Control of predators in industrial scale microalgae cultures with Pulsed Electric Fields

• We used Pulsed Electric Fields to control protozoan contamination in microalgae.
• The microalgae culture consisted of industrial 2.7 m3 microalgae photobioreactor.
• The treatment last 6 h with an average of 900 V/cm, 65 μs pulses of 50 Hz.
• Results show a 100 % reduction of the active protozoan population after few days.
• The microalgae growth rate remained unaffected.

This work describes the utilization of Pulsed Electric Fields to control the protozoan contamination of a microalgae culture, in an industrial 2.7 m3 microalgae photobioreactor. The contaminated culture was treated with Pulsed Electric Fields, PEF, for 6 h with an average of 900 V/cm, 65 μs pulses of 50 Hz. Working with recirculation, all the culture was uniformly exposed to the PEF throughout the assay. The development of the microalgae and protozoan populations was followed and the results showed that PEF is effective on the selective elimination of protozoa from microalgae cultures, inflicting on the protozoa growth halt, death or cell rupture, without affecting microalgae productivity. Specifically, the results show a reduction of the active protozoan population of 87% after 6 h treatment and 100% after few days of normal cultivation regime. At the same time, microalgae growth rate remained unaffected.