ABSTRACT
Drilling fluids are essential operating additives for extracting oil and shale gas. Thus, their pollution control and recycling utilization are significant to petrochemical development. Vacuum distillation technology was used in this research to handle waste oil-based drilling fluids and achieve reutilization. Briefly, recycled oil and recovered solids can be obtained from waste oil-based drilling fluids whose density is 1.24-1.37 g/cm3 by vacuum distillation under the condition of an external heat transfer oil temperature of 270 ± 5 °C and a reaction pressure below 5 × 103 Pa. Meanwhile, recycled oil has excellent apparent viscosity (AV, 21 mPa·s) and plastic viscosity (PV, 14 mPa·s), which could be used as a substitute for 3# white oil. Furthermore, PF-ECOSEAL prepared by recycled solids exhibited better rheological properties (27.5 mPa·s AV, 18.5 mPa·s PV, and 9 Pa yield point) and plugging performance (32 mL V0, 1.90 mL/min1/2Vsf) than drilling fluids prepared with the conventional plugging agent PF-LPF. Our work confirmed that vacuum distillation is a valid technology in innocuity treatment and resource utilization of drilling fluids and has great value in industrial applications.
ABSTRACT
Source-separated urine has been regarded as a precious treasure on account of its rich nitrogen content and is suitable for fertilizer production. In this study, a novel bioelectrical coupling with hydrophobic gas permeable tube system (BGTS) was developed to treat urine, for removing organic matter, and recover nitrogen as value-added products in the form of nitrogen fertilizer. In the presence of the electric field, the hydrolysis process of urea in the anode chamber was accelerated, and the NH4+ driven by electric field force and concentration difference reached the cathode through the cation exchange membrane. The cathode made use of oxygen and electrons to produce alkali in situ to promote the conversion of NH4+ to NH3, which was straightforwardly absorbed in hydrophobic gas permeable tube circulating sulfuric acid solution, so as to promote the rapid migration of nitrogen and build an efficient dynamic recovery of nitrogen. After a 48-h cycle, the BGTS achieved a 95.28 ± 0.60% COD removal ratio, 91.60 ± 0.29% nitrogen recovery efficiency, and 3.48 kg m-3 ammonium sulfate fertilizer. Economic analysis indicated a profit of 5.75 $ associated with the utilization of the BGTS system for nitrogen fertilizer recovery from source separation in urine. Consequently, this study manifested that the BGTS system can recover nitrogen from human urine in a high-recovery and cost-effective way, and is of great significance in the sustainable recovery of nitrogen resources.