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关键词： 污泥   活性   胞外聚合物   蛋白质   静电斥力   絮凝   聚合  

摘要： 二价阳离子能够中和活性污泥表面负电荷,影响微生物活性和生物絮凝性能。本文采用序批式生物反应器(SBR)考察Ca^(2+)对污泥活性和污泥絮体表面性质的影响,利用红外光谱和三维荧光光谱分析胞外聚合物(EPS)组分和结构的变化,揭示Ca^(2+)与污泥疏水性和zeta电位之间的联系,明确Ca^(2+)在生物絮凝中的作用。结果表明:在进水COD、TN和NH_4^+-N分别为420mg/L、40mg/L和35mg/L的条件下,当Ca^(2+)浓度达到160mg/L时,COD、NH_4^+-N和TN去除率最高(分别为96.7%、90.02%和73.2%),DHA活性和耗氧呼吸速率(OUR)达到最大,分别为124mg TF/L和3.1mg/(min·L)。Ca^(2+)促进了污泥微生物EPS的生成,增大了EPS中蛋白质含量。Ca^(2+)与EPS表面带负电的官能团形成架桥,吸附桥联的Ca^(2+)中和EPS表面的负电荷,减少了污泥表面负电荷之间的静电斥力,使污泥絮体保持稳定;同时增大了污泥表面的疏水性,改善了污泥的絮凝性和沉降性。

关键词： 玉米芯   硝态氮   亚硝态氮   氨氮   总氮   pH  

摘要： 近年来随着工农业的快速发展,水体中硝酸盐的污染已引起人们的普遍关注。针对受硝酸盐污染的水,生物反硝化脱氮技术由于具有高效低耗的特点被广为研究。生物反硝化脱氮工艺中,使用固体材料作为反硝化细菌的碳源及生长载体可望解决传统工艺中所存在的外加碳源难以控制的弊端,给反硝化细菌创造一个稳定、易于维护的生存环境。采用室内实验装置,研究了以玉米芯为反硝化碳源和反应介质的生物反应器对于污水中硝酸盐的去除效果及其影响因素。实验结果表明,玉米芯具有较好的反硝化效果,且最终有很少NO2-的积累;反应过程中无NH4+积累。随着反硝化过程的进行,pH值不断下降。

关键词： 膜生物反应器   水处理技术   改进思路  

摘要： 随着我国人口及工业生产能力的增加,污水的产生量也不断增加,因此科学、高效、应用性好的水处理技术的开发显得尤为重要。膜生物反应器(MBR)是膜处理技术跟传统的生物活性污泥法相结合的一种新兴的技术,主要用于生活污水处理、给水处理及含油污等有毒有害物质的工业废水的处理,具有广阔的发展前景。但MBR膜生物处理技术也存在一定的缺陷和不足,针对膜生物反应器在应用过程中的一些问题和缺陷,提出一些改进思路。

关键词： 厌氧折流板反应器   基质浓度   脱氮除碳   厌氧氨氧化菌   动力学特征  

摘要： 采用厌氧折流板反应器(ABR)为研究对象,以一定COD、NH+4-N和NO-2-N比例增加进水基质浓度,以明确基质负荷提高对ABR厌氧氨氧化和反硝化协同体系脱氮除碳的影响,并通过基质去除模型获得反应器对基质的耐受程度.研究表明,ABR反应器能够实现厌氧氨氧化反硝化耦合脱氮除碳,当进水基质COD、NO-2-N和NH+4-N浓度从220、168和60 mg·L^(-1)提高至420、270和110 mg·L^(-1)时,反应器脱氮效能下降,COD、NO-2-N、NH+4-N和TN去除率分别为97%、94%、30%和78%,厌氧氨氧化对TN去除的贡献率从43.08%骤降至16.49%,反硝化脱氮贡献率从53.81%增至82.07%.动力学模型拟合发现,Stover-Kincannon模型(R2=0.937,TN;R2=0.975,COD)较一级基质去除模型(R2=0.314,TN;R2=0.016,COD)更适合评价反应器对基质的承受力;Stover-Kincannon模型表明,反应器对TN和COD的最大基质利用率分别为1.43 g·L-1·d-1和3.33 g·L-1·d-1,饱和常数(KB)分别为1.2和3.79,研究认为ABR协同脱氮除碳体系理论上还有继续提升基质负荷的潜力.

关键词： 苯酚丙酮废水   生物反应器   臭氧催化氧化   达标排放  

摘要： 对苯酚丙酮生产废水进行了水质综合分析,并针对该废水进行中试试验研究,采用高效生化+臭氧催化氧化组合工艺进行处理,并向高效生物反应器投加生物菌剂加快生化系统启动及提高系统运行的稳定性。苯酚丙酮废水经过生化和臭氧催化氧化处理后,出水COD<50 mg/L,达到《石油炼制工业污染物排放标准》要求。

关键词： Bioethanol   Process intensification   Membrane integrated system   Eco-friendly process   Renewable carbon source   Direct contact membrane distillation  

