Continuous production of monosodium glutamate by electrodialysis metathesis
The traditional fermentation process of monosodium glutamate(NaGA)consumed a large amount of acid and base,produced a large amount of hypersaline organic wastewater.Electrodialysis metathesis(EDM)technology can be used to produce NaGA directly using fermentation broth and cheap salts such as sodium sulfate as raw solutions in one step,but its continuous process mode and energy saving still require in-depth and systematic research work.In this paper,a continuous EDM process with one-pass flow strategy was proposed on the basis of the previous work of NaGA production by EDM,and the influence of parameters such as inflow rate and product compartment/raw material inflow rate ratio was studied with product concentration,conversion rate and energy consumption as evaluation indicators,and then a EDM inflow process with two hydraulic stages was constructed.The results showed that when the inflow of the raw materials compartment was 1.5 L/h and the inflow rate ratio of the product to raw materials compartment was 0.6 at the current density of 45 mA/cm2,the fermentation conversion ratio of the EDM was 73.35%,and the energy consumption was 1.41 kWh/kg NaGA;furthermore,the conversion of the EDM process with two hydraulic stages was studied under the optimized conditions,and the conversion ratio of the fermentation reached 89.2%,which was 11.5%higher than the EDM process with one hydraulic stage under the conditions of same membrane logarithm,and the energy consumption was 2.01 kWh/kg NaGA at the current density of 30 mA/cm2,which was 32.6%lower than that of the batch operation mode.