木质生物质化学组分的碳释放产物特征和反硝化利用程度

Carbon release products and denitrification bioavailability from chemical components of woody biomass

木质生物质具有复杂的化学组分和结构,用作硝酸盐污染治理的碳源时,常出现反硝化速率缓慢和有机物残留。选择碎木作为原料,采用化学法逐级去除主要组分木质素(RL)和半纤维素(AF),获取的组分进行碳释放,释放溶液用于反硝化,拟合了碳释放动力学特征,测定了碳释放和反硝化产物的碳、氮类指标和光谱特征值。结果表明,碎木去除木质素后在1732和1251 cm^(-1)处的红外吸收峰消失。RL和AF的释碳速率分别为天然碎木(NW)的1.8倍和1.2倍,NW的速率为0.11 mg·g^(-1)·d^(-1)。碳释放过程符合二级反应动力学(相关系数R2>0.90)和Ritger-Peppas动力学(R2>0.98)特征。碳释放产物可被反硝化利用的效率为26.5%~49.7%,其中NW组最低,去除硝酸盐的碳氮比为1.0~1.5,残留有机物的腐殖化程度较低,主要为类酪氨酸。

Woody biomass has complex chemical components and structures,and when it is used as a carbon source for nitrate pollution control,it often suffers from slow denitrification rate and residual organic matter.Woodchip was selected as raw material.It was used to remove the lignin(RL),and hemicellulose(AF)by chemical methods.The acquired compositions were used for carbon release experiment,and then carbon release solution was utilized for denitrification experiment.The kinetic characteristics of carbon release were fitted.The carbon and nitrogen indexes and spectral characteristics were measured during experiments.The results showed that the infrared absorption peak disappeared at 1732 and 1251 cm^(-1)after removing lignin.The carbon release rate reached 0.11 mg·g^(-1)·d^(-1)for natural biomass(NW).Compared with NW,the rate for RL and AF was 1.8 and 1.2 times that of NW.Carbon release processes fitted with second-order reaction kinetics(R2>0.90)and Ritger-Peppas kinetics(R2>0.98).Utilization rates reached 26.5%—49.7%when using the carbon release products in denitrification,and the rate of NW was the lowest among the three groups.The C/N ratio reached 1.0—1.5 in the denitrification.The humification degree was low for residual organic matter,and it mainly was tyrosine.