焙烧温度对污泥陶粒烧胀过程及结构特征的影响

按质量比为m(污泥)∶m(盐渍土)∶m(蒙脱土)=75∶20∶5的配比,将料球分别烧至1000℃、1050℃、1100℃和1150℃,研究了焙烧温度对污泥陶粒烧胀过程和结构特征的影响。结果表明,1100℃时陶粒的主晶相是石英、蓝晶石和钙长石,1150℃时陶粒的主晶相是莫来石、石英和蓝晶石。莫来石是由蓝晶石转化而来,在高温时形成富硅铝和富钙的液相以及二液分相现象,最后生成莫来石、玻璃体和钙长石。陶粒烧胀的原因是在还原气氛下发生铁碳反应。陶粒内部形成玻璃体为主体,中间有莫来石增强相的结构,陶粒断面形成致密结构和均匀的封闭孔。     

Effect of sintering temperature on the characteristics of sludge ceramsite

In order to investigate the effect of sintering temperature on the characteristics of sludge ceramsite and find an optimal sintering temperature, dried sewage sludge, clay, and water glass were mixed at ratios of dried sewage sludge/clay=33% and water glass/clay=15%. Then these mixtures were heated to 850, 900, 950, 1000, 1100, and 1200 degrees C for production of sludge ceramsite. The sludge ceramsite were characterized by DTA-TGA, SEM-EDS, XRD, and XRF. The results indicate that the differences in thermal behaviours are caused by the compositional and structural variations; the ceramsite sintered at 1000 degrees C has more uniformly distributed finer pores (0.5 microm相似文献   

Solidification and leaching behaviours of Cr6+ in sludge ceramsite

Making lightweight ceramsite with sewage sludge is a new effective approach for disposal of sludge. However, there is a concern as to whether the heavy metals such as Cr6+ in sewage sludge can be solidified in ceramsite after sintering. The configuration of Cr6+ in ceramsite was analyzed by X-ray diffraction (XRD) and leaching tests were conducted to determine the effects of sintering temperature, pH and H2O2 concentration on the stabilization of Cr6+ in ceramsite. The results show that leaching of Cr6+ changes little at temperatures above 900 degrees C, and both pH and H2O2 concentration have some effects on the leaching of Cr6+. Leaching test results indicate that Cr6+ is stabilized in ceramsite and cannot be easily released to the environment again as secondary pollution, which eliminates the concern for its application. XRD analysis of ceramsite sintered at 1000 degrees C reveals that the main compounds of Cr6+ in ceramsite are Cr2O3 and FeCrO4. The test results provides a better understanding of the factors that affect the mobility of Cr6+, and show it is a safe way to make ceramsite with sludge as an additive.     

Vermistabilization of municipal sewage sludge amended with sugarcane trash using epigeic Eisenia fetida (Oligochaeta)

Efforts have been made in this study to stabilize the sewage sludge mixed with sugarcane trash in four different proportions: 20% (T(1)); 40% (T(2)); 60% (T(3)) and 80% (T(4)), under laboratory conditions using epigeic earthworm (Oligochaeta) Eisenia fetida. The composting potential of worm was also evaluated in 100% sewage sludge treatment (T(5)). The changes in chemical properties of substrate was measured at the end. The vermicomposted material showed decrease in organic C (4.8-12.7%) and exchangeable K (3.2-15.3%) content, whereas increase in total N (5.9-25.1%) and available P (1.2-10.9%), exchangeable Ca (2.3-10.9%) and exchangeable Mg (4.5-14.0%) contents. Vermicomposting process caused considerable reduction in concentration of diethylene-triaminepentaacetic acid (DTPA) extractable metals: Cu (4.98-30.5%), Fe (5.08-12.64%), Mn (3.31-18.0%), Zn (2.52-15.90%) and Pb (2.38-20.0%). E. fetida showed the better growth performances in first three treatments (T(1)-T(3)) possibly due to higher content of organic matter (supplied by bulking agent, i.e. sugarcane trash). The earthworm mortality was higher in vermibeds those contained more sludge proportions. Study revealed that vermicomposting might be an efficient technology to convert negligible municipal sewage sludge into value-added products. The feasibility of earthworms to mitigate the metal toxicity and to enhance the nutrient profile might be useful to convert noxious sludge into useful products, at low-input basis.     

