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《环境科学与技术》2017,(Z2)
中国北方村镇生活垃圾组分复杂,对鄂尔多斯市某村镇生活垃圾的实测发现有10余种垃圾组分,其中渣土(包括石块)38%、有机质30%、可回收物24%。根据村镇垃圾特点,设计了旨在有效分离有机物和可回收物的MBT分选工艺流程,建设了生产线并构建了可自动计算的Excel物料平衡图。根据鄂尔多斯市某村镇生活垃圾综合处理厂的实测数据得到各工段主要设备分选率为:一级滚筒筛80%、人工分拣房73%、二级滚筒筛70%、磁选机89%、卧式风选机68%、张弛筛65%、捞砂机61%、破碎分选一体机72%,MBT分选有机质综合分选率达到75%~85%。整套工艺系统可较好地完成生活垃圾的机械分选,为有机固体废弃物联合厌氧发酵MBT工艺的完善和推广提供技术支撑。 相似文献
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本文结合城市生活垃圾综合处理的工程实践,介绍了组合分选线上的设备及其控制,环境保护的措施.正在研制的专用分选设备将会进一步完善分选技术,有助于组合分选法的推广应用. 相似文献
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奥运期间,北京环卫工程集团第一清洁分公司小武基大型固废分选转运站投入使用,这是我国首座小区分类垃圾精分选车间,同时,也是我国第一条针对分类垃圾进行精细分类的分选线,采用最先进的近红外分选技术。据悉,北京环卫工程集团第一清洁分公司小武基垃圾精分选线项目投资1300万元,日处理能力150t,主要采用了滚筒分选、磁选、分选以及引进德国最先进的近红外分选技术,对生活垃圾中有较高回收利用价值的塑料袋、纸类等物料进行超细化分选回收。整个分选线为电脑控制,预设的光分选参数可满足分选20多种可回收物的要求,分拣出来的物品纯度可达到90%以上。 相似文献
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本文结合城市生活垃圾综合处理的工程实践,介绍了组合分选线上的设备及其控制,环境保护的措施。正在研制的专用分选设备将会进一步完善分选技术,有助于组合分选法的推广应用。 相似文献
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生活垃圾生物预处理后筛分及分选特性试验研究 总被引:1,自引:0,他引:1
堆肥化技术作为垃圾预处理方式在国内外已得到了广泛认可.本文通过现场试验,研究了生物预处理对垃圾筛分和分选特性的影响.结果表明,预处理后垃圾含水率降低了7.69%,堆体的体积从275 m~3减少到183 m~3,垃圾的容重从最初的356 kg·m~(-3)增加到470 kg·m~(-3).经过生物预处理,有机物不断被降解.预处理可以提高筛分后筛下物比例,预处理后的筛下物百分比提高了17%.预处理对可回收成分(金属、塑料、纸张、玻璃和布匹等)分选效率都较新鲜垃圾有不同程度的提高,对金属分选效果提高最显著,达到22.01%.本研究表明,生物预处理对垃圾筛分和分选均具有积极的作用,可以提高后期资源回收利用率. 相似文献
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Ziyang Lou Bernd Bilitewski Nanwen Zhu Xiaoli Chai Bing Li Youcai Zhao 《环境科学学报(英文版)》2015,27(4):173-179
Large-scale incinerators are applied widely as a result of the heavy burden of municipal solid waste(MSW) generated, while strong opposition is arising from the public living nearby. A large-scale working incineration plant of 1500 ton/day was chosen for evaluation using life cycle assessment. It was found that the corresponding human toxicity impacts via soil(HTs), human toxicity impacts via water(HTw) and human toxicity impacts via air(HTa)categories are 0.213, 2.171, and 0.012 personal equivalents(PE), and global warming(GW100)and nutrient enrichment(NE) impacts are 0.002 and 0.001 PE per ton of waste burned for this plant. Heavy metals in flue gas, such as Hg and Pb, are the two dominant contributors to the toxicity impact categories, and energy recovery could reduce the GW100 and NE greatly. The corresponding HTs, HTw and HTa decrease to 0.087, 0.911 and 0.008 PE, and GW100 turns into savings of- 0.007 PE due to the increase of the heating value from 3935 to5811 k J/kg, if a trommel screener of 40 mm mesh size is used to pre-separate MSW. MSW sorting and the reduction of water content by physical pressure might be two promising pre-treatment methods to improve the combustion performance, and the application of stricter standards for leachate discharge and the flue gas purification process are two critical factors for improvement of the environmental profile identified in this work. 相似文献
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The fractal dimensions in di erent topological spaces of polyferric chloride-humic acid (PFC-HA) flocs, formed in flocculating
di erent kinds of humic acids (HA) water at di erent initial pH (9.0, 7.0, 5.0) and PFC dosages, were calculated by e ective densitymaximum
diameter, image analysis, and N2 absorption-desorption methods, respectively. The mass fractal dimensions (Df) of PFC-HA
flocs were calculated by bi-logarithm relation of e ective density with maximum diameter and Logan empirical equation. The Df value
was more than 2.0 at initial pH of 7.0, which was 11% and 13% higher than those at pH 9.0 and 5.0, respecively, indicating the most
compact flocs formed in flocculated HA water at initial pH of 7.0. The image analysis for those flocs indicates that after flocculating
the HA water at initial pH greater than 7.0 with PFC flocculant, the fractal dimensions of D2 (logA vs. logdL) and D3 (logVsphere vs.
