Abstract:With threonine secondary mother liquor as the research object，the amino acid analyzer was used for quantitative analysis of amino acids in the mother liquor.The results showed that the concentration of threonine was 7.82 g/100 mL.Taking the decolorization rate and threonine loss rate of threonine secondary mother liquor as evaluation indexes，the decolorization effect of 9 kinds of decolorizing agents，including activated carbon，macroporous adsorption resin，anion and cation exchange resin，on threonine secondary mother liquor was compared to determine the best decolorizing agent type. The decolorization process of threonine secondary mother liquor was optimized by single factor test and response surface test. The results showed that the decolorization effect of activated carbon on threonine secondary mother liquor was better than that of other decolorants and activated carbon powder was selected as the decolorant of threonine secondary mother liquor. Through response surface optimization，the optimum decolorization process conditions were obtained as follows：natural condition pH value，decolorization temperature 35 ℃，decolorization time 40 min，activated carbon addition amount 25%.Under these conditions，the decolorization rate of threonine secondary mother liquor was 97.69%，and the loss rate of threonine was 5.02%.