Kinetics of trichloroethene dechlorination and methane formation by a mixed anaerobic culture in a bio-electrochemical system

In the present study, we investigated the use of a lab-scale, bio-electrochemical system to generate H₂ from protons reduction at controlled cathodic potentials, in support of the microbial reductive dechlorination of trichloroethene (TCE). Several batch potentiostatic experiments were performed on graphite cathodes at different potentials ranging from −0.700 to −1.000 V vs. Ag/AgCl. By appropriately changing the applied cathode potential it was possible to finely control the liquid phase H₂ concentration, which resulted from a balance between H₂ generation (from protons reduction) and consumption (from dechlorination and methanogenesis). Microbial TCE dechlorination was stimulated when the potential applied to the graphite cathode was lower than −0.800 V vs. Ag/AgCl. However, a combination of high dechlorination rate and high current efficiency was achieved only in a very narrow range of cathode potentials (i.e., −0.850 to −0.875 V vs. Ag/AgCl). Methane formation was significantly slower than TCE dechlorination, probably due to the presence in the mixed culture of a lower number of methanogens compared to dechlorinators. In spite of this fact, these two competing metabolisms were stimulated in a similar way by the application of an external potential, thereby indicating a similar affinity for H₂. Indeed, calculated half-velocity coefficients for H₂ for dechlorination and methanogenesis were 20.1 ± 7.6 and 17.9 ± 8.5 nM, respectively.     

絮凝剂添加对厌氧微生物产甲烷活性的影响

在厌氧反应器启动初期添加絮凝剂需考虑絮凝剂对厌氧微生物所产生的抑制影响,通过对聚合氯化铝(PAC)、聚丙烯酰胺(PAM)、聚季胺盐不同絮凝剂的生物化学甲烷势(BMP)测定和厌氧毒性测定(ATA),评价了其厌氧生物可降解性和絮凝剂对厌氧微生物产甲烷活性的影响,对比了所形成的生物絮体在沉降性能和抗破散强度方面的差别。确定以聚季胺盐作为厌氧污泥颗粒化促进剂,建议采用间隔10d的多次添加方式及反应器中聚季胺盐质量浓度为10mg/L。     

ABR作为产甲烷反应器的两相厌氧工艺的启动特性

用厌氧折流板反应器(ABR)作为两相厌氧工艺的产甲烷反应器进行了启动研究,寻求快速启动的办法。采取先快速提高进水COD浓度,后提高进水量的方式,使产酸相尽快维持在酸性最佳条件下,调节产甲烷相进水pH值在6.8～7.2之间,从而保证产甲烷相在最佳条件下,经过35 d的启动过程,分别在产酸反应器和产甲烷反应器中出现了性能良好的絮状活性污泥和厌氧颗粒污泥。启动后第35天,当两相反应器水力停留时间为14 h,COD负荷为36.48 kg/(m3.d)时,系统整体COD去除率达到98.0%。     

Bifurcations in a bang-bang controlled mixed culture system

A bang-bang controlled chemostat culture in which two microbial populations compete for the same nutrient was studied from the standpoint of bifurcation theory. The dilution rate was periodically switched between two fixed values. The bifurcations of periodic states due to changes in the control parameters, the period and the switching ratio were investigated and the region of co-existence in the control parameter plane was determined. The stability of each periodic state was determined by seeking the values of the corresponding characteristic multipliers. The bifurcations without any topological contradiction were determined by applying the index theory.     

Preservation of mesophilic mixed culture for anaerobic palm oil mill effluent treatment by convective drying methods

While anaerobic digestion is a reliable method that treats the waste and produces renewable biomethane fuel, the necessary sludge in liquid form is difficult to handle due to the constant biogas generation. Therefore, this study investigates the possibility of convective air drying, namely heat pump and hot air circulation oven as preservation methods for anaerobic microbial sludge. Drying was conducted at various temperatures, ranging from 22 to 70°C. The study found that heat pump drying at 22°C resulted in highest chemical oxygen demand removal of 55.3% as well as the least log reduction in methanogens and anaerobes at 1.4 and 2.4, respectively.     

工业废水中Cr3+对厌氧微生物产甲烷毒性的研究

在温度为(35±1)℃的厌氧条件下,间歇性进行了厌氧产甲烷毒性研究,探讨了不同浓度Cr3+对厌氧微生物的抑制程度和毒性机理。结果表明,Cr3+对厌氧污泥中的产甲烷菌的活性有较为显著的抑制,当Cr3+为50 mg/L时,为轻度抑制;当Cr3+为100~150 mg/L时,为中度抑制;当Cr3+200 mg/L时,为重度抑制。毒性作用机理为:当Cr3+≤50 mg/L时为代谢性毒素,当Cr3+为100 mg/L时为生理性毒素,当Cr3+≥150 mg/L时为杀菌性毒素。     

