蚯蚓对城镇污泥堆肥过程稳定化路径的影响

Effect of Earthworms on Stabilization Path of the Composting Process for Municipal Sludge

在20℃条件下,利用蚯蚓(Eisenia foetida)堆肥处理5 mm粒径城镇污泥,通过考察宏观理化指标的变化,研究了蚯蚓对城镇污泥堆肥过程稳定化路径的影响,并采用PCR-DGGE技术探究了微生物种群结构的变化。理化指标结果显示,随着堆肥时间的延长,蚯蚓处理组和对照组的有机质(OM)、DOC、NH_(4)^(+)-N变化趋势基本一致。其中,OM均显著降低、DOC先升高后降低、NH_(4)^(+)-N均显著升高,对照组的NO_(3)^(-)-N含量始终维持在较低水平,蚯蚓处理组的NO_(3)^(-)-N含量在50 d后出现激增。堆肥结束时,蚯蚓处理组的OM、DOC显著低于对照组(p<0.05),NH_(4)^(+)-N和NO_(3)^(-)-N含量显著高于对照组(p<0.05)。主成分分析(PCA)结果表明:蚯蚓处理组和对照组稳定化过程均需依次经历有机质降解、溶解性有机碳积累、氨化和硝化为特征的反应历程。蚯蚓仅提高了城镇污泥的稳定化速率,但并未改变其稳定化路径。PCR-DGGE结果显示:堆肥结束时,蚯蚓处理组和对照组均以分解木质素、纤维素、几丁质等难降解有机质的微生物种群为主,并且蚯蚓增强了系统中被孢霉目(Mortierellales)微生物的相对丰度,能够削减堆肥产物中的植物致病菌。蚯蚓通过改变系统环境,进而促进系统微生物种群的更替,但并未颠覆系统的微生物种群结构。

At 20℃,Eisenia foetida was used to treat municipal sludge with a particle size of 5 mm.The influence of earthworms on the stabilization path of municipal sludge composting process was studied by examining the changes in physicochemical indicators,and the changes in microbial population structure were explored using PCR‐DGGE technology.The results indicated that the change trend of both the earthworm treatment group and control group were essentially identical.As composting time increased,organic matter(OM)decreased significantly,dissolved organic carbon(DOC)initially increased and then decreased,NH_(4)^(+)-N increased significantly,NO_(3)^(-)-N in the control group remained low while it sharply rose after 50 days in the earthworm treatment group.At the end of composting,OM and DOC were considerably lower in the earthworm treatment group than those in the control group(p<0.05),whereas NH_(4)^(+)-N and NO_(3)^(-)-N were notably higher than those in the control group(p<0.05).Principal component analysis(PCA)revealed that both groups’stabilization process was characterized by degradation of organic matter,accumulation of DOC,ammonification and nitrification in order.Earthworms only accelerated municipal sludge’s stabilization rate but did not alter its stabilization path.The results of PCR‐DGGE analysis revealed that both the earthworm treatment group and the control group exhibited a dominance of microorganisms involved in lignin,cellulose,chitin,and other refractory organic matter at the end of composting.Additionally,there was an enhanced relative abundance of Mortierellales within the system which contributed to a reduction in plant pathogens present in the compost products.Earthworms facilitate changes in the environmental conditions promoting microbial population turnover without disrupting its overall structure.