Abstract: This paper further optimized the hydrolysis process parameters of chrome shavings based on the original experiment. The additional water washing pretreatment step can significantly reduce the ash content in chrome shavings by 40%. The results of single factor optimization experiments showed that the best process parameters are calcium oxide dechrome temperature 65 ℃, calcium oxide dosage 10%, alkali treatment solution ratio 10, the treatment time of calcium oxide 30min, the hydrolysis temperature of enzyme 60 h, the dosage of enzyme 0.8%, and the hydrolysis time of enzyme 1.0h. Orthogonal optimization experiment results showed that the optimal process conditions were as follows: calcium oxide dechromation temperature 68 ℃, calcium oxide dosage 10%, liquid ratio 9, alkali treatment time 25min, enzymatic hydrolysis temperature 57 ℃, enzyme dosage 0.7%, enzyme hydrolysis time 1.0 h, hydrolysate pH 10.5, static for 30 min, filtration, discarding residue and leaving liquid. The hydrolysis rate of the optimal process was 76.79%, and the chromium content was 44.30 mg/kg. Under the optimal process, the extraction rate of collagen is 84.86% and the ash content is 8.14%.

Key words: chrome shavings, enzymatic hydrolysis, alkaline-enzymatic method, process optimization: orthogonal test