Die-away Test Research Articles

Biodegradability of fluorinated fire-fighting foams in water

Fluorinated fire-fighting foams may be released into the environment during fire-fighting activities, raising concerns due to the potential environmental and health impacts for some fluorinated organics. The current study investigated (1) the biodegradability of three fluorinated fire-fighting foams, and (2) the applicability of current standard measures used to assess biodegradability of fluorinated fire-fighting foams.The biodegradability of three fluorinated fire-fighting foams was evaluated using a 28-day dissolved organic carbon (DOC) Die-Away Test. It was found that all three materials, diluted in water, achieved 77–96% biodegradability, meeting the criteria for “ready biodegradability”. Defluorination of the fluorinated organics in the foam during biodegradation was measured using ion chromatography. It was found that the fluorine liberated was 1–2 orders of magnitude less than the estimated initial amount, indicating incomplete degradation of fluorinated organics, and incomplete CF bond breakage.Published biodegradability data may utilize biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total organic carbon (TOC) metrics to quantify organics. COD and TOC of four fluorinated compounds were measured and compared to the calculated carbon content or theoretical oxygen demand. It was found that the standard dichromate-based COD test did not provide an accurate measure of fluorinated organic content. Thus published biodegradability data using COD for fluorinated organics quantification must be critically evaluated for validity. The TOC measurements correlated to an average of 91% of carbon content for the four fluorinated test substances, and TOC is recommended for use as an analytical parameter in fluorinated organics biodegradability tests.

Surface parameters, biodegradability and antimicrobial activity of some amide ether carboxylates surfactants

In the present investigation, a series of amide ether carboxylates surfactants RCO-NHCH2CH2O (CH2CH2O)6CH2COONa (AEC), with different alkyl chain lengths from (C12 to C18) and (C18=, C18==) were synthesized.The surface parameters particularly effectiveness (Πcmc), efficiency (PC20), maximum surface excess (Γmax) and minimum area per molecule (Amin) values were investigated. In addition, the standard free energies of micellization (ΔGmic0) and adsorption (ΔGads0) were calculated for the prepared surfactants in aqueous solution. The prepared surfactants were tested for their biodegradability in the water of the River Nile according to the Die-away test method. Their antimicrobial activity against strains of bacteria, yeast and fungi were also investigated.

Biodegradation of Anionic Surfactants with River Die-Away Test (Part 2)

Biodegradation of Anionic Surfactants with River Die-Away Test (Part 2)

Biodegradability of Nonionic Surfactants with the River Die-Away Tests

Biodegradability of Nonionic Surfactants with the River Die-Away Tests

Biodegradation of Anionic Surfactants with the River Die-Away Test

Biodegradation of Anionic Surfactants with the River Die-Away Test

Evaluation of the OECD 314B Activated Sludge Die-Away Test for Assessing the Biodegradation of Pharmaceuticals

The European Medicines Agency guideline for the environmental risk assessment of medicinal products provides a step-by-step phased approach to evaluate the potential risks of new medicines to the environment. Phase I ("prescreen") estimates the initial exposure of the new medicine in the environment. Phase II A ("screen") estimates the fate and effects in the environment. The fate screen determines the inherent properties of the new medicinal active ingredient to sorb to sludge, soil, and sediment matrices and its potential to degrade in a sewage treatment plant and in the subsequent water-sediment compartment. Current ERA Guidance (2006) recommends the OECD 301B Ready Biodegradation Test for Phase II Tier A testing without a clear recommendation for Phase II Tier B testing when further refinement may be needed. With the recent approval of the OECD 314B method for activated sludge, there is now an alternative test method that may be better suited for Phase II Tier A testing and to the data needs of the ERA. As a batch test, it fits the needs of a Tier A screen. It is not designed to simulate the operational steps of a sewage treatment plant, such as the OECD 303 tests, and yet provides the following without considerable costs or resources of OECD 303: (1) useful kinetic information in a test that reflects the conditions of the sewage-treatment environment, i.e., realistic biomass solids concentrations and low level test material concentrations to simulate first-order (nongrowth) kinetics, (2) mass balance analysis for CO(2) evolution and for residues found in mixed liquor, (3) use of an abiotic control to assess losses other than those attributed to biotic biodegradation, and (4) biotransformation profile of degradants. This paper presents the results of OECD 301B with that of OECD 314B for activated sludge biodegradation for five Pfizer drug substances. The use of this new method as an alternative to OECD 301B would strengthen the fate testing screen in Phase II Tier A of the EMEA ERA. It would provide a characterization of a substance's potential for biotransformation and mineralization during sewage treatment and provide a means for revising predicted environmental concentration of surface water for amount removed during sewage treatment.

