Greece: Occurrence and removal efficiencies
Alexandros G. Asimakopoulos1,2,
Kurunthachalam Kannan2, Nikolaos S. Thomaidis1
1Laboratory 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, School
of Public Health, State University of New York at Albany,
Albany, NY, USA.

2. Benzotriazoles (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 atom
BTHs 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

3. Target chemicals assessed in the WWTP
BTRs:
BTHs:
BTRs :
1H-benzotriazole
(1H-BTR)
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])
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.

4. Schematic diagram of Treatment Process

5. Sample collection
Wastewater 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.

6. 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 H2O
Washing: 2×5 mL acidified H2O
Elution: 10 mL CH3OH/ACN (1:1 v/v)
Liquid samples: 50/20/5 mL
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
Filtrate
3 DIAFANEIA THA LEEI PROVLIMATA
LC-ESI(+)MS/MS

7. Occurrence in 24-h composite flow proportional Influent and Effluent samples.
Target analytes
24-h composite flow proportional influent wastewater
24-h composite flow proportional effluent wastewater
Removal efficiency (%)
Dissolved phase (ng/L) D1/D2
Particulate matter (ng/L) D1/D2
Dissolved phase (ng/L) D1/D2
Particulate matter (ng/L) D1/D2
D1/D2
1H-BTR
587/580
154/146
325/385
143/162
37/25
1-OH-BTR
217/243
ND/ND
100/100
TTR
15841/7735
131/106
5156/5737
19/37
68/26
XTR
ND/ ND
ND/<1.1
-/-
BTH
1119/1160
108/210
<55/<55
132/89
87/91
2-OH-BTH
481/640
54/80
151/172
16/86
69/64
2-Me-S-BTH
346/331
39/51
50/46
18/20
82/83
2-Amino-BTH
<13/ND

8. Occurrence in primary and secondary sludge & influent bioreactor samples.
Target
analytes
Primary sludge
(grab samples)
Influent bioreactor
Secondary sludge
Dissolved phase
(ng/L)
D1/ D2
Particulate matter (ng/g)
Dissolved phase (ng/L)
Particulate matter
(ng/g)
1H-BTR
2621/4514
17/10
141/125
38/39
531/665
27/26
1-OH-BTR
173/ND
ND/ND
31/35
TTR
27109/210883
16/71
6123/4639
22/71
4964/6383
23/32
XTR
1/ND
1/1
BTH
10543/14010
<41/<41
ND/172
ND/<41
288/ND
<41.3/ND
2-OH-BTH
11545/30224
102/93
207/102
35/44
175/216
21/29
2-Me-S-BTH
1250/1887
26/33
29/21
25/28
2-Amino-BTH
108/248
<34/<34
<34/ND
A major portion is biotransformed during the activated sludge treatment process.

9. Occurrence in Sewage sludge
Target analytes
Sewage Sludge (ng/g)
D1/D2
1H-BTR
81/84
1-OH-BTR
ND/ND
TTR
116/107
XTR
BTH
174/88
2-OH-BTH
74/33
2-Me-S-BTH
61/61
2-Amino-BTH .
Removal by sorption onto sludge seems insignificant.

10. 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.

11. Solid-Liquid Distribution Coefficients, Log Kd of BTRs & BTHs
Target
Analytes
Primary
sludge
Influent
bioreactor
Secondary
1H-BTR
0.58
1.65
2.46
TTR
0.35
0.68
0.86
BTH
0.32
1.99
2.17
2-OH-BTH
0.72
2.11
2.43
2-Me-S-BTH
1.28 -*
2-Amino-BTH
0.41
*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.

12. Average Daily Loadings & Discharges

13. 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.
a principle of toxicology, expressed by Paracelsus 13

14. 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.
a principle of toxicology, expressed by Paracelsus

15. Acknowledgements
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.

16. Reference