Biodegradation:
Biodegradation in water and sediment: simulation tests.001
Administrative data
- Purpose flag:
- key study
- Study result type:
- experimental result
- Reliability:
- 1 (reliable without restriction)
Data source
Reference
- Reference Type:
- study report
- Title:
- Unnamed
- Year:
- 2005
Materials and methods
Test guideline
- Qualifier:
- according to
- Guideline:
- OECD Guideline 308 (Aerobic and Anaerobic Transformation in Aquatic Sediment Systems)
- Deviations:
- no
- GLP compliance:
- yes
Test materials
- Identity of test material same as for substance defined in section 1 (if not read-across):
- no
Test material identity
- Identifier:
- CAS number
- Identity:
- 7775-09-9
- Details on test material:
- Purity: 99.66 %
Further relevant properties:
Molecular weight: 106.5
Water solubility: 715 g/L
Vapour pressure: < 3.5 10-5 Pa (25 °C)
Log Ko/w: <-1
Hydrolysis: Stable
Solubility in organic solvents: Mixtures of chlorate and organics are explosive
Composition of the product:
H2O = 0.062 %
NaCl = 0.022 %
Ca3(PO4)2 = 0.16 %
Fe2O3 = 0.09 %
Preparation of the test solution: The test substance was dissolved in an appropriate amount of deionised water, allowing addition of 0.2 mL of the stock solution to the aqueous phase of the water sediment system.
Lot/ Batch number: 1E0103WF - Radiolabelling:
- no
Study design
- Oxygen conditions:
- aerobic/anaerobic
- Inoculum or test system:
- natural water / sediment
- Details on source and properties of sediment:
- Two sediments were collected from pristine environments:
a) Heveadorp – This was collected from a stream fed with groundwater (Fonteinallee, Heveadorp, The Netherlands). Aerobic samples were taken from a depth of 0-10 cm. These were grey to brown and had a soil-like smell. Anaerobic samples were taken from 10-20cm. These samples were also grey to brown and had a light sulphide smell.
b) OVP – This was taken from the Oostvaardersplassen (Knardijk, Lelystad, The Netherlands) Aerobic samples taken from 0-5 cm. These were a grey to black and had a slight sulphide smell. The anaerobic samples were taken at 15-25 cm, were black, with a sulphide smell.
The sediments were sieved through screens with openings of 2 mm to improve uniformity of the substrate application. Sediments were then preconditioned by incubation for one week at 20 ± 2 °C.
Initial test substance concentration
- Initial conc.:
- 25 mg/L
- Based on:
- test mat.
Parameter followed for biodegradation estimation
- Parameter followed for biodegradation estimation:
- Test mat. analysis
- Details on study design:
- For each sediment, there was one treatment, i.e. test substance added to the water sediment system. The sediment layer was ± 4.5 cm. The test was carried out in 1 L flasks closed with butyl septa (anaerobic incubations) or parafilm (aerobic incubation), which ensured that the water level was maintained for the duration of the test. Degradation of chlorate in the sediment was followed in duplicate bottles. Chlorate was introduced in the water phase. To prevent depletion of oxygen concentration in the overlying water in the aerobic incubations, the overlying water was aerated at such a rate that the overlying water was oxygen saturated throughout the duration of the test. Anaerobic conditions were established at the start of the test by flushing the gas phase with nitrogen gas. Sampling was performed with minimal disturbance of the sediment and the overlying water, using a gas pipe with a diameter of ± 10 mm.
Incubation temperature: 20 ± 2 °C
pH (sediments and overlying waters) : 6.1 – 7.3
Redox potential (aerobic/anaerobic): -76 to -180 mV *
Oxygen content (aerobic only): High concentrations
Organic carbon content (in overlying water): Decrease from 54-64 mg/L to 26-32 mg/L
* The redox potential of OVP sediment was slightly lower than Heveadorp sediment. The redox potential in the overlying water of the aerobic incubations was always higher than 240 mV.
