Recovery of Salts from Synthetic Erythritol Culture Broth via Electrodialysis: An Alternative Strategy from the Bin to the Loop

Laura Daza-Serna,Robert Ludwig Mach,Norbert Kreuzinger,Jörg Krampe,Anton Friedl,Katarina Knežević,Astrid Rosa Mach-Aigner

doi:10.3390/su14020734

Abstract

Sustainability and circularity are currently two relevant drivers in the development and optimisation of industrial processes. This study assessed the use of electrodialysis (ED) to purify synthetic erythritol culture broth and for the recovery of the salts in solution, for minimising the generation of waste by representing an efficient alternative to remove ions, ensuring their recovery process contributing to reaching cleaner standards in erythritol production. Removal and recovery of ions was evaluated for synthetic erythritol culture broth at three different levels of complexity using a stepwise voltage in the experimental settings. ED was demonstrated to be a potential technology removing between 91.7–99.0% of ions from the synthetic culture broth, with 49–54% current efficiency. Besides this, further recovery of ions into the concentrated fraction was accomplished. The anions and cations were recovered in a second fraction reaching concentration factors between 1.5 to 2.5 times while observing low level of erythritol losses (<2%), with an energy consumption of 4.10 kWh/m3.

Highlights

Erythritol is a four-carbon polyol used for foods, pharmaceutical and cosmetic products manufacture, among others [1,2,3,4,5]
Electrodialysis proved to be a suitable alternative to remove and recover salts from synthetic culture broth (SCB) solution, obtaining a remarkable desalination of 96%, comparable with values reported in the literature
The ion-removal rates followed the same trends in the three solutions (S, SP, and SCB), suggesting that ion selectivity and mobility are influenced by interactions between the species in solution and the groups attached to the membrane

Summary

Introduction

Erythritol is a four-carbon polyol used for foods, pharmaceutical and cosmetic products manufacture, among others [1,2,3,4,5]. The growth and metabolism of microorganisms are affected by osmotic stress modulated by salts, polyethyleneglycol, and carbon source addition [12,13,14,15]. At high osmotic pressure conditions, the growth rate decreases, while osmotolerant erythritol-producing microorganisms favour erythritol production and accumulation as a protective response to hyperosmotic conditions [16,17,18]. The effect of the hyperosmotic conditions by adding salts has been studied in the production of erythritol using NaCl and KCl as osmotic agents in concentration levels up to 50 g/L increasing the concentration of erythritol up to 50% compared to the control without the addition of salt [17,18,19,20,21]

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