摘要： The work analyses process intensification in production of fermentative biofuel (bioethanol) in a multi-staged membrane integrated bioreactor system from sugarcane juice (SCJ) using Saccharomyces cerevisiae (NCIM 3205). Membrane based clarification, sterilization and concentration of sugar cane juice could replace several energy-intensive and polluting steps of conventional production schemes. Integration of traditional bioreactor with membrane-based devices for downstream purification of bioethanol enabled the system for recycling of cells and residual sugars to the fermentation unit through largely fouling free cross flow microfiltration and nanofiltration membrane modules. The new process design is characterized by high yield (0.48 g/g), productivity (14.6 g/L/h) and concentration capability (97.6 g/L) using concentrated SCJ of 22 wt% under high cell density in a flexible, compact, eco-friendly and modular plant. The final membrane distillation stage concentrated similar to 98% pure ethanol in a solar-driven direct contact membrane distillation configuration using PTFE/PET hydrophobic membrane with enhanced flux with vis-a-vis the existing processes. A rectangular flat sheet cross flow membrane module in counter-current flow mode of hot and cold streams was employed. The membrane-based system achieves quite high levels of process intensification essential to sustainable operation at industrial scale. The achieved process intensification in the new system has been analysed vis-a-vis the existing conventional systems in terms of eco-friendliness, flexibility, cost of equipment and production, consumption of energy and material, profitability, E-factor, atom efficiency and business sustainability.

关键词： Machine learning   Reinforcement learning   Neural networks   Nonlinear control   Bioreactor control   Interacting multiple tank control  

摘要： In recent years, researchers have explored the application of Reinforcement Learning (RL) and Artificial Neural Networks (ANNs) to the control of complex nonlinear and time varying industrial processes. However RL algorithms use exploratory actions to learn an optimal control policy and converge slowly while popular inverse model ANN based control strategies require extensive training data to learn the inverse model of complex nonlinear systems. In this paper a novel approach that avoids the need for extensive training data to construct an exact inverse model in the inverse ANN approach, the need for an exact and stable inverse to exist and the need for exhaustive and costly exploration in pure RL based strategies is proposed. In this approach an initial approximate control policy learnt by an artificial neural network is refined using a reinforcement learning strategy. This Partially Supervised Reinforcement Learning (PSRL) strategy is applied to the economically important problem of control of a semi-continuous batch-fed bioreactor used for yeast fermentation. The bioreactor control problem is formulated as a Markov Decision Process (MDP) and solved using pure RL and PSRL algorithms. Model based and model-free RL control experiments and simulations are used to demonstrate the superior performance of the PSRL strategy compared to the pure RL and inverse model ANN based control strategies on a variety of performance metrics. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Gas-liquid mass transfer   Bubble coalescence   Syngas fermentation   Carbon monoxide   Bioethanol  

摘要： This study investigated the effects of electrolytes (CaCl2, K2HPO4, MgSO4, NaCl, and NH4Cl) on CO mass transfer and ethanol production in a HFMBR. The hollow fiber membranes (HFM) were found to generate tiny gas bubbles;the bubble coalescence was significantly suppressed in electrolyte solution. The volumetric gas-liquid mass transfer coefficients (k(L)a) increased up to 414% compared to the control. Saturated CO (C*) decreased as electrolyte concentrations increased. Overall, the maximum mass transfer rate (R-max) in electrolyte solution ranged from 106% to 339% of the value obtained in water. The electrolyte toxicity on cell growth was tested using Clostridium autoethanogenum. Most electrolytes, except for MgSO4, inhibited cell growth. The HFMBR operation using a medium containing 1% MgSO4 achieved 119% ethanol production compared to that without electrolytes. Finally, a kinetic simulation using the parameters got from the 1% MgSO4 medium predicted a higher ethanol production compared to the control.

关键词： Wastewater treatment   Nanocomposite membrane bioreactor   Biofouling   Biogas backwash   Extracellular polymeric substances (EPS)  

摘要： Considering the biofouling issue in membrane bioreactors, an anaerobic nanocomposite membrane bioreactor was developed for an efficient wastewater treatment. Silver nanoparticles were deposited on the Poly(vinylidene-fluoride) and Polyethersulfone surfaces. An anaerobic baffled reactor was operated for 240 days at a hydraulic retention time of 30 h for the synthetic wastewater treatment, and then its effluent permeated through nanocomposite membranes in 7 days of continuous operations. Moreover, the membranes were scoured with the recirculation of the produced biogas of the anaerobic baffled reactor. Scanning electron microscopy, inhibitory zone and inductively coupled plasma mass-spectrometry were carried out. Extracellular polymeric substances were quantified to compare the effect of the backwash by the produced ABR biogas and the air, as control, on the membrane reactor performance. As results revealed, the flux reduction was more than 30% in unmodified membranes while it was limited to 12.5% in nanocomposite membranes. The results demonstrated that EPS formation decreased 51% and 91% in the pure PVDF and the nanocomposite PVDF and 57% and 81% in the pure PES and the nanocomposite PES, respectively, after cleaning by the biogas. All in all, the anaerobic nano composite membrane bioreactor can be considered as an appropriate wastewater treatment package for non potable reuse applications.

关键词： carboxydotrophs   Clostridium   bioelectrochemistry   syngas   formate nitrite transport  

摘要： The high genetic similarity between some carboxydotrophic bacteria does not allow for the use of common sequencing techniques targeting the 16S rRNA gene for species identification. 16S rRNA sequencing fails to discriminate among Clostridium ljungdahlii and 'Clostridium autoethanogenum', despite this two species exhibit significant differences in CO2 assimilation and alcohol production. In this work we designed PCR primers targeting for the DNA gyrase subunit A (gyrA) and a putative formate/nitrite transporter (fnt) to specifically detect the presence of 'C. autoethanogenum', C. ljungdahlii or Clostridium carboxidivorans. We could confirm the simultaneous presence of C. ljungdahlii and 'C. autoethanogenum' in different bioreactors, and a preference of the latter for high CO2 content.