超高温预处理对畜禽粪便好氧堆肥腐殖化影响的机制

Composting, especially when rapid, is a useful way of transforming organic wastes into valuable organic amendments for soils. The amounts and chemical structure of the humic material constitute are the main indice for assessing the stability and maturity of the compost. Previous study showed hyperthermophilic (>80℃) pretreatment of animal wastes for 1 to 2 hours was able to increase composting efficicency and accelerate the process of composting significantly, but the regularity and mechanism are not clear. It is hypothesized that hyperthermophilic pretreatment could accelerate and enhance the humification process by promoting the production and transformation of humic precusors and changing the microbial evolution in composting process. As a result, indoor simulation and compost experiments will be carried out to study the degree of humification during the pretreatment process and the subsequent composting process of pig manure by using advanced analysis techniques including fourier transform infrared spectroscopy (FTIR), 13C nuclear magnetic resonance (13C-NMR), real-time PCR and MiSeq high throughput sequencing. The reponses of humic precursors, Fe-, Mn-oxides and microbes in the feedstocks to the hyperthermophilic pretreatment will also be investigated. The factors influencing the humification process of pig manure composting by thermophilic pretreatment were explained from the aspects of composition of organic matter and microbial evolution. The results obtained will enrich compost theory and provide scientific basis for developing low-carbon and high-efficiency composting technology.

腐殖化是堆肥过程主要特征之一，腐殖化进程与程度可表征堆肥中微生物学过程与堆肥产品质量优劣。前期研究发现，1～2h超高温预处理(>80℃)可显著加速后续堆肥腐殖化进程，且腐殖化程度与常规堆肥差异显著。推断：超高温预处理可能影响堆肥腐殖质合成前体物质生成和微生物学过程，进而影响堆肥腐殖化。为此，以猪粪为原料，采用室内模拟与堆肥试验，运用傅立叶红外光谱、13C核磁共振、定量PCR、高通量测序等手段，分析原料在预处理过程和后续堆肥过程中腐殖化进程和程度，探讨腐殖质前体物质、铁锰氧化物、微生物对预处理的响应；从预处理对原料物质结构组成和微生物区系等方面阐释超高温预处理促进畜禽粪便腐殖化的影响因素和作用机制，为丰富堆肥理论与开发低碳高效堆肥新技术提供科学依据。

腐殖化是堆肥过程主要特征之一，腐殖化进程与程度可表征堆肥中微生物学过程与堆肥产品质量优劣。项目以猪粪为原料，采用室内模拟与堆肥试验，运用傅立叶红外光谱、13C核磁共振、高通量测序等手段，分析原料在预处理过程和后续堆肥过程中腐殖化进程和程度，探讨腐殖质前体物质、微生物对预处理的响应；从预处理对原料物质结构组成和微生物区系等方面阐释超高温预处理促进畜禽粪便腐殖化的影响因素和作用机制。研究发现,常规堆肥（CK）有机质最大降解度（42.58%）比超高温预处理堆体（HPC）（49.29%）小，但降解速率常数(0.1 d-1)高于HPC (0.07 d-1)，两种堆肥工艺碳素降解率差异不显著。HPC堆体NH4+-N、TN质量分数平均比CK高143.9%、11.2%，而NO3--N质量分数则比CK低58.8%。HPC堆肥后期胡敏酸含量及腐殖质聚合程度分别比CK高45.2%~56.8%、59.1%~65.3%。堆肥物料经过超高温预处理，腐殖酸合成前体物质多酚和氨基酸的浓度分别提高了76.3％和10.6％，多糖和还原糖分别增加了15.17%、21.17%。与CK相比，HPC中的纤维素含量明显下降，堆肥中后期HPC纤维素酶活性比CK高18.13%。HPC处理的HS含有较大比例的O-烷基C（56和72 ppm，38.9％）和芳族C（148和153 ppm，25.6％），但与CK相比，烷基C的比例较低（30和34 ppm，16.2％）。高通量测序与传统平板计数结果均表明，HPC堆肥高温和腐熟阶段嗜热细菌和放线菌的数量要显著高于CK。嗜热细菌增加幅度为9.7~121.1倍，嗜热放线菌增加幅度为0.9~14.8倍。堆肥过程中放线菌种群数量的增加可能是超高温预处理可以加快纤维素，半纤维素和木质素等大分子的降解，提高堆肥效率，加快腐殖化进程的微生物机制。以上研究结果为丰富堆肥理论与开发低碳高效堆肥新技术提供科学依据。