Inoculation of a submerged filter for biological denitrification of nitrate polluted groundwater: a comparative study

Activated sludge from a wastewater treatment plant and pure culture of Hydrogenophaga pseudoflava were utilized for the development of a denitrifying biofilm in a submerged filter in order to remove nitrate from polluted groundwater. Nitrate removal efficiency, nitrite accumulation, turbidity, COD and faecal indicators persistence in the treated water were determined at different superficial hydraulic loading (10, 20 and 30 m(3)/m(2) d) and superficial nitrate loading rates (1, 2, 3, 6 and 9 Kg NO(3)(-)/m(2) d) in the submerged filter. The application of H. pseudoflava as inocula allowed better results in terms of system stability, higher superficial hydraulic loading and superficial nitrate loading rates (30 m(3)/m(2)d and 9 kg NO(3)(-) /m(2) d, respectively). These values improve those obtained when the system was inoculated with activated sludge. In addition, the pure microbial inocula improved design parameters and running of the process due to its biofilm homogeneity, obtaining treated water with better characteristics to its final use as drinking water than that obtained with an activated sludge inocula.     

An inspiration from crawl behavior of the earthworm

The target of this research is to obtain valuable inspiration for tissue engineering in nerve regeneration. The effect of topographic feature of plate material surface on the crawl behavior of earthworm was studied. A total of 278 earthworms, with weight 1.2–5.1 g and diameter 2.5–7.0 mm, were divided into three groups (A, B, C) according to their weight. Earthworms always crawl straightly to a certain direction on ground or plate material. When earthworm crawled on the ground surface with regular grooves (straight line or curve with different curvature, depth and width of 3.0–6.0 mm), it was found that (1) earthworm crawled faster on surface with less grooves curvature, fastest on surface with straight grooves and that (2) the earthworm got into grooves easier with less the acute angle between the crawl direction and the grooves. When the earthworm crawled on the plate with different roughness, it was also found that the earthworm crawled much slower on smooth surface, such as glass, than on rough surface, such as cement plate, without calendering. We thought that, in point of the effect of the surface topographic feature of contacting materials, there may be some analogy between crawl behavior of the earthworm and the nerve growth of mammal.     

Changes in bacterial numbers and microbial activity of pig slurry during gut transit of epigeic and anecic earthworms

In soils, organic matter decomposition and stabilization largely occur as a result of microbial activity, although when present, earthworms are important drivers of the processes through their interactions with microflora which begin during organic matter digestion by earthworms. Here, we studied the effects of gut transit on the number of bacteria and the microbial activity in pig slurry, using three epigeic (Eisenia fetida, Eisenia andrei, Eudrilus eugeniae) and one anecic (Octodrilus complanatus) species of earthworm. Bacterial counts revealed that the effect of gut transit on microbes differed depending on the earthworm species. Thus, no changes in the number of bacteria were found in the gut contents of E. fetida and E. eugeniae, whereas large decreases were recorded in those of O. complanatus and E. andrei (2.7 and 1.3 times, respectively). We suggest that, unlike in the three epigeic earthworm species, microorganisms are preferentially utilized by O. complanatus to meet its nutrient requirements, because of its limited digestive capacity. Despite the decrease in bacterial numbers, there were no differences in the gut contents of the four earthworm species or undigested pig slurry in terms of dehydrogenase activity. Therefore, we suggest that after gut transit in the four earthworm species under study the potential microbial degradation of pig slurry remains unaltered.     

