HRT control as a strategy to enhance continuous hydrogen production from sugarcane juice under mesophilic and thermophilic conditions in AFBRs

The objective of this study was to evaluate the effects of hydraulic retention time (HRT) (8–1 h) on H₂ production from sugarcane juice (5000 mg COD L⁻¹) in mesophilic (30 °C, AFBR-30) and thermophilic (55 °C, AFBR-55) anaerobic fluidized bed reactors (AFBRs). At HRTs of 8 and 1 h in AFBR-30, the H₂ production rates were 60 and 116 mL H₂ h⁻¹ L⁻¹, the hydrogen yields were 0.60 and 0.10 mol H₂ mol⁻¹ hexose, and the highest bacterial diversities were 2.47 and 2.34, respectively. In AFBR-55, the decrease in the HRT from 8 to 1 h increased the hydrogen production rate to 501 mL H₂ h⁻¹ L⁻¹ at the HRT of 1 h. The maximum hydrogen yield of 1.52 mol H₂ mol⁻¹ hexose was observed at the HRT of 2 h and was associated with the lowest bacterial diversity (0.92) and highest bacterial dominance (0.52).     

UASB+接触氧化法处理食品废水的工程应用

介绍了采用隔油+调节池+UASB+接触氧化法工艺处理高浓度食品废水的工艺设计实例,并对运行效果进行了分析。从该运行结果看,食品废水采用该工艺是成功的,该工艺占地面积小,产生剩余污泥量少,处理成本低,适应强,且运行效果稳定,出水水质各项指标均可达到现行的排放标准。     

Experimental Study of Differences in DNB Heat Flux between Upflow and Downflow in Vertical Rectangular Channel

Experiments were carried out on DNB (Departure from Nucleate Boiling) heat flux for both upflow and downflow in a rectangular vertical channel simulating a subchannel in the fuel element of the research reactor JRR-3, which is scheduled to be upgraded at 20MWt with 20% low enriched uranium (LEU) fuel. The experiments were carried out for the conditions of pressure and velocity which are important for the safety design of the JRR-3. With the investigation of the data of the present experiment along with already existing data for both rectangular channels and other channels, a scheme of DNB heat flux correlations was obtained for upflow and downflow. With the all available data, the errors of the correlations adopted in this scheme were so evaluated as to utilize these results in the safety analysis of the JRR-3. This scheme includes a new correlation of DNB heat flux for upflow and the identification of a region of high coolant flow rate where no remarkable differences in the DNB heat flux are observed between upflow and downflow. This scheme is considered to be applicable not only to the rectangular channels of the JRR-3 but also to other channels.     

Novel design of a multitube microbial fuel cell (UM2FC) for energy recovery and treatment of membrane concentrates

A two-stage treatment process, consisting of a flat sheet membrane system and a novel upflow multitube microbial fuel cell (UM²FC), was investigated to simultaneously treat concentrate streams—as well as produce electricity. This study tested the treatment of the retained part (i.e membrane concentrate) of the membrane process and electricity production using an air-cathode UM²FC inoculated with sediment sample collected from Golden Horn, Istanbul. The electrochemical behaviors were investigated using electrochemical methods to identify how membrane concentrates effects the reactor performance. The treatment of domestic wastewater was performed using a lab-scale cross-flow filtration apparatus with a UH050 membrane and the chemical oxygen demand (COD) removal efficiency as a result of membrane treatment was 87%. Then the UM²FC was fed sequentially from the feed tank when desired retained ratios (25% and 50%) observed. The maximum power density obtained was 25.138 mW m⁻² in the 50% concentrate or a volume concentration ratio (VCR) of 2 fed UM²FC which was 244% higher than that achieved using raw wastewater (7.303 mW m⁻²) and COD removal was >65% in UM²FC. The contribution of different resistances such as ohmic, charge transfer and mass transfer resistances of the reactor under different stages was ascertained through the measurements using electrochemical impedance spectroscopy (EIS) and the results showed that an increasing organic loading reduced the internal resistance and enhanced power. On the whole, study reported new findings such as a new treatment technology for membrane concentrate treatment and gives insight to literature on reactor design.     

Selection of metabolic pathways for continuous hydrogen production under thermophilic and mesophilic temperature conditions in anaerobic fluidized bed reactors

This study evaluated the influence of hydraulic retention time (HRT) on hydrogen (H₂) production in anaerobic fluidized bed reactors at mesophilic (30 °C, AFBR-M) and thermophilic (55 °C, AFBR-T) temperatures. Reactors were fed sucrose-based synthetic wastewater (5000 mg chemical oxygen demand·L^?1) in the HRT of 8, 6, 4, 2, or 1 h. H₂ production rate increased from 67.8 ± 14.8 to 194.9 ± 57.0 ml H₂·h^?1 L^?1 (AFBR-T) and from 72.0 ± 10.0 to 344.4 ± 74.0 mL H₂·h^?1·l^?1 (AFBR-M) when HRT decreased from 8 to 1 h. Maximum H₂ yields for AFBR-T and AFBR-M were 1.93 ± 0.21 and 2.68 ± 0.48 mol H₂·mol^?1 sucrose, respectively. The main metabolites were acetic acid (31.3%–41.5%) and butyric acid (10.2%–20.7%) (AFBR-M) and acetate (20.1%–39.3%) and ethanol (14.3%–29.9%) (AFBR-T). Denaturing gradient gel electrophoresis profiles revealed selective enrichment of microbial populations responsible for H₂ production by the aceto-butyric route (AFBR-M) and ethanol-type fermentation (AFBR-T).     

