Water Sterilization by Pulsed Electric Field – The Effects of Electric Field Strength over the Energy Consumption in Microsecond Pulses.

RODRIGUEZ OSUNA, ISAAC AARON; FERRARO N.; CABALEIRO J.M.; N. OLAIZ

CABA

Congreso; WCCE11 - 11th WORLD CONGRESS OF CHEMICAL ENGINEERING; 2023

The lack of drinking water for the future is considered a major global problem that threatens people's well-being, actually,1 out of 3 people in the world does not have access to drinking water [1]. It is universally known that large-scale watertreatment is carried out in large industrial plants with considerable investment and operating costs [2], as well asprocesses involving chemical reagents that can be harmful in the long term for a large number of people and in the shortterm for a few others [3]. In this last aspect, pulsed electric field technology acquires special relevance as it is a purelyphysical phenomenon. For this reason, it is necessary to develop new low-cost technologies and optimized energyconsumption (around 250-500 J/g) that allows reducing the bacterial load of water effluents. The application of electricfields in food pasteurization is widely known [4], for this reason, this work focuses on the sterilization of water bodiesthrough a low-cost and easily scalable microfluidic device with the objective of studying the amount of energy neededto achieve the sterilization (reduce 6 Log).The objective is to study the amount of energy needed to achieve the sterilization (reduce 6 Log) [5], for different electricfield strengths (4 – 6 – 8 kV/cm) with low voltage pulses (200-400V), into a low-cost microfluidic device, manufacturewith polymethylmethacrylate (PMMA) and Stainless steel 316L such electrodes with 500um of gap. We used aninoculum of Saccharomyces cerevisiae (as sterilization market) with a concentration >1x106 CFU/mL into a suspensionof physiological solution (NaCl 0.09 mg/L). The suspension was feed to the chamber with different flow rates (23 – 200– 700 μL/min) and applied pulsed electric field of short duration (10 us) with different frequencies (1Hz – 3kHz) toguarantee the amount of energy constant. The pulses waveform voltage and the current was monitored online by RigolMS08204 2GHz Oscilloscope and Generated by Einsted S.A Micropulse generator. The treated samples were collectedin laminar flow (Biotraza CJ-600p) and subsequently seeded in Petri dishes with 50 μL. The incubation period was 72Hr for the measurement of the colonies with Image method.The results show that when increase the electric field strength the amount of energy necessary to reduce 6 log decrease,but for another hand the effect of electrolysis and spark generation increase due the pulse duration [6], both effectsreduce the life time of the device and increase the amount of the consumption of energy. We recommend reduce thepulse duration in order to increase the electric field strength and avoid the bubble generation and the spark formation