从含重金属废渣堆积区的土壤中筛选分离出一种对重金属Pb（2＋）和Cd（2＋）具有高耐受性的功能菌株,采用包埋法制成固定化生物吸附剂,用于吸附废水中的重金属,考察了重金属的初始浓度、吸附时间、废水pH值及吸附剂添加量等因素对吸附性能的影响.结果表明,筛选出的菌株为短杆菌,对Pb（2＋）和Cd（2＋）的最大耐受浓度分别为2200和700 mg/L;吸附剂投加量为10 g/L、废水pH为6时,Pb（2＋）和Cd（2＋）达最大吸附率,分别为87.77%和57.50%;Pb（2＋）和Cd（2＋）基本可在40 min内被快速吸附达平衡,最大吸附量分别为114.3和82.12 mg/g;废水初始pH为5？7利于吸附;Pb（2＋）和Cd（2＋）初始浓度增加使吸附率降低,且Pb（2＋）初始浓度比Cd（2＋）初始浓度对吸附速率影响更大.Langmuir和Freundlich吸附方程拟合表明,Pb（2＋）和Cd（2＋）的吸附主要为单分子层表面吸附;Pseudo-second order动力学方程拟合表明,吸附过程的限速步骤主要为化学吸附,且Pb（2＋）比Cd（2＋）更易被吸附.
The functional strains with a high tolerance to heavy metals Pb2＋ and Cd2＋ were isolated from the soil of containing heavy metal waste accumulation zone. The immobilized biological adsorbent was made by embedding method and used for treatment of wastewater containing heavy metals. The effects of initial concentration, adsorption time, pH value of wastewater and dosage of adsorbent on the adsorption performance were investigated. The experimental results showed that the selected strains were brevibacteria and their maximum tolerated concentration for Pb2＋ and Cd2＋ were 2 200 and 700 mg/L, respectively, pH of the wastewater is 6, and the adsorbent dosage is 10 g/L, Pb2＋ and Cd2＋ reached the maximum adsorption rate are 87.77% and 57.50%, Pb2＋ and Cd2＋ basic can be rapidly adsorbed in the 40 min and reached equilibrium, and the saturated adsorption capacity reached 114.36 and 82.12 mg/g, respectively. The most suitable pH of initial wastewater for adsorption is 5-7. The increase of the initial concentration of Pb2＋ and Cd〉 will decrease the adsorption rate, and the initial concentration of Pb2＋ is greater than the initial concentration of Cd2＋. Langmuir and Freundlich adsorption equations show that the surface adsorption of Pb〉 and Cd2＋ in wastewater is mainly single molecular layer adsorption process. Kinetic equation fitting of Pseudo-second order shows that the rate limiting step of adsorption process is mainly chemical adsorption, and Pb2＋ is more easily absorbed than Cd2＋.
Chinese Journal of Process Engineering
immobilized biological adsorbent
heavy metal waste water