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| The leaching characteristics of heavy metals from hydrochars of digested swine manure |
| Received:June 19, 2017 |
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| KeyWord:hydrochar;digested swine manure;heavy metal;leaching characteristics |
| Author Name | Affiliation | E-mail | | ZHENG Meng-jie | Circular Agriculture Research Center, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
College of Environment, Hohai University, Nanjing 210098, China | | | JIN Hong-mei | Circular Agriculture Research Center, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
Jiangsu Agricultural Waste Treatment and Recycle Engineering Research Center/East China Scientific Observing and Experimental Station of Development and Utilization of Rural Renewable Energy, Ministry of Agriculture, Nanjing 210014, China | hmjin@jaas.ac.cn | | ZHANG Song-he | College of Environment, Hohai University, Nanjing 210098, China | | | LI Ji-zhou | College of Environment, Hohai University, Nanjing 210098, China | |
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| Abstract: |
| Hydrothermal carbonization(HTC) is an effective way to treat high water content waste, such as digested animal manure. In order to clarify the leaching characteristics of heavy metals in hydrochars derived from digestates, research was conducted on digested swine manure(M-R) that was hydrothermally carbonized at 190℃ and 250℃, and the corresponding hydrochars(M-190 and M-250, respectively) were used to study the total contents of Zn, Cu, As, Pb, and Cd and their leaching characteristics from the hydrochars under different pH conditions. Compared with M-R, the total contents of Zn, Cu, and As in M-190 were higher by 4.12%, 7.00%, and 26.57%, respectively, whereas those in M-250 were higher by 18.99%, 14.00%, and 289.70%. On the contrary, the total amount of Pb and Cd decreased after HTC. The contents of dissolved heavy metals in M-190 and M-250 were significantly(P<0.001) lower than those in M-R. Meanwhile, the contents of dissolved heavy metals in M-250 were remarkably(P<0.001) lower than those in M-190. The contents of dissolved Zn, Cu, Pb, and Cd in M-250 were lower by 50.99%, 95.50%, 66.47%, and 100.00%, respectively, compared to those in M-190. The leaching contents of heavy metals in the hydrochars reached their maximum at pH 2. After that, their leaching contents decreased sharply with an increase of pH. The leaching contents were similar as the pH ranged from 4 to 10. The results showed that HTC had an enrichment effect on Zn, Cu, and As in M-190 and M-250, and appropriately raising the HTC temperature reduced the contents of dissolved heavy metals in the hydrochars. This study is not only beneficial to the safety assessment of hydrochars of digested swine manure, but HTC is an effective way to treat digested swine manure harmlessly. |
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