Amir Hossein Baghaie; Mohammad Fereydoni
Abstract
Background: This descriptive study was conducted to evaluate the interaction effects of sewage sludge and its biochar on anthracene biological degradation in a Pb polluted soil under sunflower cultivation Methods: Treatments consisted of applying three rates of anthracene (0, 12.5 ...
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Background: This descriptive study was conducted to evaluate the interaction effects of sewage sludge and its biochar on anthracene biological degradation in a Pb polluted soil under sunflower cultivation Methods: Treatments consisted of applying three rates of anthracene (0, 12.5 and 25 mg/kg soil), two levels of sewage sludge and its biochar (0 and 30 t/ha) in the presence of Azetobacter bacteria and Piriformospora indica (P. indica) fungus. After 60 days, plants were harvested and plant Pb concentration was measured using atomic absorption spectroscopy. In addition, the soil petroleum hydrocarbons concentration and soil microbial respiration were measured by the method described by Besalatpour et al. (2011). The catalyze enzyme activity was assayed. Results: Plant inoculation with P.indica and Azotobacter significantly increased the degradation of anthracene in soil by 12.8% in the soil treated with 25 mg anthracene/kg soil. In addition, the soil Pb availability was decreased by 14.6% in the mentioned treatment. Applying 30 t/ha sewage sludge and its biochar significantly increased the plant biomass and anthracene degradation in the soil treated by 12.5 mg anthracene /kg soil by 13.5% and 12.6%, respectively. Conclusion: Soil treated with sewage sludge and its biochar had a positive effect on plant resistance to abiotic stresses and degradation of anthracene in the soil. Among this, plant inoculation with P. indica and Azotobacter had also an additive effect on bio-remediation of anthracene in the soil that is a positive point in environmental studies. However, soil pollution with heavy metals had an adverse effect on it.
Hassan Hashemi; Abbas Khodabakhshi; Bahram Alinia; Fariba Abbasi
Abstract
Background: This study investigated the bioremediation of lead and zinc in contaminated soils by the compost worm Eisenia Fetida. Methods: The initial concentrations of 50 and 100 mg/kg for zinc and lead respectively as well as 40 mg/kg and 80 mg/kg for the control group were studied. 30 earthworms were ...
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Background: This study investigated the bioremediation of lead and zinc in contaminated soils by the compost worm Eisenia Fetida. Methods: The initial concentrations of 50 and 100 mg/kg for zinc and lead respectively as well as 40 mg/kg and 80 mg/kg for the control group were studied. 30 earthworms were used for bioremediation of 500g samples of the polluted soils during 14 and 28 days. Then, Pb and Zn were measured by atomic absorption kit (Varian 240) in the soil and earthworm’s tissue. Results: The mortality rate of earthworms was insignificant statistically, so that it was lower than 20% when exposed to 86 mg/L of lead. Moreover, the removal efficiency of Pb and Zn was higher than 90% in th soil. Initial concentration of Pb and Zn was 3 and 6 mg/kg and the bioaccumulation was 0.16 and 32 μg/g respectively during 14 days, while they were 0.31 and 59 μg/g at the end of 28 days. The removal efficiency of Pb and Zn was increased as the exposure time and concentration of Pb and Zn in the earthworm bodies increased. Conclusion: As a consequence, the use of earthworms is an appropriate organic and cost-effective method for bioremediation of Pb and Zn significantly. However, the improvement and modification of bioaccumulation in earthworm bodies is an environmental challenge that should be managed.
majid nozari; Mohammad Reza Samaei; Mansooreh Dehghani
Volume 2, Issue 3 , July 2014, , Pages 113-124
Abstract
Background: Among Alkanes, N-Alkanes with medium chain have been identified as the most important contaminants of the soil. N-hexadecane (C16H34) with low solubility in water also belongs to this group and has been used by many researchers as a model contaminant. The present study aimed to investigate ...
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Background: Among Alkanes, N-Alkanes with medium chain have been identified as the most important contaminants of the soil. N-hexadecane (C16H34) with low solubility in water also belongs to this group and has been used by many researchers as a model contaminant. The present study aimed to investigate the effect of the external source of carbon (glucose) as co-substrate on removal of hexadecane from the soil.Methods: In this study, a Slurry Sequencing Batch Reactor (SSBR) was used as a pilot by a bacterial consortium, including bacterium Acinetobacter radioresistens, Bacillus subtilis, and Pseudomonas aeruginosa, in order to remove different concentrations of hexadecane (1,4,7, and 10 percent).Sampling was performed four times during the sedimentation step. Then, the samples were analyzed by GC-FID and the results were analyzed statistically.Results: The results showed that hexadecane removal (%) by the microbial consortium was higher in lower initial concentrations in such a way that the biological removal of hexadecane was respectively 45.95%, 38.55%, 34.39%, and 32.40% in the concentrations of 1%, 4%, 7%, and 10% on the third day. Moreover, adding the external carbon source (glucose) on the first day caused a 16% increase in hexadecane removal, which is 1.4 times more than the amount of hexadecane removal in the conditions without co-metabolism.Conclusion: The results showed that SSBR could be used as an exit-situation effective method for hexadecane removal in low concentrations through considering the effective factors in its function, such as dissolved oxygen, pH, and temperature. Also, adding the secondary carbon source could be effective in hexadecane removal from the soil. Yet, this effect might vary on different days.
