堆肥过程中有机质和微生物群落的动态变化

Dynamics of organic matters and microbial population during aerobic composting process

利用3个容积约为50 L的平行生物反应装置研究堆肥过程中温度、湿度(水分含量)、pH值和有机质的动态变化情况。按照Van Soest方法根据有机质不同的溶解特性将其分为:溶于沸水的有机质H2O、溶于中性试剂的有机质SOLU、半纤维素(HEMI)、纤维素(CELL)和木质素(LIGN)。结果表明:反应装置内环境湿度调控在60%左右时,堆肥系统内借助生化反应,温度最高可达到约50℃。堆肥材料在反应初期呈现偏酸性(pH=6.5),而随着反应的发生,pH逐渐变为中性或弱碱性(pH=7.4)。经过20 d的堆肥实验,有机质总量降解了约47%。在微生物作用下的各类有机质的降解率不同,按大小排序为H2O>HEMI>CELL>SOLU>LIGN,其降解率分别是85%、56%、36%、32%和27%。为了深入理解堆肥过程中有机质的降解机制,文章采用磷脂脂肪酸(PLFAs)技术对体系中的微生物群落变化进行了初步分析,发现微生物优势群落随反应温度的改变发生明显变化,在堆肥初期和堆肥中期,细菌占优势,而堆肥末期时真菌比例较高。在堆肥的过程中,革兰氏阴性菌的比例呈下降趋势,而革兰氏阳性菌的比例呈上升趋势。

Three horizontal reactors were used for investigating the evolution of organic substrates during composting process.The variation of the process parameters such as the temperature in each compost layer,moisture（water content） and pH was studied,as well as the hydrolysis constant of each type of organic substrates characterised by the method of Van Soest,which separated the or-ganic substrates into four fractions： soluble in hot water（SOLW）;soluble in NDF（SOLU）,hemicellulose（HEMI）,cellulose（CELL） and lignin（LIGN）.The results showed that the surrounding temperature in reactors arrived at about a maximum value of 50°C by controlling the moisture.During the composting process,the pH changed from acidic（pH=6.5） to alkaline value（pH=7.4）.With de evolution of temperature,the organic fractions decomposed differently through the microbial activities.The most easily degradable fraction was SOLW with a degradation rate of 70%,no significant change was observed for HEMI and CELL,while the concentra-tion of SOLU and LIGN increased during the composting process.In order to better understand the biological mechanism in the or-ganic matter degradation thoroughly in the compost process,this research used the traditional PLFAs technology for analysis.The results showed that the occupied microbial population varied with the evolution of temperature,which led to the different degrada-tion rate in organic fractions.