微生物菌剂对厨余垃圾堆肥温室气体减排的影响

为对厨余垃圾堆肥过程中的温室气体进行减排，在60 L强制通风静态堆肥装置中进行为期35 d的厨余垃圾和园林废弃物的联合好氧堆肥试验。在堆肥原料中分别添加复合微生物菌剂VT1000（VT）、枯草芽孢杆菌（BS）和地衣芽孢杆菌（BL）三种菌剂，并以不加菌剂的堆肥处理（CK）作为对照，监测堆肥过程中的CH4和N2O排放，以研究不同微生物菌剂对于厨余垃圾堆肥温室气体排放的影响。结果表明：微生物菌剂的添加会加快堆体升温和促进腐熟，同时能够实现不同程度的温室气体减排。堆肥过程中N2O的排放量在总温室气体二氧化碳排放当量中占比远高于甲烷，达到总排放当量的76.83%～88.57%，排放高峰期分别出现在堆肥初期和腐熟期。甲烷的排放高峰期出现在堆肥降温期，累计排放量达到温室气体总排放当量的1.65%～2.40%。各处理的总温室气体排放当量分别为95.84 kg·t-1（CK）、52.31 kg·t-1（VT）、42.03 kg·t-1（BS）和62.49 kg·t-1（BL）。与CK处理相比，BS处理的总温室气体的减排效果最好，减排率为56.15%，BL处理的减排率最低，为34.80%，VT处理减排率为45.42%。相较于CH4，菌剂对N2O的减排效果更好，可达35.32%～61.86%。结合堆肥过程的温度及各腐熟度指标，该研究选取的微生物菌剂能够在保证堆肥效率和产品质量的前提下有效减少温室气体排放。

Mitigation effects of microbial agents on greenhouse gas emissions from kitchen waste composting

High-temperature aerobic composting technology is developing rapidly, but many studies point to the production of greenhouse gases during the composting process, mainly including CH4 and N2O. In order to reduce greenhouse gases emission in the composting process of kitchen waste, a 35-day aerobic co-composting of kitchen waste and yard trimming (chipped stems) was carried out in 60 L forced aerated static composting reactors. Three commercial microbial agents of VT1000 compound consortia (VT), Bacillus subtilis (BS) and Bacillus licheniformis (BL) were added to compost materials respectively, the amount of fungi added was 1.5% of the dry weight of all raw materials composted, and the treatment without bacterial agents was used as the control (CK). CH4 and N2O emissions during composting process were monitored to investigate the effect of microbial agents on greenhouse gas (GHG) emission. The results showed that the addition of microbial agents not only accelerated temperature rising and maturity of compost, but also significantly reduced GHG emission in varying degrees. In terms of reactor heating, the high temperature duration of all treatments could meet the harmless requirements, but the treatment with added microbial agents had better secondary heating effect, VT had the fastest temperature recovery and the highest temperature, followed by BS, and BL was slower than CK. From the perspective of maturity, the electric conductivity and pH value of all treatments meet the compost quality requirements, the treatment of uninoculated microbial agents (CK) cannot meet the rot standard, and the treatment of Bacillus subtilis (BS) had a slight advantage over the treatment added with VT1000 (VT) and the treatment added with Bacillus licheniformis (BL) in terms of compost maturity. About greenhouse gas emission reduction, N2O emissions amounted to 76.83%-88.57% of the total GHG emission expressed as CO2-C equivalent, which was much higher than CH4. The emission peaks occurred at the initial stage and mature phase, respectively. The emission peak of CH4 occurred at the cooling stage, and the cumulative emissions reached 1.65%-2.40% of the total greenhouse gas emissions equivalent. The cumulative CH4 emissions of the four treatments were CK>BL>BS>VT in descending order, and the CH4 emission reduction effect of VT teratment was the best, which was 18.89%, while the addition of Bacillus subtilis had the best emission reduction effect on N2O in this study, with a reduction rate of 61.86%, followed by VT, with a emission reduction rate of 49.22%, and Bacillus licheniformus was the lowest, with a emission reduction rate of 35.32%. Total GHG emissions equivalent of each treatment were 95.84 kg·t-1 (CK), 52.31 kg·t-1 (VT), 42.03 kg·t-1 (BS), and 62.49 kg·t-1 (BL), respectively. Compared with CK treatment, BS treatment showed the best total greenhouse gases mitigation, with the reduction rate of 56.15%, BL treatment was the lowest of 34.80%, while VT treatment was 45.42%. N2O abatement was better achieved than methane by the addition of the inoculants, ranging from 35.32% to 61.87%. Taken together, addition of the microbial agents in the experiment can effectively mitigate greenhouse gases on the premise of ensuring the quality of composting products, and overall, the treatment with 1.5% Bacillus subtilis (BS) had the best effect.