[Survey of efficiency of electrochemical treatment in cyanid removal from industrial wastewaters]

Cyanide is a highly toxic compound which is Normally found in numerous industries, such as electroplating wastewater. Release of this compounds in to the Enviroment has a lot health hazards.The Purpose of this study is to Determine the efficiency of electrochemical oxidation method for Cyanide removal from industrial wastewaters. This study conducted in a pilot system experimentally .In this study the effect of pH, voltage and operation time on total cyanide removal from industrial wastewaters by Electrochemical Oxidation was investigated by applying a Stainless Steel as a Anode and copper as a cathode. The average percentage removal of cyanide was about 88 with SD=2.43. The optimal condition obtained at voltage of 9V and pH=13 and The operation time of 90 minutes. The volume of sludge which formed in this condition was about 20 percent of a one liter pilot reactor. The results statistically confirmed the significant relationship between input and cyanide concentration removal efficiency [p< 0.05], and confirmed The this confirmed The relation between cyanide and cyanat oxidation and hydroxyl ions consumption 1:2.[L.Szpyruowicz]. therefore the best pH is 12.5-13.5 by Considering the need of alkaline environment to remove cyanide

[Survey of crude oil toxicity component removal by adsorbtion with powdered activated carbon]

Background and aims: Crude oil is very complex composition with harmful effect in human health, such as carcinogenesis and blood dyscrasia. Because of the entry of relatively high volume of these compounds in aquatic environments, effective controlling is very important. The aim of this study was to investigate the effect of powdered activated carbon [PAC] for reducing the toxicity of crude oil in water

Methods: Water soluble fraction standard samples were prepared with one part crude oil in 9 part water. For toxicity test, different concentrations of crude oil water soluble fraction in water and larvae of rainbow trout were used. Before and after the addition of 10, 20, 40 and 60 mg/l powdered activated carbon, TOC and bioassay tests were performed. LC50 and evaluation of results was done with probit statistic program

Results: LC50 for samples 24, 48, 96 hrs after addition of different concentration of PAC were 94.8, 106.6, 117.8, 138.3 and 181.5 mg/l. Values of TOC for these samples was 44.81, 43.88, 38.16, 36.62 and 35.14 mg/l

Conclusion: The use of activated carbon reduced toxicity and TOC. With increase in the concentration of activated carbon, toxicity was decreased, but intensity of TOC removal wasn't similar to toxicity removal. Using of powdered activated carbon for treatment, in case of accidents and entering crude oil in drinking water supplies, can be considered