畜禽粪便与秸秆混合发酵及贮藏阶段沼液中碳氮元素变化

为研究沼液从产生到贮藏期间碳氮元素的变化规律,将猪粪、鸡粪和秸秆混合,进行中温厌氧发酵,并在常温下以密闭静置、密闭搅拌、敞口静置、敞口搅拌等4种方式贮藏沼液,跟踪并分析了猪、鸡粪和秸秆混合发酵沼液在厌氧发酵及贮藏期间碳、氮元素的形态和含量变化。结果表明:厌氧发酵阶段,沼液中的总有机碳(TOC)和总氮(TN)浓度均有所增加,增加幅度在15.0%~36.1%之间,其中TOC在第18 d达到最高浓度(6467 mg·L~(-1)),TN在第23 d达到最高浓度(4181 mg·L~(-1))。贮藏阶段,沼液中的TOC、TN浓度均有所降低,TOC先下降后升高,总体降低幅度较小(2.9%~12.0%),降幅顺序为敞口静置敞口搅拌密闭静置密闭搅拌;TN先升高后降低,总体降低幅度较大(4.2%~56.2%),降幅顺序为密闭静置密闭搅拌敞口静置敞口搅拌。综上,厌氧发酵18~23 d的沼液碳氮元素含量最高,采用密闭静置方式并缩短贮藏时间可减少沼液贮藏过程氮元素的损失。

Changes in carbon and nitrogen in biogas slurry during mixed anaerobic fermentation and storage of animal manure and straw

In order to investigate changes in carbon and nitrogen in biogas slurry during anaerobic fermentation and storage, in the present study, pig manure, chicken manure, and straw were mixed to perform mesophilic anaerobic fermentation for 30 days. Afterwards, the biogas slurry was stored at room temperature for 30 days under 4 treatment conditions:closed and settled (CS), closed and agitated (CA), opened and settled (OS), and opened and agitated (OA). The forms and concentrations of carbon and nitrogen were tracked and analyzed in biogas slurry over the entire duration of the fermentation. Results showed that during anaerobic fermentation, total dissolved organic carbon and organic nitrogen in biogas slurry increased significantly, while other forms of carbon and nitrogen increased slightly, which resulted in a 15.0%~36.1% increase in total organic carbon (TOC) and total nitrogen (TN). TOC concentration reached its peak (6467 mg·L^-1) on day 18 of fermentation, and TN concentration reached its peak (4181 mg·L^-1) on day 23. After 30 days of storage of biogas slurry, TOC and TN concentrations both decreased. TOC concentrations first decreased and then increased slowly during storage, with an overall decrease of between 2.9% and 12.0%. The order of decrease of TOC concentrations from the lowest to the highest degree was:OS < OA < CS < CA. TN concentrations first increased and then decreased during storage, with an overall decrease of between 4.2% and 56.2%. The order of decrease of TN concentrations was:CS < CA < OS < OA. Therefore, during the period between days 18 and 23 of anaerobic fermentation, TOC and TN concentrations reached peak levels in biogas slurry. The use of the closed and settled treatment and shorter storage time could effectively reduce nitrogen loss in biogas slurry during its storage.