Enhancing oil removal from wastewater by combining inclined plate settler and electrocoagulation

ABSTRACT

This work is aimed at developing a novel apparatus that combines inclined plate settler (IPS) and electrocoagulation (EC) to improve the emulsified oil removal efficiency with lower energy consumption. The combined process (IPS-EC) was optimized at various reactor configurations and electric field parameters of the EC process in dynamic oily wastewater treatment experiments. The results indicated that the effective removal of oil from wastewater was achieved due to the synergistic effect of EC and IPS at very low energy consumptions. The IPS could remove 74.1%±1.1% of the oil droplets from the oily wastewater. When an external pulsed direct current was applied to the metallic plates of IPS, the oil removal efficiency of IPS-EC increased to 97.0%±0.9% at a current density of 1 mA/cm², pulsed frequency of 2000 Hz, and duty ratio of 0.9. Uniform pitting corrosion occurred on the aluminum electrode surface in a pulsed direct current waveform, which favors mitigation of electrode passivation. The energy consumption of IPS-EC was recorded as 0.66 kW.h per kilogram of oil, which is much lower than the conventional EC. The results provide a basis for the treatment of highly emulsified oily wastewater using the IPS-EC method.

KEYWORDS:

• Oily wastewater
• electrocoagulation
• inclined palate settler
• pulsed direct current

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was supported by the SINOPEC Research Project (No. 320047), the Joint Fund of the Beijing Municipal Education Commission and Beijing Municipal Natural Science Foundation (No. KZ202010017026) and the National Natural Science Foundation of China (No. U20B2030).