logdL) of PFC-HA flocs decreased with the increase of PFC dosages, and PFC-HA flocs showed a gradually looser structure. At the
optimum dosage of PFC, the D2 (logA vs. logdL) values of the flocs show 14%–43% di erence with their corresponding Df, and they
even had di erent tendency with the change of initial pH values. However, the D2 values of the flocs formed at three di erent initial pH
in HA solution had a same tendency with the corresponding Df. Based on fractal Frenkel-Halsey-Hill (FHH) adsorption and desorption
equations, the pore surface fractal dimensions (Ds) for dried powders of PFC-HA flocs formed in HA water with initial pH 9.0 and 7.0
were all close to 2.9421, and the Ds values of flocs formed at initial pH 5.0 were less than 2.3746. It indicated that the pore surface
fractal dimensions of PFC-HA flocs dried powder mainly show the irregularity from the mesopore-size distribution and marcopore-size
distribution. 相似文献
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《Journal of Manufacturing Processes》2000,2(2):108-115
High-speed machining (HSM), specifically end milling and ball end cutting, is attracting interest in the aerospace industry for the machining of complex 3D aerofoil surfaces in titanium alloys and nickel-based superalloys. Following a brief introduction on HSM and related aerospace work, the paper reviews published data on the effect of cutter/workpiece orientation, also known as engagement or tilt angle, on tool performance. Such angles are defined as ±βfN and ±βf.Experimental work is detailed on the effect of cutter orientation on tool life, cutting forces, chip formation, specific force, and workpiece surface roughness when high-speed ball end milling Inconel 718™. Dry cutting was performed using 8 mm diameter PVD-coated solid carbide cutters with the workpiece mounted at an angle of 45° from the cutter axis.A horizontal downward (-βfN) cutting orientation provided the best tool life with cut lengths ∼50% longer than for all other directions (+βfN, +βf, and –βf). Evaluation of cutting forces and associated spectrum analysis of results indicated that cutters employed in a horizontal downward direction produced the least vibration. This contributed to improved workpiece surface roughness, with typical mean values of ∼0.4 μm Ra as opposed to ∼1.25 μm Ra when machining in the vertical downward (–βf) direction. 相似文献
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取成熟的好氧颗粒污泥,在同一测试装置中采用相同的曝气条件进行体积溶氧传递系数(kLa)的测试,当传统活性污泥和成熟好氧颗粒污泥浓度MLSS为2 000、4 000、6 000、8 000 mg·L-1时,其kLa(min-1)值分别为0.586 1±0.009 5、0.586 1±0.027 2、0.555 6±0.016 8、0.533 8±0.026 8和0.645 5±0.027 6、0.632 0±0.075 5、0.618 5±0.062 5、0.640 6±0.055 5,表明颗粒污泥kLa值高于同浓度条件下的絮体污泥,且随浓度增加,絮体污泥氧传递效率下降而颗粒污泥无明显变化.对好氧颗粒污泥进行筛分后,大颗粒和小颗粒在污泥浓度相同、体积相同、表面积相同以及个数相同的情况下二者的kLa值均无明显差别,由此可以推断,这些因素对好氧颗粒污泥kLa的影响可以忽略.研究结果对于污水处理厂节能运行具有一定的参考价值. 相似文献
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In this paper, KMnO4 was used to pre-treat Co3Fe-layered double hydroxides (LDH) precursor to prepare MnO2 decorated Co3Fe1Ox catalyst. The toluene oxidation performance of the catalyst was investigated systematically. The optimized 0.1MnCF-LDO catalyst exhibited the best catalytic performance, and the temperatures of 50% and 90% toluene conversion (T50 and T90) were 218 and 243°C, respectively. The apparent activation energy (Ea) was 31.6 kJ/mol. The characterization results showed that the pre-redox reaction by KMnO4 could increase the specific surface area, Co3+ species amount and oxygen defect concentration of the catalyst, which are the main reason of the improved toluene catalytic activity. Besides, this method was also applied to enhance toluene oxidation of iron mesh based monolithic catalyst. The 0.1MnCF-LDO/Iron mesh (IM) catalyst showed a 90% toluene conversion at around 316°C which was much lower than that of without MnO2 addition (359°C). In addition, the water resistant of all the catalysts was studied as well, all the samples showed relatively good water resistance. The toluene conversion still remained to be over >80% even in the presence of 10 vol.% water vapor. 相似文献
