超高温预处理装置及其促进鸡粪稻秸好氧堆肥腐熟效果

为提高畜禽粪便堆肥效率和质量,设计了一种超高温预处理好氧堆肥工艺,并以鸡粪和稻秸为原料,进行了为期62 d的堆肥试验。设置了3个处理,即:高温好氧堆肥(CK);超高温(85℃)预处理4 h+高温好氧堆肥(HPC);超高温(85℃)预处理4 h+接种0.5%新鲜鸡粪+高温好氧堆肥(I-HPC)。监测了堆体的温度、含水率、pH值等参数的变化情况,并以C/N、可溶性有机碳(dissolved organic carbon,DOC)、铵态氮、硝态氮、腐殖化指数(humification index,HI)、种子发芽指数(germination index,GI)为指标评价了堆肥腐熟度和质量。结果表明,与CK相比,超高温预处理可以提高后续堆料升温速率和最高温度、延长高温期天数、缩短堆肥周期,I-HPC、HPC的最高温度比CK分别高出13.6、12.8℃,≥50℃的天数分别比CK多3、2 d。但与HPC相比,接种新鲜鸡粪并没有加快后续堆肥进程。超高温预处理后,物料容重由0.81 g/cm~3下降为0.72 g/cm~3、pH值下降了1~2;而DOC质量分数由106 g/kg上升到124 g/kg;总挥发性脂肪酸(total volatile fatty acids,TVFAs)、NH_4~+-N质量分数分别为预处理前的3.2倍、2.45倍。HPC、I-HPC堆体有机质降解速率常数分别为0.0501、0.0534 d-1,比CK(0.00143 d-1)大,因此,HPC、I-HPC堆肥产品的TOC质量分数(182.1、192.1 g/kg)分别比CK(205.3 g/kg)低;TN质量分数(19.70、21.28 g/kg)比CK(17.96 g/kg)高;腐殖化指数(0.77、0.71)比CK(0.64)高。但HPC、I-HPC堆肥产品之间TN质量分数、腐殖化指数无显著差异。因此,超高温预处理好氧堆肥法能明显缩短堆肥周期、提高堆肥产品质量,具有较大的应用潜力。

Hyperthermophilic pretreatment device and its application on improving decomposition effect for chicken manure and rice straw aerobic composting

Composting is a process of controlling and enhancing the biological decomposition of organic residues into usable end product such as organic fertilizer. However, the disadvantages of malodor problems, long processing cycle and N loss caused by traditional composting plants, and are particularly problematic in countries with high population densities. The particle size, moisture content, C/N ratio and temperature are the key parameters influencing the process. In this study, we established a novel hyperthermophilic pre-treatment (HTPRT) method that used a temperature-adjustable HTPRT reactor for pre-heating of feedstocks, and then the in-vessel post-composting (IPC) process to mature composts. The feedstocks for composting were mainly chicken manures and rice straw. Three treatments included the control (conventional composting, CK), HTPRT (85℃, 4 h) followed by an IPC process (HPC), the HTPRT process (85℃, 4 h) followed by an IPC process inoculated with fresh chicken manures (0.5%, dry weight basis) (I-HPC). The composting treatments were in triplicate and lasted for 62 days. Temperature, pH value and moisture dynamics and organic material decrement were determined. C/N ratio, dissolved organic carbon (DOC), NH4+-N, NO3--N, humification index (HI) and germination index (GI) had been chosen for the determination of compost stability and maturity, and the comparison among the three composting techniques. HTPRT accelerated organic matter degradation during the thermophilic phase and prolonged the thermophilic phase in the IPC process. The maximum composting temperature in HPC and I-HPC treatments were 13.6 and 12.8℃ higher than that in CK. The thermophilic period of composting (≥50℃) in HPC and I-HPC treatments lasted 2 and 3 days longer than that in CK. The IPC process was reduced significantly in comparison with the traditional composting process. However, addition of the fresh chicken manure did not accelerate HTPRT-IPC process, no significant difference was found in composting cycle between HPC and I-HPC. After HTPRT, the bulk density of the residues was reduced from 0.81 to 0.72 g/cm3and the pH value was declined by 1-2. However, the content of DOC was increased from 106 to 124 g/kg, and total volatile fatty acids (TVFAs) and ammonium N contents were increased by 3.2 and 2.45 folds, respectively. The organic matter degradation rate constants in I-HPC and HPC were 0.0501, 0.0534 d-1, significantly larger than that in CK (0.00143 d-1). Consequently, the total organic carbon content in the mature product of HPC and I-HPC (182.1, 192.1 g/kg) were 11.3% and 6.4% lower than that in CK (205.3 g/kg). TN contents in the mature product of HPC and I-HPC (19.70, 21.28 g/kg) were 9.7% and 18.5% higher than that in CK (17.96 g/kg). The humification indice (HI) in the mature product of HPC and I-HPC (0.77, 0.71) were 20.3% and 10.9% higher than that in CK (0.64). The humification indices of HPC and I-HPC were 20.3% and 10.9% higher than that in CK. The study suggested HTPRT-IPC as a novel method for shortening the composting cycle and improving the quality of compost, and had great potential for practical use.