Aqueous Solution Properties, Biodegradability, and Antimicrobial Activity of some Alkylpolyglycosides Surfactants

Abstract In the present investigation, a series of alkyl polyglycosides with alkyl chain length of C 8, 9, 10, 12 and 14 were synthesized using transacetalization method. Purity of the products was investigated using high performance liquid chromatography. Surface parameters particularly Effectiveness πcmc, Efficiency Pc20, maximum surface excess Γmax, minimum surface area Amin and HLB values are investigated, in addition to thermodynamic parameters (ΔGads and ΔGmic). Resistance to hydrolysis for the prepared compounds was investigated. The synthesized compounds were tested for their biodegradability in Nile river water according to Die-away test method and their antimicrobial activity against different strains of bacteria, yeast and fungi was investigated.

An Evaluation of the OECD 308 Water/Sediment Systems for Investigating the Biodegradation of Pharmaceuticals

In recent times, trace levels of pharmaceuticals detected in wastewater effluents and surface waters have raised the level of attention around the ultimate fate and the potential persistence of pharmaceuticals in the environment. We have seen the European Agency for the Evaluation of Medicines (EMEA) recently include more rigorous environmental fate testing in European Union (EU) Environmental Risk Assessment (ERA) guidance to assess the ultimate fate in water/sediment systems. Yet to date, there is little data available that covers the fate of pharmaceuticals in the water/sediment compartment, and little that assess whether current aerobic and anaerobic methods are appropriate for pharmaceuticals. In this study, the biodegradation profiles of 3 Pfizer products were investigated following the latest ERA guidance and its recommendation for OECD 308 water/sediment biodegradation testing. Experiments included 14C-labeled exemestane, azithromycin, and varenicline representing neutral and cationic pharmaceuticals with average K(oc) values of 3704, 49 400, and 10 483 respectively. Specific HPLC/radioactive monitoring (RAM) methods were used to profile water and sediment samples for biotransformation products. Binding to sediment, as "non-extractables", was considerable for all three pharmaceuticals, though most notable for the cationic pharmaceuticals varenicline and azithromycin ranging from 52% to 94% at study termination, respectively. In general, for all 3 pharmaceuticals studied, the anaerobic conditions demonstrated less biotransformation and mineralization than the aerobic; though their biotransformation profile (number of metabolites) and amount bound to sediment were similar. Based on these findings and our current understanding of anaerobic biodegradation, we would recommend a tiered approach to the OECD 308 water/ sediment test: with default testing just for aerobic conditions; and then if needed, anaerobic testing only for those compounds potentially amenable to typical anaerobic processes. We suggest that as a simulation test would be better suited in later tier testing under EU ERA guidance. Inherent biodegradation or die-away tests seem better suited to derive biodegradation rate constants for subsequent environmental modeling of water and sediment compartments.

