“…The absence of a substantial shift in bacterial community cluster patterns and PL distribution curves associated with the period of accelerated TPH removal suggested that the changes observed in the bacterial community were related to incubation periods rather than to treatments. A similar trend was reported by Makadia et al (2011), showing that soil TPH reduction may not always be accompanied by changes in bacterial communities. The mid-range PL value (45-55 %) observed in this community coupled with minimal alterations in the community evenness can be reflective of an adapted microbial community with sufficient functional redundancies (Marzorati et al 2008).…”
Section: Microbial Community Analysessupporting
confidence: 87%
“…The replicate microcosms consisted of (1) 200 g of tank bottom sludge-contaminated soil and test isolate (0.1 g dry cell weight) in BH medium (8 %, w/w) (2) 200 g of tank bottom sludgecontaminated soil and BH medium, (3) 200 g of tank bottom sludge-contaminated soil and consortium of hydrocarbonoclastic bacteria (0.5 g L -1 ) in BH medium and (4) 200 g of tank bottom sludge-contaminated soil only. Inoculum generation for the fungal isolate was performed according to Makadia et al (2011). The microcosms were incubated for up to 9 weeks at 40 % soil water holding capacity (WHC) with samples being obtained weekly for TPH analysis.…”
Section: Viscosity Measurements and Microcosmsmentioning
confidence: 99%
“…It can also involve the biostimulation of indigenous sludge degrading microorganisms with nutrients and aeration or inoculation with known hydrocarbon-degrading organisms (Deka et al 2005;Makadia et al 2011). Surfactants can be added to oil tank bottom sludge to enhance microbial contaminant removal while land farming has also been used for sludge degradation (Al-Futaisi et al 2007;Zhang et al 2010).…”
In this study, biological methods (biostimulation and bioaugmentation) were used to treat oil tank bottom sludge contaminated soils to total petroleum hydrocarbon (TPH) levels suitable for landfill disposal. The sludge's hydrocarbon-degrading microbial capacities were initially compared to those from other contaminated environments using culture-based methods. Results indicated that a fungus, Scedosporium dominated the sludge microbial community. Its application in a nutrient formulation resulted in greater reduction in oil tank bottom sludge viscosity (44 %) and residual soil hydrocarbon compared to hydrocarbonoclastic microorganisms from other sources (26.7 % reduction in viscosity). Subsequent field-based experiments showed greater TPH reduction (54 %) in fungal-nutrient-treated sludge-waste soils than in naturally attenuated controls (22 %) over 49 days. 16S ribosomal ribonucleic acid and internal transcribed spacer regionbased polymerase chain reactions and denaturing gradient gel electrophoresis analyses showed minimal effects on the microbial communities during this time. TPH reduction to landfill disposal levels occurred at a slower rate after this, falling below the 10,000 mg kg -1 legislated TPH disposal threshold earlier in amended samples (91.2 %; 9,500 mg kg -1 ) compared to the control (82 %; 17,000 mg kg -1 ) in 182 days. The results show that the intrinsic hydrocarbon-degrading microbial capacities in sludge are better suited for sludge degradation than those from other sources. The substantial TPH reduction observed in control samples demonstrates the beneficial effects of natural attenuation with waste soils for oil tank sludge treatment. Microbial capacities in sludge and treated waste soils can therefore be successfully employed for treating oil tank bottom sludge.
“…The absence of a substantial shift in bacterial community cluster patterns and PL distribution curves associated with the period of accelerated TPH removal suggested that the changes observed in the bacterial community were related to incubation periods rather than to treatments. A similar trend was reported by Makadia et al (2011), showing that soil TPH reduction may not always be accompanied by changes in bacterial communities. The mid-range PL value (45-55 %) observed in this community coupled with minimal alterations in the community evenness can be reflective of an adapted microbial community with sufficient functional redundancies (Marzorati et al 2008).…”
Section: Microbial Community Analysessupporting
confidence: 87%
“…The replicate microcosms consisted of (1) 200 g of tank bottom sludge-contaminated soil and test isolate (0.1 g dry cell weight) in BH medium (8 %, w/w) (2) 200 g of tank bottom sludgecontaminated soil and BH medium, (3) 200 g of tank bottom sludge-contaminated soil and consortium of hydrocarbonoclastic bacteria (0.5 g L -1 ) in BH medium and (4) 200 g of tank bottom sludge-contaminated soil only. Inoculum generation for the fungal isolate was performed according to Makadia et al (2011). The microcosms were incubated for up to 9 weeks at 40 % soil water holding capacity (WHC) with samples being obtained weekly for TPH analysis.…”
Section: Viscosity Measurements and Microcosmsmentioning
confidence: 99%
“…It can also involve the biostimulation of indigenous sludge degrading microorganisms with nutrients and aeration or inoculation with known hydrocarbon-degrading organisms (Deka et al 2005;Makadia et al 2011). Surfactants can be added to oil tank bottom sludge to enhance microbial contaminant removal while land farming has also been used for sludge degradation (Al-Futaisi et al 2007;Zhang et al 2010).…”