Feasibility of nutrient recovery from industrial sludge by vermicomposting technology

Transformation of industrial sludges into vermicompost is of double interest: on the one hand, a waste is converted into value added product, and, on the other, it controls a pollutant that is a consequence of increasing industrialization. This paper reports the feasibility of utilization of vermicomposting technology for nutrient recovery from industrial sludge in laboratory scale experiment employing Eisenia fetida earthworm. A total of nine vermireactors, having different percentage of wastewater treatment plant sludge of a food industry and cow dung, were established and monitored for fertilizer quality of vermicompost and growth and fecundity of the earthworms for 3 months. The earthworms were unable to survive in 100% FIS. There was a decrease in pH, organic carbon content, organic matter, C:N ratio, and increase in ash content, EC, nitrogen, potassium and phosphorus content in all the vermireactors. Total Kjeldhal nitrogen (TKN) content increased in the range of 12.2–28.7 g kg⁻¹ in different vermireactors after vermicomposting. C:N ratio was 1.59–5.24 folds lesser in final vermicomposts than initial raw substrate. The heavy metals’ content in final vermicomposts was higher than initial feed mixtures. Maximum worm biomass was observed in control, i.e., 100% CD (836 mg earthworm⁻¹) and the lowest in 30% CD + 70% FIS feed mixture (280 mg earthworm⁻¹). Cocoon production was started during 6–7th week in all feed mixture except in feed mixture no. 9. After 12 weeks maximum cocoons (57) were counted in 100% CD and minimum (2) in 30% CD + 70% FIS feed. The results indicated that food industry sludge could be converted into good quality manure by vermicomposting if mixed up to 30% with cow dung.     

海泥陶粒制备高性能轻集料混凝土的试验研究

通过正交试验,研究了水泥用量、粉煤灰用量、体积砂率等因素对高强高性能轻集料混凝土的强度、密度和工作性的影响规律.给出了利用700级海泥陶粒制备高强高性能轻集料混凝土的适宜配合比:水泥用量为385 kg/m3~450 kg/m3,Ⅱ级粉煤灰用量为125 kg/m3~150 kg/m3,体积砂率为35%,外加剂为胶凝材料的1.5%,水约150 kg/m3~160 kg/m3.该混凝土的密度等级为1800级,28d强度可达45 MPa~50 MPa,快速冻融循环可超过300次,RCM法测得的氯离子扩散系数仅为8.95×10-12m2/s~7.73×10-12m2/s,且工作性较好,基本克服了陶粒的上浮问题.     

球磨时间对石英砂粉体性能的影响

为有效利用长江沿岸低品位石英砂来开发研制高性能的保温隔热砖,利用球磨法研究球磨时间对低品位石英砂粉体性能的影响。结果表明:随着球磨时间的延长,石英砂的平均粒径逐渐减小,粉体振实密度总趋势不断减小,但石英砂粉体形成的圆锥高度逐渐增大,即随着球磨时间的延长,石英砂粉体的流动性逐渐变差。综合整个工艺考虑,球磨时间定为60 min较好。     

Stabilization of heavy metals in ceramsite made with sewage sludge

In order to investigate stabilization of heavy metals in ceramsite made with sewage sludge as an additive, the configuration of heavy metals in ceramsite was analysed by XRD and while leaching tests were conducted to find out the effect of sintering temperature (850 degrees C, 900 degrees C, 950 degrees C, 1000 degrees C, 1100 degrees C, and 1200 degrees C), pH (1, 3, 5, 7, 9, and 12), and H2O2 concentration (0.5molL(-1), 1molL(-1), 1.5molL(-1), 3molL(-1), and 5molL(-1)) on stabilization of heavy metals (Cd, Cr, Cu, and Pb) in ceramsite. The results indicate that leaching contents of heavy metals do not change above 1000 degrees C and sintering temperature has a significant effect on stabilization of heavy metals in ceramsite; leaching contents of heavy metals decrease as pH increases and increase as H2O2 concentration increases. XRD analysis reveals that the heavy metals exist in steady forms, mainly Pb2O(CrO(4)), CdSiO3, and CuO at 1100 degrees C. It is therefore concluded that heavy metals are properly stabilized in ceramsite and cannot be easily released into the environment again to cause secondary pollution.     

