Bock Emily, Smith Nick, Rogers Mark, Coleman Brady, Reiter Mark, Benham Brian, Easton Zachary M
J Environ Qual. 2015 Mar;44(2):605-13. doi: 10.2134/jeq2014.03.0111.
Denitrifying bioreactors (DNBRs) are an emerging technology used to remove nitrate-nitrogen (NO) from enriched waters by supporting denitrifying microorganisms with organic carbon in an anaerobic environment. Field-scale investigations have established successful removal of NO from agricultural drainage, but the potential for DNBRs to remediate excess phosphorus (P) exported from agricultural systems has not been addressed. We hypothesized that biochar addition to traditional woodchip DNBRs would enhance NO and P removal and reduce nitrous oxide (NO) emissions based on previous research demonstrating reduced leaching of NO and P and lower greenhouse gas production associated with biochar amendment of agricultural soils. Nine laboratory-scale DNBRs, a woodchip control, and eight different woodchip-biochar treatments were used to test the effect of biochar on nutrient removal. The biochar treatments constituted a full factorial design of three factors (biochar source material [feedstock], particle size, and application rate), each with two levels. Statistical analysis by repeated measures ANOVA showed a significant effect of biochar, time, and their interaction on NO and dissolved P removal. Average P removal of 65% was observed in the biochar treatments by 18 h, after which the concentrations remained stable, compared with an 8% increase in the control after 72 h. Biochar addition resulted in average NO removal of 86% after 18 h and 97% after 72 h, compared with only 13% at 18 h and 75% at 72 h in the control. Biochar addition also resulted in significantly lower NO production. These results suggest that biochar can reduce the design residence time by enhancing nutrient removal rates.
反硝化生物反应器（DNBRs）是一种新兴技术，用于在厌氧环境中通过向反硝化微生物提供有机碳来去除富营养化水体中的硝酸盐氮（NO）。实地规模的调查已证实可成功去除农业排水中的NO，但DNBRs修复农业系统中过量输出的磷（P）的潜力尚未得到研究。基于先前研究表明生物炭改良农业土壤可减少NO和P的淋溶并降低温室气体产量，我们推测在传统木屑DNBRs中添加生物炭可提高NO和P的去除率并减少一氧化二氮（NO）排放。使用九个实验室规模的DNBRs、一个木屑对照以及八种不同的木屑 - 生物炭处理来测试生物炭对养分去除的影响。生物炭处理采用了三个因素（生物炭源材料[原料]、粒径和施用量）的全因子设计，每个因素有两个水平。通过重复测量方差分析进行的统计分析表明，生物炭、时间及其相互作用对NO和溶解性P的去除有显著影响。在生物炭处理中，18小时后观察到平均P去除率为65%，此后浓度保持稳定，相比之下，对照在72小时后增加了8%。添加生物炭后，18小时后平均NO去除率为86%，72小时后为97%，而对照在18小时时仅为13%，72小时时为75%。添加生物炭还导致NO产量显著降低。这些结果表明，生物炭可通过提高养分去除率来缩短设计停留时间。
