River Die-away Test Research Articles

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

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

Biodegradation of Anionic Surfactants with the River Die-Away Test

Biodegradation of Anionic Surfactants with the River Die-Away Test

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.

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.

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.

Biodegradation of 2-Sulfonatofatty Acid Methyl Ester (α-SFMe)

The biodegradability of 2-sulfonatofatty acid methylester (a-SFMe), an anionic surfactant recently developed for heavy-duty household detergents, was studied by the shake culture method, river die-away test and biochemical oxygen demand measurment method (MITI test).Biodegradation was followed by the methylene blue active substances (MBAS) analysis and/or dissolved organic carbon (DOC), or biochemical oxygen demand (BOD).The biodegradation of α-SFMe was found to start quickly, and then to proceed rapidly to ultimate degradation at sewage treatment plants and in natural river water.

A shake-flask test for estimation of biodegradability of toxic organic substances in the aquatic environment

Disadvantages of current biodegradation tests are examined: the need for high substrate concentrations, lack of parent compound concentration measurements, no estimation of sediment effects, failure to indicate compounds to which microbial populations must adapt to degrade, and lack of site specificity in innocula selection. A modified river die-away test is proposed for determining biodegradability of organic compounds and testing for toxic degradation products. The present test uses shake flasks containing sterile (2% formalin) and nonsterile site water: both with, and without, site sediment (500 mg/liter). Concurrent toxicity testing with mysids or daphnids provides a sensitive assay for the detection of toxic metabolites. Examples of three test compounds are given: methyl parathion, which undergoes rapid, sediment-mediated biodegradation; dibutylphthalate, to which some microbial communities exhibit an adaptation phenomenon; and methoxychlor, which has a relatively low water solubility and high sediment partition coefficient. The relative merits of this test procedure are discussed.

界面活性剤の河川水中での生分解

To predict the behavior of the surfactants used in the new domestic phosphate-free-built detergents in natural waters, the effect of water temperature and chemical structure of the surfactants on primary biodegradation was examined by a river die-away test using the water collected from Tama River. The extent of biodegradation was dependent on water temperature and varied between the surfactant types tested. Alkyl sulfates or alkyl poly(oxyethylene) ethers were biodegraded rapidly at high to low water temperature. Decreased biodegradation rates were observed for alkylpoly(oxyethylene) sulfates and α-olefin sulfonates. Linear alkylbenzenesulfonates (LAS) or alkylphenyl poly(oxyethylene) ethers were biodegraded moderately at high water temperature, but were poor at low water temperature.These results suggest that large quantities of LAS, being most widely used until now, may persist in natural waters at lower water temperature. The use of the new detergent surfactants may reduce a surfactant concentration in natural waters, as they would biodegrade more rapidly than LAS.

Biodegradation of Some Anionic Surfactants in the River Die-Away Test

The biodegradability of some anionic surfactants in the river die-away test was studied. The biodegradability was evaluated by the methylene blue activity and total organic carbon (TOC). Sodium α-olefin sulfonate (AOS), sodium n-dodecyl sulfate (SDS), sodium polyoxyethylene glycol n-dodecyl ether sulfate (DES), sodium linear alkylbenzene sulfonate (LAS), sodium branched alkylbenzene sulfonate (ABS) and sodium stearate (Soap) were used as test material in this study.It was observed that these surfactants, except ABS, were biodegraded intoneinorganic substances in this experimental period. The relative biodegradation rate, estimated by methylene blue activity was SDS_??_DES>AOS>LAS>>ABS, and estimated by TOC was Soap_??_SDS_??_AOS>DES>LAS>>ABS. The methylene blue activity was disappeared in shorter period than TOC.

Biodegradability of Nonionic Surfactants in River Die-away Test using Tama River Water

A testing method for biodegradability of nonionic surfactant has recently been legislated by Japanese Industrial Standards Committee. As the method is, however, concerned only with the disappearance of surface activities, a comparison of results of several kinds of tests is preferred in oder to evaluate the complete degradability. As a part of the evaluation work the authors conducted river die-away tests of some commercial nonionic surfactants using the river water taken from the upper, the middle and the lower reaches of Tama River, in which biodegradabilities were followed by three analytical methods, i.e. (A) foam, (B) CTAS and (C) COD (Cr).It was found that nonylphenol ethoxylate was not degraded at all in clean water of the upper reaches and was degraded slowly in highly polluted water of the middle or lower reaches as compared with primary or secondary alcohol ethoxylate. In view of COD (Cr), only a part corresponding to the ethoxyl chain of nonylphenol ethoxylate was seemed to be degraded even in the water of the lower reaches, while alcohol ethoxylates were seemed to be degraded completely in all cases.