Microbial cleaning of hydrocarbon-contaminated soil - by adding complexing agent, pref. cyclodextrin, to increase bio-availability of hydrocarbon

摘要

Microbial cleaning of soil contaminated by hydrocarbons (I), esp. aromatic (I), is improved by adding a complexing agent (II) for (I) directly to the soil or to at least part of a sepd. contaminated soil layer. (II) pref. forms an inclusion complex with polycyclic aromatic (I), monocyclic aromatics (BTX) and/or aliphatic (I). (II) is esp. cyclodextrin (IIa). (II) is added to the fines of a sepd. soil layer, after removal of coarse particles by wet classification. (II) is mixed with the soil fines in a bioreactor, and (I) are microbially degraded with controlled nutrient addn., oxygen supply and pH adjustment. Esp. (II) is added to the suspended fines with mixing for 30-60 mins. to form a suspended or colloidally dissolved (I)/(II) complex, followed by microbial degradation for several days and repeating the first stage (i.e. mixing with (II)). ADVANTAGE - By forming a complex with (II), (I) are desorbed from fine soil particles and made available to microorganisms, esp. if (I)/(II) complexes are water-soluble or form a colloidal soln. or stable suspension. The increased bioavailability of (I) accelerates degradation and improves the cleaning efficiency. Unlike surfactants, (II) are non-toxic to microorganisms and do not disrupt biological membranes.