The initial concentration of the chlorate in the overlying water was calculated by assuming an even distribution of the test substance in the overlying water and the water in the sediment. Due to the immediate start of chlorate reduction and limited mixing of the overlying water at the start of the test, it is not expected that the chlorate concentrations measured at the start agree with the calculated initial chlorate concentration.
Duration of the test:
OVP: 28 days
Heveadorp: 56 days
Samples of overlying water and sediment: 0, 3, 7, 10, 14, 28, 42 (both sediments) and 56 (Heveadorp).
The following time intervals were adopted for the anaerobic bottles starting after introducing the anaerobic conditions: day 0, 1, 3, 7, 10, 14, 21, 28 (both sediments) and only 56 (only Heveadorp).
Reference substance
- Reference substance:
- not required
Results and discussion
Material (mass) balance
% Degradation of test substance
- % Degr.:
- 100
- Parameter:
- Test mat. analysis
- Remarks:
- By the end of the study an excess of chloride was produced in the water sediment systems. This excess already strongly indicates that the chlorate added was reduced to chloride.
- Transformation products:
- yes
Identity of transformation products
- No.:
- #1
- Identifier:
- common name
- Identity:
- Chloride
- Details on transformation products:
- The complete conversion of chlorate to chloride by the end of the study period indicates that no intermediates were present after 28 or 56 days.
- Details on results:
- Mass balances of chlorine in water sediment systems may be used to demonstrate the complete conversion of chlorate to chloride. Excess of chloride was produced in the water sediment systems. This excess already strongly indicates that the chlorate added was reduced to chloride. The controls incubated for the determination of the biomass concentration enabled the assessment of the “endogenous” formation of chloride in the sediment water systems. The chloride formed in the control was subtracted from the chloride produced in the sediment water systems with chlorate. The chloride concentrations ranged from 181 to 298 µmol/L. This demonstrates that almost 100 % of the chlorate-chlorine in the aerobic OVP sediment water system is recovered as chloride. The high rates of biodegradation in both water-sediment systems are highly suggestive of the existence of a large and active population of microorganisms capable of reducing chlorate.
The microbial biomass concentrations decreased after an incubation period of 28 days. The active microbial biomass concentrations in aerobic and anaerobic sediment of Heveadorp were 7 and 6 µg/g respectively. The biomass concentration in both sediments of Heveadorp was 5 µg/g after 56 days. - Any other information on results incl. tables:
- Table A7_1_2_2_2-3: Sodium chlorate and sodium chloride concentrations in two sediments and overlying waters incubated under aerobic conditions (average of duplicates)Time (days)OVPHeveadorpOverlying waterSedimentOverlying waterSediment[NaClO3] (µmol/L)020243415130131953214777138481861381045316214014152141123280060424221125676Time (days)[NaCl] (µmol/L)0780785673704378915316819157108811447828281013521499857866141485151288389828151414359319244210379735610981037Table A7_1_2_2_2-4: Sodium chlorate and sodium chloride concentrations in two sediments and overlying waters incubated under anaerobic conditions (average of duplicates)Time (days)OVPHeveadorpOverlying waterSedimentOverlying waterSedimentNaClO3 (µmol/L)01622641452891247024321232130234537145312161821067141951671438211861522800136122420010576562118Time (days)NaCl (µmol/L)077878667169317878007236853801165569296471082130380987510141015139079171415621581923957281609163393094242147615219819835610651087Table A7_1_2_2_2-5: DT50, DT75 and DT90 values of chlorate reduction in two sediments and their overlying water incubated under aerobic and anaerobic conditions.OVP (high organic carbon content)AerobicAnaerobicWaterSedimentWaterSedimentDT50 (days)8391DT75 (days)103121DT90 (days)123151Heveadorp (low organic carbon content)DT50 (days)20182924DT75 (days)31264136DT (days)42345451Table A7_1_2_2_2-6: Chloride concentrations in test and control flasks at the end of the experiments and the chloride formed calculated by subtracting the concentrations measuredSample id.Chloride (µmol/L)ControlTestTest - ControlHeveadorp anaerobic132394262Heveadorp aerobic81379298OVP anaerobic474717242OVP aerobic510692181Control (biomass) = without chlorate
Applicant's summary and conclusion
- Conclusions:
- Complete conversion is also indicative of the conversion of chlorite to chloride, with no remains of chlorite, i.e. chlorite is completely degraded.
