Impact of 5-hydroxy methyl furfural on continuous hydrogen production from galactose and glucose feedstock with periodic recovery

A continuous stirred tank reactor (CSTR) was operated for more than 120 days with fixed hydraulic retention time of 6 h at mesophilic temperature along with a periodic recovery phase towards hydrogen production and stimulated by the existence of 5-hydroxy methyl furfural concentration (5-HMF). Interestingly, CSTR mixed with a small amount of 5-HMF, range of 0.3–0.6 g/L showed at least 50% higher hydrogen production rate than control without 5-HMF. However, when 5-HMF concentration was higher than 0.6 g/L, the performance was significantly inhibited. The bacterial community shifted by 5-HMF from Clostridium-dominated to Lactobacillus-dominated population. Regardless of the remain 5-HMF concentration in CSTR, the microbial community and hydrogen producing performance were restored by stop mixing the 5-HMF from the feedstock. The high-rate hydrogen production of 20.0 ± 1.8 L H₂/L/d was achieved in the presence of 5-HMF using the threshold information and recovery strategy.     

RIBBING INSTABILITY IN COATING FLOWS: EFFECT OF POLYMER ADDITIVES

Data are presented which show the effect of dilute addition of polymer on the ribbing instability in coating flows. A qualitative model which treats the growth of a disturbance as an extensional flow suggests that elasticity is a destabilizing factor, in agreement with the observations.     

An analysis of performance models for free water surface wetlands

Although treatment wetlands are intended to attenuate pollutants, reliably predicting their performance remains a challenge because removal processes are often complex, spatially heterogeneous, and incompletely understood. Although initially popular for characterizing wetland performance, plug flow reactor models are problematic because their parameters exhibit correlation with hydraulic loading. One-dimensional advective-dispersive-reactive models may also be inadequate when longitudinal dispersion is non-Fickian as a result of pronounced transverse gradients in velocity (preferential flow). Models that make use of residence time distributions have shown promise in improving wetland performance characterization, however their applicability may be limited by certain inherent assumptions, e.g. that transverse mixing is nil. A recently-developed bicontinuum (mobile-mobile) model that addresses some of these weaknesses may hold promise for improving wetland performance modeling, however this model has yet to be tested against real-world wetland data. This paper examines the state of the science of free water surface wetland hydrodynamics and transport modeling, discusses the strengths and weaknesses of various steady state models, and compares them to each other in terms of each model’s ability to represent data sets from monitored wetlands.     

有色噪声条件下的子空间辨识改进方法及应用

针对工业生产过程中噪声往往为有色噪声的情况,提出一种改进的子空间辨识方法。传统的子空间辨识方法在系统存在有色噪声时辨识效果不佳,改进方法则采用变换系统模型形式来克服有色噪声对系统的影响,在辨识时直接利用变换系统模型后的数据得到系统较为准确的状态空间模型,实践证明,状态空间模型更适用于工业过程。连续搅拌反应釜（CSTR）系统是一类典型的工业生产系统,将子空间辨识方法应用于CSTR过程的仿真实验,通过比较改进前和改进后的系统预测误差,验证了所提方法的有效性。     

Improvement of energy recovery from water hyacinth by using integrated system

The conventional methods for biofuel production provide a clean and renewable approach for bioenergy generation. However, the efficiency of these processes is still too low to compete with the existing technologies. Integrated bioprocesses could help in improving the overall yield and cost-effectiveness of the process. The present study deals with the evaluation of process efficiency in single, two and three-stage operation of dark fermentation, biomethanation and microbial fuels cells for recovering maximum energy from the invasive aquatic plant, water hyacinth. The merits and demerits of each process operated individually or in combination were evaluated. The results showed the integrated three-stage process yielded maximum energy recovery of 60% in the form of hydrogen, methane, and electricity with an overall COD removal of 94%. The present research work thus highlights the possibility of integrated hydrogen or methane-based biorefinery approach for the recovery of bioenergy from biomass.     

CSTR和ACR丁酸型发酵制氢系统的运行特性比较

为寻求更好的连续流发酵生物制氢反应器模式,以稀释糖蜜为底物,控制反应系统为丁酸型发酵,比较研究了搅拌槽式反应器（CSTR）和厌氧接触式反应器（ACR）的启动运行特性。结果表明,以经曝气培养的下水道污泥为接种物,在接种量4.8 g MLVSS·L^-1、进水COD 5000 mg·L^-1、HRT 12 h、温度（35±1）℃和pH 5.5～6.0等相同条件下,CSTR系统可以更快地达到稳定的丁酸型发酵状态,而ACR系统因其有效的生物持有能力而在产氢性能方面更具优势。在稳定运行状态下,ACR系统的底物酸化率、产氢速率和污泥的比产氢速率分别为44%、9 L·d^-1和0.15 L·(g MLVSS·d)^-1,分别是CSTR系统的1.62、2.05和1.15倍。     

An integrated system for hydrogen and methane production during landfill leachate treatment

The patent-pending integrated waste-to-energy system comprises both a novel biohydrogen reactor with a gravity settler (Biohydrogenator), followed by a second stage conventional anaerobic digester for the production of methane gas. This chemical-free process has been tested with a synthetic wastewater/leachate solution, and was operated at 37 °C for 45 d. The biohydrogenator (system (A), stage 1) steadily produced hydrogen with no methane during the experimental period. The maximum hydrogen yield was 400 mL H₂/g glucose with an average of 345 mL H₂/g glucose, as compared to 141 and 118 mL H₂/g glucose for two consecutive runs done in parallel using a conventional continuously stirred tank reactor (CSTR, System (B)). Decoupling of the solids retention time (SRT) from the hydraulic retention time (HRT) using the gravity settler showed a marked improvement in performance, with the maximum and average hydrogen production rates in system (A) of 22 and 19 L H₂/d, as compared with 2–7 L H₂/d in the CSTR resulting in a maximum yield of 2.8 mol H₂/mol glucose much higher than the 1.1–1.3 mol H₂/mol glucose observed in the CSTR. Furthermore, while the CSTR collapsed in 10–15 d due to biomass washout, the biohydrogenator continued stable operation for the 45 d reported here and beyond. The methane yield for the second stage in system (A) approached a maximum value of 426 mL CH₄/gCOD removed, while an overall chemical oxygen demand (COD) removal efficiency of 94% was achieved in system (A).     

基于神经网络的容错控制方法在CSTR中的应用研究

针对一个连续搅拌釜式反应器,将容错控制(FTC)与故障诊断(FDD)方法相结合,提出了一种关于传感器故障的容错控制方法。用RBF神经网络建立传感器故障模型,对系统的状态和故障参数进行在线估计,将故障参数与修正的Bayes分类算法相结合,进行传感器故障的在线检测、分离和估计。当传感器发生故障时,认为是系统处于不同的工作模式,利用估计出的状态值在线训练神经网络控制器的参数,使网络适应系统新的(故障)状态,维持系统性能。仿真结果表明,方法具有很强的关于传感器故障的容错能力。