Mechanisms of allicin exposure for the sludge fermentation enhancement: Focusing on the fermentation processes and microbial metabolic traits

As a frequently used product with antimicrobial activity, consumed allicin might be discharged and concentrated in waste-activated sludge (WAS). However, the influence of allicin (as an exogenous pollutant) on WAS fermentation has not been clearly revealed. This study aimed to disclose the impacts of allicin on volatile fatty acid (VFA) generation during WAS fermentation. The results showed that the appropriate presence of allicin (10 mg/g TSS) significantly enhanced the VFA yield (1894 versus 575 mg COD/L in the control) with increased acetate proportion (24.3%). Further exploration found that allicin promoted WAS solubilization, hydrolysis and acidification simultaneously. Metagenomic analysis revealed that the key genes involved in extracellular hydrolysis metabolism (i.e., CAZymes), membrane transport (i.e., gtsA and ytfT), substrate metabolism (i.e., yhdR and pfkC) and fatty acid synthesis (i.e., accA and accD) were all highly expressed. Allicin also induced the bacteria to produce more signalling molecules and regulate cellular functions, thereby enhancing the microbial adaptive and regulatory capacity to the unfavourable environment. Moreover, the variations in fermentative microbes and their contributions to the upregulation of functional genes (i.e., ytfR, gltL, INV, iolD and pflD) for VFA generation were disclosed. Overall, the simultaneous stimulation of functional microbial abundances and metabolic activities contributed to VFA production in allicin-conditioned reactors.     

苯生产中污染最小化的计算机仿真计算

采用改进工艺操作条件对甲苯生产苯工艺的污染最小化进行分析，用计算机模拟的方法对工艺流程的温度，原料进料配比，物料循环配比及能量再利用等参数进行优化，若经实验或工厂生产验证，可在减少毒性较大副产物联苯排放量的同时，达到最佳的经济效益。     

小型砂滤池在废水处理中的应用

本文通过湿式除尘后的废水治理及工程实例,探讨了小型砂滤池在废水处 理中应用的可行性。     

Diffusion test of 20 kinds of waste molten slags and competitive materials

“Waste molten slag” is a glass-like material produced by the vitrification of solid waste or solid waste incineration residue. When using slags of this kind in a natural environment, their impact is anticipated to be at the same level as competitive or substituted materials. In this study, we made comparative evaluations between waste molten slags and competitive materials, using 20 samples in total. It was proved that release fluxes of metals from molten slags of municipal solid waste were almost at the same level as competitive or substituted materials. However, a larger impact will be caused from some types of slag that contain harmful metals in high concentrations, such as the slag from shredded automobile residues. The results of release flux showed that nearly 80% of the slope of the flux did not fit with the diffusion range. However, the linearity of every flux was extremely high, regardless of the slope.     

“白色污染”综合防治对策研究

针对目前我国废塑料造成的“白色污染”,总结了其治理途径及不足 ,并对其综合防治提出了建设性的对策。     

The Health of the Oceans - A 1994 Update

Three collectives of substances - plastics, plant nutrients, biotoxins - are candidates for monitoring programmes that could keep track of the quality of ocean waters for vital life processes. All three are not subject to systematic surveillance at present. They are each characterized by long residence times in the marine environment, by increasing influx, and by growing evidence of their deleterious impacts on living systems.     

废轮胎热解油脱色工艺研究

为解决废旧轮胎热解油颜色过深和存在异味而无法直接利用问题,文章采用活性炭对热解油吸附脱色工艺,将液相中含有的杂质、色素、异味等舍弃物吸附于活性炭表面上,以达到精致的目的。试验表明:热解油活性炭吸附脱色技术的最佳工艺条件为炭粒度550~1 700μm、脱色温度为室温、吸附时间为300 min、振荡频率为150 r/min。并证明了平2均孔径、中孔孔容积和中孔比表面积为26.4、0.307 m L/g和280 m/g的烟煤基活性炭对热解油具有很好的脱色能力。     

