生物炭填充方式与老化对生物滞留氮磷淋失的影响

Effect of Biochar Filling Mode and Aging on Leaching of Nitrogen and Phosphorus in Bioretention Facilities

为了考察添加生物炭对生物滞留设施基质特性以及养分淋失的影响,采用去离子水对不同基质进行降雨淋洗模拟实验。结果显示,添加生物炭后基质的饱和导水率、滞留能力平均提高21%、41%,并且N、P养分的累积淋失量降低。添加老化前的生物炭,混合式填充方式比分层式填充方式基质的饱和导水率更高、滞留能力更好;生物炭老化后,亲水性、极性、酸性官能团增加,静电斥力降低,而且干湿交替方式比恒湿方式的老化作用更强。基质的饱和导水率、滞留能力、氮磷的累积淋失减控能力随生物炭老化作用的增强而增强,生物炭的这一特性有望用于生物滞留设施基质中N、P淋失的长效控制。

In order to investigate the effects of biochar addition on characteristics and nutrient leaching in bioretention facilities,deionized water was used to simulate the precipitation leaching of different substrates.After adding biochar,saturated water conductivity and retention capacity of the substrates increased by 21%and 41%on average,and the accumulative leaching of nitrogen and phosphorus nutrients was reduced.After adding pre-aging biochar,the substrate with mixed biochar filling showed higher saturated hydraulic conductivity and retention capacity than those of stratified filling.After aging,the hydrophily,polarity and acidic functional groups of the biochar increased and the electrostatic repulsion decreased,and alternating wetting and drying mode had stronger aging effect than the constant wetting mode.The saturated water conductivity,retention capacity and cumulative leaching loss control ability of nitrogen and phosphorus increased with aging of the biochar.Therefore,this property of biochar was expected to be used for long-term control of nitrogen and phosphorus leaching in substrate of bioretention facilities.