Site characterization

The soil used for the biotreatability and intermediate scale tests in Italy comes from an Enilive Station, a mobility services hub for drivers, owned by Eni in Borgo Faiti, a town near to Rome.

The soil used for the full-scale pilot test was collected from another contaminated site located in Cisliano, a town next to Milan. In this case, the contamination originated from an oil pipeline break-in occurred in 2015 at an agricultural field.

Both sites undergo a remediation procedure managed by Eni Rewind, pursuant with the Italian environmental law.

The Enilive Station in Borgo Faiti is currently in operation and the soil for laboratory and pilot test were collected next to the area where fuel underground tanks were located (these having been removed in 2019). This soil is mainly composed of clay with silt and sand whereas the soil from the agricultural field in Cisliano is mainly sandy.

Small pilots

The biotreatability trials performed previously enabled the identification of two strains that were tested in the small-scale biopiles, namely P. ostreatus P24 and P80 strains.

The fungal inocula for each of the two strains amounted to 30 kg and was composed of wheat straw-colonized substrate (24 kg) and grain-supported mycelium (6 kg).

The experimental design also included the implementation of P. ostreatus spent mushroom substrate (SMS) at two different dosages, either arranged in a central monolayer or multi-layer, plus a non-inoculated amended incubation control.

The sole bulking agent was wheat straw in the mesocosms, inoculated with in-house-made inocula and in the lignocellulose-amended control.

Full-scale pilot

For full-scale treatment, two piles with 50 m³ of soil were set up and named:

• Biopile → control pile made of not amended contaminated soil.
• Mycopile → pile made of contaminated soil amended with spent mushroom substrate (SMS) from Agaricus bisporus (premixed with soil) and Pleurotus ostreatus, (arranged in alternating layers of 50 cm of soil and 30 cm of SMS); both SMS samples for the pilot test were provided from local mushroom growers.