Distributed generation by energy from waste technology: A life cycle perspective

Municipal Solid Waste in general and its organic fraction in particular is a potential renewable and non-seasonal resource. In this work, a life cycle assessment has been performed to evaluate the environmental impacts of two future scenarios using biogas produced from the organic fraction of municipal solid waste (OFMSW) to supply energy to a group of dwellings, respectively comprising distributed generation using solid oxide fuel cell (SOFC) micro-CHP systems and condensing boilers. The London Borough of Greenwich is taken as the reference case study. The system is designed to assess how much energy demand can be met and what is the best way to use the digestible waste for distributed energy purposes.The system is compared with two alternative scenarios fuelled by natural gas: a reference scenario, where the electricity is supplied by the grid and the heat is supplied from condensing boilers, and a fuel cell micro-CHP system. The results show that, although OFMSW alone can only supply between 1% and 4% of the total energy demand of the Borough, a saving of ∼130 tonnes of CO₂ eq per year per dwelling equipped with micro-CHP is still achievable compared with the reference scenario. This is primarily due to the surplus electricity produced by the fuel cell when the micro-CHP unit is operated to meet the heat demand. Use of biogas to produce heat only is therefore a less desirable option compared with combined heat and power production. Further investigation is required to identify locally available feedstock other than OFMSW in order to increase the proportion of energy demand that can be met in this way.     

North–south trade in reusable goods: Green design meets illegal shipments of waste

In a stylized model of international trade, firms in the North indirectly export second-hand products to a representative firm in the South to be reused as intermediate goods, with potential trade gains. The level of reusability of waste products – or green design – is a crucial choice variable in the North. This is because, in the presence of imperfect international monitoring, non-reusable waste can be illegally mixed with reusable waste. I explore the driving forces for illegal waste movement, with a particular focus on local waste regulations such as the EU׳s Directive on Waste Electrical and Electronic Equipment. Under mild conditions, it is shown that increasingly stringent regulations in the North can induce Northern firms to reduce product reusability. Consequently, the flow of non-reusable waste to the South increases, magnifying the pollution haven effect.     

The evaluation of an analytical protocol for the determination of substances in waste for hazard classification

The classification of waste as hazardous could soon be assessed in Europe using largely the hazard properties of its constituents, according to the the Classification, Labelling and Packaging (CLP) regulation. Comprehensive knowledge of the component constituents of a given waste will therefore be necessary. An analytical protocol for determining waste composition is proposed, which includes using inductively coupled plasma (ICP) screening methods to identify major elements and gas chromatography/mass spectrometry (GC–MS) screening techniques to measure organic compounds. The method includes a gross or indicator measure of ‘pools’ of higher molecular weight organic substances that are taken to be less bioactive and less hazardous, and of unresolved ‘mass’ during the chromatography of volatile and semi-volatile compounds. The concentration of some elements and specific compounds that are linked to specific hazard properties and are subject to specific regulation (examples include: heavy metals, chromium(VI), cyanides, organo-halogens, and PCBs) are determined by classical quantitative analysis. To check the consistency of the analysis, the sum of the concentrations (including unresolved ‘pools’) should give a mass balance between 90% and 110%. Thirty-two laboratory samples comprising different industrial wastes (liquids and solids) were tested by two routine service laboratories, to give circa 7000 parameter results. Despite discrepancies in some parameters, a satisfactory sum of estimated or measured concentrations (analytical balance) of 90% was reached for 20 samples (63% of the overall total) during this first test exercise, with identified reasons for most of the unsatisfactory results. Regular use of this protocol (which is now included in the French legislation) has enabled service laboratories to reach a 90% mass balance for nearly all the solid samples tested, and most of liquid samples (difficulties were caused in some samples from polymers in solution and vegetable oil). The protocol is submitted to French and European normalization bodies (AFNOR and CEN) and further improvements are awaited.