Pretreatment of Wastewater Streams from Petroleum/Petrochemical Industries Using Coagulation

Abstract

Coagulation-flocculation processes using different types of conventional coagulants, namely, ferric chloride (FeCl<sub>3</sub>), aluminum sulfate (AL<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>·18H<sub>2</sub>O), lime and ferrous sulfate (FeSO<sub>4</sub>) were investigated using the Jar-test technique. A further aim is to determine the optimum conditions for the treatment of industrial wastewater effluents i.e. coagulant dosage, mixing rate, temperature and pH control. Under optimal condition of process parameters, coagulation/flocculation process was able to lower the turbidity well below the permissible level (1.8 NTU). The results indicate that ferric chloride had superior efficiency compared with other coagulants with efficient dose of 800 mg/l. The optimal initial pH of the effluents that enhanced the turbidity removal was 8.6. The temperature showed no significant effect on the turbidity removal

Optimization of Fenton-based treatment of petroleum refinery wastewater with scrap iron using response surface methodology

“…At the end of the reaction time (90 min), oxidation was terminated by adjusting pH to 8.5. This pH value also falls within the optimum range for the coagulation process reported by many researchers (Altaher et al 2011;Tchobanoglous et al 2003;Yoon et al 2002). Hydrogen peroxide breaks down into oxygen and water at pH values above 7.0 (Kallel et al 2009).…”

“…While in most of literatures the precipitation of iron ions has just been considered as a stage to remove them from the solution and terminate the oxidation, it can be exploited as a post-coagulation process to enhance the overall treatment efficiency. Hydrolyzed metal ions in the solution can act as coagulants by neutralizing charge of colloidal particles (adsorption of metal ions onto the surface particles) and promoting them to agglomerate, or by bridging between two or more particles, which eventually leads to settling of the flocs; nevertheless, the dominant removal mechanism in the post-coagulation process is enmeshment of colloidal particles by sweeping flocs of metal hydroxide (Tchobanoglous et al 2003;Altaher et al 2011). This mechanism may occur due to the precipitation of iron hydroxides by modulating pH to 8.5 to terminate the Fenton reactions.…”

“…Efficiency of this process depends on the formation and precipitation of iron hydroxide flocs. The solubility of Fe(OH) 3 is a function of pH and the optimum pH range for the sweep floc mechanism is between 7.0 and 9.0 (Tchobanoglous et al 2003;Altaher et al 2011;Yoon et al 2002). In this study, the post-coagulation process was investigated using 1.7 g/L iron (optimal concentration for the Fenton process) without introduction of H 2 O 2 (the other experimental conditions were the same of those used for the Fenton process).…”

Treatment of petroleum wastewater by conventional and new technologies A review

“…Wagner and Nicell (2001) revealed that subsequent coagulation/H2O2 removed 58% of COD and 78% of BOD5 from petroleum refinery wastewater. Altaher et al, (2011) used coagulation for pre-treatment of petroleum and petrochemical wastewater. Their results indicated that the alum was more removal efficiency of COD than ferric chloride (FeCl3) and promoted turbidity removal when the pH increased from an acidic range to an alkaline range.…”

Response Surface Methodology optimization of chito-protein synthesized from crab shell in treatment of abattoir wastewater

“…Wastewater from abattoir is categorized under strong wastewater, since it possesses high concentrations of suspended solids, BOD, COD, soluble and insoluble organics. Wastewater putrefies fast, and is highly proteineous, this leads to environmental pollution problems ( Altaher et al., 2011 ). Other characteristics of abattoir wastewater is the presence of suspended solids due to rumen contents, high volume of blood from the animals slaughtered, undigested food, flesh pieces, feathers, and pieces of bone.…”