جستجوی مقالات مرتبط با کلیدواژه « آزمون زیستی » در نشریات گروه « پزشکی »

Catechol is one of the most common compounds in the industrial wastewater including oil and petrochemical, pesticides industries. The drainage of these industries leads to aquatic organisms poisoning and adverse effects on the environment. Therefore, this study aimed to evaluate the effects of catechol toxicity changes before and after the catalytic ozonation process by Daphnia Magna bioassay. This study is an applied research in which the toxicity of catechol and its products from degradation was evaluated by bioassay method during the Catalytic ozonation process. First stock solution was prepared at concentration of 250 mg/l followed by preparation of 10 samples that each contained 0 (control), 0.5, 1, 3, 6, 12, 25, 50, 75 and 100% of volume of primary solution. Initial samples were prepared from reactor effluent in the same volume. Based on the standard method, 10 Daphnia infants were added to prepared samples. Samples were evaluated after 24, 48, 72 and 96 hours. Finally, lethal concentration (LC50) and toxic units (TU) were calculated using probit analysis. According to the results, LC50 (24 hours) of raw effluent with an initial concentration of 250 mg / L of catechol increased from 13.30 ml/100 ml to 33.9 ml/100 ml after 60 minutes treatment. Consequently, the toxicity unit decreased from 7.51 TU to 0.9 TU which means that the toxicity dropped by 88%. Finally, the toxicity of treated effluent decreased during catalytic ozonation process to degradation of catechol. Bioassay is a simple and effective way to evaluate the toxicity potential of Catechol to discharge it to surface water. Based on the bioassay by Daphnia Magna, Catalytic ozonation process is able to reduce the toxicity of catechol by degradation this compound and breaking into other products.

Discharge of industrial wastewater containing Catechol has adverse effects on human and environmental health. Purpose of this study was to determine the effects of catechol toxicity before and after advanced oxidation process (ozonation process) by bioassay test with Daphnia Magna.
This study is an applied research in which the toxicity of catechol was determined by Daphnia Magna bioassay test during the ozonation process. First, Catechol stock solution was prepared at a concentration of 250 mg/L. Then, 10 samples were prepared that each contained 0 (control), 0.5, 1, 3, 6, 12, 25, 50, 75 and 100% of volume of primary solution. Initial samples were prepared from reactor effluent in the same volume as those of the samples. According to standard method, 10 Daphnia infants were added to each sample. The samples were observed after 24, 48, 72 and 96 hours. Finally, lethal concentration (LC50) and toxicity unit (TU) were calculated using Probit analysis.
According to the results, Daphnia magna was affected by the toxicity of catechol. LC50 (24-hour) for raw effluent was increased from 13.30 mL/100 mL to 30.4 mL/100 mL after 60 minutes Treatment. The toxicity unit was decreased from 7.51 TU to 3.29 TU accordingly, showing reduction of 56% in toxicity. The toxicity of the treated effluent decreased during ozonation process of catechol.
Based on the bioassay test, ozonation process was able to reduce the toxicity of catechol. Therefore, this process can be used as an option to treat wastewater that contains catechol.

Phenol is one of the industrial pollutants in wastewaters, which due to its toxicity for biological systems various pretreatment processes have been used for its detoxification. In this study, the combination of catalytic ozonation process (COP) and sequencing batch reactor (SBR) were used for detoxification of these types of wastewaters.Materials and In this study, the effect of COP on phenol degradation, COD removal, and detoxification of wastewater was investigated. To determine the acute toxicity of effluents and identification of intermediate compounds produced in COP, bioassay using Daphnia Magna and GC / MS were used, respectively. Then, phenol and COD removal of pretreated wastewater was investigated in SBR. It was found that under optimal conditions in COP (time = 60 min), the concentrations of phenol and COD reduced from 500 and 1162 to 7.5 and 351 mg/L respectively and pretreated effluent toxicity (TU = 36), after rising in the initial stage of reaction, effectively reduced at the end of process (TU=2.3). the integration of this process with SBR could decreased the COD and phenol concentration less than the detectable range by HPLC. Results showed that COP has a high effect on biodegradability, detoxification, and mineralization of phenol and combination of COP with SBR process can effectively treat wastewaters containing phenol.

