The Recovery Of Astaxanthin And Protein From Discharged Wastewater During The Production Of Chitin Or Chitosan And The Utilization Of Chitosan In The Treatement Of Wastewater

In recent years, the manufacture of chitin has developed rapidly. However, the process of chitin and chitosan from shrimp waste imposes serious environmental problems, especially disposal problems of wastewater containing astaxanthin and protein. At present, there are no efficient methods to recover astaxanthin and protein or handle the wastewater, so most of the factories discharge the wastewater directly. In this study, when the discharged wastewater during the production of chitin or chitosan was handled, astaxanthin with various biological functions and protein which can be added to feed were extracted from the wastewater, which were beneficial for the development of chitin industry and the protection of ocean environment. On the other hand, due to the excellent absorption property, chelation property, regeneration property and biodegration property of chitosan, it showed wider applied foreground. In this paper, we used chitosan to handle the soaked water of seaweed, which not only protect environment and utilize resources fully, but also save energy and resources.Firstly, studies were carried out to extract astaxanthin from discharged wastewater during the production of chitin and determine the scavenging effect of the obtained astaxanthin against 1,1-diphenyl-2-picrylhydrazyl(DPPH) radical. Different organic solvent and mixed organic solvent were used to recover astaxanthin from wastewater, respectively. And the optimal conditions of recovering astaxanthin were determined. The results showed that the effect of the mixed organic solvent was better than that of organic solvent. After silica gel column chromatography and saponification, the obtained pigment was analyzed by HPLC. And the concentration of free astaxanthin in the obtained pigment was 30.02%. The scavenging effect of the obtained pigment on DPPH radical were determined. The results showed that the obtained pigment possessed strong scavenging ability on DPPH radical and IC50 was 0.84mg/ml.The inclusion complex of the obtained astaxanthin withβ-cyclodetrin was synthesized and the complex is 1:4 for astaxanthin:β-cyclodetrin. The aqueous solubility of the inclusion complex was <0.5mg/ml, which was better than that of astaxanthin. Large aggregates were observed in the aqueous solution of the inclusion complex. Furthermore, the stability of the inclusion complex against temperature and light was greatly enhanced.Secondly, studies were carried out to recover protein from discharged wastewater during the production of chitin. The optimal conditions for the recovery of protein were determined. The amino acids of the obtained protein sediment were analyzed. The results showed that the obtained protein sediment contained abundant amino acids. The total content of the amino acids was up to 20.56%, which indicated that the obtained protein sediment might be added into feed.After astaxanthin and protein were recovered, the wastewater was handled, and the optimal experimental conditions were determined. The indexes of the handled wastewater were determined by Qingdao Environment Protection Supervisory Center. The results showed that the indexes met the standard of GB8978-1996.Finally, chitosan was used to handle the soaked water of seaweed. The results showed the effect of chitosan on flocculation of glycine in the soaked water was better than that of common method used in industry. The optimal experimental conditions to handle the soaked water by chitosan were determined. On the other hand, the change of the I- concentration in the soaked water was slight, which showed this method did not affect the extraction of iodine.