Xylene is a hydrocarbon, ...

Xylene is a hydrocarbon, degree of difficulty level 1. All organic compounds are capable of being reduced into their elemental/nutritional forms by using the RNA microbial group called Archaea. The process is known as bioremediation.  This information is available at the UN Environmental Services Dept.  Here is a list of this and other organic compounds cleaned insitu using the inexpensive Archaea.