Increased use of nanoparticles in industries leads to entering hazardous substances to environment. Nanoparticle toxicity due to release of toxic substances into the environment is a concern for communities. One of the common nanoparticles ingredients are zinc oxide. In this study toxicity of the solution containing the Reactive Red 120 dye after Nano-catalytic process UV/ ZnO using biological test Daphnia magna was studied. this is a fundamental – practical study، which done on laboratory scale. Toxicity assay tests were carried out using Daphnia magna a bio-indicator. Then results of toxicity tests using SPSS software were analyzed and Lc50were determined. Results showed that the Lc50 value ​​at 24،48،72،96 hr is 73. 16، 55. 93، 41. 32، 30. 45 mg/l and the toxicity unit values are 1. 36، 1. 78، 2. 42، and 3. 28، respectively. the results generally indicated that toxicity increased in process and over time and showed that Reactive Red 120 after UV/ ZnO process was toxic to Daphnia magna.

This study was conducted to investigate the toxicity of Titanium Oxide (TiO2) and Zinc Oxide (ZnO) nanoparticles as two of most widely used nanoparticles. The result of this study can help to designing environmental standard and legislations for nanoparticles. Different concentrations of nano ZnO and TiO2 nanoparticles were added to nutrient Agar culture media. Then, definite numbers of Escherichia coli and Staphylococcus aureus bacteria were added to culture media and inhibition of these bacteria growth was measured in comparison to controls. Obtained data were analyzed to determine nanoparticles’ EC50 and NOEC (No Observed Effect Concentration) using SPSS ver.16 and Probit standard test. 24-hours EC50 of nano ZnO using E. coli and S. aureus determined to be 5.47 mg/L and 2.38 mg/L respectively. In addition, 24-hours EC50 of nano TiO2 using E. coli and S. aureus determined to be 5366 mg/L and 3471 mg/L respectively. In the case of ZnO nanoparticles, no observed effect concentration determined to be 1.15 and 3.28 mg/L for E. coli and S. aureus respectively and in the case of TiO2 nanoparticles no observed effect level determined to be 1937 and 1184 mg/L for E. coli and S. aureus respectively. This study showed that acute toxicity of nano ZnO is by farmore than that of nano TiO2. Regarding the EPA acute toxicity criteria, nano ZnO is categorized as moderately toxic and nano TiO2 is categorized as practically non toxic. Hence, regarding the acute toxicity, in recommending exposure criteria and environmental disposal standards, compared to nano TiO2, nano ZnO requires more attention.

Specific and unique characteristics of nanoparticles may entail specific and unique hazards. In addition, they may also exhibit toxicity under certain conditions. This study was conducted to investigate the toxicity of phenol-exposed and phenol-unexposed nano-TiO2 and nano-Fe/TiO2 particles. Stock solutions of the afore-mentioned nanoparticles were prepared at different concentrations and a sample of each was exposed to phenol. This was followed by exposing Daphnia Magna to the phenol- and non-phenol-exposed nanoparticles. LC50, NOEC and the concentrations at which mortality rates were 100% were determined 12 to 96 hours after exposure, while for the determination of the mortality rate of Daphnia the Probit model in SPSS version16 software was used. The results revealed that (1). The 48-hr LC50 values for phenol-unexposed nano-TiO2 and nano-Fe/TiO2 particles were 2705 and over 15000 mg/m3, respectively. The corresponding values for the phenol-exposed samples were 414 and 1253. (2). The 48-hr NOEC values for the phenol-exposed TiO2 and FeTiO2 were 41 and 789, respectively, the corresponding values for unexposed samples being 1253 and over 15000 mg/m3. (3). In addition, the 48-hr 100% mortality rates for phenol-unexposed nano-TiO2 and nano-Fe/TiO2 particles were, respectively, 1253 and over 15000 mg/m3, while for the phenol-exposed samples the corresponding rates were 1090 and over 2108. With regard to 48-hr LC50, the findings show that the toxicity of both nano-Fe: TiO2 and TiO2 increases as a result of exposure to phenol, the increase being 12-fold for the former and 6.5-fold for the latter. In general, however, based on LC50, it can be said that the toxicity of Fe:TiO2 nanoparticles, which has better catalytic characteristics, is lower in comparison to TiO2 nanoparticles. Thus, using Fe:TiO2 in preference to pure TiO2 should be investigated further, as it will be less hazardous to the environment.