Alborz University

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Background and Objectives: Cyanide is a toxic pollutant that is can be discharged from different industries such as iron and steel industry, coal mining and metal plating. Presence of this toxin in water and wastewater is a serious hazard and lead to undesirable effects on both the environment and human. Thus, its concentration control is essential for human health. The aim of this study was investigation of Cyanide Removal from aqueous solution using precipitation process (FeCl3). Material and Methods: This study is an experimental study in lab scale that was carried out in a batch system by jartest. Variations of this study including pH, FeCl3 concentration, reaction time and desired concentration of cyanide were investigated. Data were analyzed using Excel (version 2007) software. Results: The results of this research were showed that Cyanide with initial concentration of 10 mg/l in precipitation process was removed by 40% (conditions pH=90, FeCl3=0.4 g/l and the time 60 minutes). Also, the precipitation process efficiency to cyanide removal decreased of 40 to 23%, by increasing of the initial cyanide concentration of 10 to 15 mg/l. Conclusion: Precipitation process can be considered as a suitable alternative for recovery of cyanide to be re-used. Although, this process has limitations for treat total cyanide to environmental standards level. So, it is better be used in combination with other processes of these contaminants removal.

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Background: Coagulation process has a important place in water treatment. Currently, poly aluminum chloride is used in Kian-abad water treatment plant. The purpose of this study is to compare and investigate the efficiency of coagulants of poly ferric sulfate(PFS) against poly aluminum chloride (PAL) in removing turbidity and coliform bacteria in Ahwaz water treatment plant.

Methods: This study, was performed in lab scale and using of jartest apparatus in Ahwaz water treatment. Experiments was conducted in 35NTU turbidity in Ahwaz water treatment plant. The studied parameters included concentrations of coagulants, pH, turbidity, total coliform, fecal coliform and heterotrophic bacteria.

Results: The most optimal efficiency conditions of poly aluminum chloride were pH=8, rapid mixing of 120rpm and optimal dose of 5ppm which was 93.14% in pH=8 and 93.80% for optimal dose of 5ppm. The most optimal condition for poly ferric sulfate included pH=8, rapid mixing of 120 rpm and optimal dose of 8ppm.

In optimal condition of performance for poly aluminum chloride, efficiency of removing total coliform, fecal coliform and heterotrophic bacteria were 90.12, 83.70, 84.08% respectively. In optimal condition of poly ferric sulfate in dose of 8ppm efficiency removing total coliform, fecal coliform, and heterotrophic bacteria were 90.48, 84.83, and 84.69.

Conclusion: Finally, there was small difference between both PFS and PAC group about turbidity removal efficiency that was not significant statistically.