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Biodegradation in water

Biodegradability of 4-[(E)-2-(5-{[(2Z,4E)-6-chloro-4-[(3-sulfophenyl)imino]-1,2,3,4-tetrahydro-1,3,5-triazin-2-ylidene]amino}-2-sulfophenyl)diazen-1-yl]-5-oxo-1-(4-sulfophenyl)- 4,5-dihydro -1H-pyrazole-3-carboxylic acid (CAS no. 93858 -25 -4) is predicted using QSAR toolbox version 3.3 (2018) with logKow as the primary descriptor. Test substance undergoes 1.8% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 4 -[(E)-2 -(5 -{[(2Z,4E)-6 -chloro-4 -[(3 -sulfophenyl)imino]-1,2,3,4 -tetrahydro-1,3,5 -triazin-2 -ylidene]amino}-2 -sulfophenyl)diazen-1 -yl]-5 -oxo-1 -(4 -sulfophenyl)- 4,5 -dihydro -1H-pyrazole-3-carboxylic acid was estimated to be not readily biodegradable in water.

Additional information

Biodegradation in water

Various predicted data for the target compound 4-[(E)-2-(5-{[(2Z,4E)-6-chloro-4-[(3-sulfophenyl)imino]-1,2,3,4-tetrahydro-1,3,5-triazin-2-ylidene]amino}-2-sulfophenyl)diazen-1-yl]-5-oxo-1-(4-sulfophenyl)-4,5-dihydro-1H-pyrazole-3-carboxylic acid (CAS No. 93858-25-4) and supporting weight of evidence studies for its functionally similar read across substance were reviewed for the biodegradation end point which are summarized as below:


In a prediction done by SSS (2018) using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor, percentage biodegradability of test chemical4-[(E)-2-(5-{[(2Z,4E)-6-chloro-4-[(3-sulfophenyl)imino]-1,2,3,4-tetrahydro-1,3,5-triazin-2-ylidene]amino}-2-sulfophenyl)diazen-1-yl]-5-oxo-1-(4-sulfophenyl)-4,5-dihydro-1H-pyrazole-3-carboxylic acid(CAS No. 93858-25-4) was estimated.Test substance undergoes 1.8% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical4-[(E)-2-(5-{[(2Z,4E)-6-chloro-4-[(3-sulfophenyl)imino]-1,2,3,4-tetrahydro-1,3,5-triazin-2-ylidene]amino}-2-sulfophenyl)diazen-1-yl]-5-oxo-1-(4-sulfophenyl)-4,5-dihydro-1H-pyrazole-3-carboxylic acidwas estimated to be not readily biodegradable in water.


In another prediction using the Estimation Programs Interface Suite (EPI suite, 2018), the biodegradation potential of the test compound, 4-[(E)-2-(5-{[(2Z,4E)-6-chloro-4-[(3-sulfophenyl)imino]-1,2,3,4-tetrahydro-1,3,5-triazin-2-ylidene]amino}-2-sulfophenyl)diazen-1-yl]-5-oxo-1-(4-sulfophenyl)-4,5-dihydro-1H-pyrazole-3-carboxylic acid(CAS No. 93858-25-4) in the presence of mixed populations of environmental microorganisms was estimated.The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical4-[(E)-2-(5-{[(2Z,4E)-6-chloro-4-[(3-sulfophenyl)imino]-1,2,3,4-tetrahydro-1,3,5-triazin-2-ylidene]amino}-2-sulfophenyl)diazen-1-yl]-5-oxo-1-(4-sulfophenyl)-4,5-dihydro-1H-pyrazole-3-carboxylic acidis expected to be not readily biodegradable.


In a supporting weight of evidence study from peer reviewed journal (Yasuhide TONOGAI et. al; 1978) for the read across chemical Trisodium 5-hydroxy-1-(4-sulphophenyl)-4-(4-sulphophenylazo)pyrazole-3-carboxylate (CAS no. 1934-21-0),biodegradation study was conducted under aerobic conditions for evaluating the percentage biodegradability of read across substance Trisodium 5-hydroxy-1-(4-sulphophenyl)-4-(4-sulphophenylazo)pyrazole-3-carboxylate (CAS no. 1934-21-0). Activated sludge was used as a test inoculum obtained from the municipal sewage treatment plant, Nakahama, Osaka. The return sludge was acclimated to the synthetic sewage for a week or longer, and it was used for the aerobic and anaerobic decomposition experiments. Synthetic sewage was prepared by dissolving Glucose, peptone and potassium dihydrogen phosphate, 30g each, in 1 liter water and the pH was adjusted to pH 7.0 with sodium hydroxide. Concentration of inoculum used for the study was3000 mg/l. Percentage degradation of chemical was determined by measuring the absorbance (test material analysis), oxygen uptake and BOD parameter. For the aerobic decomposition of dyes with sludge, 250 ml of O.03 M dye solution was added to 750ml of sludge (MLSS ca, 3,000 ppm), and bubbled with air sufficiently at 20°C. 5ml sample was taken out once a day. After sampling 5ml of synthetic sewage was added to the mixture. Each sample was filtered through filter paper and diluted twenty times prior to the spectrophotometric measurement at the absorption maximum within the visible range. The decrease of dyes concentration was expressed in terms of percent to the initial absorption whereas measurement oxygen uptake by sludge involve 2.0 ml of sludge, 0.2 ml of 1,000 ppm dye solution, and O.2 ml of 20% potassium hydroxide were pipetted into the vessel, the side arm and central well, respectively. The sludge and the dye solution were mixed and the vessel was shaken at 25"C. The oxygen uptake was measured. The oxygen uptake by sludge alone was subtracted from the dye addition. For determining the BOD values, test chemical solutions (10, 20 and 40 ppm) were prepared with the seeded dilution water and kept at 20°C. The dissolved oxygen contents were then measured by using a dissolved oxygen meter. The percentage degradation of test chemical Trisodium 5-hydroxy-1-(4-sulphophenyl)-4-(4-sulphophenylazo)pyrazole-3-carboxylatewas determined to be 20% in 10 days by using the test material analysis parameter. From the oxygen uptake by Warburg’s manometer, the low activity of the sludge to dye was obtained and by using the dissolved oxygen meter, the dissolved oxygen contents on the 5th day were essentially the same to initial ones. Thus, based on percentage degradation, the chemical Trisodium 5-hydroxy-1-(4-sulphophenyl)-4-(4-sulphophenylazo)pyrazole-3-carboxylatewas considered to be not readily biodegradable in nature.


