木本泥炭添加比例对猪粪堆肥腐熟度和污染及温室气体排放的影响

针对当前猪粪好氧堆肥过程中存在的腐熟度低、氮素损失严重、污染气体排放量大等问题,该研究以木本泥炭作为添加剂与猪粪进行联合堆肥,研究了不同木本泥炭添加量(添加比例依次为占物料湿基质量的5%、10%、15%和20%的4个处理)对猪粪好氧堆肥产品腐熟度和堆肥过程中CH4、NH3和H2S等污染气体排放变化的影响。结果表明:在猪粪堆肥中添加木本泥炭作为调理材料,堆体可成功启动升温,在第2~4天堆体可进入高温期,并持续7 d以上,达到无害化卫生标准;经28 d好氧堆肥以后,堆肥产品p H值为8.0左右,电导率值为1.47~1.82 m S/cm,发芽指数均大于80%,达到腐熟标准;木本泥炭添加量增加至15%以上时,有机质分解程度高,物料干质量降解率达22%左右,28 d堆体含水率下降35%左右,CH4、NH3和H2S排放量分别减少82.12%~89.48%、53.47%~63.31%、50.98%~62.76%,总温室气体排放当量减少70.34%~83.26%,堆体总氮损失减少率达44%~63%,保氮效果显著。因此,建议木本泥炭用作猪粪堆肥添加剂的最优添加量为15%~20%(以物料总湿重计)。

Effects of woody peat addition on maturity and gaseous emissions during pig manure composting

The large amount of animal dung becomes a serious problem of environmental pollution with the development of large-size livestock farming. Aerobic composting, as an effective and accepted technology, has been often used to treat solid organic waste. However, the process of aerobic composting of pig manure faces several problems, such as low degree of maturity, severe nitrogen losses as well as large release of contamination gases, which can be controlled and mitigated by using different bulking agents. Peat is a natural and organic mineral resource and its application in composting is an important research site due to its better adsorption. Therefore, this research used woody peat as bulking agent and investigated the influence of different quantities of woody peat (with ratio of 5%, 10%, 15% and 20% on quality of wet mass) on pig manure compost maturity and CH4、NH3 and H2S emissions. The results showed that the composting matrix can be activated successfully for all treatments. In addition, the temperature entered into thermophilic phase on day 2~4, and the thermophilic phase lasted more than 7 d to completely meet the sanitary standard in all reactors; and after 28 d, the pH values of all compost were 8.0, the electrical conductivities (EC) were 1.47~1.82 mS/cm and the germination index (GI) were all larger than 80%. Therefore, all treatments can perform well and achieve the standard of ripe composting under the addition of woody peat. Moreover, according to the results, adding at least 15% woody peat could make a better compost product with better maturity, less physiology toxicity and more nitrogen element. In addition, the treatments with 15%~20% addition had more active microbial activities and higher biodegradation rate during 28 d, whose moisture content could decrease by 35% and degradation rate of dry material was around 22%. Compared with the 5% addition, woody peat addition at 15%~20% also reduced total CH4、NH3 and H2S emissions by 82.12%~89.48%, 53.47%~63.31% and 50.98%~62.76%, respectively. Consequently, these two treatments decreased total greenhouse gas emissions by 70.34%~83.26%. Furthermore, the effect of adding woody peat on keeping nitrogen was significant, and the 15%~20% addition could reduce total nitrogen losses by 44%~63%. Hence, woody peat is an alternative and good bulking agent for composting and the optimal addition of woody peat in the pig manure composting in this study is 15~20% of total wet weight.