Evaluation of the effectiveness of various amendments on trace metals stabilization by chemical and biological methods

We evaluated the effects of five different kinds of amendments on heavy metals stabilization. The five amendments were: zero valent iron, limestone, acid mine drainage treatment sludge, bone mill, and bottom ash. To determine bioavailability of the heavy metals, different chemical extraction procedures were used such as, extraction with (Ca(NO(3))(2), DTPA; toxic characteristic leaching procedure (TCLP), physiologically based extraction test (PBET) that simulates gastric juice, and sequential extraction test. Bioavailability was also determined by measuring uptake of the heavy metals by lettuce (Lactuca sativa L.) and earthworms (Eisenia fetida). In addition, dehydrogenase activity was measured to determine microbial activity in the soil with the different amendments. The addition of amendments, especially limestone and bottom ash, resulted in a significant reduction in extractable metal contents. Biological assays using lettuce, earthworm, and enzyme activity were found as appropriate indicators of available metal fraction after in situ stabilization of heavy metals. In conclusion, TCLP and sequential extraction test appear to be promising surrogate measure of metal bioavailability in soils for several environment endpoints.     

Combination of laser-induced fluorescence and diffuse-reflectance spectroscopy for the in situ analysis of diesel-fuel-contaminated soils

Results of our laser-induced fluorescence (LIF) and diffuse-reflectance investigations of quartz sand and different soils spiked with Diesel fuel are reported. The LIF calibration functions, which were found to be significantly different for the various matrices, and the limits of detection were determined. For excitation at lambda(ex) = 266 nm, the limits of detection obtained ranged from 7 parts in 10(6) for quartz sand to ~200 parts in 10(6) for dark sand with organic matter and for dark peat. Furthermore, the diffuse-reflectance spectra of the matrices in the ultraviolet-near-IR range were determined. An attempt to correlate the slopes of the LIF calibration functions with the reflectances of the matrices is presented. The obtained normalized calibration functions are well suited to take into account relevant optical soil parameters and to reduce the variability of the LIF calibration behavior significantly.     

Management of arsenic-laden water plant sludge by stabilization

When arsenic is co-precipitated with iron hydroxide in an arsenic-removal water plant, a large quantity of sludge is generated which contains a good amount (an average of 6.1 kg As/m³ of sludge) of arsenic. The present paper attempts to find some suitable solutions to disposal of this arsenic-bearing sludge. As a safe means of disposal, stabilization processes such as briquette production, cement mortar and concrete making have been attempted in the present investigation. It has been found that in the preparation of briquette, cement–sand mortar and concrete, mixing up to 10, 18 and 40% of arsenic-bearing sludge by volume, respectively with the other common ingredients did not produce a TCLP leachate beyond its permissible direct inland water discharge standards of 0.2 g/m³ as stipulated by the Ministry of Environment & Forest, Government of India. Also, it was noted that 25% (by volume) of cement could be replaced by fly ash to stabilize arsenic-laden sludge to the tune of 11% by volume of cement–sand (1 : 3) mortar.     

A new triply rotated quartz cut for the fabrication of low loss IF SAW filters

Analysis of the quartz properties shows the existence of unexplored angular domains for which Rayleigh waves can be efficiently excited, exhibiting physical characteristics better than the ones of the (ST,X) cut. This paper presents a family of quartz cuts allowing significant improvements of surface acoustic wave (SAW) devices on quartz. A first set of experiments has been performed, confirming the theoretical predictions of the basic properties of SAW on these cuts. A second set of measurements then was achieved to refine the identification of coefficients needed to perform industrial SAW design. A demonstration of the improvements accessible using this new cut is presented. A low loss SAW filter working at 71 MHz has been fabricated using smaller aluminum thickness than that for standard quartz cuts, and exhibiting all the properties required for its industrial implementation.     

含油污泥颗粒的流态化行为研究

在一内径为0.056m、高为1.6m的冷模玻璃流化床中研究含油污泥与石英砂混合颗粒的冷模流化行为,含油污泥干基含油率为17.63%(质量分数),筛分成0.20~0.30、0.30~0.45、0.45~0.90mm3种粒径范围,与石英砂混合后进行流化实验。结果表明:各种颗粒混合物中油泥质量分数在0~30%范围内均可以实现正常流化,超出此范围,流化中出现明显的粘壁、沟流等不正常的流化现象;混合颗粒中含油率越高,初始流化速度越大;含油泥混合颗粒与典型的B类颗粒纯石英砂的塌落行为有显著差别,塌落时间较长,而床层膨胀率却较低。     

