A multidisciplinary three-step methodology is being developed to diagnose the extent and type of petroleum pollutants and resulting technological approaches to restore a contaminated site. At first, the site was delimitated and its zones identified by using remote sensors. An area of 307 ha considered of major importance to the national Mexican oil company, Petróleos Mexicanos (PEMEX), was identified. 75% of total analyzed soil samples ranged between 10-50,000 ppm of total petroleum hydrocarbons (TPH) and 25% between 50,000 and 434,000 ppm. Aliphatic and asphaltene groups were predominant and technological alternatives were proposed. In a second phase the identification of native botanical and microbial capabilities to biodegrade pollutants was achieved. Three native botanical species were selected for greenhouse studies: Cyperus laxus showed low sensitivity to TPH resulting in higher seed germination efficiency and growth rate. Since microbial consortia isolated from C. laxus rhizosphere were able todegrade up to 70% of TPH in 30 days laboratory cultures, a phytoremediation-reforest alternative was finally proposed to PEMEX. In a third step, the construction of a pilot plant in situ is now in course wherein both treatability studies and reforest strategies are being developed.

This study aims to explore an innovative approach consisting of the Fenton's process to stabilise organic wastes as an alternative to the traditional aerobic decomposition (composting). Digestate from the anaerobic digestion of the organic fraction of municipal solid wastes was taken from a mechanical-biological treatment plant and was thoroughly characterised regarding physical, chemical and biological properties. This sludge contained around 7.8 g Fe kg TS -1 , which can be beneficial to the chemical oxidation. However, the use of zero-valent iron nanoparticles or iron(II) salt revealed treatment can be improved by adding extra iron into the system. The response surface methodology determined that the best peroxidation conditions were 35.6 g H 2 O 2 kg TS -1 and 33.1 g Fe 2? kg TS -1 , while maintaining constant pH 3, L/S 5 and room temperature. The chemical treatment enhanced the stability, reducing the oxygen uptake rate from 4.63 to 2.57 g O 2 kg VS -1 h -1 . Moreover, the germination index increased from 37 to 99.9 %, which means the treatment yielded a non-phytotoxic product. The outcomes of the present study are promising and open a new pathway for the Fenton peroxidation in semi-solid processes since this fast method can be very competitive when compared with the slow composting technology.