纳米铁对水中大肠杆菌的去除

The removal of E.coli in water by nanoscale zero-valent iron

目的研究纳米铁去除水体中大肠杆菌的影响因素及特性。方法将纳米铁(40~200 mg/L)投加到不同p H值(5.0~9.0)、温度(20~40℃)和大肠杆菌初始浓度(104~106 CFU/ml)的细菌悬液中,振荡培养(120 r/min),在预设时间点(10、30min和1、2、4、6、8 h)取样培养后用平板计数法进行大肠杆菌计数。同时将纳米铁与普通铁对大肠杆菌的去除能力进行比较,并且将纳米铁(120 mg/L)残渣进行重复利用,考察纳米铁残渣对大肠杆菌的去除效果。结果随着纳米铁投加量的增加、大肠杆菌初始浓度的降低、pH值的降低和温度的降低,纳米铁对大肠杆菌的去除量增加。纳米铁(120 mg/L)对大肠杆菌的去除能力(2.72 log)比普通铁粉(2.21 log)高,并且在剩余纳米铁的连续反应中,3次反应后的剩余纳米铁对大肠杆菌仍然有较强的去除能力。结论纳米铁对大肠杆菌具有优异的去除效果,明显优于普通铁,且纳米铁去除效果受纳米铁投加量、大肠杆菌初始浓度、温度和pH值的影响。

Objective To investigate the influencing factors and characteristics in the removal of E.coli by nano zero-valent iron （nZVI）. Methods A quantity of nZVI or common iron powder was added into the reactor with E.coli. Samples were collected for determination of tile concentration of E.coli at a certain interval time. In addition,in the experiments for nZVI （120 mg/L）, the remaining liquid of the reactor was poured out after 1 h, and E.coli was added into the residue system, then samples were collected for determination of the concentration of E.coli after 1 h. The above experiment was repeated three times. Results The removal of E.coli by nZVI increased with the increase of nZVI dosage （40-200 mg/L）,but the removal decreased with the into＇ease of E.coli initial concentration （104-106 CFU/ml）,pH value （5.0-9.0） and temperature （20-40℃）. The removal of E.coli by nZVI （2.72 log） was higher than that of common iron powder （2.21 log）. As for the continuous removal of E.coli by residual nZVI, the removal efficiency of bacteria was close to zero by the residual nZVI after first reaction, the removal efficiency was 0.25 log by the residual nZVI after second reaction,and the removal efficiency was 1.16 tog by the residual nZVI after the third reaction. Conclusion The removal of E.coli by nZVI is negatively correlated with pH value,temperature and E.coli initial concentration, and positively correlated with the dosage of nZVI. Compared with common iron powder, nZVI showes excellent ability to remove E.coli. And the residual nZVI after three reactions still have strong ability to remove E.coli in the continuous reaction of residual nZVI with E.coli.