Study On Utilizations As Feed Of Blue Algae In Taihu Lake

The outbreak of blue algae in lake-eutrophication made ecological disasters like dererioration of water quality happen in Taihu Lake. Salvageing the blue algae becomes a very important treatment way for the lake water, and this blue algae must be disposed timely, otherwise it would easily cause secondary pollution. At present, the utilizations of cyanobacteria are mainly producing fertilizer, biogas and other low-value ways. To make full use of blue algae protein and to develop high-value feed products, the hydrolysis of blue algae under reflux in HCl to obtain mixture of amino acids was studied in this paper. The toxicity of the hydrolysis products, and the affective factors of arginine, threonine, methionine and lysine seprated by solvent extraction from hydrolysate was also investigated.The single factor experiments and the orthogonal experiment were used to optimize the condition of parameters. The results showed that the highest amount of total amino acids, threonine and lysine were obtained in hydrolysis time of 14h and the ratio of the acid volume to the raw material mass was 10:1. As for arginine and methionine, the highest yield were obtained in reaction time of 14h,12h, respectively. Accordingly, the ratio of the acid volume to the raw material mass were 10:1,8:1, respectively. The simplified hydrolysis model base on the obtained results was(?)[exp(-k1t)-exp(-k2t)], and the generation rate and further degradation rate of the total amino acids were obtained in the temperature of 110℃, the value were 0.2162/h,0.0108/h, respectively.The toxicity of hydrolyzate from blue green algae was studied. After hydrolysis of 16h in HCl, the concentration of microcystin-RR, microcystin-LR in hydrolyzate were 0.98μg/kg, 1.0μg/kg, respectively, lower than the microcystin toxins limit of national drinking water. Accordingly, the removal rates of microcystin-RR, microcystin-LR were high to 99.99%. The result of the acute toxicity test indicated that the LD50 of blue algae acidolysis product was more than 9.09g/kg BW, revealing no obvious heredity toxicity The results of micronucleus test of bone marrow and sperm abnormaity test were negative. It indicated that the acidolysis product of blue algae is safe for edibility.The method of reactive extraction with di-(2-ethylhexyl)phosphoric acid (D2EHPA) for the separation of arginine,threonine, methionine and lysine from acidolysis solution was studied. Through the single factor experiments and the orthogonal experiment, the optimum extracting conditions were determined. As for arginine, the best extraction rate was obtained at pH 4, extracting time of 100min, extractant/solution(v/v) of 0.7, the value of extraction rate was 16.83%. The maximum extraction rate of thereonine was 18.43%, obtained at pH 3, extracting time of 80min, extractant/solution(v/v) of 0.8. In can be observed that the optimum extraction conditions of methionine and lysine were at pH value 3, extracting time of 100min, extractant/solution(v/v) of 0.6. The value of extraction rates were 26.23%,12.25%, respectively.