Bioremediation Of Crude Oil Contaminated Soil Using Fe-SOM As Catalyst In Fenton

Compared with the dissolved iron,the Fe-SOM catalyzed H2O2 to produce hydroxyl radicals(·OH)in the solid phase,which oxidized oil nearby.And the removal rate was improved.In this paper,the composition of Fe-SOM and the effect of SOM on the catalytic activity of Fe-SOM were studied.At the same time,the effects of hydroxyl radical oxidation on the indigenous bacteria in solid phase and liquid phase were compared.On this basis,the effects of two kinds of solid iron Fe-SOM oxides and organic Fe-SOM on the subsequent bioremediation were further investigated.The experiment of conclusions as below:(1)The catalytic activity of organic bound iron was much higher than that of iron oxide,which the removal rate of eight long-chain C23-C30 was up to 79%,its removal(1265 mg/kg)of long chain hydrocarbon C23-C30 was 2 times of the latter(583 mg/kg).(2)According to the intensity of hydroxyl radicals(·OH),the intensity of ·OH catalyzed by Fe-SOM was 2 times of the control.And the corresponding TPH removal rate(58%)was also significantly higher than that of the control(15.6%).(3)The number of the residual indigenous bacteria was relate to the instantaneous intensity of ·OH.The number of indigenous bacteria was reduced from 109cfu/g to104cfu/g after high instantaneous liquid hydroxyl radicals.However,the hydroxyl radicals of low instantaneous intensity had little harm to indigenous bacteria,and the number of residual indigenous bacteria was as high as 107cfu/g.(4)Fenton pre-oxidation of Fe-SOM was benefited to the early bioremediation,especially in the first 15 days.The utilization of DOC was as high as 2035.98mg/kg,which was higher than liquid phase(N-Fe2+)system 493.6mg/kg.The utilization of NH4+ was as high as 95.8mg/kg,which was 1.52 times of liquid phase(N-Fe2+)system utilization(62.9mg/kg).Moreover,the biodegradation of TPH was 589.6mg/kg,which was 1.9-4.2 times of liquid phase system.(5)Chemical pre-oxidation,Fe-SOM as a catalyst,has little damage to the indigenous bacteria.During of 0-40 days,NH4+utilization rate was about 45% and DOC utilization rate was 40%,so 11 kinds of hydrocarbons(C20-C30)biodegradation was significantly increased.However,it was the Fe-SOM as catalyst that caused hardly damage to indigenous bacteria.After 40 days,NH4+utilization rate was about 3%-6%and DOC utilization rate was 10%-17%,respectively.