Abstract:

River filtration system is a natural purification.It means that during the river water passing through the soil and the aquifer material,potential contaminants in the river water are filtered and attenuated by a series of physical,chemical and biological action. Multiple analogue experiments including soil test and static adsorption experiments were applied in this study in order to reveal the environmental behaviors and removal mechanism of BTEX (benzene,toluene,ethylbenzene and xylene）in the river filtration system.Adsorption and microbial degradation were the primary environmental behaviors of BTEX in the river filtration system.The purification effect of adsorption was limited.On the other hand,BTEX contamination could be well removed by degradation.Among the removal ratios of the four components of BTEX,Mxylene was the highest,the second was Toluene and Ethylbenzene,and that of Benzene was the lowest.The stability of the structure of Benzene determined its relatively lower degradation efficiency,and the low removal ratio of Toluene was due to the effect of adsorption on degradation.The soilwater partition coefficient Kd of each component of BTEX was higher,the degradation ratio was lower.As a natural purification,river filtration could efficiently remove the BTEX mixed pollution within a quite high concentration range and protect the ground water from being contaminated,but its purification effect was limited within a certain range of time and concentration.When the adsorption saturation was achieved and microbial activity was restrained,BTEX contamination would penetrate through the unsaturated zone and threaten the security of the ground water