知识与财富的链接
厌氧消化-微生物电解池(Anaerobic digestion-Microbial electrolysis cell,AD-MEC)具有有机物降解速度快、降解率高的优点,但其所产沼气中依然存在CO_2含量较高的问题.为降低AD-MEC所产沼气中CO_2的含量,本研究将矿物碳酸化耦合入AD-MEC中,研究添加硅灰石对AD-MEC中CO_2的固定效果.实验结果表明,添加硅灰石可使AD-MEC中CO_2产生量减少40.0%,沼气中CO_2含量从10.0%±1.3%减少到4.5%±1.1%;X射线衍射(XRD)及扫描电镜-能谱(SEM-EDS)分析表明了CaCO_3沉淀的生成,证明硅灰石介导矿物碳酸化固定了AD-MEC中的CO_2.此外,添加硅灰石使Ca~(2+)溶出,缓冲了pH,减轻了厌氧消化产酸阶段对产甲烷菌的抑制,促进了有机物的降解,可溶性化学需氧量(SCOD)去除率提高了11.2%,并使CH_4产量提高18.0%,CH_4产率达到305 mL·g~(-1),沼气中CH_4含量达到95.5%±1.2%.硅灰石的添加实现了AD-MEC中CO_2的原位捕获,同时增益了厌氧消化效果,提高了甲烷产量.
Anaerobic digestion-Microbial electrolysis cell (AD-MEC) has the advantages of high degradation rate and high degradation efficiency for organic matters. However, CO2 still exists in its produced biogas with relatively high content. In order to reduce the CO2 content in biogas, mineral carbonation was coupled in AD-MEC with wollastonite addition in this study. The experimental results show that the addition of wollastonite reduced the CO2 production in AD-MEC by 40.0%, decreased CO2 content in biogas from 10.0%±1.3% to 4.5%±1.1%. Results of X-ray diffraction (XRD) and scanning electron microscopy-energy spectroscopy (SEM-EDS) indicate the formation of CaCO3 precipitate, indicating that CO2 was fixed in AD-MEC by wollastonite mediated mineral carbonation. In addition, the release of Ca2+ from the wollastonite buffered pH during VFAs production and alleviated the inhibition of methanogenesis in the AD-MEC, and improved the degradation of organic matters, with SCOD removal increased by 11.2%. The yield of CH4 improved by 18.0%, while the productivity of CH4 reached 305 mL·g-1, and the content of CH4 in biogas reached 95.5%±1.2%. Wollastonite addition simultaneously achieved in-situ CO2 sequestration and CH4 production promotion in AD-MEC.
