Recovery of ammonia and acetic acid from amino acid byproduct using an integrated RO and evaporation system: Process simulation, energy analysis, and optimisation

Abstract

Methionine is an essential α-amino acid for protein synthesis and a precursor to various metabolic substances such as glutathione and biotin. During methionine production, byproducts such as acetic acid and ammonia are generated, which must be recovered for reuse in fermentation. It has been demonstrated that integrating a reverse osmosis (RO) process with conventional thermal-based recovery methods can significantly reduce total energy costs [1]. The performance of RO processes is highly influenced by feed conditions (flowrates, concentrations, and pressures) and module arrangement. Therefore, understanding how key RO performance indicators respond to process fluctuations is crucial. To address this, a two-stage spiral wound RO process was developed at an industrial scale based on a module-level mathematical model designed to simulate the recovery of acetic acid and ammonia. Model parameters were estimated and validated using actual plant data. With the validated process model, extensive simulations were conducted across a wide range of operating conditions and RO configurations to evaluate their impact on performance metrics such as permeate recovery, concentration factor, and energy consumption (both electrical and thermal). Most notably, simulations demonstrated that integrating RO with thermal processes is highly energy-efficient, reducing total energy costs by approximately 76 % compared to a standalone evaporation system. Additionally, it revealed potential improvements to the RO configuration by optimising the number of modules in each stage and adjusting operating conditions, such as feed flowrates and pressures, to meet specific production targets and constraints. The developed simulation platform and results provide a solid foundation for a decision-making tool to guide process configuration and operating conditions in industrial RO applications.