---

Background & Objectives: Cyanide is a very hazardous compound that enters into the environment by different industries. In this study performance of Electrofenton process (EFP) for elimination of cyanide from aquatic environment in presence of humic Acid as an interfering compound was evaluated. Methods: In this experimental study, at every step of experiment, 1000 mL of cyanide solution with known concentrations was added to a reactor. The effects of selected parameters such as pH (3-10), reaction time (5-20 min) cyanide concentrations (100–1000 mg/l), voltage (10-30V), hydrogen peroxide concentrations (5-50 ml/lit), and humic acid levels (25-100 mg/L) on cyanide removal were investigated. Results: The results showed that efficiency of EFT process decreased with increasing pH, concentrations of cyanide and humic acid and increased with increasing voltage and hydrogen peroxide levels. The efficiency of 72% was achieved for EFP process in optimum conditions of pH = 3, initial concentration of cyanide = 100 mg/lit, hydrogen peroxide level = 25 ml/lit, voltage = 30V, and humic acid concentration = 25 mg/lit. In the same conditions, however, EFP efficiency was 96% in the absence of humic acid Conclusion: The overall results show that this process has high ability on removal of cyanide. This process was influenced by the parameters studied and the removal efficiency was varied with variation of each parameter.

---

Background & Objectives: The presence of phenol in effluents may cause risk to human health. By Taguchi statistical model, the process can be optimized by certain number of experiments. The aim of this study was optimization of catalytic ozonation process in removal of phenol from aqueous environments by Nano Fe / MgO with Taguchi statistical model. Methods: In this experimental study, experiment design was set based on the statistical model. Parameters such as pH (3, 5, 9, and 11), initial concentration of pollutant (500, 1000, 1500, and 2000 mg/L), reaction time (10, 20, 30, and 40 min) and catalytic dose (0.1, 0.2, 0.3 and 0.4 g/L) in 4 layers and 4 levels were investigated. Data were analyzed with Minitab ver.16 software. Residual concentration of phenol was measured according to standard method book. Results: The results showed that, efficiency of phenol removal depends on various operational parameters. The optimum conditions of phenol removal was obtained at reaction time=30 min, pH=5, the phenol initial concentration of 1000 mg/L and catalyst dose of 0.1 g/L. Among the factors investigated initial concentration of phenol has the maximum effect (69.5%) and reaction time the minimum (3.2%) effect in optimum conditions. S/N ratio of 39.39 was estimated at optimum conditions. Conclusions: By using Taguchi statistical model, phenol removal was optimized in certain number of experiments. Ozonation process has high capability in phenol removal.

---

Background & objectives: Conventional methods are not an efficient method in the removal of resistant organic pollution. Ozone molecules in the presence of anion persulfate can be used as an appropriate method for the removal of these pollutants. The aim of this study is to determine the efficiency of the combined process of ozone and radical sulfate in decomposition of SDBS and reduce the concentration of this pollutant in aqueous.
Methods: In this experimental study, use of semi-batch reactor by one liter volume was used semi-continuously. The effect of pH (3-11), concentration of persulfate (10-100 mM/L), concentration of O₃ (1-5 mg/L.hr) and initial concentration of SDBS (10-100 mg/L) were investigated. The kinetics of the reaction, effect of radical scavenger and COD removal in the proper conditions of the process was determined. The concentration of SDBS and COD were measured using a standard reference method.
Results: The efficiency of process in 40 minute was more than 97 percent while the process parameters were pH=3, initial concentration of SDBS was 10 mg/L, concentration of O₃ was 5 mg/L.hr and persulfate anions was 20 mM/L. By changing the parameters and the presence of radical scavenger, process efficiency decreased. The efficiency of COD removal in 70 minutes was 80 percent. The reaction kinetic followed by first order kinetic.
Conclusion: The ozonation process in the presence of persulfate anion due to the production of active persulfate radical can be suitable method for the removal of POPs such as SDBS. By this method, it is possible to increase the treatment of the wastewater containing this pollutant and reduce the organic loading to environment.