黄磷净化脱砷研究进展

介绍了国内外黄磷净化脱砷的研究进展。比较详细地讨论了真空法和氧化法的研究工艺     

来自混合菌群的聚乙烯醇降解酶的性能

以在无锡桃花山垃圾填埋场筛选出的具有较好降解聚乙烯醇（PVA）能力的混合菌群所产的PVA降解酶为研究对象,对其对不同聚合度和醇解度的PVA的降解能力以及降解条件进行了研究,并对其降解PVA的机理进行了初步探索。实验结果表明,PVA降解酶降解PVA的能力受PVA聚合度和醇解度的影响较大,对PVA1799的降解效率远远高于对PVA1788和PVA124的降解效率;混合菌群产生的PVA降解酶降解PVA的最适温度为40℃,最适pH为7.0;Fe²⁺对PVA降解酶酶活有一定的促进作用,外加Fe²⁺能使酶活提高26%左右。PVA降解酶在最适条件下作用1 g/L的PVA1799 6 h后,PVA相对分子质量降低14.8%,熔点由221.3℃ 降低至216.7℃。高效液相色谱（HPLC）结果分析表明降解产物中存在乙酸,碘仿反应表明降解产物中存在甲基酮,PVA的降解途径有可能是长碳链上相邻的两个羟基被氧化成羰基后水解断裂并最终产生乙酸。     

Extraction and Characterization of Starch from Oak Acorn,Sorghum, and Potato and Adsorption Application for Removal of Maxilon Red GRL from Wastewater

Pure starch has been isolated from different samples: oak acorn, sorghum, and potato using alkali steep and wet-milling procedure. The structure of the extracted starches was analyzed using Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction. Their physicochemical properties (water content, ash content, pH, amylose content, swelling power, and water solubility index) were determined. The FT-IR spectra of isolated native starches have shown the main bands characterizing the starch. For sorghum starch (SS) and oak acorn starch (OAS), X-ray diffractograms exhibited an A-type diffraction pattern, while potato starch (PS) displayed typical B-type pattern. Compared to sorghum and oak acorn, potato starch has shown the highest level of both swelling power and water solubility index.

To estimate the color removal quality of the extracted starches, a sorption of a dye named maxilon red GRL has been carried onto them.

The results of equilibrium isotherms in batch adsorption process were analyzed according to the Langmuir and Freundlich model. The characteristic parameters were determined for each model. Furthermore, the effect of initial pH and ionic strength on adsorption capacity was considered, and regeneration studies were carried out.     

去除牛粪厌氧生物转化过程中的H2S

The main aim of this research was the experimental study at lab scale to check the absorption technolOgytor the in situ removal of H2S from biogas during anaerobic digestion process.The reagent FeCll was used to check the removal efficiency of H,S produced from dairy manure during anaerobic bioconversion process.The expenments werc conducted under mesophilic conditions.Thc composition of biogas was analyzed by gas chromatography analyzer equipped with flame photometer and thermal conductivity detectors.Experimental results under the same conditions demonstrate that high concentration of HES in the form of FeS can be removed totally from the biogas using FeCl3 dosing with in anaerobic batch digester.     

反向离子对色谱分析活性黄ME-4GL

本文采用反相离子对色谱方法对活性黄ME-4GL(C.I Reactive Yellow 160)进行了分析,找到了较好的色谱分离条件:色谱柱为UP-ODS,5μm,250mm×4.6mm中φ;流动相为A/B=60/40(V/V)。其中A代表CH30H,B代表2.5％[N-(c4H9)4]Br(w)溶液,分析波长λ=260nm,该分析方法对指导生产和与国外同种染料的质量比较有参考作用。     

混合炸药废水的厌氧生化可降解性研究

结合火炸药工业生产的工艺特点,针对混合炸药废水的特性,进行了混合炸药废水的厌氧生化可降解性研究。研究结果表明:废水中N、P含量能够满足厌氧微生物的生长需要;COD的去除率为80.1%,厌氧生物可降解性为85.3%,pH的变化也能达到厌氧反应器正常运行的要求;废水中有毒物质的整体毒性抑制作用为26.1%,属于代谢毒素,微生物通过驯化可以适应。实验表明,混合炸药废水具有良好的厌氧生化可降解性,用厌氧生物法处理火炸药废水切实可行。     

Effect of a chemical synthesis‐based pharmaceutical wastewater on performance,acetoclastic methanogenic activity and microbial population in an upflow anaerobic filter