Biodegradability of imidazolium and pyridinium ionic liquids by an activated sludge microbial community

Ionic liquids (ILs) are novel organic salts that have enormous potential for industrial use as green replacements for harmful volatile organic solvents. Varying the cationic components can alter the chemical and physical properties of ILs, including solubility, to suit a variety of industrial processes. However, to complement designer engineering, it is crucial to proactively characterize the biological impacts of new chemicals, in order to fully define them as environmentally friendly. Before introduction of ILs into the environment, we performed an analysis of the biodegradability of six ILs by activated sludge microorganisms collected from the South Bend, Indiana wastewater treatment plant. We examined biodegradability of 1-butyl, 1-hexyl and 1-octyl derivatives of 3-methyl-imidazolium and 3-methyl-pyridinium bromide compounds using the standard Organisation for Economic Cooperation and Development dissolved organic carbon Die-Away Test, changes in total dissolved nitrogen concentrations, and 1H-nuclear magnetic resonance analysis of initial and final chemical structures. Further, we examined microbial community profiles throughout the incubation period using denaturing gradient gel electrophoresis (DNA-PCR-DGGE). Our results suggest that hexyl and octyl substituted pyridinium-based ILs can be fully mineralized, but that imidazolium-based ILs are only partially mineralized. Butyl substituted ILs with either cation, were not biodegradable. Biodegradation rates also increase with longer alkyl chain length, which may be related to enhanced selection of a microbial community. Finally, DGGE analysis suggests that certain microorganisms are enriched by ILs used as a carbon source. Based on these results, we suggest that further IL design and synthesis include pyridinium cations and longer alkyl substitutions for rapid biodegradability.

Comparison of biodegradation of poly(ethylene glycol)s and poly(propylene glycol)s

The biodegradation of poly(ethylene glycol)s (PEGs) and poly(propylene glycol)s (PPGs), both being major by-products of non-ionic surfactants biodegradation, was studied under the conditions of the River Water Die-Away Test. PEGs were isolated from a water matrix using solid-phase extraction with graphitized carbon black sorbent, then derivatized with phenyl isocyanate and determined by HPLC with UV detection. PPGs were isolated from a water matrix by liquid–liquid extraction with chloroform, then derivatized with naphthyl isocyanate and determined by HPLC with fluorescence detection. The primary biodegradation of both PEGs and PPGs reached approximately 99% during the test. The tests show different biodegradation pathways of PEG and PPG. During PEG biodegradation, their chains are shortened leading to the formation of ethylene glycol and diethylene glycol. During PPG biodegradation, no short-chained biodegradation products were found.

Isotachophoretic determination of carboxylic acids in biodegradation samples

In the current study a method of isotachophoretic separation of selected carboxylic acids was developed. The method was used for the determination of carboxylated oligo(ethylene glycol)s and their degradation products in biodegradation tests of PEG 250 DA [a mixture of dicarboxylated oligo(ethylene glycol)s]. Two tests were performed in the studies: the Organization for Economic Cooperation and Development (OECD) screening test and the river water die-away test. Both the biodegradation tests proved relatively fast biodegradation of the studied compounds. In the OECD screening test the biodegradation was faster than in the river water die-away test which can be ascribed to a higher concentration of bacteria in the biodegradation liquor. The minimal sample pretreatment and relatively low cost of analysis by the isotachophoretic method used here make it a good alternative to existing methods of carboxylic acids analysis.

Characteristics of Biodegradation of Cyanobacterial Toxin Microcystin LR in Environmental Water Under the River Die-away Test.

The biodegradability of microcystins produced by water-bloom was examined using the river die-away test. Although microcystin LR was not degraded during the first eight days after starting the test, after the eighth day, it began to be degraded rapidly, suggesting that microcystin LR was degraded by inductive metabolism and specific biodegradation. The activity of specific degradation of microcystin LR in the samples from a pond in which water-bloom was occurring was higher than from a pond with no water-bloom. Furthermore, the activity of specific degradation of microcystin LR in the samples taken during the water-bloom season (July 2001) was higher than on no water-bloom season (June 2001) . These results show that the bacteria that can degrade microcystin LR act accompanying the occurrence of water-bloom. Also, under the alkaline condition, microcystin LR was not degraded in the sample from the pond without water-bloom, but was degraded rapidly in the sample from the pond with water-bloom. We suggest that alkaliphilic or tolerant alkaline bacteria are strongly involved in the degradation of microcystin LR in the pond with water-bloom. We concluded that the fate of microcystin in the environment depend on specific bacteria which could adapt to two requirements, specific degradation metabolism for microcystin and tolerance to alkaline environment.

