Microbial treatments of certain non-hydrocarbon pollutants in lubricating oil wastes
Amal Salah Mohamed Hassan;
Abstract
Used lubricant oils are the most frequent environmental pollutants which contain contaminants such as heavy metals. They massively discharged to the environment due to their large scale use. This study attempted to apply an environmentally friendly and effective technology to remove heavy metals and degrade hydrocarbons of used lubricant oil.
Caltex lubricant motor oil (1000 Km) was selected as a model of used motor oil for the present study. The used motor oil was chemically analyzed by Inductively Coupled Plasma Optical Emission Spectrometer (ICP -OES). Different metals were found with different concentrations. The most abundant metals were Zn, Ca, Ni and Fe in concentrations 1139.5 ±1.7, 382 ±1.4, 202 ±1.4 and 195 ± 0.18 ppm respectively. According to the previous results and previously known health hazards of heavy metals, Zn and Ni were targeted for removal from used oils in the present study.
In this study, five soil samples (S1, S2, S3, S4, S5) were collected from different locations in Egypt. Soil samples: S1, S2 and S3 were collected from mechanical workshops from different areas in Cairo, while S4 and S5 were collected upon Maize field and Clover field soils from El –kalubia respectively. Soil samples were chemically and microbiologically analyzed. They contained different heavy metals in different concentrations. The concentrations of Ni in the collected soil samples ranged from 6.7 ± 0.28 (S5) to 40.95 ± 1.2 (S1) ppm and the concentrations of Zn ranged from 68.2 ± 1.3(S5) to 113.5 ±1.2 (S1) ppm respectively. While, the total petroleum hydrocarbons in samples ranged from 1570 ± 1.1 (S5) to 103240 ± 1.6 (S1) µg/g, the total heterotrophic bacterial counts (HC) in all samples ranged from 1.6 x 107 ± 0.08 to 3.2 x 107 ± 0.04 CFU/g, while for heavy metals resistant bacterial counts (HRB) grown on MSO plates containing 5mM of Ni and Zn separately, Ni resistant bacterial counts ranged 1.8x 104 ± 0.03 to 3.5 x 105 ± 0.02 CFU/g, while Zn resistant bacterial counts ranged from 1.6 x 105 ± 0.06 to 3.7 x 106 ± 0.02 CFU/g. The ratio (HRB/HC) % ranged from 0.09 to 10.8 % for all samples.
25 bacterial isolates were isolated from the five soil samples on MSO plates. Only 15 bacterial isolates were selected as promising isolates for Ni and Zn removal and TPH biodegradation of used lubricant oil due to their short incubation periods required to grow on MSO plates which contain used lubricant oil as a sole source of carbon and energy. Also due to their abilities to grow at broad range of incubation temperatures (15 to 42 oC) in addition to their special ability to grow well at very high concentrations of used lubricant oil (up to 50000ppm).
All the selected (15) isolates were able to remove Ni, Zn and degrade TPH of used lubricant oil. The maximum removal of Ni and Zn as well as TPH biodegradation was recorded by HM16, HM24 and HM7. Also, the consortia from soil sample (S1) showed the highest percentage of Ni and Zn removal and TPH biodegradation of used lubricant oil.
The optimal environmental conditions for Ni and Zn removal as well as TPH degradation by HM16, HM24 and HM7 were found to be 10 days incubation period, 37 o C incubation temperature, pH 7, aeration condition 150 rpm and fertilizing system W4.
The most promising bacterial isolates HM16, HM24 and HM7, respectively, were exposed to increasing doses of gamma radiation 0.25, 0.5, 1.0, 1.5, 2.0 and 2.5kGy. The calculated D10-values of HM16, HM24 and HM7 were found to be 0.45, 0.54 and 0.37 kGy, respectively.
The irradiated bacterial cell mixtures of each of the most promising isolates HM16, HM24 and HM7, showed higher percentage in Ni, Zn and TPH loss than the control (non-irradiated). On the other hand, The highest percentages of Ni and Zn removal and TPH biodegradation (47.5 ± 0.51, 39.2 ± 0.47and 39.5 ± 0.98 %), (46.5 ± 0.48, 33.6 ± 0.46 and 35.6 ± 0.78 %) and (43.3 ± 0.46 , 27.2 ± 0.63 and 31.7 ± 1.1 %) respectively have been obtained by HM16, HM24 and HM7 isolates, respectively, exposed to 0.7 kGy.
