Assessment of physical pre-treatments for the recovery of biosurfactants in corn steep water prior to advanced membrane-based water treatment

Abstract

The aim of this work is to evaluate different physical pre-treatments for corn steep water (CSW) to obtain a cleaner, concentrated water stream in biosurfactants for further advanced water treatment, involving not only the decontamination of water but also the complete recycling of CSW. Three physical treatments were tested: i) decantation, ii) centrifugation, and iii) vacuum filtration under different temperatures. After these pre-treatments, several parameters were evaluated. Results showed that centrifugation at 4 °C (C4L) is the best alternative for concentrating biocompounds as it produced a cleaner stream with a greater lightness (from 0.45 to 92.9–96.2) and lower turbidity than decantation or vacuum filtration but with a higher content in biosurfactants. Moreover, it was observed that acidification of C4L produced a decrease in the surface tension properties of CSW compatible with the precipitation and/or denaturalization of lipopeptides and proteins, whereas basification did not produce any relevant effect. Acidification or basification during pre-treatment of CSW was therefore dismissed with the recommendation of performing a simple centrifugation step at 4 °C as a pre-treatment, prior to recovering bioactive compounds using advanced membrane water treatments.