Influence Of The Bamboo Charcoal Immobilized Microbial On Transport And Biodegradation Of Atrazine In Soils

Organic pollutants can easily transport into surface water, soil and groundwater withrain or irrigation, which will lead to the pollution of soil and water bodies. It is a naturalprocess of biological degradation of organic pollutants by indigenous microorganisms inmost environments. Because of some natural conditions, such as lack of dissolved oxygen,nutrients, and effective microorganisms, decreased the rate of purificate organic pollutants.Therefore, we need to study the rule about migrates in soil, analyze different factors whicheffect the growth of microorganisms and degradation ability, and strengthen degradationefficiency by various methods.This paper studied the leaching and biodegradation of atrazine in soils by bamboocharcoal immobilized a degradation bacterium. A degradation bacterium was purified fromthe sewage Zhongshan Chemical Factory in Zhejiang province called AHAT-3. Then weset chitosan and sodium alginate as auxiliary carrier in order to form a "cell network"structure, and immobilized microorganism into bamboo charcoal pores. Finally, we appliedimmobilized microorganism to degradation of atrazine in soils. At the same time, wesimulated quartz sand as soil particles, and studied microorganism migration in quartz sandcolumn, and analyzed the leaching of atrazine in soils through imitating soil columnexperiment. The findings will provide the theory for microorganism remediation ofpesticide pollution, and provides the new way for fast degeneration of residual chemicalsin the soil-water environment.The main research contents and the results were as follows:1. Through cultivation method from purification in sewage sludge in Zhejiang ZhongshanChemical Factory, we obtained the degradation bacterium which called AHAT-3. Then weobserved degradation bacterium microscopic structure by Environmental ScanningElectron Microscopy （ESEM）, and comprised with GenBank16S rDNA sequence, andconstructed phylogenetic tree. Finally, we basically identified the degradation bacterium isOchrobactrum sp.The degradation bacterium could only use atrazine as carbon and nitrogen source, andits growth reached logarithmic phase at48h, and the amount of degradation bacteriumreached3.79×10⁹cfu, and the degradation rate of atrazine reached43.17%. Somecharacteristics about degradation bacterium in inorganic salt culture with20mg·L^-1 atrazine were as follows: infant cells were rod-shaped, single, and formed a team with achain. The colony chains was small, round, red and without exudation, gloss, smoothsurface, edge rules, translucent, and translucent, Gram stain was negative. The best pH forstrains was7.0to8.0, and the optimum growth temperature was between20³0℃.2. Bamboo charcoal with a porous structure has the ability to adopt microorganism. Weimmobilized microorganism into bamboo charcoal pores, and applied immobilizedmicroorganism to degradation of atrazine in soils and solutions. The results showed:degradation bacterium AHAT-3grew well in the bamboo, and the adsorption effect ofdegradation microorganism was significantly affected by bamboo charcoal particle size.During the amount of bacteria was at the same level, the number of degradation bacteriumfixed by bamboo charcoal increased with decreasing particle size; The effect ofimmobilized microorganism was significantly improved after adding sodium alginate,chitosan as an auxiliary agent, and the treatment of1%chitosan+5%sodium alginate wasbetter in immobilized microorganism and degradation of atrazine.3. We set up soil column to studied the effect of atrazine leaching in soils, the resultsshowed that:（1） The ability of atrazine leaching downward in vertisol column was strongerthan its in red soil column under the same water volume. After adding the degradationbacterium, the atrazine concentrations in leaching solution both declined in vertisol and redsoil columns, and the leaching rates were19.88%and33.66%, and the decline were25.93%and23.20%, respectively.（2）The more water, the higher of the leachate of atrazine.After adding the degradation bacterium, the atrazine concentrations in leaching solutionboth declined in two soil types.4. We simulated quartz sand as soil particles, and studied microorganism migration inquartz sand column. The results showed that:（1） the microorganisms leached in quartzsand column appeared lag phenomenon with increasing dose of bamboo charcoal, whichshowed immobilized microorganism enhanced with increasing dose of bamboo charcoal,and it weakened the ability of microorganisms migration in the quartz sand column.（2）Compared with adding charcoal homogeneous into quartz sand column, the lagphenomenon of atrazine in leaching solution appeared more obviously with addingbamboo charcoal in surface of quartz sand column.