Mehdi Ahmadi - Environmental Technologies Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran- Department of Environmental Health Engineering, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
Zahra Tamimi - Department of Environmental Sciences, Ahvaz Science and Research Branch, Islamic Azad University, Ahvaz, Iran
Nemat Jaafarzadeh - Environmental Technologies Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran- Department of Environmental Health Engineering, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
pari Teymouri - Environmental Health Research Center, Kurdistan University of Medical Sciences, Sanandaj, Iran- Department of Environmental Health Engineering, Kurdistan University of Medical Sciences, Sanandaj, Iran

Background & Aims of the Study: Industrial wastewater sludges must be disposed in a safeway because they have hazardous effects on the human and environment. The aim of thisstudy is to investigate the physicochemical characteristics and disposal options of sludgesfrom oil-water separator (OWS) and dissolved air flotation (DAF) clarifier of a Refinerywastewater treatment plant.Materials & Methods: Sludge samples were collected in grab sampling manner, in 6month (April-September 2013) in order to be analyzed for their physicochemicalcharacteristics. Kolmogorov-Smirnov Z, independent t-test, Mann-Whitney U test, onesample t-test and Wilcoxon signed rank test were used for statistical analysis. Canadian SoilQuality Guidelines (CSQG) and Florida Department of Environmental Protection SoilCleanup Target Levels (FDEPSCTLs) were used to discuss the disposal fate of thegenerated sludge.Results: As, Cd, Cu, Pb and Se were not detected in the studied sludge. As compared withCSQG, the investigated sludge were polluted for residential/parkland, agricultural,commercial and industrial applications, because they contained high concentrations of Cr,Ni and Zn. Also, according to FDEPSCTLs, the studied sludges were not suitable forresidential and non-residential applications due to their high Al and Ni contents. DAFsludge had a high Zn concentration for residential application, too.Conclusions: present sludge management in the studied plant needs to be revised becausemetals’ concentrations are above the international standards and guidelines.

Disposal, Dissolved airflotation, Oil refinery, Oilwaterseparator, Sludge,Iran