Predicting pH rise as a control measure for integration of CO2 biomethanisation with anaerobic digestion
Predicting pH rise as a control measure for integration of CO2 biomethanisation with anaerobic digestion
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DOI：
10.1016/j.apenergy.2020.115535
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发表时间：
2020-11
期刊：
影响因子：
11.2
通讯作者：
Bing Tao;Yue Zhang;S. Heaven;C. Banks
中科院分区：
文献类型：
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作者：
Bing Tao;Yue Zhang;S. Heaven;C. Banks
原位CO2生物甲烷化提供了一种将联合收割机沼气升级与提高甲烷生产率相结合的方法，但由于对过程稳定性和控制的担忧，其对电力到天然气的潜在贡献往往被忽视。该研究提出了一个来自基本化学平衡的方程，该方程预测了CO2分压和消化池pH值之间的关系，并允许估计与稳定运行兼容的最大可实现沼气甲烷含量。一个快速的实验测定也被开发来支持这些预测。使用合成原料与不同的氨浓度（2和3克N L-1）的长期实验的结果进行了验证。进一步的试验表明，在沼气甲烷含量分别为92和90%CH4，pH值分别为8.5和7.9时，使用食物垃圾和污水污泥作为底物进行了稳定的操作。CO2生物甲烷化成功地证明了在食物垃圾消化器与总氨氮的4.8克N L-1的体积甲烷产量提高了2倍以上，从2.29至5.01升CH4每升消化器每天。所使用的预测方法适用于消化器喂养不同的原料和混合动力系统与生物甲烷化的内源性和外源性的CO2，并提供了一个基础的工艺设计准则和操作控制。因此，这项工作的成果为工程师、操作人员和工厂设计人员提供了一个有价值的工具，用于在厌氧消化器中成功实施原位生物甲烷化。
In-situ CO2biomethanisation offers a means to combine biogas upgrading with increased methane productivity, but its potential contribution to power-to-gas is often ignored due to concerns over process stability and control. The research presents an equation derived from fundamental chemical equilibria which predicts the relationship between partial CO2pressure and digester pH, and allows estimation of the maximum achievable biogas methane content compatible with stable operation. A rapid experimental determination was also developed to support these predictions. The results were validated by long-term experiments using synthetic feedstock with different ammonia concentrations (2 and 3 g N L-1). Further trials carried out using food waste and sewage sludge as substrates showed stable operation at biogas methane contents of 92 and 90% CH4and pH 8.5 and 7.9, respectively. CO2biomethanisation was successfully demonstrated in a food waste digester with a total ammoniacal nitrogen of 4.8 g N L-1with volumetric methane production enhanced by more than 2 times, from 2.29 to 5.01 L CH4per L digester per day. The predictive approach used is applicable to digesters fed on different feedstocks and to hybrid systems with biomethanisation of both endogenous and exogenous CO2; and offers a basis for both process design guidelines and operational control. The output from the work thus provides engineers, operators and plant designers with a valuable tool for the successful implementation of in-situ biomethanisation in anaerobic digesters.