- Validity criteria fulfilled:
- yes
Biodegradation in water and sediment: simulation tests.002
Administrative data
- Purpose flag:
- key study
- Study result type:
- experimental result
- Reliability:
- 2 (reliable with restrictions)
Data source
Reference
- Reference Type:
- other company data
- Title:
- Unnamed
- Year:
- 2007
Materials and methods
- Principles of method if other than guideline:
- An investigation into the degradation of chlorine dioxide in aqueous systems was performed using water from three sources – industrial wastewater, surface (river) water and tap (drinking) water. Chlorine dioxide (0, 1, or 3 mg/L) was added to 500 mL of water in a flask which was then Stoppered and stirred. Samples of the solution were removed at 0, 5, 10, 30 and 60 minutes and 20 hours and the level of chlorine dioxide residual measured using a spectrophotometric method at 340 nm. The pH of the test waters was between 7.0 – 7.9 and the temperature was 22 °C.
- GLP compliance:
- no data
Test materials
- Identity of test material same as for substance defined in section 1 (if not read-across):
- yes
Test material identityopen allclose all
- Details on test material:
- Specification: Prepared as an aqueous solution at 32.3 mg/L
Purity: Pure
Preparation of the test solution: Pure chlorine dioxide solution was produced by adding small amounts of sulphuric acid to the Purate® solution (NaClO3 + H2O2) contained in bottle 1. The chlorine dioxide gas formed is adsorbed into the chilled deionized water in bottle 2. Bottle 3 catches any residual chlorine dioxide gas escaping from bottle 2. - Radiolabelling:
- no
Study design
- Oxygen conditions:
- aerobic/anaerobic
- Inoculum or test system:
- other: Industrial effluent, surface water and tap water
- Details on source and properties of surface water:
- Industrial effluent: Waste water from a tissue mill. Sample was taken just before being dispatched in the recipient (river Göta Älv).
Surface water: The River Göta Älv which supplies the Gothenburg Drinking water works with water. Sample was taken in the river outside EKA Chemicals
Tap water: Drinking water from the city of Gothenburg, disinfected with monochloramine (< 0.3 mg/L as Cl2)
Initial test substance concentrationopen allclose all
- Details on study design:
- Industrial effluent: Waste water from a tissue mill. Sample was taken just before being dispatched in the recipient (river Göta Älv).
Surface water: The River Göta Älv which supplies the Gothenburg Drinking water works with water. Sample was taken in the river outside EKA Chemicals
Tap water: Drinking water from the city of Gothenburg, disinfected with monochloramine (< 0.3 mg/L as Cl2)
Duration of the test: 0, 5, 10, 30, 60 minutes or 20 hours
Reference substance
- Reference substance:
- not required
Results and discussion
Material (mass) balance
% Degradation of test substanceopen allclose all
- % Degr.:
- ca. 100
- Parameter:
- Test mat. analysis
- Sampling time:
- 5 min
- Remarks:
- In wastewater effluent, an initial dose of 3 mg/L chlorine dioxide was completely reacted after 5 minutes contact time.
- % Degr.:
- > 50 - < 100
- Parameter:
- Test mat. analysis
- Sampling time:
- 60 min
- Remarks:
- In surface (river) water, residual chlorine dioxide was detected in the test solution 60 minutes after addition of either 1 or 3 mg/L.
- % Degr.:
- ca. 100
- Parameter:
- Test mat. analysis
- Sampling time:
- 20 h
- Remarks:
- No residual chlorine dioxide was detected in the 3 mg/L test solution after 20 hours contact time.
