The bioventing systems may inject, circulate, extract and reinject hydrocarbons such as butane or other alkanes...http://www.google.es/patents/US7314548?utm_source=gb-gplus-sharePatente US7314548 - Bioventing remediation system B???squeda avanzada de patentes N???mero de publicaci???nUS7314548 B2Tipo de publicaci???nConcesi???n N???mero de solicitudUS 10/641,736 Fecha de publicaci???n1 Ene 2008 Fe