In this study, biological methods (biostimulation and bioaugmentation) were used to treat oil tank bottom sludge contaminated soils to total petroleum hydrocarbon (TPH) levels suitable for landfill disposal. The sludge's hydrocarbon-degrading microbial capacities were initially compared to those from other contaminated environments using culture-based methods. Results indicated that a fungus, Scedosporium dominated the sludge microbial community. Its application in a nutrient formulation resulted in greater reduction in oil tank bottom sludge viscosity (44 %) and residual soil hydrocarbon compared to hydrocarbonoclastic microorganisms from other sources (26.7 % reduction in viscosity). Subsequent field-based experiments showed greater TPH reduction (54 %) in fungal-nutrient-treated sludge-waste soils than in naturally attenuated controls (22 %) over 49 days. 16S ribosomal ribonucleic acid and internal transcribed spacer regionbased polymerase chain reactions and denaturing gradient gel electrophoresis analyses showed minimal effects on the microbial communities during this time. TPH reduction to landfill disposal levels occurred at a slower rate after this, falling below the 10,000 mg kg -1 legislated TPH disposal threshold earlier in amended samples (91.2 %; 9,500 mg kg -1 ) compared to the control (82 %; 17,000 mg kg -1 ) in 182 days. The results show that the intrinsic hydrocarbon-degrading microbial capacities in sludge are better suited for sludge degradation than those from other sources. The substantial TPH reduction observed in control samples demonstrates the beneficial effects of natural attenuation with waste soils for oil tank sludge treatment. Microbial capacities in sludge and treated waste soils can therefore be successfully employed for treating oil tank bottom sludge.
“…An overall reduction in TPH levels together with a substantial shift in microbial populations occurred in all the soils studied with the exception of soil BP-5. Makadia et al (2011) also reported that rapid changes in TPH of previously contaminated soils but that these may not always be accompanied by changes in the microbial community. …”
Section: Bacterial Diversity In the Microcosm Soils During Bioremediamentioning
This research investigated the factors influencing bioremediation (biopile) of arid soils contaminated by weathered hydrocarbons. Five soils were thoroughly characterised to determine total petroleum hydrocarbons (TPH), their physicochemical properties and microbial diversity. Identified biopile-limiting factors are to be elevated petroleum hydrocarbon concentrations, high electrical conductivity and the magnitude of the recalcitrant hydrocarbon fraction. To optimise the biopile parameters, microcosm study was conducted which showed significant TPH reduction in three of five soils (BP-1, BP-2 and BP-4) but not in other two (BP-3 and BP-5), where BP-3 had a very high hydrocarbon concentration (123,757 mg kg -1 ) and BP-5 had a high proportion of recalcitrant hydrocarbons ([70 % of C 29 ). Highest TPH removal (68 %) occurred in soil BP-2 and the lowest (5 %) in soil BP-3 over 56 days. Surfactant (Triton) addition, nutrient amendment or the soil dilution did not improve TPH degradation in soils BP-3 and BP-5. Phylogenetic analysis conducted during the remediation process found that hydrocarbon concentration and hydrocarbon fraction exerted the main effect on bacterial abundance, diversity and assemblage composition. At lower concentrations (*1000-4000 mg kg -1 ), bacterial diversity and abundance increased significantly, whilst decreased in higher concentrations. Although high TPH content and detection of TPH degraders, TPH biodegradation is limited in soil (BP-5) due to the presence of less soluble hydrocarbon fraction which indicated low TPH bioavailability (*7 %). Biopile could be applied as a technology to remediate three soils (BP-1, BP-2 and BP-4) but further modification of the biopile treatments required for other two soils BP-3 and BP-5.
“…The addition of nutrients is known to increase the activity of indigenous microorganisms, including hydrocarbon degrading organisms. The addition of nutrients in two treatments (biostimulation and combinations bioaugmentation-biostimulation) has contributed to increased degradation of hydrocarbons that will be visible in the first three weeks of the incubation process [5].…”
Petroleum contamination in the soil is known to reach the location of groundwater resources thereby potentially contaminating groundwater that is used as the primary source of clean water. Hydrocarbon compounds contained in the petroleum are also compounds that are most difficult to breakdown. One way of overcoming this problem is by bioremediation, which is a recovery of environmental condition by utilizing biological microorganism activity to reduce levels of toxicity of pollutant compounds. The research was conducted in laboratory scale for 30 days using biostimulation methods with NPK fertilizer as nutrient. Variations are done in the level of NPK fertilizer nutrients to the contaminated soil (control, 10%, and 20%). The parameters tested include the value of total petroleum hydrocarbons (TPH), temperature, pH and total microbial colonies contained in the contaminated soil samples. Results of research showed that the addition of nutrients is as much as 20% (w/w). Bioremediation was able to reduce TPH up to 4.23% (initially 8.37% TPH) in week 4 of the research. Addition of nutrition in the form of NPK fertilizer highly affects the TPH value degradation rate in oil-contaminated soil samples. Higher concentration of NPK fertilizer added leads to better degradation rate of NPH value
Subject AreasBiological Materials
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