- % Degr.:
- ca. 40
- Parameter:
- Test mat. analysis
- Sampling time:
- 20 h
- Remarks:
- In tap water (drinking water) the initial dose of 1 mg/L was reduced to 0.6 mg/L after 20 hours contact time.
Half-life of parent compound / 50% disappearance time (DT50)open allclose all
- Compartment:
- other: Tap water
- Half-life:
- 27.7 h
- Type:
- no data
- Remarks (e.g. regr. equ., r², DT90):
- 1 mg/L initial ClO2 concentration
- Compartment:
- other: surface water
- Half-life:
- 16 min
- Type:
- no data
- Remarks (e.g. regr. equ., r², DT90):
- 1 mg/L initial ClO2 concentration
- Compartment:
- other: surface water
- Half-life:
- 22 min
- Type:
- no data
- Remarks (e.g. regr. equ., r², DT90):
- 3 mg/L initial ClO2 concentration
- Transformation products:
- no data
- Details on results:
- In wastewater effluent, an initial dose of 3 mg/L chlorine dioxide was completely reacted after 5 minutes contact time.
In surface (river) water, residual chlorine dioxide was detected in the test solution 60 minutes after addition of either 1 or 3 mg/L. No residual chlorine dioxide was detected in the 3 mg/L test solution after 20 hours contact time.
In tap water (drinking water) the initial dose of 1 mg/L was reduced to 0.6 mg/L after 20 hours contact time. - Any other information on results incl. tables:
- No standard deviations available
Applicant's summary and conclusion
- Conclusions:
- Although selective, chlorine dioxide reacts with a number of inorganic and organic substances like iron, sulphur compounds (organic as well as inorganic), phenolic compounds and humus acids.
Every surface water, ground water, waste water etc. is unique regarding composition of substances that can react with chlorine dioxide. The lab study has consequently to be seen as an example of how chlorine dioxide may decay in the aqueous environment.
No decay of ClO2 could be detected using tap water during the evaluated time frame. The reason for the slow decay in tap water is the low amount of substances that can be oxidized. Still a low amount of ClO2 in the water leaving the water plant is desired in order to prevent recontamination of the water and to avoid bio fouling of the water pipes. - Purpose flag:
- key study
- Study result type:
- experimental result
- Reliability:
- 2 (reliable with restrictions)
- Reference Type:
- other company data
- Title:
- Unnamed
- Year:
- 2007
- Principles of method if other than guideline:
- Testing was performed in the disinfection basin of a conventional activated sludge plant. The chlorine dioxide demand of wastewater entering the basin was measured daily during the study. Chlorine dioxide was produced on site starting from sodium chlorite 25 % w/w solution and hydrochloric acid 33 % with a new concept generator at a production capacity in the range 2000-5000 g/h: the chlorine dioxide production was linked to the water to be treated flow rate to maintain the desired dosage (0.9-1.1 mg/L). Disinfected wastewater was collected at the end of the basin and analysed for residual chlorine dioxide and disinfection by-products.
- GLP compliance:
- no data
- Identity of test material same as for substance defined in section 1 (if not read-across):
- yes
- Details on test material:
- Purity: > 97 %
- Radiolabelling:
- no
- Oxygen conditions:
- aerobic/anaerobic
- Inoculum or test system:
- other: Municipal waste water
- Duration of test (contact time):
- ca. 18 min
- Initial conc.:
- 0.9 - 1.1 mg/L
- Based on:
- test mat.
- Parameter followed for biodegradation estimation:
- Test mat. analysis
- Details on study design:
- Chlorine dioxide was dosed through a diffuser into the wastewater from a conventional activated sludge plant at the entrance to the disinfection basin.
The disinfected water was sampled at the exit of the disinfection basin in clean and sterilized glass bottles: for microbiological analyses sodium thiosulphate was added to destroy any possible chlorine dioxide residue. Many analyses were carried out directly in the plant laboratory. The disinfectant residue was determined immediately after the sampling. All the analyses were, at any rate performed within 24 hours, adopting, for the different parameters, all the procedures required by the analytical methods in terms of sample stabilization.
