D-gluconic acid, compound with N,N''-bis(4-chlorophenyl)-3,12-diimino-2,4,11,13-tetraazatetradecanediamidine (2:1)

Monitoring data

Administrative data

Endpoint:

monitoring data

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Screening of biocides, metals and antibiotics in Swedish sewage sludge and wastewater.

Author:

Östman M, Lindberg RH, Fick J, Björn E, Tysklind M

Year:

2017

Bibliographic source:

Water Research 115 (2017) 318-328

Reference 2

Reference Type:

publication

Title:

Detailed mass flows and removal efficiencies for biocides and antibiotics in Swedish sewage treatment plants.

Author:

Östman M, Fick J, Tysklind M

Year:

2018

Bibliographic source:

Science of the Total Environment 640–641 (2018) 327–336

Reference 3

Reference Type:

other: Dissertation

Title:

Antimicrobials in sewage treatment plants Occurrence, fate and resistance

Author:

Östman M

Year:

2018

Bibliographic source:

Dissertation for PhD. ISBN: 978-91-7601-938-2

Materials and methods

Principles of method if other than guideline:

In 2015, several sewage treatment plants in Sweden have been monitored for biocides and antibiotics. During this study Chlorhexidine has been analysed in the incoming sewage, aqueous and solid phase, the treated effluent, as well as in the digested sludge.
Incoming sewage was seperated into aqueous and solid phase by centrifugation. Treated effluent were measured without filtration. Sludge samples were extracted using a bead beater. SPE was used to concentrate the analytes. Internal standard was used to consider losses during sample preparation. All samples were analysed using two different LC-MS/MS methods with different columns in order to obtain optimal peak shapes for the substances.

Test material

Test material information

Constituent 1

Reference substance name:

D-gluconic acid, compound with N,N''-bis(4-chlorophenyl)-3,12-diimino-2,4,11,13-tetraazatetradecanediamidine (2:1)

EC Number:

242-354-0

EC Name:

D-gluconic acid, compound with N,N''-bis(4-chlorophenyl)-3,12-diimino-2,4,11,13-tetraazatetradecanediamidine (2:1)

Cas Number:

18472-51-0

Molecular formula:

C22H30Cl2N10.2C6H12O7

IUPAC Name:

N',N'''''-hexane-1,6-diylbis[N-(4-chlorophenyl)(imidodicarbonimidic diamide)] - D-gluconic acid (1:2)

Study design

Details on sampling:

Overall 15 STPs have been monitored in 2015.
For the 2017 publication 11 STPs, for the 2018 publication three specific STPs (Ön (Umea), Bromma (Stockholm) and Rya (Göteborg)), and in the PhD 15 STPs

Sample preparation
Water samples were separated into a particle fraction and a water fraction by centrifugation at 4700 rpm for 25 min at 4 °C, using a WVR Mega Star 1.6 R centrifuge. The particle phase, as well as all the sludge samples, were freeze-dried prior to analysis using a Steris SRK Lyovac GT2 freeze-drier (Germany). Treated effluent samples were not separated into two phases but analysed as a water sample (no filtration).
All samples were weighed before and after freeze-drying to make it possible to determine the mass of particles in the water and allow calculations of mass balances.
Sludge samples for LC-MS/MS analysis
Approximately 1 g of wet sludge was spiked with 300 ng of internal standards and extracted using a bead beater (BioSpec, USA) with zirconium/silica beads in three cycles using methanol with different amounts of acid/base. The extracts were pooled together and evaporated, then diluted with MilliQ to a final volume of 15 mL. The samples then underwent SPE clean-up using Oasis HLB 200 mg 6 cc extraction cartridges (Waters, Ireland). The samples were eluted using 5 mL of methanol with 5% (v/v) FA followed by 5 mL of ethyl acetate. The extract was then evaporated to 200 mL and analysed using LC-MS/ MS.
Water samples for LC-MS/MS analysis
For each water sample, a 200 mL aliquot was centrifuged at 4700 rpm for 25 min at 4 °C and the water phases were spiked with 300 ng of internal standards and 30 mL 25% NH4OH. The same SPE procedure as described above was used before the sample was analysed using LC-MS/MS. The particulate phase was freeze-dried, spiked with internal standards, then underwent the same extraction procedure described for sludge above. Both water and the particulate phases were weighed at each step to allow back calculations of the total amounts of the compounds in the incoming water. The treated effluent samples underwent the same procedure as described above but no centrifugation or filtration was carried out.

Results and discussion

Any other information on results incl. tables

Screening (publication in 2017) shows that the chlorhexidine in the incoming sewage is mainly adsorbed to the particles (n=3). After treatment, chlorhexidine is adsorbed in the digested sludge and only minor amounts will be found in the treated effluent. For two sewage treatment plants the removal efficiency can be calculated, as measured values are available in the effluent, for all other sewage treatment plants the concentration in the effluent was below the LOQ.

	Percentage in treated effluent from total incoming	Removal efficiency
Göteborg	1.12%	98.88%
Norrköping	1.73%	98.27%

In the second publication from 2018, for three sewage treatment plants values for in total 9 days are available. Total amount (aqueous and solid) in incoming sewage are not given in the publication only the separate values. Mass flows were calculated.

	Percentage in treated effluent from total incoming	Percentage in digested sludge from total incoming
Göteborg	2%	81%
Stockholm	1.5%	124%
Umea	1.2%	102%

Applicant's summary and conclusion

Conclusions:

Chlorhexidine is well eliminated from the sewage waste water. The main amout is adsorbed to digested sludge.
Fraction of emission directed to water: <2%
Fraction of emission directed to sludge: > 80%