Journal of School of Public Health and

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Background and Aim: 2,4-Dichlorophenol (DCP) is a compound  generated in a variety of industrial processes and also by chlorine disinfection of water polluted with phenolic compounds . Dumping of DCP into the environment and water resources is of great concern because of the compound's intense odor and toxicity. DCP is very soluble and resistant to biodegradability so it cannot be removed through conventional water and wastewater treatment processes. On the other hand, pollution prevention (P₂) strategies have not been able to resolve the problem.

Material and methods: In this study, one of the AOP_S named Fenton was used for DCP degradation. The method is based on simultaneous use of hydrogen peroxide and ferrous sulfate.

Results: Results of treatment with hydrogen peroxide and ferrous ion (as Fenton reagent ingredients) indicate that by oxidation of 50 mg/L DCP at 60 minutes contact time with iron concentration kept at 15 mg/L and various concentrations of H₂O₂ (50 and 100 mg/L), the efficiency of COD(Chemical Oxygen Demand) reduction would go up from 65% to 80% with higher concentrations of H₂O₂. We also determined the effect of various concentrations of ferrous ion on DCP oxidation rate. The results showed the prominent role of this ion in DCP treatment: increasing Fe concentration from 5 to 15mg/L produced a 60% reduction in COD occurred in 10 and 60 minutes contact times. Another conclusion was that the oxidation of DCP solutions by Fenton had a major effect on biodegradability so that BOD: COD ratios of these solutions increased significantly after this oxidation.

Conclusion: Pretreatment of waste containing dichlorophenol by the Fenton reagent can enhance the biodegradability of this chemical and perhaps of similar compounds in a short time interval.

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Background and Aim: 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.
Materials and Methods: 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.
Results: 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.
Conclusion: 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.

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  Background and Aim: Chlorophenols are acidic Organic compounds and priority Pollutants. One of the best ways to removal chlorophenols was using different absorbents . In this study, removal efficiency of ortho- chlorophenol as one of the most common organic contaminants in aquatic environments was investigated with absorption method using activated Fly Ash.

  Materials and methods: In this experimental study, Fly ash of collected from Zarand Power plant was activated by sulfuric acid. Factors affecting in sorbent activation process including temperature, time, amount and concentration of the acid and also factors influencing in the adsorption process were adjusted for optimum conditions. Experiments was followed on real wastewater samples from coal washing plant of zarand . Data was analyzed by SPSS software.

  Results : The sorbent activation was performed in optimized condition acid concentration 1.8 mM, time 5h, temperature 29±2˚C and acid/fly ash ratio 7. Removal efficiency of zarand coal washing plant Effluent at the optimal conditions (pH: 2, adsorbent doze: 1g, time: 3h) was 84.4%.

  Conclusion: In addition to the high efficiency of ortho-chlorophenol absorption because of sorbent activation does not require complex and expensive technology, the adsorbents can be used to remove these contaminants from industry effluent.