ماندانا زارعی

The aimes of the present work were to investigate the effect of active oxygen, produced by using cold plasma sterilizer, on the concentration of Hydrogen sulfide, Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Total suspended solids, temperature and pH in wastewater of 6th, 7th and 8th refineries of the South Pars Gas Complex (SPGC) and Mobin Petrochemical Company, also to calculate the removal efficiency and removal optimum time of the studied parameters. Sampling from the studied areas had been carried out in May 2012 and the parameters were analyzed in the laboratory of 7th Refinery of South Pars Gas Complex. On the basis of the results: The negative and strong correlations were observed between active oxygen with concentrations of COD, H2S and TSS in wastewater of 6th, 7th and 8th SPGC refineries and Mobin Petrochemical Company. It means that by increasing the concentration of active oxygen, the concentration of above parameters reduced in the treated wastewater. The negative and strong correlation were observed between active oxygen with BOD5 and pH in wastewaters of 7th SPGC Refinery and Mobin Petrochemical Company, and the moderate and positive relationship were observed between these variables in wastewaters of 6th and 8th SPGC refineries. It means that by increasing the concentration of active oxygen, the BOD5 and pH amounts reduced in the treated wastewaters of 7th SPGC Refinery and Mobin Petrochemical Company, while that these parametes increased in the treated wastewaters of 6th and 8th SPGC refineries. Despite the initial rise in the temperature of exposured wastewaters of 7th SPGC Refinery and Mobin Petrochemical Company, the overall wastewaters temperature are reduced by increasing the exposure time of wastewaters to the active oxygen. The lowest amount of BOD5, H2S and TSS in the treated wastewaters were less than the Iranian Environmental Protection Organization (EPO) regulations for discharge limit into surface water, while the amou