Study On Heavy Metal Contents With Raising Pigs Of Biological Fermentation Bed, Screening A Bacterium Of High Copper Resistance And Its Adsorption Behavior

With the rapidly development of economy, the pollution of heavy metal has become one of the most serious problems concerning the environment of the earth. It is known that biosorption shoud be a cost-effective technology to solve the problem of heavy metal. Many researches have showed that the bacteria can be of great tools in dealing with the adsorption of heavy metals. This paper studied on the biosorption efficiency of Cu-resistance of bacterial as heavy metal adsorption which were isolated from De Xing Copper Mine and the padding of fermentation beds. The results showed as follows:This paper made an analysis of 7 kinds of heavy metal such as Cu, As, Hg and so on, together with the test of the content of heavy metal in the litter and the pig feed from different companies. The research showed that the contents of copper and zinc in the padding of fermentation beds which have been used for two or three years were close to or exceed the maximum allowable content of the national standard called GB4284-84.The content of copper and zinc in the feed additives of Piglets, big pig and A company exceed the corresponding provisions in the national standards, and the content of Hg、Cd、Cr、 Pb are below the maximum allowable content of the provisions of the national standard GB4284-84.Recognizing the fact that some bacteria who could resist the heavy metal pollution areas have the characteristics of resistance to heavy metals, the research of screening bacteria resistance copper from De Xing Copper Mine and the padding of fermentation beds successfully obtained two strains. The strain K7-532 was Gram-positive bacteria that had the highest tolerance to Cu2+ concentration of 500 mg/L. The strain Y225 was Gram-negative bacteria that has the highest tolerance to Cu2+ concentration of 700mg/L. The Screen of a strain with high resistance to copper by NTG combining with UV mutagenesis, and the genetic stability of mutant Y225-10 was obtained, which the highest tolerance to Cu2+ concentration is 1000 mg/L.The research showed that time, pH, and the Cu2+ initial concentration were the important factors affecting the consequence of biosorption. Within 24 hours, the longer the time, the higher the absoption rate would be. The rate of biosorption decreases as the Cu+ initial concentration increases.Temperature and speed have little effect to the biosorption. pH value would be changed in the solution when living bacteria are biosorbing. The initial strain and mutagenic strain of best conditions for bioabsoption were difference. The best condition for Y225 to adsorb Cu2+ is that pH value is 7.0 and temperature was 30℃ together with the spinning speed of 180r/min and 24 hours of incubating time, the maximum absorption rate was 68.10%. The best conditions for Y225-10 to adsorb Cu2+ is that pH value was 8.0 and temperature was 25℃ together with a speed of 210r/min as well as 24 hours of incubating time. The maximum absorption rate was 62.91%. The same condition in the solution where Cu2+ concentration is 50 mg/L, the adsorption rate of Y225 and Y225-10 are 77.45% and 75.32%.