活性污泥耗氧速率的测定及其影响因素试验分析

本文首先介绍了活性污泥净化能力判别指标——耗氧速率的原电池氧测定法,继而通过试验研究了一些相关的影响因素同比耗氧速率的关系,最后分析说明了比耗氧速率在监控活性污泥系统运行中所起的作用。     

Dechlorination and destruction of PCDD,PCDF and PCB on selected fly ash from municipal waste incineration

The potential of fly ash to dechlorinate and destroy PCDD, PCDF and PCB was tested under oxygen deficient conditions in the laboratory. Specifically, two types of fly ash were compared, originating either from a fluidized bed incinerator using Ca(OH)₂ spray (FA1), or a stoker incinerator without Ca(OH)₂ impact (FA2).

Results from the present study indicate that on FA2 type fly ash, the degradation processes of OCDD, OCDF and D₁₀CB occurred primarily via dechlorination/hydrogenation up to temperature settings of 340 °C. In contrast, FA1 type fly ash was found to effect both dechlorination and destruction of these compounds already at temperature settings of 260 °C.

The dechlorination velocity of PCDD and PCDF did not differ significantly. However, the first dechlorination step of OCDF in the 1,9-position occurred faster compared to the first dechlorination step of OCDD.

The isomer pattern resulting from the dechlorination processes was quite similar on both FA1 and FA2, indicating that differences in alkalinity or elemental composition of the two types of fly ashes do not have a significant influence on the position of dechlorination. PCDD and PCDF dechlorination of the 2,3,7,8-positions was not favoured over dechlorination of the 1,4,6,9-positions on either type of fly ash. In contrast, dechlorination of PCB occurred predominantly on the toxicological relevant 3- and 4-positions.

The dechlorination/destruction processes were completed on both types of fly ash at 380 °C within one hour, which correlates well with results obtained from actual plant operation practices.     

Defect-enhanced photocatalytic removal of dimethylarsinic acid over mixed-phase mesoporous TiO2

Much attention has been paid to the pollutant dimethylarsenic acid(DMA),because of its high toxicity even at very low doses.Although TiO_2 photocatalytic oxidation(PCO) is one of the few effective methods for treating DMA-containing water,the efficient decomposition of DMA and simultaneous removal of toxic arsenic species remains a significant but challenging task.Here,defective mesoporous TiO_2 with mixed-phase structure was synthesized and used as both photocatalyst and adsorbent for DMA removal.Due to the reduced band-gap and enhanced separation of photogenerated charge carriers, the oxygen-deficient TiO_2 nanostructures exhibited 4.2 times higher PCO efficiency than commercial TiO_2(P25).More importantly,the high surface area of the mesoporous TiO_2 provided sufficient active sites for in-situ adsorption and reaction,resulting in the efficient removal of as-formed As(V).Combining the experimental and characterization results,the different roles of reactive species during PCO reactions were clarified.In the presence of hole(h~+) as the dominant oxidation species,DMA was demethylated and transformed into MMA.Thereafter,MMA was subsequently reduced to As(Ⅲ) by photo-generated electrons.Superoxide radicals(O_2~(·-)) played a significant role in oxidizing As(Ⅲ) into As(Ⅴ),which was finally adsorptively removed by the mesoporous TiO_2.     

河道最小环境需水量确定方法及其应用研究(Ⅰ)--理论

从水污染问题出发，探讨河道环境需水的内涵，指出河道最小环境需水量是指维系河流的最基本环境功能不受破坏，所必须在河道中常年流动着的最小水量的阈值，在此概念的基础上，提出了一种适用于污染比较严重河流的河道最小环境需水量的确定方法－－段首控制方法，该方法为河流生态系统的环境需水量研究提供了一种思路和可借鉴的方法。     

硫磺回收装置酸性气配风控制方案探讨

主要介绍采用克劳斯制硫工艺的硫磺回收装置制硫转化炉配风调节的几种控制方案以及气体分析仪对稳定操作。提高硫回收率所起的重要作用。     

Oxygen tolerance capacity of upflow anaerobic solid-state (UASS) with anaerobic filter (AF) system

