Treating Efficiency Of ASP Flooding Produced Wasterwater And Oily Sludge By Ultrasound Enhancement Process

The produced water from ASP(Alkali,Surfactant and Polymer) flooding oil recovery process contained polymer, surfactant and alkali, which was hard to be removed by the traditional treatment process. Furthermore, lots of flocculants were added during the ASP process, which produced a large amount of refractory oily sludge.Compared with produced water from polymer process, the produced water from ASP process has several different characteristics: Firstly, it had higher suspended solids(SS) concentration due to the dissolution of clay mineral; secondly, it had higher viscosity because of the presence of polymer residues, which made the separation of oil and water even harder; In addition, the surfacta nts in effluent hinders the demulsification and flocculation process. Thus, the traditional process failed to treat the ASP effluent effectively, which reduced the coalescence demulsification efficiency and lost the filter material.In a new laboratory study, the inorganic PFS and organic UT-4 were chosen as the flocculant to treat the ASP effluent at the proportion of 500:40. The degradation of polymer by using ultrasonic enhanced O3 oxidation was also performed in(40k Hz+28k Hz+20k Hz) three orthogonal field with the intensity of 1.5w/m2 and the addition of 7.5mg/L O3 for 15 min. The variance ratio of dynamic viscosity could attain 86.1%. The competition effect in the degradation process was found between the polymer and oil, thus the oil concentration in the effluent could be controlled below 100mg/L after the treatment.The process for treating the ASP effluent was consisted by coagulation sedimentation, coalescence oil removal device, ultrasonic enhanced O3 oxidation degradation of polymer and two stage filtration. Among them, the novel coalescence oil removal device and filter were developed to enhance the treating efficiency. Based on the theoretical calculation, the two-way coalescence oil removal equipment was also designed by optimizing coalescence mate rial, improving the internal structure and setting up the backwashing system. The double-layer stir filter was developed by using the agitator structure to break the material with the application of ultrasonic enhanced O3 oxidation degradation of polymer to reduce viscosity.After the treatment, the oil and SS in the effluent was decreased from 847.24mg/L and 159.06 mg/L to 5.01 mg/L and 9.93 mg/L. The oil and SS removal rate reached 99.39% and 93.21%, respectively. The treatment cost of new process was reduced by 1/3 than the traditional process.The excess sludge produced during the ASP process had high oil content,which was mostly heavy oil. The inorganic impurities in sludge were mainly composed by Fe and Al from the flocculation components, which emul sified the oil and made it difficult to separate from sludge. To meet the oil sludge recycle standard(oil concentration <2%), the detergents of sodium silicate and sodium dodecyl sulfate with hot water, as well as the ultrasonic demulsification device were applied for the removal of oil from sludge. The oil sludge were firstly treated by the thermal chemical cleaning process for 40 min, cleaning agent dosage was 1%, water temperature was 60℃. After that, the ultrasonic treatment process was conducted for 20 min. For separating the water from sludge, a centrifuge device was applied with the addition of 10 mg/L demulsifier and 2% flocculation dose, the centrifuge speed was 2500 r/min. After the treatment, the oil and water content in the sludge was less than 2% and 80%, respectively.The reuse of sludge residue by producing bricks was also studied in this work. The proportion of sludge, cement, fly ash, bentonite and ion addition was 1:0.2:0.3:0.3:0.005. After immobilization, the strength of the product was 3.89 Mpa, which met the concrete pavement standard. After 120 h leaching, the oil content in the leaching liquid was lower than 3 mg/L, no poisonous and harmful material were detected.The novel treatment process of ASP produced water based on ultrasonic techniques could attain promising efficiency and the water quality could meet the reinjection water standard. The oil in excess sludge could also be removed by the high temperature cleaning-ultrasonic process, the oil concentration in sludge residue was lower than 2% after treatment. The sludge residues were further reused for the brick production by using immobilized technology. In general, the effluent and excess sludge of the ASP process could be treated effectively, which facilitated the application of ASP flooding oil recovery technology.