Holistic Approach to Process Design and Scale-Up for Itaconic Acid Production from Crude Substrates

Abstract

Bio-based bulk chemicals such as carboxylic acids continue to struggle to compete with their fossil counterparts on an economic basis. One possibility to improve the economic feasibility is the use of crude substrates in biorefineries. However, impurities in these substrates pose challenges in fermentation and purification, requiring interdisciplinary research. This work demonstrates a holistic approach to biorefinery process development, using itaconic acid production on thick juice based on sugar beets with Ustilago sp. as an example. A conceptual process design with data from artificially prepared solutions and literature data from fermentation on glucose guides the simultaneous development of the upstream and downstream processes up to a 100 L scale. Techno-economic analysis reveals substrate consumption as the main constituent of production costs and therefore, the product yield is the driver of process economics. Aligning pH-adjusting agents in the fermentation and the downstream process is a central lever for product recovery. Experiments show that fermentation can be transferred from glucose to thick juice by changing the feeding profile. In downstream processing, an additional decolorization step is necessary to remove impurities accompanying the crude substrate. Moreover, we observe an increased use of pH-adjusting agents compared to process simulations.

Balancing pH and Yield: Exploring Itaconic Acid Production in Ustilago cynodontis from an Economic Perspective

“…The outstanding fermentation yield at pH 3.6 cuts costs signi cantly while speci c operational costs are visibly larger at high and low pH values due to the poor substrate to product conversion. This cannot be outweighed by higher DSP yields as at lower pH as discussed in Saur et al (14). The speci c operational costs of approximately 1.04 EUR kg − 1 at pH 3.6 achieved in this work are approximately 0.40 EUR kg − 1 lower than those previously obtained for this strain (14).…”

“…Consequently, U. cynodontis ITA MAX pH was identi ed as a preferable candidate for subsequent characterization. If itaconic acid is to become a bulk chemical, yield is one of the most relevant production parameter because substrate cost is a decisive price-determining factor (14). The availability of nitrogen and the resulting C/N ratio offer a dimension to optimize the product to substrate yield by controlling the biomass density.…”

“…Therefore, we focus on Ustilago, which with its stable yeast-like morphology, may enable such further e ciency gains in scaled up fermentation processes by providing greater degrees of freedom in handling of the fermentation broth (11,12). These gains may be further boosted by utilizing untreated industrial feedstocks (13), as the substrate cost remains a critical factor in itaconic acid production (14). Moreover, the long history of safe use and lower biosafety level of Ustilago simpli es the itaconic acid production process in Europe compared to A. terreus.…”

“…Most of the itaconic acid puri cation techniques require the free acid. Therefore, the fully protonated state is required to obtain high yields during DSP (14,21,(23)(24)(25)(26). As a result, the pH needs to be lowered after fermentation by acid addition.…”

Dynamic Modeling of a Liquid–Liquid Extraction Column─An Industrial Approach

“…Liquid–liquid extraction is a thermal separation technology that is used for the separation of temperature-sensitive multicomponent systems such as the purification of desired biomolecules, for the separation of rare earth in the mining industry, for the separation of mixtures with a very low or very high boiling point or an azeotrope leading to an energy-saving process compared to a process solely based on distillation, or for the separation of a target component (TC) of low concentration in an (aqueous) feed …”