(293e) Electrostatic Destabilization of W/O Microemulsions–Application to the Extraction of Phospholipids From Sludge In Wastewater Treatment

The destabilization of emulsions through the application of electrostatic coalescence is important in the petroleum industry to remove salts from crude.  The process consists on the application of high voltage, 13 kV - 20 kV, to break emulsion drops in short residence times.  The process could be used to separate microbial mixtures with high lipid contents from water, minimizing drying.  This study shows the application of electrostatic coalescence in the de-emulsification of water-in-organic solvent microemulsions (W/O emulsions) for the system lecithin + water + decane using a voltage of 3,000 V.  Lecithin was used as a surrogate of microbial cell membranes.  Water separation was evaluated from mixtures that contained lecithin and decane with 10 % to 20% (by weight) and 50 % to 70 % (by weight), respectively (balance being water).  Experimental tests were carried out in an electroporation apparatus with aluminum electrodes using 800-µL, rectangular cuvettes as the coalescence cell.  All tests were done by applying a voltage of 3,000 V to a stable emulsion in the cuvette.  Results showed that up to a 70 % of water separation could be achieved in 30 minutes.  Application of higher voltage could result in shorter times for breaking up the emulsion and possibly higher water-separation percentages.  This technology will be evaluated to separate microbial mixture (without drying) present in secondary sludge in wastewater treatment plants specifically grown for lipid accumulation.  The technology could be also of interest to separate lipids from lipid-rich microalgae, a process that faces similar challenges as those encounter in the case of sewage sludge.  The results of these evaluations will be discussed in the presentation.