Each day during the trial water was sampled at the entrance of the disinfection basin and chlorine dioxide demands were performed during the period 12 April – 4 May. The residual chlorine dioxide was determined according to the CPR method (Chlorophenol red method – UNICHIM method.77; I.J.Fletcher, P.Hemmings, Determination of chlorine dioxide in potable water using Chlorophenol red”, Analyst, 1985) dosing 8 mg/L of chlorine dioxide from a stock pure chlorine dioxide 1025 mg/L (prepared in lab according to Standard Methods for the examination of water and wastewater,19th ED, 1995, met. 4500-ClO2 B- Iodometric Method). The residual chlorine dioxide was checked at 15, 30, 45 and 60 minutes and the chlorine dioxide demand calculated. - Reference substance:
- not required
- % Degr.:
- 100
- Parameter:
- Test mat. analysis
- Sampling time:
- 18 min
- Remarks:
- No residual chlorine dioxide was detected at the exit of the disinfection basin on any of the test days.
- Transformation products:
- yes
- Details on results:
- No residual chlorine dioxide was detected at the exit of the disinfection basin on any of the test days.
The chlorine dioxide demand of water entering the disinfection basin varied between 4.4 and 7.1 mg/L during the study. - Any other information on results incl. tables:
- Table A7_1_2_2_1-2: Chlorine dioxide demand vs. Time, pH : 6,5-7, temperature 18-21 °CTimeCHLORINE DIOXIDE DEMANDmeasure unit12-April13-April19-April28-April4 May15 minmg/L4,44,74,64,856,1830 minmg/L5,45,155,25,686,845 minmg/L5,95,65,55,79760 minmg/L5,9565,755,987,1Table A7_1_2_2_1-3: Chemical and microbiological data of the water after the chlorine dioxide disinfectionDate12-apr13-apr19-apr19-apr28-apr04-maySampling time16,2010,3011,3014,3011,3010,30Chlorine dioxide dosage0,91,01,01,11,01,1pH6,56,56,756,456,56,93Redox potentialmV298320195200339260conductivitymS/cm12751200102610569871283oxygenmg/L44,33,73,54,63colourPt/Co534547492783turbidityNTU21,922,12,33,5Chlorine dioxide residuemg/lnrnrnrnrnrnrActive chlorinemg/L0,040,050,030,020,020,03CODmg/L18202529825TOCmg/L1311,51112,5DOCmg/L11,51110,612UV 254 nmAbs/cm0,2170,190,2120,2120,2260,187DUV 254 nmAbs/cm0,1930,1780,2040,1960,2150,168fluoridemg/L0,150,140,130,160,120,15chloritemg/L0,520,590,560,590,530,54chloridemg/L12111010310295,2112,5nitritemg/L0,130,140,190,120,340,59bromidemg/L0,170,130,10,110,120,11chloratemg/L0,070,030,070,070,030,05nitratemg/L18,312,818,522,919,73,75sulphatemg/L107110969690,1109,8sodiummg/L1081099193,6101,5ammoniamg/L9,914,46617,2potassiummg/L16,616,712,912,915,7magnesiummg/L18,218,415,615,716,6calciummg/L10199,48485,591TTHMsmg/L1,21,20,711,11,4CHCl3mg/L1,21,20,711,11,4CHCl2Brmg/Ln.r.n.r.n.r.n.r.n.r.n.r.CHBr2Clmg/Ln.r.n.r.n.r.n.r.n.r.n.r.CHbr3mg/Ln.r.n.r.n.r.n.r.n.r.n.r.Esch. colicfu/100 mL120400202350150Coli. totcfu/100 mL1,6*10^31,8*10^44*10^34*10^37,6*10^23,5*10^3Salmonella sppndndNdndndNdAcute toxicityBioluminescentbacteriaNo toxNo toxNo toxNo toxNo toxNo toxnr = not detectable
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