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基于虚拟撞击原理的固定源PM10/PM2.5采样器的研制 总被引:1,自引:3,他引:1
目前我国尚无固定源PM2.5采样标准方法,现有商业化的固定源PM2.5采样器在使用中存在明显不足,因此本研究开发了一种固定源PM10/PM2.5双级虚拟撞击采样器.经实验室标定,该采样器切割效率曲线优于国际标准ISO 7708:1995对采样器的规定,采样器横截面直径为74 mm,满足我国固定源采样口尺寸要求.采样器既可以安装滤膜,也可以安装滤筒,适用于不同浓度的烟尘采样.虚拟撞击器的切割点与次流所占比值呈负相关,比值减小时,切割点增大.为降低颗粒物损失,虚拟撞击器喷嘴距收口的距离至少应为喷嘴直径的1.5~2倍. 相似文献
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Optimising yield and resource utilisation of summer maize under the conditions of increasing density and reducing nitrogen fertilization 总被引:1,自引:0,他引:1
Shanshan Wei Xiangyu Wang Qicen Zhu Dong Jiang Shuting Dong 《Die Naturwissenschaften》2017,104(11-12):86
The inefficient use of resources always poses risks of maize (Zea mays L.) yield reduction in China. We performed this research to monitor the effects of increasing plant density and reducing nitrogen (N) rate on radiation-use efficiency (RUE), N efficiency traits, grain yield (GY) and their inter-relationships. Besides, whether GY and resource-use efficiency can both be maximized was examined. Hence, a 2-year field experiment was conducted using a widely grown variety “Denghai 618” in Shandong, China. Treatments contained two different plant densities [67,500 (D1) and 97,500 (D2) plant ha?1] and three N levels [0 (N?2), 180 (N?1), 360 (Nck) kg ha?1], set D1Nck as control. Significant increases in grain yield, biomass, RUE, above-ground N uptake (AGN) and N efficiency were observed when density increased from D1 to D2. Declining N application was accompanied by reductions in yield, RUE and AGN especially under high density, yet an obvious improvement in N recovery efficiency (NRE), agronomic N efficiency and N partial factor productivity. The increased GY was positive related with population biomass (r = 0.895**), RUE (r = 0.769**) and AGN (r = 0.923**), whereas it has no significant correlation with N efficiency. In this study, D2Nck obtained 18.8, 17.9, 24.8 and 29.7% higher grain yield, RUE, AGN and NRE respectively, compared to control, optimizing both yield and the efficiencies of radiation and N use. Furthermore, higher yield and RUE with more desirable N efficiency may be possible via optimizing density and N rate combination. 相似文献
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The effect of K deactivation on V_2O_5/WO_3-TiO_2 and Ce-doped V_2O_5/WO_3-TiO_2 catalysts in the selective catalytic reduction(SCR) of NOxby NH_3 was studied.Ce-doped V_2O_5/WO_3-TiO_2 showed significantly higher resistance to K deactivation than V_2O_5/WO_3-TiO_2.Ce-doped V_2O_5/WO_3-TiO_2 with K/V = 4(molar ratio) showed 90% NOxconversion at 350°C,whereas in this case V_2O_5/WO_3-TiO_2 showed no activity.The fresh and K-poisoned V_2O_5/WO_3-TiO_2 and Ce-doped V_2O_5/WO_3-TiO_2 catalysts were investigated by means of in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS),NH_3-temperature progress decomposition(NH_3-TPD),X-ray photoelectron spectroscopy(XPS) and H2-temperature program reduction(H_2-TPR).The effect of Ce doping on the improving resistance to K of V_2O_5/WO_3-TiO_2 were discussed. 相似文献
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阿魏酸和香豆素对铜绿微囊藻的化感作用 总被引:4,自引:2,他引:2
通过对铜绿微囊藻(Microcystis aeruginosa)的藻液D680、叶绿素a、电导率(EC)值以及超氧阴离子自由基O.2-含量的测定,研究了不同浓度的阿魏酸和香豆素对铜绿微囊藻的生长抑制作用及其机制.结果表明,阿魏酸和香豆素对铜绿微囊藻的生长均产生"低促高抑"作用,浓度高于100 mg.L-1的阿魏酸和香豆素对铜绿微囊藻表现出明显的抑制作用,200 mg.L-1的阿魏酸和香豆素第6 d的平均抑藻率分别为80.3%和58.0%.在高浓度阿魏酸和香豆素抑制作用下,铜绿微囊藻的叶绿素a含量迅速降低、EC值和O.2-含量明显增大,说明化感物质可能通过破坏细胞膜、增加O.2-含量、降低叶绿素a含量等作用抑制藻细胞的生长.此外,种子发芽实验结果表明,阿魏酸较香豆素毒性小. 相似文献