基于温差的规模化生活垃圾干式厌氧发酵工艺的产气特征

Performance of biogas production in a full-scale dry anaerobic digestion of municipal solid waste based on the temperature difference

以北京某生活垃圾干式厌氧发酵工程为对象,通过对厌氧发酵运行温度与环境气温之间的温差调控,分析了不同季节下中温干式厌氧发酵工艺的产气特征。结果表明,干式厌氧发酵运行温度受环境气温影响较大,夏季平均运行温度最高,VS产气率以夏季和秋季较高,容积有机负荷波动大,不同季节平均容积产气率从高到低依次为:夏季>春季>冬季>秋季。统计分析结果表明,该干式厌氧发酵工程的产气能力与运行温度显著相关(p<0.01),春、夏、冬3季的温差与VS产气率显著相关(p<0.05),秋季温差与缓冲能力显著相关(p<0.05)。因此,在具备较大pH缓冲能力的条件下,加强春秋季变温期的温差调控,通过加温和增加回流比等方式提升春秋季变温期、冬季低温期的厌氧运行温度,并提高夏季容积有机负荷,有助于提高该干式厌氧发酵工程的产气效能和运行稳定性。本研究结果可为工程规模干式厌氧发酵工艺的稳定运行及高效产沼气提供参考。

A full scale dry anaerobic digestion(AD)plant of municipal solid waste in Beijing was selected in this study to investigate biogas production performance throughout one year on the basis of the difference between the AD operational temperature and the ambient temperature.Results showed that the operational temperature of this dry AD plant was significantly affected by the ambient temperature,and the average operational temperature of the dry AD in summer was higher than that in other seasons,while the biogas production rate per VS was higher in summer and autumn.The organic loading rate(OLR)of the dry AD plant fluctuated greatly,and the order of the average volume biogas production rate from high to low in different seasons was as follows:Summer((2.44±0.33)m^(3)·(m^(3)·d)^(-1))>Spring((2.31±0.28)m^(3)·(m^(3)·d)^(-1))>Winter((2.25±0.29)m^(3)·(m^(3)·d)^(-1))>Autumn((2.10±0.14)m^(3)·(m^(3)·d)^(-1)).Results of correlation analysis showed that the gas production performance of the dry AD was significantly corelated with the operational temperature of the dry AD(p<0.01).The temperature differences in Spring,Summer and Winter were significantly related to the VS biogas production rate(p<0.05),and that in autumn was significantly related to buffer capacity(p<0.05).In a word,it was recommended to strengthen the control of temperature difference in the ambient temperature change period in Spring and Autumn.It was recommended that as far as the improvement of biogas production and operational stability of the full-scale dry AD plant was concerned,the operational temperature of the dry AD plant in the Spring,Autumn,and Winter should be increased by heating and increasing the return ratio,as well as increasing the OLR of the dry AD plant in summer with adequate pH buffer capacity.This study can provide a practical reference for the stable operation and efficient biogas production of engineering-scale dry digestion of municipal solid waste.