Self-cleaning filtration with spark discharge in produced water

• High-voltage plasma spark discharge generated powerful shock waves in produced water.
• Spark discharge prevented suspended particles from being accumulated on filter surface.
• Spark discharge kept filter surface clean over time.
• Pressure drops across filter surface were significantly less with spark compared to those without spark.
• Co-axial electrode was developed to generate spark discharges in water.

The objective of the present study was to investigate the feasibility of using spark type plasma discharges to provide a self-cleaning effect for filtration of produced water. A new co-axial electrode system was developed for the generation of spark discharges in high-conductivity produced water. The validation experiment was conducted with the spark-assisted self-cleaning (SASC) filtration system in both synthetic produced water and actual produced water at different total dissolved solids (TDS) and total suspended solids (TSS) levels and at three different flow rates of 0.126, 0.315, and 0.631 L/s (i.e., 2, 5 and 10 gpm). The pressure drop across the filter surface was measured over time. The pressure drop obtained without spark discharges increased consistently over time, often resulting in pump failure due to excessive pressure buildup at the pump. The pressure drop obtained with spark discharges was significantly smaller than those obtained without spark discharges. The present study sufficiently demonstrated the validity of the SASC filtration concept. The range of water properties that were shown to be treatable with the SASC filtration system using 10-in cartridge filter of 3- and 5-micron pores was TDS level ⩽50,000 mg/L and TSS level ⩽2500 mg/L.