Caltex lubricant motor oil (1000 Km) was selected as a model of used motor oil for the present study. The used motor oil was chemically analyzed by Inductively Coupled Plasma Optical Emission Spectrometer (ICP -OES). Different metals were found with different concentrations. The most abundant metals were Zn, Ca, Ni and Fe in concentrations 1139.5 ±1.7, 382 ±1.4, 202 ±1.4 and 195 ± 0.18 ppm respectively. According to the previous results and previously known health hazards of heavy metals, Zn and Ni were targeted for removal from used oils in the present study.
In this study, five soil samples (S1, S2, S3, S4, S5) were collected from different locations in Egypt. Soil samples: S1, S2 and S3 were collected from mechanical workshops from different areas in Cairo, while S4 and S5 were collected upon Maize field and Clover field soils from El –kalubia respectively. Soil samples were chemically and microbiologically analyzed. They contained different heavy metals in different concentrations. The concentrations of Ni in the collected soil samples ranged from 6.7 ± 0.28 (S5) to 40.95 ± 1.2 (S1) ppm and the concentrations of Zn ranged from 68.2 ± 1.3(S5) to 113.5 ±1.2 (S1) ppm respectively. While, the total petroleum hydrocarbons in samples ranged from 1570 ± 1.1 (S5) to 103240 ± 1.6 (S1) µg/g, the total heterotrophic bacterial counts (HC) in all samples ranged from 1.6 x 107 ± 0.08 to 3.2 x 107 ± 0.04 CFU/g, while for heavy metals resistant bacterial counts (HRB) grown on MSO plates containing 5mM of Ni and Zn separately, Ni resistant bacterial counts ranged 1.8x 104 ± 0.03 to 3.5 x 105 ± 0.02 CFU/g, while Zn resistant bacterial counts ranged from 1.6 x 105 ± 0.06 to 3.7 x 106 ± 0.02 CFU/g. The ratio (HRB/HC) % ranged from 0.09 to 10.8 % for all samples.
25 bacterial isolates were isolated from the five soil samples on MSO plates. Only 15 bacterial isolates were selected as promising isolates for Ni and Zn removal and TPH biodegradation of used lubricant oil due to their short incubation periods required to grow on MSO plates which contain used lubricant oil as a sole source of carbon and energy. Also due to their abilities to grow at broad range of incubation temperatures (15 to 42 oC) in addition to their special ability to grow well at very high concentrations of used lubricant oil (up to 50000ppm).
All the selected (15) isolates were able to remove Ni, Zn and degrade TPH of used lubricant oil. The maximum removal of Ni and Zn as well as TPH biodegradation was recorded by HM16, HM24 and HM7. Also, the consortia from soil sample (S1) showed the highest percentage of Ni and Zn removal and TPH biodegradation of used lubricant oil.
The optimal environmental conditions for Ni and Zn removal as well as TPH degradation by HM16, HM24 and HM7 were found to be 10 days incubation period, 37 o C incubation temperature, pH 7, aeration condition 150 rpm and fertilizing system W4.
The most promising bacterial isolates HM16, HM24 and HM7, respectively, were exposed to increasing doses of gamma radiation 0.25, 0.5, 1.0, 1.5, 2.0 and 2.5kGy. The calculated D10-values of HM16, HM24 and HM7 were found to be 0.45, 0.54 and 0.37 kGy, respectively.
The irradiated bacterial cell mixtures of each of the most promising isolates HM16, HM24 and HM7, showed higher percentage in Ni, Zn and TPH loss than the control (non-irradiated). On the other hand, The highest percentages of Ni and Zn removal and TPH biodegradation (47.5 ± 0.51, 39.2 ± 0.47and 39.5 ± 0.98 %), (46.5 ± 0.48, 33.6 ± 0.46 and 35.6 ± 0.78 %) and (43.3 ± 0.46 , 27.2 ± 0.63 and 31.7 ± 1.1 %) respectively have been obtained by HM16, HM24 and HM7 isolates, respectively, exposed to 0.7 kGy.
Other data
| Title | Microbial treatments of certain non-hydrocarbon pollutants in lubricating oil wastes | Other Titles | المعالجات الميكروبيه لبعض الملوثات غير الهيدروكربونيه الموجوده فى مخلفات زيوت التشحيم | Authors | Amal Salah Mohamed Hassan | Issue Date | 2015 |
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