添加剂对堆肥过程中挥发性有机物(VOCs)的减排效果

Emission reduction of volatile organic compounds(VOCs)in composting using additives

为明确添加剂对堆肥挥发性有机物(Volatile organic compounds,VOCs)排放的减排效果和影响因素,通过文献筛选出吸附类添加剂(活性炭和沸石)与有机酸类添加剂(柠檬酸和草酸)开展实验研究。在鸡粪-玉米秸秆堆肥实验中,设置5个处理,分别为对照(CK)、添加活性炭、添加沸石、添加柠檬酸和添加草酸处理。研究对象包括115种VOCs、三甲胺和6种含硫有机挥发气体(二甲硫醚、二甲基二硫醚、二甲基三硫醚、甲硫醇、乙硫醇、乙硫醚)。结果表明:在28 d的好氧发酵中,所有处理均达到50℃并维持7 d,满足无害化标准。检出110种VOCs、三甲胺和3种含硫有机挥发气体(二甲硫醚、二甲基二硫醚,二甲基三硫醚)。VOCs的排放集中在前9 d,在第3天时VOCs达到峰值。5个处理在堆肥第3天检测到的VOCs浓度范围为169.22~548.26 mg·m^(-3)。4种添加剂对各类VOCs均有减排效果。在第3天,活性炭、沸石、柠檬酸和草酸对烷烃类的减排效率分别为79%、26%、77%和46%,对卤烃类的减排效率分别为96%、38%、93%和97%,对芳香烃类的减排效率分别为28%、11%、24%和53%。从堆肥第6天开始只有沸石对各类VOCs有减排效果,最高减排效率为30%。针对含硫有机挥发气体减排,减排效果依次是草酸>柠檬酸>沸石>活性炭。4种添加剂对含硫有机挥发气体均有减排效果,但是对三甲胺没有减排效果。综合堆肥前9 d VOCs的减排情况,4种添加剂中沸石对各类VOCs减排效果最好。堆肥过程中添加沸石有利于VOCs和其他气体的协同减排,并且对土壤和农作物不存在风险,所以沸石在堆肥工程中有广阔的应用前景。

In order to clarify the effect and influencing factors of additives on the reduction of volatile organic compounds(VOCs)emission from compost,adsorption additives(activated carbon and zeolite)and organic acid additives(citric acid and oxalic acid)were screened.In the composting experiment,five treatments were set up:control(CK),activated carbon,zeolite,citric acid,and oxalic acid.The research objects included 115 VOCs,trimethylamine,and six sulfur-containing organic volatile gases(dimethyl sulfide,dimethyl disulfide,dimethyl trisulfide,methanethiol,ethyl mercaptan,and ethyl sulfide).The emission reduction characteristics of VOCs and changes in physical and chemical parameters of four additives in the composting process were studied.The results showed that within 28 days of composting,all treatments reached 50℃,and this temperature was maintained for 7 days,meeting the harmless standard.110 VOCs,trimethylamine,and 3 sulfur-containing organic volatile gases(dimethyl sulfide,dimethyl disulfide,and dimethyl trisulfide)were detected.The emission of VOCs was concentrated in the first 9 days,with an emission peak on the third day.The concentration of VOCs in the five treatments ranged from 169.22 mg·m^(-3)to 548.26 mg·m^(-3).All four additives had emission reduction effects on various VOCs.On the third day,the emission reduction efficiencies of activated carbon,zeolite,citric acid,and oxalic acid for alkanes were 79%,26%,77%,and 46%,respectively;the emission reduction efficiencies for halogenated hydrocarbons were 96%,38%,93%,and 97%,respectively;the emission reduction efficiencies for aromatic hydrocarbons were 28%,11%,24%,and 53%,respectively.From the 6th day of composting,only zeolite had an emission reduction effect on various VOCs,and the highest emission reduction efficiency was 30%.For the reduction of sulfur-containing organic volatile gases,the order of reduction effect was oxalic acid>citric acid>zeolite>activated carbon.All four additives had an emission reduction effect on sulfur-containing volatile gas but had no effect on trimethylamine.Considering the emission reduction of VOCs in the first 9 days of composting,zeolite had the best emission reduction effect among the four additives.Zeolite in composting is beneficial for the synergistic emission reduction of VOCs and other gases and poses no risk to soil and crops;therefore,zeolite has broad application prospects in composting engineering.