Electrochemically Induced Crystallization as a Sustainable Method for Product Recovery of Building Block Chemicals: Techno-Economic Evaluation of Fumaric Acid Separation

Abstract

Carboxylic acids are key platform chemicals for use as biobased alternatives for fossil-based applications. State-of-the-art fermentations of carboxylic acids at neutral pH with downstream product recovery by pH-shift crystallization are not sustainable due to the accompanied production of waste salts. To earn the label''sustainable,'' salts should be converted into the original base and acid required for fermentation and product recovery. This paper shows that electrochemically induced crystallization (EIC) integrated with fermentation reduces both capital and operating expenditures (CAPEX and OPEX, respectively). EIC is a novel process that utilizes electrolysis of water to induce localized pH-shift crystallization of the carboxylic acid, while neutral bulk conditions are maintained.In the current study, a techno-economic evaluation of the fermentative production of fumaric acid integrated with product removal by crystallization was performed. Three cases were evaluated, two based on classical pH-shift crystallization and one based on fermentation integrated with EIC. The first so-called base case produces a solid waste, while the second employs electrodialysis at the end of downstream processing to regenerate the waste salt and re-use the base and acid. With EIC, electrochemistry obviates the use of chemicals and hence solid waste cannot be formed. Cost estimates for EIC unit operation were based on the mass and energy balances of laboratory-scale experimental work and the resultant conceptual design. Assuming return on investment (ROI) of 15%, the first base case has the lowest required sales price of e2.2/kg fumaric acid (USD2.84/kg fumaric acid). EIC eliminates the necessity of water removal, hence reduces CAPEX and OPEX by 35% and 19%, respectively. Sensitivity analysis reveals that with an augmenting penalty on solid waste disposal (greater than e128/ton; USD164/ ton), EIC is the most economical option. This paper demonstrates that the integration of fermentation with product recovery improves the overall process economics and, by applying EIC, a more sustainable process is obtained.

Application of In Situ Product Crystallization and Related Techniques in Biocatalytic Processes

“…Nasrollahnejad et al continued this work with at echnoeconomic evaluation of the proposed process for the production of fumaric acid. [58] They compared conventional fermentativep roduction, production and subsequent salt regeneration, and productiont hrough electrochemically induced crystallization. The conventional methodr equired af inal pH shift to induce the crystallization of fumarica cid in the bulk phase, whichp roduced about 1.3 tons of solid waste per ton of product.…”

“…Nasrollahnejad et al. continued this work with a technoeconomic evaluation of the proposed process for the production of fumaric acid . They compared conventional fermentative production, production and subsequent salt regeneration, and production through electrochemically induced crystallization.…”

Evaluation of a Prototype for Electrochemical pH-Shift Crystallization of Succinic Acid

“…Furthermore, several works illustrate the synergies between electrified downstream processes and pH-control of fermentation processes [ 8 , 9 , 10 , 11 ]. However, these processes usually can not compete with conventional processes due to high operation costs or low stability of the membranes due to scaling or fouling [ 5 , 18 ]. In previous work, we showed that crystallization on the membrane can be prevented and pure succinic acid can be produced via electrochemical pH-shift crystallization [ 19 , 20 , 21 ].…”

Electrochemical Crystallization Concept for Succinic Acid Reduces Waste Salt Production

“…Several works illustrate the synergies between different electrochemical membrane processes and fermentations by producing base for the pH control of the fermentation, while simultaneously removing the product from the broth [13][14][15][16]. Techno-economical evaluations illustrate ecological advantages, but also conclude that membrane fouling and operating costs limit the economic feasibility of these approaches [3,5,7,16,17].…”