liquid swine manure was studied by Barrington et al. (2002). In this study nitrogen
losses by volatilization were correlated with CO 2 emission while CO 2 emission was
correlated with biological oxygen demand (BOD) of the bulking agent.
Studies performed at small laboratory scale enable better control of the process
and thus distinction and analysis of factors influencing the efficiency. During fullscale experiments strict control of the operating conditions is not always possible.
However, some processes are connected with the scale of experiment and cannot be
observed during batch or microcosm tests. For example, the temperature rising up to
50
C during composting may occur only during large-scale treatments due to higher
amount of active bacteria and better heat isolation in the middle of the composting
tank. To complete the picture of soil composting, Table 5.4 displays a set of
operating conditions for large-scale operations.
In the study of Rojas-Avelizapa et al. (2007), soil originating from oil-based drill
muds, with high content of recalcitrant TPH, was mixed with urea, mineral nutrients,
and straw as a bulking agent (Table 5.4). The authors have observed almost complete
depletion of the contaminant after 180 day of composting. In another composting
experiment, soil polluted with fuel oil was fertilized with mineral nutrient and
amended with soft wood sawdust, and river sand as a bulking agent (Beškoski
et al. 2011). The final 94% decrease of TPH concentration after 150 day of
bioremediation was manifested by 96, 97, and 83% reductions of the aliphatic,
aromatic, and NSO-asphaltene fraction, respectively (Beškoski et al. 2011). In the
study of Coulon et al. (2010), bunker C fuel oil-contaminated soil fertilized with
mineral nutrient and installed active air pumping system revealed 80% TPH removal
efficiency; however, human risk criteria were not fulfilled. Jørgensen et al. (2000)
composted lubricating oil-contaminated soil as well as diesel oil-contaminated soil
with mineral nutrients and bark chips as a bulking agent. During 150 day of
bioremediation, for both soils, the highest degradation intensity was observed within
two first months of the treatment and followed a first-order degradation pattern. The
authors highlighted that aged contaminants at concentrations of TPH below
1800 mg kg
À1 are more difficult to remediate in comparison with freshly contaminated soil, thus final low end-point concentration was not achieved. Li et al. (2002)
observed low decrease of TPH content, reaching maximally 57% after 53 day of
composting of oil-contaminated soil fertilized with organic pellet and amended with
rice hulk as a bulking agent. Degradation of resins and asphaltenes was much slower
in comparison to aromatic and saturated fraction, in the end affecting the total
process efficiency.
5.3.2 Biological Stability, Nutrient Status, and Native
Microflora of Digestate
Biological stability can be defined as the extent to which easily biodegradable
organic matter has been decomposed (Lasaridi and Stentiford 1998). In other
258
A. Gielnik et al.
losses by volatilization were correlated with CO 2 emission while CO 2 emission was
correlated with biological oxygen demand (BOD) of the bulking agent.
Studies performed at small laboratory scale enable better control of the process
and thus distinction and analysis of factors influencing the efficiency. During fullscale experiments strict control of the operating conditions is not always possible.
However, some processes are connected with the scale of experiment and cannot be
observed during batch or microcosm tests. For example, the temperature rising up to
50
C during composting may occur only during large-scale treatments due to higher
amount of active bacteria and better heat isolation in the middle of the composting
tank. To complete the picture of soil composting, Table 5.4 displays a set of
operating conditions for large-scale operations.
In the study of Rojas-Avelizapa et al. (2007), soil originating from oil-based drill
muds, with high content of recalcitrant TPH, was mixed with urea, mineral nutrients,
and straw as a bulking agent (Table 5.4). The authors have observed almost complete
depletion of the contaminant after 180 day of composting. In another composting
experiment, soil polluted with fuel oil was fertilized with mineral nutrient and
amended with soft wood sawdust, and river sand as a bulking agent (Beškoski
et al. 2011). The final 94% decrease of TPH concentration after 150 day of
bioremediation was manifested by 96, 97, and 83% reductions of the aliphatic,
aromatic, and NSO-asphaltene fraction, respectively (Beškoski et al. 2011). In the
study of Coulon et al. (2010), bunker C fuel oil-contaminated soil fertilized with
mineral nutrient and installed active air pumping system revealed 80% TPH removal
efficiency; however, human risk criteria were not fulfilled. Jørgensen et al. (2000)
composted lubricating oil-contaminated soil as well as diesel oil-contaminated soil
with mineral nutrients and bark chips as a bulking agent. During 150 day of
bioremediation, for both soils, the highest degradation intensity was observed within
two first months of the treatment and followed a first-order degradation pattern. The
authors highlighted that aged contaminants at concentrations of TPH below
1800 mg kg
À1 are more difficult to remediate in comparison with freshly contaminated soil, thus final low end-point concentration was not achieved. Li et al. (2002)
observed low decrease of TPH content, reaching maximally 57% after 53 day of
composting of oil-contaminated soil fertilized with organic pellet and amended with
rice hulk as a bulking agent. Degradation of resins and asphaltenes was much slower
in comparison to aromatic and saturated fraction, in the end affecting the total
process efficiency.
5.3.2 Biological Stability, Nutrient Status, and Native
Microflora of Digestate
Biological stability can be defined as the extent to which easily biodegradable
organic matter has been decomposed (Lasaridi and Stentiford 1998). In other
258
A. Gielnik et al.