Carbon Footprint of Monosodium Glutamate Production in China

Monosodium glutamate (MSG) production has been attracting environmental concerns due to its high energy consumption and high pollutant discharge, especially to water and the air. The water footprint of MSG has been investigated in previous studies; however, the carbon emissions have not been evaluated. This study conducted a carbon footprint analysis on monosodium glutamate production, to identify the critical material and stage that contribute the most to the carbon footprint during MSG production. The results indicated that the carbon footprint of producing 1 t of MSG is 3.14 × 103 kgCO2eq, and 32.92 % of which is from the extraction and refinement process. Indirect emissions from raw materials used in MSG production, such as caustic soda liquid and concentrated sulfuric acid, and on-site emissions from the prodsteam production are major carbon footprint contributors. In addition, the glutamate fermentation stage accounts for 23.35 % of the total carbon footprint of MSG production due to the use of steam and liquid ammonia. In terms of the hotspot of carbon footprint in MSG production, it is identified that the steam used is the largest contributor, accounting for 34.90 % of the total carbon footprint in MSG production, followed by coal (16.47 %). Based on the research results, several cleaner production suggestions, such as greener raw materials utilization, green supply chain construction, and industrial symbiosis network establishment are proposed to further reduce the overall carbon footprint of MSG production.