The Electrokinetic Movement and in Situ Biodegradation of Phenanthrene in Soil Coupled with Non-uniform Electrokinetics

摘要

The poor bioavailability of polycyclic aromatic hydrocarbons(PAHs)in soil matrix frequently results in slowbioremediation processes.PAHs are generally retained in soil matrix as a result of sorption，sequestration，or even forminginto non-aqueous phase liquids and their mobility is thus greatly reduced.While PAHs-degrading bacteria tend to adhere to soil particle surfaces forming into continuous or/and discontinuous biofilms.Consequently, the relative movement and masstransfer between the PAHs and the bacteria are extremely limited.As all in situ mixing tool，non-uniform electrokinetictransport processes(namely，non-uniform electrokinedcs)induced by non-uniform electric field applied have the potentialfor accelerating the movement and biodegradation of PAHs in soil.This study investigated the feasibility by using abench-scale electrokinetic system with periodic polarity-reversal and a natural sandy loam spiked with phenanthrene as amodel PAH.The results showed that non-uniform electrokinetics could effectively accelerate the desorption and movementof phenanthrene and bacteria in the soil through dielectrophoresis and electrophoresis.The phenanthrene could be movedtowards electrode regions at a rate of about 0.3～0.7 cm/d-V，while the bacteria towards anode regions at 4.7 cm/d-V.Theresults also showed that non-uniform electrokinetics could effectively enhance in situ biodegradation of phenanthrene in thesoil depending upon the operation mode.Bidirectional operation stimulated the phenanthrene biodegradation moreeffectively than unidirectional operation.At the same time，a smaller polarity-reversing interval induced a higher and moreuniform removal of phenanthrene from the soil.