掺硼金刚石膜电极电化学消毒中有机物与大肠杆菌的相互作用

The interactions between organics and Escherichia coli in the electrochemical disinfection using a boron-doped diamond anode

【目的】考察掺硼金刚石膜电极电化学体系同时降解有机物和消毒的效果及互相影响机制。【方法】研究掺硼金刚石膜电极电化学体系在有无大肠杆菌存在情况下,对含有邻苯二甲酸二甲酯、邻苯二甲酸二乙酯、苯酚、间苯二酚和间苯三酚5类有机物的水溶液的电解效果,分别测定有机物的降解速率常数及大肠杆菌的对数灭活率;并以间苯二酚为例,探讨有机物浓度及酸碱度对共存体系中有机物的降解效果及大肠杆菌的对数灭活率的影响。【结果】在大肠杆菌存在的情况下,有机物的降解率上升,邻苯二甲酸二甲酯、邻苯二甲酸二乙酯、苯酚、间苯二酚和间苯三酚在大肠杆菌存在下的降解速率常数分别为0.774、0.972、0.990、1.818和7.902h-1,大于不含大肠杆菌时的降解速率常数(0.762、0.870、0.972、1.650、7.686h-1);与之相反,大肠杆菌的灭活变慢。初始浓度为0.030mmol/L时,0.230mg/L间苯二酚在5min内实现完全降解,而初始浓度为0.009mmol/L时只有0.080mg/L被降解;间苯二酚浓度从0.000到0.030mmol/L时,对应的大肠杆菌灭活率从5.40下降到3.24。酸碱度对共存体系有影响,pH=10体系与pH=7体系对间苯二酚的降解率快于pH=4体系。【结论】共存体系中有机物与微生物间的吸附,使得有机物的降解速率变快。同时,有机物的降解速率随其浓度的增加而减慢,但是降解量逐渐增加,在碱性(pH=10)条件下电解对有机物和大肠杆菌的处理效果最优。

【Objective】The influence mechanism underlying the efficiency of both organics degradation and disinfection was simultaneously investigated in an electrochemical cell using a boron-doped diamond anode.【Method】Electrolysis was conducted with only organics,only Escherichia coli(E.coli),or both organics and E.coli,respectively.The five organics pollutant were dimethyl phthalate(DMP),diethyl phthalate(DEP),phenol,resorcinol and trihydroxylbenzene(THB).Both the constants of organic degradation rate and log removal of E.coli were detected in the electrolysis system.With resorcinol as an example,the effect of organic concentration and pH on organic degradation result and log removal rate of E.coli was investigated in the coexisting systems.【Result】It was indicated that E.coli inactivation got slower,while organic removal got a little faster in the coexisting process compared with the condition with each alone.The degradation rate constant of DMP,DEP,phenol,resorcinol,and THB was 0.774,0.972,0.990,1.818,and 7.902 h-1 in the presence of E.coli,while it was 0.762,0.870,0.972,1.650,and 7.686 h-1 in the absence of E.coli.With an initial concentration of 0.030 mmol/L resorcinol,0.230 mg/L resorcinol could be degraded completely in 5 min,while only 0.008 mg/L resorcinol could be degraded,in case,the initial value of resorcinol was 0.009 mmol/L.The corresponding log removal of E.coli was reduced from 5.40 to 3.24 when the initial concentration of resorcinol was in the range of 0.000 to 0.030 mmol/L.Moreover,pH showed a significant influence on the coexisting system.The experiment result of degradation rate of resorcinol in different pH showed that resorcinol degradation was faster in pH=10 system as well as pH=7 system compared with pH=4 system.【Conclusion】The adsorption interaction between organic molecules and the microorganisms was strengthened under electric field and thus facilitated the organics degradation.Organic degradation rate constants got slower with the increase of their concentration,while the degraded organic amount was increased gradually.In combination with organic degradation and E.coli inactivation,the electrolysis in alkaline condition(pH=10)showed the best performance.