Abstract:

A 4-compartment anaerobic baffled reactor (ABR) was operated for organic wastewater treatment at a constant hydraulic retention time (HRT) of 40 h and temperature of 35°C, with the influent COD increased from 2000 to 8000 mg·L^-1 stage by stage. Based on the reactor performance, Andrews model was constructed firstly for substrate degradation in the ABR. And then a prediction model for methane production was constructed by combining the stoichiometry of methane fermentation with the developed substrate degradation model. The results showed that the simulated COD of the calibrated Andrews model was well agreed with the measured data in the ABR. The experimental data were used to calibrate the dynamics parameters. k as the estimated maximum specific substrate degradation rate and K_s as the semi-saturation constant were kept at 2 d^-1 and 100 mg COD·L^-1, respectively, though the influent COD increased by stages. On the contrary, K_i as the inhibition parameter of volatile fatty acids (VFAs) rose following the increased influent COD. With a COD of 2000, 4000, 6000 and 8000 mg·L^{-1 in influent, K}_i was counted for 1500, 1700, 4000 and 6000 mg COD·L^-1, respectively. The equivalent COD of VFAs in the first compartment was close to or higher than the estimated K_i, indicating that a serious inhibition of VFAs to methane fermentation had occurred. Meanwhile, the equivalent COD in the last 3 compartments was lower than their K_i and showed a decreasing trend, suggesting that the inhibitory effect of VFAs on methane fermentation became weaker compartment by compartment. The methane production in the 4 compartments was ranged from 1.12—6.42, 2.54—8.96, 1.24—4.48 and 0.16—0.58 L·d^-1, respectively, and the developed model could predict the measured data very well. The calibrated Andrew model and the prediction model for methane production would provide an approach to the design and operation control of ABRs.

Key words: anaerobic baffled reactor, waste water, substrate degradation, methane, reaction kinetics, stoichiometry, model-predictive control

摘要：

利用Andrews模型构建了4格室厌氧折流板反应器（ABR）的基质降解动力学模型，并将其与甲烷发酵的化学计量学耦合，构建出有机废水产甲烷预测模型。在HRT 40 h、35℃和进水COD分阶段从2000提高到8000 mg·L^-1条件下，校准的Andrews模型能准确模拟COD在系统中的变化规律，通过拟合得出的最大比基质去除速率（k）和饱和常数（K_s）在不同进水COD浓度下均为2 d^-1和100 mg COD·L^-1，而挥发性脂肪酸（VFAs）对甲烷发酵的抑制系数（K_i）随进水COD的提高而增大。VFAs的当量COD在第1格室接近或高于K_i，对甲烷发酵抑制明显；而在后3格室低于K_i且逐格降低，抑制甲烷发酵的作用越来越小。第1~第4格室的甲烷产量实测值分别为1.12~6.42, 2.54~8.96, 1.24~4.48和0.16~0.58 L·d^-1，而构建的产甲烷预测模型能够准确预测这一变化趋势。校准的Andrew模型和甲烷预测模型可为ABR的设计与调控运行提供指导。

关键词: 厌氧折流板反应器, 废水, 基质降解, 甲烷, 反应动力学, 化学计量学, 模型预测控制