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| Comprehensive comparison of different nitrogen in situ conservation agents during composting |
| Received:July 16, 2017 Revised:September 19, 2017 |
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| KeyWord:composting;ammonia;struvite;greenhouse gas;cost |
| Author Name | Affiliation | E-mail | | JIANG Tao | College of Chemistry, Leshan Normal University, Leshan 614004, China
College of Resources and Environment Sciences, China Agricultural University, Beijing 100193, China | | | CHANG Jia-li | College of Chemistry, Leshan Normal University, Leshan 614004, China | | | MA Xu-guang | College of Chemistry, Leshan Normal University, Leshan 614004, China | | | LI Guo-xue | College of Resources and Environment Sciences, China Agricultural University, Beijing 100193, China | ligx@cau.edu.cn |
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| Abstract: |
| Different nitrogen in situ conservation agents, including H3PO4+MgO(PMO), superphosphate(SP), and phosphoric acid(PA), were systematically evaluated in terms of their effects on nitrogen loss control, greenhouse gas emissions during composting, and compost product quality and cost. Pig feces and maize straw were chosen as the raw materials. Sixty-liter composting vessels were used and the aeration rates were all set to 0.25 L·kg-1 DW·min-1. The application rate of the PMO and PA treatments was 15%(mole ratio) of initial total nitrogen. Compared with the CK treatment(without any additives), the PMO treatment could reduce the NH3 emissions by 55.4%, but showed no significant effect on the N2O and CH4 emissions. The composting product of the PMO treatment could be thoroughly decomposed, with the relative quantity of struvite reaching 78.3%. The SP treatment could reduce the NH3 and CH4 emissions by 37.5% and 75.0%, respectively, without any influence on N2O emissions. Calculation of the cost of nutrients conserved in the compost showed that the highest profit of 4 CNY·t-1 was obtained in the SP treatment. Although the PA treatment had the lowest NH3 emission rate(12.4% of initial TN), it conserved the nitrogen in the form of ammonium, which caused the premature termination of the compost. Even though struvite precipitation technology plays a key role in nitrogen loss control during composting, the high cost of PA prevents widespread utilization of this technology. In general, it is necessary to find cheaper alternative materials as alternatives to PA in future studies. |
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