Removal of Some Hydrocarbon Pollutants from Baiji Oil Refinery Wastewater Using Granular Activated Carbon Column

Abstract

Petrochemical industry, specially oil refineries produces large quantities of wastewater that isstrongly polluted with hydrocarbon compounds. Although Baiji oil refinery has wastewatertreatment plant, it discharges water to Tigris river that is strongly polluted with hydrocarboncompounds that exceed the Iraqi permissible limits. Thus the aim of the present work is toremove phenol, parachlorophenol, and benzene from the wastewater of Baiji oil refinery usinggranular activated carbon(GAC)column. A laboratory scale apparatus is designed andconstructed in order to perform this study taking into account the ability to control the mostimportant parameters affecting adsorption process. Actual wastewater samples taken from thefinal discharge point of wastewater treatment unit of Baiji oil refinery are used to conduct allexperiments.The results indicated that these pollutants could be removed completely. Moreover, it indicatesthat breakthrough and exhaustion time are directly proportional with GAC thickness and inverselyproportional with pollutants concentration and liquid hourly space velocity (LHSV). The resultsshow that maximum breakthrough time is 39.26, 21.35, and 16.58 hours at LHSV of 0.5 hr-1 and35cm of GAC thickness for phenol, parachlorophenol, and benzene respectively. Thecorresponding minimum breakthrough time is 9.24, 5.23, and 6.08 hours at LHSV of 129 hr-1.However, the corresponding maximum exhaustion time is 49.6, 48.7, and 43.84 hours, while theminimum exhaustion time are 27.5, 16.54, and 10.89 hours. The results show that breakthroughtime for phenol is 27.23 hours when the phenol inlet concentration is 5.212 mg/l, it decreased to13.83 hours at inlet phenol concentration of 19.31 mg/l. The corresponding exhaustion time is68.83 and 37.22 hours. Other two pollutants have similar trend. Based on the experimental data,dynamic adsorption capacities are calculated and found to be increased with the increase ofpollutants concentration and LHSV. It is also found that calculated adsorption zone thickness isproportional with LHSV. The calculated maximum dynamic carbon adsorption capacity are 115.4,67.62, and 12.628 mg/g for phenol, parachlorophenol, and benzene respectively at LHSV of 129hr-1. The corresponding minimum capacity at LHSV of 0.5 hr-1 are found to be 1, 0.99, and 0.257mg/g. Calculated values of minimum and maximum adsorption zone thickness for the threepollutants at LHSV of 0.5 and 129 hr-1 are (0.0729, 0.1965, and 0.2176) and (0.2324,0.2118,and 0.1545)cm respectively.Application of the most famous the adsorption models shows that only Freundlich model givesexcellent agreement with experimental data. Finally, new three models are developed. The firstand second relate breakthrough and exhaustion time with LHSV, wastewater pollutantsconcentration, and GAC thickness while the third relates adsorption velocity with LHSV and inletpollutant concentration.