铁氧化物生物多孔陶粒的制备工艺及性能

以针铁矿（Goethite,GT）、锯末（成孔剂）和凹凸棒石黏土（粘结剂）为原料,在空气气氛下煅烧,制备出符合国家水处理标准的铁氧化物生物多孔陶粒（Iron Oxide-based Porous Ceramsite,IPC）。利用所制备IPC的抗压强度作为评价IPC质量的指标,通过单因素实验、正交实验来优化IPC的物料配比和煅烧工艺,并通过XRD、SEM,偏光显微镜（Polarizing Microscope-PM）,比表面积（BET-SSA）等技术来表征IPC孔结构特征及其特性。结果表明：IPC材料的孔连通性好,大孔孔径为10~20 μm,抗压强度达到51~78 N,比表面积为79 m²/g,是一种以开放孔隙为主的多孔生物陶粒。在一定培养条件下进行陶粒的挂膜实验,结果表明,微生物可以通过IPC开放性孔隙深入IPC内部附着生长,该多孔陶粒生物负载量高于市售陶粒和颗粒沸石,可望为曝气生物滤池提供新的功能性载体材料。     

Can intergranular force transmission be identified in sand?

This work tackles the challenge of assessment of force distributions in granular media. Spatially resolved neutron and x-ray diffraction are used to measure internal strains of sand grains under load. These approaches are sensitive to the crystallographic strains of the sand grains (quartz crystals) such that each grain acts as a local 3D strain gauge and so, for elastic deformations, a force gauge. First results are presented from recent experiments that provide tantalising indications of the potential of these techniques in the investigation of the mechanics of granular media.     

Environmental optimization of chromium recovery from tannery sludge using a life cycle assessment approach

Life cycle assessment (LCA) was used to evaluate the environmental impact of an oxidative chromium recovery method from tannery sludge, in comparison with the usual landfilling process. Three improvement options (water reduction, byproduct use and anaerobic sludge digestion) were considered. The results showed that the proposed chromium recovery process would be better environmentally than conventional landfilling in all the evaluated impact categories if the amount of chromium recovered was 43 kg per ton of sludge. This amount could be recovered if the chromium concentration was about 20 times higher than that considered in this study. Alternatively, a lower chromium concentration would produce a better result if the recovery method was optimized and implemented at industrial rather than laboratory scale, and if more accurate data were provided on environmental credits for avoiding the chromium production process. Thus, the recovery method is environmentally beneficial when tannery sludge contains a chromium concentration of about 100,000 ppm. According to the literature, such concentrations are not unusual. The results could serve as the basis for further environmental improvements in chromium recovery and tannery sludge management and should be used in decision-making processes, especially for end-of-pipe treatments.     

High mobility of SDBS-dispersed single-walled carbon nanotubes in saturated and unsaturated porous media

Knowledge of the mobility of carbon nanotubes (CNTs) in porous media is very important to assess their impacts on the environment. In this study, a series of laboratory experiments were conducted to explore the transport mechanisms of sonication shortened, sodium dodecylbenzene sulfonate (SDBS) dispersed single-walled nanotubes (SWNTs) in both saturated and unsaturated sand columns. Laboratory columns packed with quartz sand with different combinations of moisture content and grain-size distribution were used to examine the breakthrough behavior of the SDBS-dispersed SWNTs. Bubble column experiments were also conducted to study the interactions between the SDBS-dispersed SWNTs and the air-water interface. Packed-column experimental results showed that the SDBS-dispersed SWNTs were highly mobile for most of the experimental conditions tested. The surface deposition of the SWNTs in the sand columns was low because all the interactive surfaces were negatively charged. Physical trapping was not observed for the SWNTs in the saturated porous media of different grain-size distributions because the SWNTs might orient parallel to the streamlines in flow to reduce their retention. Retention of the SWNTs in unsaturated porous media occurred only at a very low moisture content (<0.10). Otherwise, reduction in moisture content showed little impact on the retention and transport of the SWNTs in unsaturated porous media. Findings from the bubble-column experiments confirmed that the SDBS-dispersed SWNTs did not attach to the air-water interface. A mathematical model based on the advection-dispersion equation coupled with reaction-rate laws successfully described the retention and transport of the SDBS-dispersed SWNTs in both water-saturated and unsaturated columns.