larger-scale trial was accomplished. Also in this case, the percentage of degraded
PAHs in soil under field condition was extremely high, but the efficiency of both
treatments (P. velutina-inoculated and non-inoculated soil) was similar. Therefore,
the degradation of PAHs in this test could not be ascribed univocally to the use of the
allochthonous fungus.
Concerning this white-rot fungus, P. velutina was selected also for another pilotscale (0.3 t) treatment trial of a TNT-contaminated soil (Anasonye et al. 2015). Pine
bark was used as growth substrate and the contaminated soil was diluted with
composted green waste (1:20). TNT was efficiently degraded up to 80% in
107 days. The quantification of the fungal Internal Transcribed Spacer (ITS) region
DNA copy number by quantitative PCR (qPCR) using specific primers for
P. velutina proved that the fungus could withstand high concentration of TNT and
autochthonous microorganisms. However, the real efficiency of the fungus in TNT
removal could not be proved because non-inoculated soil was not prepared as control
due to economical and practical issues and thus the degradation ability of P. velutina
could not be compared with the indigenous microbiota one.
The mycoremediation of a pentachlorophenol (PCP)-contaminated soil was also
assessed at field scale (Walter et al. 2005). The soil was collected from a timber
treatment plant where PCP was widely used as a wood preservative. In this case, the
capability of the white-rot fungus T. versicolor in the remediation of this contaminated matrix was evaluated in 500 L soil cells. At first, the contaminated soil
(1000 mg/kg) was diluted with non-contaminated soil and mixed with wood chips
obtained from cuttings and shreds. Thereafter, such blended pile of material was
mixed with a formulation composed of sawdust, cornmeal, and starch previously
inoculated with T. versicolor to obtain a final ratio of soil:woodchips:fungal inoculum of 40:20:40 or 60:20:20. A significant decrease in PCP concentration was
observed within the first 25 weeks of incubation, while the degradation rate remarkably decreased in the following weeks. Nonetheless, more than 90% of the original
PCP content was removed in both cells (20 or 40% of fungal inoculum used) after
2.5 years. These results confirmed that the PCP depletion efficiency was similar
regardless of the amount of fungal inoculum used.
P. ostreatus was also applied in several field-scale tests. Explosive-contaminated
soil from the Naval Weapons Station Yorktown (Virginia, USA), where munitions
manufacturing was carried out for decades, was treated using this fungus (Axtell
et al. 2000). Two plots (4.59 m
3 ) of contaminated soil were blended with 2.29 m
3 of
a substrate mixture previously colonized by P. ostreatus. The concentration of three
target explosives was monitored during the treatment which lasted 62 days. The
content of these compounds noticeably decreased; however, the degradation extent
and rate in P. ostreatus-augmented plots was comparable to those achieved in soil
amended only with the substrate mixture during the same period. This outcome
showed that the addition of amendments enhanced the growth and activity of
indigenous microorganisms promoting the degradation of the explosives in soil.
As for other fungi, the role of the P. ostreatus in this field-scale test was not
elucidated.
22 Mycoremediation of Contaminated Soils
455
PAHs in soil under field condition was extremely high, but the efficiency of both
treatments (P. velutina-inoculated and non-inoculated soil) was similar. Therefore,
the degradation of PAHs in this test could not be ascribed univocally to the use of the
allochthonous fungus.
Concerning this white-rot fungus, P. velutina was selected also for another pilotscale (0.3 t) treatment trial of a TNT-contaminated soil (Anasonye et al. 2015). Pine
bark was used as growth substrate and the contaminated soil was diluted with
composted green waste (1:20). TNT was efficiently degraded up to 80% in
107 days. The quantification of the fungal Internal Transcribed Spacer (ITS) region
DNA copy number by quantitative PCR (qPCR) using specific primers for
P. velutina proved that the fungus could withstand high concentration of TNT and
autochthonous microorganisms. However, the real efficiency of the fungus in TNT
removal could not be proved because non-inoculated soil was not prepared as control
due to economical and practical issues and thus the degradation ability of P. velutina
could not be compared with the indigenous microbiota one.
The mycoremediation of a pentachlorophenol (PCP)-contaminated soil was also
assessed at field scale (Walter et al. 2005). The soil was collected from a timber
treatment plant where PCP was widely used as a wood preservative. In this case, the
capability of the white-rot fungus T. versicolor in the remediation of this contaminated matrix was evaluated in 500 L soil cells. At first, the contaminated soil
(1000 mg/kg) was diluted with non-contaminated soil and mixed with wood chips
obtained from cuttings and shreds. Thereafter, such blended pile of material was
mixed with a formulation composed of sawdust, cornmeal, and starch previously
inoculated with T. versicolor to obtain a final ratio of soil:woodchips:fungal inoculum of 40:20:40 or 60:20:20. A significant decrease in PCP concentration was
observed within the first 25 weeks of incubation, while the degradation rate remarkably decreased in the following weeks. Nonetheless, more than 90% of the original
PCP content was removed in both cells (20 or 40% of fungal inoculum used) after
2.5 years. These results confirmed that the PCP depletion efficiency was similar
regardless of the amount of fungal inoculum used.
P. ostreatus was also applied in several field-scale tests. Explosive-contaminated
soil from the Naval Weapons Station Yorktown (Virginia, USA), where munitions
manufacturing was carried out for decades, was treated using this fungus (Axtell
et al. 2000). Two plots (4.59 m
3 ) of contaminated soil were blended with 2.29 m
3 of
a substrate mixture previously colonized by P. ostreatus. The concentration of three
target explosives was monitored during the treatment which lasted 62 days. The
content of these compounds noticeably decreased; however, the degradation extent
and rate in P. ostreatus-augmented plots was comparable to those achieved in soil
amended only with the substrate mixture during the same period. This outcome
showed that the addition of amendments enhanced the growth and activity of
indigenous microorganisms promoting the degradation of the explosives in soil.
As for other fungi, the role of the P. ostreatus in this field-scale test was not
elucidated.
22 Mycoremediation of Contaminated Soils
455