Concerted chemical and microbial degradation of sulfophthalimides formed from sulfophthalocyanine dyes by white-rot fungi.

3- and 4-sulfophthalimide (SPI) have recently been shown to be the major product formed by white-rot fungi upon decolorization of sulfophthalocyanine (SPC) textile dyes. To make use of this metabolic potential in textile wastewater treatment, the fungal breakdown products should be degradable by activated sludge. Here,the aerobic degradation of SPI was studied in die-away tests, and biodegradation intermediates and degradation products were analyzed by liquid chromatography-electrospray ionization-mass spectrometry. The degradation of SPI is initiated by a chemical hydrolysis to sulfophthalamic acid (SPAA) with half-lives of 8 and 40 h at pH 6.5 for 4- and 3-SPI, respectively. Then, 4-SPAA can be mineralized by aerobic mixed cultures, while 3-SPAA remained stable throughout the experiment (35 d). Analogously, the potential intermediate in 4-SPAA degradation, the 4-sulfophthalic acid, but not its 3-isomer, can be completely mineralized aerobically by mixed cultures. In all chemical and microbialtransformations of these aromatic sulfonates the 4-sulfo-isomer is more reactive than the 3-isomer. The triade of fission of the SPC-system by white-rot fungi to SPI, chemical hydrolysis of SPI to SPAA, and microbial degradation of SPAA offers a pathway to mineralize the major part of the SPC system of textile dyes, whether in a respective effluent treatment system or in the aquatic environment. More general, these results illustrate on a molecular level how white-rot fungi and bacteria may cooperate in mineralizing structurally complex colored substances.

Biodegradation of household chemicals in river water under untreated discharge conditions

A series of batch die-away tests was conducted to evaluate the decay rates of MBAS and COD under conditions simulating untreated discharge. Under aerobic conditions, decay of MBAS was consistently faster than that of COD, and dilution into river water had no effect on either rate. Under strictly anaerobic conditions, neither MBAS nor COD decreased in concentration. Additional testing examined the fate of 14C-LAS and the results showed that LAS disappeared and was mineralized after a lag period. Half-lives were 8–10 hours for loss of parent and 11–12 hours for mineralization. Addition of 14C-LAS in sewage to systems previously exposed to raw sewage resulted in no lag and shorter half-lives. This work indicates that MBAS and LAS degrade more rapidly than COD, suggesting these materials would be at low levels once a stream had recovered from the addition of untreated sewage.

Biodegradation of a nonylphenol ethoxylate by the autochthonous microflora in lake water with observations on the influence of light

Alkylphenol polyethoxylates (APE) are routinely used as additives in pesticide formulations. Biodegradation of APEs results in the accumulation of persistent short chain mono-, di- and tri-ethoxylates (AP1EO, AP2EO AP3EO) that are more toxic than the parent compounds and potentially oestrogenic. Accumulation of persistent APE metabolites in shallow or ephemeral waters may pose a hazard to aquatic fauna. This study has followed the degradation and formation of individual oligomers in freshwater in static die-away tests with and without illumination. Over 33 days in darkness there was a progressive and complete loss of long chain oligomers (NP8-17EO), transient increases and subsequent loss of short to medium chain oligomers (NP4-7EO), and large persistent increases (∼1000%) in short chain oligomers (NP1-3EO). In the presence of illumination, biodegradation was retarded and heterotrophic bacterial proliferation was inhibited. After 33 days there was complete loss of long chain oligomers (NP9-17EO), incomplete loss of medium chain oligomers (NP6-8EO) and increases in short chain oligomers (NP1-5EO).

