Caffeine degradation by methanogenesis: Efficiency in anaerobic membrane bioreactor and analysis of kinetic behavior
Caffeine degradation by methanogenesis: Efficiency in anaerobic membrane bioreactor and analysis of kinetic behavior
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DOI：
10.1016/j.cej.2017.10.052
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发表时间：
2018-02
影响因子：
15.1
通讯作者：
Rong-zhong Chen;Hongyu Jiang;Y. Li
中科院分区：
文献类型：
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作者：
Rong-zhong Chen;Hongyu Jiang;Y. Li
咖啡因是一种广泛存在于食品和药品中的成分，由于其非生态友好性和难降解性，当其排放到环境中时会对生态系统造成危害。在人工生物反应器中首次成功地通过产甲烷完全降解咖啡因。我们通过连续操作生物反应器、测试甲烷潜力和确定动力学行为证实了成功。在连续运行中，厌氧膜生物反应器对咖啡加工废水的长期处理中，咖啡因的去除率为87.5 ± 5.3%。在以咖啡因为唯一底物的甲烷潜力试验中，在咖啡因浓度高达2000 mg/L的富咖啡因环境中，咖啡因完全转化为甲烷。基于咖啡因降解产物与增加的终产物CH 4、NH 4 +-N和CO2之间的化学计量关系，提出并验证了产甲烷降解咖啡因的反应方程。在动力学行为实验中，定期监测残留咖啡因和终产物表明，咖啡因的产甲烷降解明显包括两个主要步骤：咖啡因转化为中间体和中间体转化为CH 4。水解产物是咖啡因降解的主要中间产物，水解产物转化为挥发性脂肪酸的过程是咖啡因降解的限速步骤。本研究为微生物降解咖啡因提供了新的思路，并将有助于开发在咖啡因脱除的同时收获生物能源的创新技术。
Caffeine, a widely found component in food and pharmaceuticals, is harmful to ecosystem when discharged into the environment because of its non-eco-friendly nature and recalcitrant properties. Complete caffeine degradation by methanogenesis was successful for the first time in a man-made bioreactor. We confirmed the success through continuously operating a bioreactor, testing the methane potential and determining the kinetic behaviour. In the continuous operation, an 87.5 ± 5.3% removal efficiency of caffeine was observed using an anaerobic membrane bioreactor for the digestion of coffee processing wastewater in the long-term process. In methane potential tests with caffeine as the sole substrate, the complete conversion from caffeine to CH4was achieved in a caffeine-rich environment with a caffeine concentration up to 2000 mg/L. We have proposed and confirmed a reaction equation for the caffeine degradation by methanogenesis based on the stoichiometric relationship between the degraded caffeine and the increased end-products: CH4, NH4+-N and CO2. In the kinetic behaviour experiment, the regular monitoring the residual caffeine and the end-products indicated that methanogenic degradation of caffeine clearly includes two major steps: caffeine converting to intermediates and the intermediates converting to CH4. The major accumulated intermediates should be hydrolysis products and the process of hydrolysis products converting to volatile fatty acids was identified to be the rate-limiting step of caffeine degradation. This work provided a new thought to microbial caffeine degradation and will be useful in developing innovative technology for bioenergy harvest at the same time of decaffeination.