In order to investigate the oxygen tolerance capacity of upflow anaerobic solid-state(UASS)with anaerobic filter(AF) system, the effect of microaeration on thermophilic anaerobic digestion of maize straw was investigated under batch conditions and in the UASS with AF system. Aeration intensities of 0–431 m L O2/gvswere conducted as pretreatment under batch conditions. Aeration pretreatment obviously enhanced anaerobic digestion and an aeration intensity of 431 m L O2/gvsincreased the methane yield by 82.2%. Aeration intensities of 0–355 m L O2/gvswere conducted in the process liquor circulation of the UASS with AF system. Dissolved oxygen(DO) of UASS and AF reactors kept around 1.39 ±0.27 and 0.99 ± 0.38 mg/L, respectively. p H was relatively stable around 7.11 ± 0.04. Volatile fatty acids and soluble chemical oxygen demand concentration in UASS reactor were higher than those in AF reactor. Methane yield of the whole system was almost stable at 85 ± 7 m L/gvs as aeration intensity increased step by step. The UASS with AF system showed good oxygen tolerance capacity.     

Experimental and life cycle assessment analysis of gas emission from mechanically–biologically pretreated waste in a landfill with energy recovery

The global gaseous emissions produced by landfilling the Mechanically Sorted Organic Fraction (MSOF) with different weeks of Mechanical Biological Treatment (MBT) was evaluated for an existing waste management system. One MBT facility and a landfill with internal combustion engines fuelled by the landfill gas for electrical energy production operate in the waste management system considered. An experimental apparatus was used to simulate 0, 4, 8 and 16 weeks of aerobic stabilization and the consequent biogas potential (Nl/kg) of a large sample of MSOF withdrawn from the full-scale MBT. Stabilization achieved by the waste was evaluated by dynamic oxygen uptake and fermentation tests. Good correlation coefficients (R²), ranging from 0.7668 to 0.9772, were found between oxygen uptake, fermentation and anaerobic test values. On the basis of the results of several anaerobic tests, the methane production rate k (year^?1) was evaluated. k ranged from 0.436 to 0.308 year^?1 and the bio-methane potential from 37 to 12 N m³/tonne, respectively, for the MSOF with 0 and 16 weeks of treatment. Energy recovery from landfill gas ranged from about 11 to 90 kW h per tonne of disposed MSOF depending on the different scenario investigated. Life cycle analysis showed that the scenario with 0 weeks of pre-treatment has the highest weighted global impact even if opposite results were obtained with respect to the single impact criteria. MSOF pre-treatment periods longer than 4 weeks showed rather negligible variation in the global impact of system emissions.     

When work is wanted after hours: Testing weekly stress of information communication technology demands using boundary theory

Information communication technologies (ICTs; e.g., smartphones) enable employees to work anywhere and anytime, blurring work and family boundaries. Building on this trend, this study draws from work–family border/boundary theory to examine antecedents and consequences of employees' weekly experiences of ICT demands (i.e., being accessible and contacted for work after hours via ICTs). A sample of 546 elementary teachers completed a registration survey and a weekly diary for 5 weeks. Multilevel modeling results suggest that ICT demands as a form of work intrusion in the home can constitute a source of significant weekly strain (i.e., negative rumination, negative affect, and insomnia). As border crossers, teachers' adoption of a technological boundary tactic (i.e., keeping work email alerts turned off on mobile phones) was related to lower weekly ICT demands. As important border keepers at work, school principals' work–family support was related to teachers' lower weekly ICT demands, whereas parents' after-hours boundary expectations were related to teachers' higher weekly ICT demands. Moreover, teachers' boundary control was found as a mediating mechanism by which the two border keepers influenced teachers' ICT demands−negative rumination link. That is, teachers who received fewer boundary expectations and/or more work–family support had greater boundary control, which in turn buffered the ICT demands–negative rumination relationship.     

SBR工艺处理皂素废水的实验研究及对策分析

废水处理是皂素产业可持续发展的关键,为解决这一问题,我们综合考虑了皂紊废水处理的技术、经济和运行管理等方面,预选了SBR工艺,并以反应时间为中心,试验分析了基质浓度、污泥浓度、温度和曝气强度对反应时间的影响。试验结果表明,氧的传质是SBR工艺处理皂素废水的核心问题,并据此分析了提高经济性和运行管理可操作性的对策。     

测定废水BOD5时水样稀释倍数的确定

根据测定BOD5所须具备条件,经过理论推导,得出水样稀释倍数的大致范围,对多种工业废水测试证,表明方法简便易行。