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| Bioleaching of heavy metals from pig manure via indigenous sulfur-oxidizing bacteria |
| Received:April 24, 2018 Revised:July 03, 2018 |
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| KeyWord:bioleaching;pig manure;heavy metals;sulfur-oxidizing bacteria |
| Author Name | Affiliation | E-mail | | WEI Xiao-cheng | College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | | | LIU Dong-fang | College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | dongfangl@nankai.edu.cn | | LIAO Li-rui | College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | | | WANG Zhen-dong | College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | | | LI Wen-jiao | College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | | | DU Li-qiong | College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | | | LI Zhen-dong | College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China | |
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| Abstract: |
| In this study, the feasibility of employing indigenous sulfur-oxidizing bacteria to remove heavy metals from pig manure was investigated. Batch experiments were conducted to explore the effect of initial pH, inoculation level, and temperature on the bioleaching of heavy metals from pig manure. In addition, an airlift bioreactor was utilized to bioleaching heavy metals from pig manure. The results of the batch experiments showed that adjusting the pH to lower than 4 promoted the solubilization of heavy metals during pig manure bioleaching only slightly. However, increasing the level of inoculation with sulfur-oxidizing bacteria from 0 to 10% significantly accelerated the rates of pH reduction and heavy metal solubilization. Hence, the optimum inoculation volume recommended was 5% (V/V). The results also showed that the temperature significantly influenced the growth of sulfur-oxidizing bacteria and further affected the solubilization of heavy metals. The optimum temperature range for the growth of indigenous sulfur-oxidizing bacteria was 28~38℃. Finally, after 10 days of bioleaching, under the conditions of 28℃ and 180 r·min-1 with inoculation of sulfur-oxidizing bacteria, the solubilization of Cu, Zn, and Mn were all higher than 90%. In addition, when treated in the airlift bioreactor at 30℃±2℃, with an inoculation volume of 5% (V/V)and aeration of 2 L·min-1, 91.9% of the Cu, 94.9% of the Zn, 97.8% of the Mn, and 92.5% of the Cd were leached out from the pig manure after 10 days. These results demonstrate that heavy metals in pig manure can be efficiently removed by indigenous sulfur-oxidizing bacteria without having to pre-acidify the manure. |
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