The effect of temperature on the biodegradation of a nonylphenol polyethoxylate in river water

In this paper a study is made of the biodegradability of a non-ionic surfactant, a nonylphenol polyethoxylate, in river water by means of monitoring the residual surfactant matter and the metabolites that may be generated. The influence of temperature on the extent of primary and ultimate biodegradation, and the kinetics of degradation are also determined.The method used was the river die-away test, and the biodegradation process was monitored by normal and reversed phase high-performance liquid chromatography (HPLC). These results are supported by other indirect measurements and indicators of the existence of microbial degradation process, as well as the parameters for the control of the process.The results obtained indicate that temperature has a strong influence on the period of acclimation of the microorganisms and on the rate of biodegradation. The percentages of primary biodegradation vary from 68% at 7°C to 96% at 25°C, and at all the temperatures studied, metabolites are generated during the biodegradation process which do not totally disappear at the end of the assay. The percentages of mineralization reached in the various assays, ranging from 30% at 7°C to 70% at 25°C, also show the great influence of temperature.Finally, a kinetic study of the biodegradation process has been carried out, with excellent fit of the experimental data to the kinetic model of Quiroga and Sales.

Aquatic biodegradation behavior of pentachlorophenol assessed through a battery of shake flask die-away tests

The aerobic aquatic biodegradability of pentachlorophenol (PCP) was studied in standard Organization for Economic Cooperation and Development/International Organization for Standardization shake flask screening tests for ready biodegradability and in more environmentally realistic surface water die-away tests with low chemical concentrations. Screening tests were conducted with either activated sludge or supernatant from settled activated sludge. Concentrations of activated sludge were 30 and 0.3 mg suspended solids per liter. Sludges were either freshly collected or initially preexposed to PCP. With supernatant, only low inoculum levels were used (0.5 ml/L). Some surface water tests were carried out with sediment amendment. Added chemical concentrations ranged from 1 to 74,000 μg/L. At nontoxic concentrations, PCP was rapidly biodegradable after an adaptation period of about 10 to 20 d. At concentrations below about 10 μg/L, degradation rates decreased, and the shape of the degradation curves indicated a shift from growth-linked degradation to non-growth-linked degradation. Addition of sediment to surface water reduced the acclimation periods but did not influence the subsequent degradation rate. Preexposure of activated sludge to PCP drastically eliminated the acclimation period and increased the tolerance of the sludge to PCP toxicity. With PCP used as a model compound, the results show that a battery of simple shake flask tests is suitable for provision of a detailed characterization of the biodegradability chemical compounds.

Litter decomposition of a tropical understory species ( Ctenanthe lubbersiana) grown under ambient and elevated CO 2

A CO 2 evolution and a dissolved organic carbon (DOC)-die-away test were used to determine the inherent decomposability of plant litter of Ctenanthe lubbersiana grown under ambient (340 ppm) and elevated CO 2 (610 ppm). The CO 2 evolution of leaf litter in a 10 day decomposition assay was retarded by 7% (P=0.046). In the DOC-die-away test, the decomposition of a leaf litter hot water extract was retarded by 8% (P=0.039). The decomposition of the solid litter fraction was retarded by 16% (P=0.101). The decomposition rate of petioles was not affected by elevated CO 2. Despite the differences were small, the results suggest possible effects on ecosystem C cycling.

Response of River Water Bacterial Communities to Aniline in Two Biodegradation Test Systems.

Novel HNPP/Fast Red TR in situ hybridization method was used to study the response of river water microbial communities to aniline, as a model chemical pollutant, in two biodegradation test systems: a river die-away (TOC-HANDAI) test and acultivation (HANDAI) test. Pseudomonas rRNA group I and Acinetobacter were the most abundant groups during peak biodegradation activity in both test systems in spite of the differences in test conditions and initial community structures. Burkholderia-Pseudomonas rRNA III-authentic Alcaligenes group were significant only in the cultivation test under highly polluted conditions. Vibrio-Aeromonas and Flavobacterium-Cytophaga groups were adversely affected by aniline in both test systems.

Biodegradation of Chemical Compounds in a Newly Developed Modified River Die-away Test.

Biodegradation of Chemical Compounds in a Newly Developed Modified River Die-away Test.