The performance of an upflow anaerobic filter (UAF) treating a chemical synthesis‐based pharmaceutical wastewater was evaluated under various operating conditions. During start‐up, the UAF was initially fed by glucose till an organic loading rate (OLR) of approximately 7.5 kg COD m^?3 day^?1 with a hydraulic retention time of 2.3 days. A soluble COD removal efficiency of 98% was achieved before the addition of the wastewater. Initially, the filter inertia was acclimatized to the wastewater by sequential feeding of 10% (w/v), 30% (w/v) and 70% (w/v) of the pre‐aerated wastewater mixed with glucose followed by a 100% (w/v) pre‐aerated wastewater. During the operation, the COD removal efficiency and methane yield decreased to 75% and 0.30 m³ CH₄ kg^?1 COD_removed respectively. As the UAF became accustomed to the pre‐aerated wastewater, raw wastewater was fed in increasing ratios of 20% (w/v), 60% (w/v) and 80% (w/v) with the pre‐aerated wastewater as the remaining part. During this stage of the operation, a COD removal efficiency in a range of 77–86% was achieved and the methane yield decreased to 0.24 m³ CH₄ kg^?1 COD_removed. Finally, 100% (w/v) raw wastewater was fed and a COD removal efficiency of 65% was achieved with a methane yield of 0.20 m³ CH₄ kg^?1 COD_removed. At the end of the operation, acetoclastic methanogenic activity was only measured in the bottom section of the UAF, this showed a 90% reduction in comparison with activity of inoculation sludge. Microscopic examinations revealed that rod‐shaped methanogens remained as the dominant species whereas Methanosarcina‐like species and filaments were present only in insignificant numbers along the UAF. © 2002 Society of Chemical Industry     

黄磷精制脱砷工艺试验研究

通过使用添加剂,用稀硝酸溶液处理工业黄磷,可使黄磷中砷含量由１９０×１０－６降至３．０×１０－６,脱砷率达９５％。通过正交试验,获得了最佳工艺条件。结果表明,本法工艺流程和设备简单,过程危险性小,易于实现工业放大     

混合溶剂法脱除煤沥青的喹啉不溶物

以中温煤沥青为原料,以洗油和石油烷烃组成的混合溶剂,通过溶剂离心法脱除其中的喹啉不溶物,考察了芳烷比、溶剂比、离心时间、离心温度对精制沥青的QI含量和收率的影响.结果表明:当芳烷比一定时,精制沥青QI和收率随溶剂比的增大而减小;当溶剂比一定时,精制沥青QI和收率均随芳烷比的增大而增加;离心时间越长,所得精制沥青QI越低,收率也越低;离心温度升高,有利于QI脱除,特别是80℃以上时,所得精制沥青QI显著降低,能满足要求;通过调整混合溶剂的比例,可以方便地控制净化过程的收率和QI含量.     

黄磷的物理法脱砷新方法探索研究

针对我省黄磷精制现状,研究一种黄磷除砷新方法。利用高压静电场对工业黄磷进行处理,结果显示:在电场的作用下能分离除去砷,经三级处理脱砷率可达90%以上,黄磷回收率在99.9%以上。简要介绍了此处理方法的原理及工艺。     

Determination of potential methane production capacity of a granular sludge from a pilot‐scale upflow anaerobic sludge blanket reactor using a specific methanogenic activity test

A 450 dm³ pilot‐scale upflow anaerobic sludge blanket (UASB) reactor was used for the treatment of a fermentation‐based pharmaceutical wastewater. The UASB reactor performed well up to an organic loading rate (OLR) of 10.7 kg COD m^?3 d^?1 at which point 94% COD removal efficiency was achieved. This high treatment efficiency did not continue, however and the UASB reactor was then operated at lower OLRs for the remainder of the study. Specific methanogenic activity (SMA) tests were, therefore, carried out to determine the potential loading capacity of the UASB reactor. For this purpose, the SMA tests were carried out at four different initial acetate concentrations, namely 500 mg dm^?3, 1000 mg dm^?3, 1500 mg dm^?3 and 2000 mg dm^?3 so that substrate limitation could not occur. The results showed that the sludge sample taken from the UASB reactor (OLR of 6.1 kg COD m^?3 d^?1) had a potential acetoclastic methane production (PMP) rate of 72 cm³ CH₄ g^?1 VSS d^?1. When the PMP rate was compared with the actual methane production rate (AMP) of 67 cm³ CH₄ g^?1 VSS d^?1 obtained from the UASB reactor, the AMP/PMP ratio was found to be 0.94 which ensured that the UASB reactor was operated using its maximum potential acetoclastic methanogenic capacity. In order to achieve higher OLRs with desired COD removal efficiencies it was recommended that the UASB reactor should be loaded with suitable OLRs pre‐determined by SMA tests. © 2001 Society of Chemical Industry     

一个降解聚乙烯醇混合菌系的降解特性及培养基碳氮源优化

从某纺织厂筛选到一个能够降解1g/LPVA的混合菌系,研究了碳、氮源对该混合菌系降解PVA的影响.实验表明,有机氮源比无机氮源更适合该混合体系降解PVA.通过平板稀释涂布从该混合菌系中分离出3株可以利用PVA的菌株,其中2株细菌和1株霉菌.其中1株细菌和霉菌能产生胞外PVA降解酶,但它们产生的胞外酶只能部分降解PVA.