Another biodegradation study was conducted for evaluating the percentage biodegradation of the same read across chemical C. I. Acid Yellow 23 (CAS no. 1934-21-0) (from peer reviewed journal Glenn M. Shaul et. al; 1991 and secondary source Glenn M. Shaul et. al; 1988). The study was carried out in pilot activated sludge process system using several wastewater and mixed liquor at a temperature of 21-25°C and pH range of 7.0-8.0, respectively. Mass balance calculations were made to determine the amount of the dye compound in the waste activated sludge (WAS) and in the activated sludge effluent (ASE). Activated sludge was used as test inoculum for the study. Test chemical conc. used for the study was 1 and 5 mg/l, respectively. Screened raw wastewater from the Greater Cincinnati Mill Creek Sewage Treatment Plant was used as the influent (INF) to three pilot-scale activated sludge biological treatment systems (two experimental and one control) operated in parallel. Each system consisted of a primary clarifier (33 L), complete-mix aeration basin (200 L), and a secondary clarifier (32 L). Each water soluble dye was dosed as commercial product to the screened raw wastewater for the two experimental systems operated in parallel at targeted active ingredient doses of 1 and 5 mg/L of influent flow (low and high spike systems, respectively).All systems were operated for at least three times. All samples were 24 hr composites made up of 6 grab samples collected every 4 hr and stored at 4°C study. The possible removal mechanisms for a dye compound in the ASP system include adsorption, biodegradation, chemical transformation, photodegradation, and air stripping. Dye analytical recovery studies were conducted by dosing the purified dye compound into organic-free water, influent wastewater, and mixed liquor. These studies were run in duplicate and each recovery study was repeated at least once to ensure that the dye compound could be extracted. Purified dye standards were analytically prepared from the commercial dye product by repeated recrystallization. The INF, primary effluent (PE), and ASE were filtered, and the filtrate was passed through a column packed with resin. The filter paper and resin were soaked in an ammonia-acetonitrile solution and then Soxhlet extracted with ammonia-acetonitrile. The extract was concentrated and brought up to 50 mL volume with a methanol/dimethylformamide solution. The mixed liquor (ML) samples were separated into two components, the filtrate or soluble (SOL) fraction and the residue (RES) fraction. The SOL fraction was processed similar to the INF, PE, and ASE samples. The RES fraction and the filter paper were processed similar to these samples but the resin adsorption step was omitted. All extracted samples were analyzed by HPLC with an ultraviolet-visible detector. Total suspended solids (TSS) analyses were also performed on the INF, PE, ML, and ASE samples. Percentage recovery of chemical C. I. Acid Yellow 23was determined to be 103-107%,thus, it appeared that little or no chemical transformation occurred for test chemical because of contact with the variable wastewater and/or sludge matrix under these conditions. Also it was evaluated that the chemical C. I. Acid Yellow 23 was adsorbed at a level of˂1% on the ML solids, indicating that the compound was substantially untreated by the activated sludge process (ASP). Thus, based on %recovery of test chemical, chemical C. I. Acid Yellow 23 was can be considered to be not readily biodegradable in nature.


On the basis of above results for target chemical 4-[(E)-2-(5-{[(2Z,4E)-6-chloro-4-[(3-sulfophenyl)imino]-1,2,3,4-tetrahydro-1,3,5-triazin-2-ylidene]amino}-2-sulfophenyl)diazen-1-yl]-5-oxo-1-(4-sulfophenyl)-4,5-dihydro-1H-pyrazole-3-carboxylic acid(from OECD QSAR toolbox version 3.3 and EPI suite, 2018) and for its read across substance (from peer reviewed journals and secondary source), it can be concluded that the test substance 4-[(E)-2-(5-{[(2Z,4E)-6-chloro-4-[(3-sulfophenyl)imino]-1,2,3,4-tetrahydro-1,3,5-triazin-2-ylidene]amino}-2-sulfophenyl)diazen-1-yl]-5-oxo-1-(4-sulfophenyl)-4,5-dihydro-1H-pyrazole-3-carboxylic acid can be expected to be not readily biodegradable in nature.