Enhancing filterability of activated sludge by DC electric field

The purpose of the current study is to enhance filterability of activated sludge by applying controlled DC electric field via perforated aluminum electrodes while providing an ineffective electric current on bacterial life. The studies were conducted in a 12 L laboratory scale cylindrical reactor. Recirculated activated sludge was provided from a full scale advanced biological wastewater treatment plant. The effects of exposure time (2, 5, 10, 15, and 30 min) and potential gradient (0.2, 0.5, 0.8, and 1 V/cm) are evaluated mainly by the results of specific resistance to filtration (SRF). The results also supported with variations in physical (pH, oxidation-reduction potential (ORP), and temperature) and soluble biochemical (chemical oxygen demand (COD), orthophosphate (PO4-P), and ammonia nitrogen (NH3-N)) properties of activated sludge. Electrical parameters (current density, energy consumption, and theoretical aluminum consumption) were studied to evaluate the most cost effective DC field vs. exposure time variation. Based on SRF experiments, energy consumption, and theoretical aluminum generation, optimal condition for enhancing filterability is recommended as 0.2 V/cm potential gradient applied for 5 min.