Hoover Natasha L, Bhandari Alok, Soupir Michelle L, Moorman Thomas B
J Environ Qual. 2016 May;45(3):803-12. doi: 10.2134/jeq2015.03.0161.
Woodchip denitrification bioreactors, a relatively new technology for edge-of-field treatment of subsurface agricultural drainage water, have shown potential for nitrate removal. However, few studies have evaluated the performance of these reactors under varied controlled conditions including initial woodchip age and a range of hydraulic retention times (HRTs) and temperatures similar to the field. This study investigated (i) the release of total organic C (TOC) during reactor start up for fresh and weathered woodchips, (ii) nitrate (NO-N) removal at HRTs ranging from 2 to 24 h, (iii) nitrate removal at influent NO-N concentrations of 10, 30, and 50 mg L, and (iv) NO-N removal at 10, 15, and 20°C. Greater TOC was released during bioreactor operation with fresh woodchips, whereas organic C release was low when the columns were packed with naturally weathered woodchips. Nitrate-N concentration reductions increased from 8 to 55% as HRT increased. Nitrate removal on a mass basis (g NO-N m d) did not follow the same trend, with relatively consistent mass removal measured as HRT increased from 1.7 to 21.2 h. Comparison of mean NO-N load reduction for various influent NO-N concentrations showed lower reduction at an influent concentration of 10 mg L and higher NO-N reductions at influent concentrations of 30 and 50 mg L. Nitrate-N removal showed a stepped increase with temperature. Temperature coefficient () factors calculated from NO-N removal rates ranged from 2.2 to 2.9.
木片反硝化生物反应器是一种用于农田边缘地下农业排水处理的相对较新的技术，已显示出硝酸盐去除的潜力。然而，很少有研究评估这些反应器在不同控制条件下的性能，包括初始木片年龄以及一系列与田间相似的水力停留时间（HRT）和温度。本研究调查了：（i）新鲜木片和风化木片在反应器启动期间总有机碳（TOC）的释放；（ii）水力停留时间在2至24小时范围内时硝酸盐（NO₃-N）的去除情况；（iii）进水NO₃-N浓度为10、30和50 mg/L时的硝酸盐去除情况；以及（iv）在10、15和20°C下的NO₃-N去除情况。使用新鲜木片时，生物反应器运行期间释放的TOC更多，而当柱中填充天然风化木片时，有机碳释放量较低。随着水力停留时间的增加，硝酸盐氮浓度降低率从8%增加到55%。以质量计的硝酸盐去除量（g NO₃-N m⁻² d⁻¹）并未遵循相同趋势，随着水力停留时间从1.7小时增加到21.2小时，质量去除量相对稳定。对不同进水NO₃-N浓度下平均NO₃-N负荷降低情况的比较表明，进水浓度为10 mg/L时降低率较低，而进水浓度为30和50 mg/L时NO₃-N降低率较高。硝酸盐氮去除率随温度呈阶梯式增加。根据NO₃-N去除率计算的温度系数（θ）因子范围为2.2至2.9。