湿法磷酸装置中原料的闭路湿磨工艺

根据磨矿分级的原理,采用两段一闭路流程（粗磨-分级-细磨-浓密）,选用湿式棒磨机、湿式球磨机、斜窄流分级机和高效深锥浓密机,成功地运用于云天化国际化工三环分公司（原云南磷肥厂）磷矿磨矿系统,并运用此项技术的原理分别对四家公司以往的工艺进行改进,达到良好的磨矿分级效果。     

基于UHOFe处理制浆造纸废水体系的计算模拟与优化

在保证废水水力停留时间的情况下,为研究上流式多相废水处理氧化塔（UHOFe）的结构及进水参数、搅拌转速对反应器内部流态均匀度的影响,通过计算流体力学（CFD）的数值模拟方法,考察装载搅拌桨叶对UHOFe反应器内部流场的影响情况。首先建立了反应器的参数化模型,通过引入平面内速度变异系数（MF）作为进水均匀度的评价指标,然后使用计算机流体力学软件ANSYS 2022,结合单因素实验以及正交实验,对反应器的内部流体流态进行三维流场数值模拟仿真。模拟仿真结果表明,装载搅拌桨叶可加强反应器内部液体的混合,且当出水口高度为12 850 mm、入水口速率为3 m/s、搅拌桨叶尺寸为1 300 mm、搅拌转速为140 r/min时,反应器内的进水均匀度效果最优,最有利于提升Fenton体系的药剂间混合效率,最终提高废水处理效率。     

柱塞气-液-固并流上行系统的确定性混沌行为

柱塞气－ 液－ 固并流上行系统表现出占据全部管截面的气栓段和气液固混合段间隔出现的流动结构。本文通过标准统计方法（ 功率谱） 和非线性混沌分析方法从定性和定量两方面证明了气栓和气－ 液－ 固混合段运动都是混沌运动。气栓运动的混沌动力学参数（ 相关维和Ｋｏｌｍｏｇｏｒｏｖ 熵） 明显比气－ 液－ 固混合段运动的小,从理论上表明描述气栓运动的动力学比气－ 液－ 固混合段运动的动力学简单,可预测度明显要大。文中还讨论了较精确确定重建伪相空间滞时的方法。     

抗高盐菌株的驯化及其对高盐含氮废水的处理

针对生物处理法处理高盐废水时普遍存在微生物易失活甚至死亡的问题,在上流式固定床反应器中,通过小幅度提高进水盐度来驯化抗高盐厌氧氨氧化菌株。实验结果表明,盐度从0增加至30g/L,系统对氨氮、亚硝氮、总氮的去除率平均值分别为72.56%、92.54%、73.83%,氨氮、亚硝氮、总氮的容积负荷去除分别为0.81、1.03、1.74kg/(m3·d);盐度高于30g/L时,细菌活性受到抑制,系统脱氮能力显著下降;减小盐度,细菌活性恢复。此外,系统能较快适应负荷的变化,具有较强的抗负荷冲击的能力。     

Design of Settlement Tanks and the use of Chemicals to Aid Precipitation of Suspended Solids

Traditionally, the design of settlement tanks has been based on practical experience linked to key criteria, which have evolved from many sources. In this paper, the design criteria which affect the performance of both primary and secondary tanks are examined and a procedure, linked to critical velocities and loading rates, is put forward to enable the design requirements to be rationalized.
Based on the authors' considerable practical experience, the proposed procedure can be used with confidence to design tanks which will achieve required performance, particularly in the case of secondary tanks (for separation of both activated and humus sludges). In particular, the importance of a correctly sized inlet stilling chamber, to reduce the feed velocity to around 0.003–0.005 m/s is explained.
The use of chemicals to aid removal of suspended solids (and hence BOD) has been practised for many years. Today, there is renewed interest, particularly for phosphate removal and for the treatment of some industrial wastewaters. The composition and nature of sewage affects the potential benefits of coagulant chemicals when added at the treatment works' inlet. The introduction of organic polymers has significantly improved performance and reduced costs. The major disadvantage of using chemicals relates to the significant increase in quantity of sludge that is produced, which will require both treatment and disposal, increasing operational costs.