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1.
垃圾土渗透性和持水性的试验研究   总被引：5，自引：2，他引：3  
张文杰  陈云敏  邱战洪 《岩土力学》2009,30(11):3313-3317
通过室内常水头试验测定了垃圾土的饱和渗透系数,通过室内压力板仪试验测得垃圾土的土-水特征曲线。基于土-水特征曲线预测了垃圾土的非饱和渗透系数,并通过室内入渗试验进行了初步验证。常水头试验得到深层、中层和浅层垃圾土的饱和渗透系数分别为3.56×10-4、3.50×10-3、4.81×10-2 cm/s。土-水特征曲线试验表明,垃圾土饱和含水率和残余含水率较高,进气值很小,土-水特征曲线在低基质吸力时存在陡降段,其中浅层垃圾土的陡于深层垃圾。验证试验表明,预测得到的非饱和渗透系数与实测结果接近,基于土-水特征曲线预测垃圾土非饱和渗透系数的方法基本可行。  相似文献   

2.
Compacted soil–bentonite liners, consisting of a sandy soil mixed with bentonite as backfill, are used extensively as engineered barriers for contaminant containment. This paper studies the valorization of local materials containing calcareous sand, tuff obtained from Laghouat region (in the South Algeria), to associate with bentonite in order to improve their hydraulic characteristics for use as landfill liner material. Firstly, a geotechnical characterization of mixtures chooses from a fixed percentage to 10% bentonite and different percentages of calcareous sand and tuff so that they are complementary to 90% by not 10%. Thereafter, the determination of saturated hydraulic conductivity at falling-head permeability (Kv) and oedometer (Kid, indirect Measure) tests of all compacted mixtures at Optimum Normal Proctor have been carried out using both permeates by tap water and a landfill leachate in order to simulate long-term conditions. The results showed that the saturated hydraulic conductivity of tap water is relatively lower than the one saturated by leachate in the falling-head test, unlike the oedometer test. The B10CS20T70 mixture has satisfied the hydraulic conductivity criterion of bottom barriers (i.e. water permeated: kv20° = 1.97 × 10?9 and kid from 7 × 10?9 to 1.83 × 10?10 < 10?9m/s; leachate permeated: kv20° = 2.91 × 10?9 and kid from 7 × 10?9 at 1.44 × 10?10 < 10?9 m/s). Finally, a comparison between direct measurements of the saturated hydraulic conductivity by triaxial (Kd) test and oedometer test (Kid) in the range of effective stress applied 100–800 kPa led to propose equations of correlations between these two methods. In conclusion, adopted formulation B10CS20T70 perfectly meets the regulatory requirements in force and constitutes an economic product based on available local materials for engineers barriers.  相似文献   

3.
The potential of the autoclaved Tunisian landfill leachate treatment using microalgae (Chlorella sp.) cultivation was investigated in this study. Landfill leachate was collected from Borj Chakir landfill, Tunisia. A full factorial experimental design 22 was proposed to study the effects of the incubation time and leachate ratio factors on the organic matter removal expressed in chemical oxygen demand (COD) and ammoniacal nitrogen (NH4─N) and on the biological response of Chlorella sp. expressed by the cell density and chlorophyll content. All experiments were batch runs at ambient temperature (25 ± 2 °C). The Chlorella sp. biomass and chlorophyll a concentrations of 1.2 and 5.32 mg L?1, respectively, were obtained with 10% leachate spike ratio. The obtained results showed that up to 90% of the ammoniacal nitrogen in landfill leachate was removed in 10% leachate ratio spiked medium with a residual concentration of 40 mg L?1. The maximum COD removal rate reached 60% within 13 days of incubation time indicating that microalgae consortium was quite effective for treating landfill leachate organic contaminants. Furthermore, with the 10% leachate ratio spiked medium, the maximum lipid productivity was 4.74 mg L?1 d?1. The present study provides valuable information for potential adaptation of microalgae culture and its contribution for the treatment of Tunisian landfill leachate.  相似文献   

4.
The behavior of the Gimpo #2 landfill, which is an active landfill and the largest in Korea, is analyzed using field measurement data obtained from various field instruments installed within the landfill. The data included in this analysis are the leachate head within the landfill, waste load data using soil pressure plate and settlement data from settlement plate on the surface of the waste of each stage fill including the settlement of the soft foundation clay soil. Landfill blocks are selected both near the embankment and in the center area of the landfill. The analysis of the field-monitored data showed that the leachate head increase was negligible near the embankment. It was significant in the central block as the waste loads increase and reached 15 m at the fourth stage of waste disposal. The reason that the leachate head is higher in the central block than near the embankment is due to the long drainage path and the loss of gradient of drain pipes. The range of unit weight of the waste converted from the measurement data of earth pressure cell was 0.91–1.24 t/m3 and the average value was 1.05 t/m3. The values reflect well the waste compositions recently buried in GML #2, since from 1998 the waste disposed in GML #2 did not contain food waste. The magnitude of final settlements that occurred in each stage loading of 5 m thickness in the peripheral block was very close to 120 cm. The settlement rate of the waste by dividing the thickness of waste was 24 %. This rate can be divided into 10 % by waste loading and 14 % by waste decomposition. The delay of settlements is recognized in each waste layer for second and third loading in the central block due to the accumulation of leachate within the landfill.  相似文献   

5.
This paper presents an experimental study on a deeply dewatered sewage sludge produced by using a new technique of membrane filter press. The experiments involve measurements of sludge composition, basic physical properties, shear strength, water permeability, and leaching toxicity. The measurements of shear strength and permeability were also performed on the sludge specimens soaked in a low acid leachate or distilled water for 1 and 2 months. This is to investigate the influence of chemical change in pore fluid as a result of rainfall infiltration or leachate seepage at landfills. Comparison tests were also carried out on silty clay that is commonly used for landfill cover material. The experimental results show that the deeply dewatered sludge contains 66 % organic content and 85 % water content (dry mass basis). The undrained shear strength of the sludge is >25 kPa even after 2-month soaking in the leachate and distilled water, meeting the requirement of the Chinese standard [CJ/T249-2007, Disposal of sludge from municipal wastewater treatment plant: sludge quality for co-landfilling. Ministry of Building and Construction, P.R. China (in Chinese), 2007]. The measured cohesion and friction angle for the sludge are >20 kPa and 22.3°, respectively. The soaking of sludge specimens in either leachate or distilled water resulted in an increase in frictional angle by several degrees. The water permeability for the sludge ranges from 0.68 × 10?8 to 1.3 × 10?8 cm/s, and permeability after 2-month soaking is less than the minimum requirement for the barrier layer of landfill covers (i.e., 1.0 × 10?7 cm/s). The concentrations of heavy metals leaching from the dewatered sludge are lower than the limit values of leaching toxicity for the wastewater discharge standard of China. The experimental results indicate that deeply dewatered sludge can be used as an alternative material for the barrier layer of landfill covers.  相似文献   

6.
The Khor Arbaat basin is the main source of potable water supply for the more than 750,000 inhabitants of Port Sudan, eastern Sudan. The variation in hydraulic conductivity and storage capacity is due to the heterogeneity of the sediments, which range from clay and silt to gravely sand and boulders. The water table rises during the summer and winter rainy seasons; it reaches its lowest level in the dry season. The storage capacity of the Khor Arbaat aquifer is estimated to be 21.75?×?106 m3. The annual recharge through the infiltration of flood water is about 1.93?×?106 m3. The groundwater recharge, calculated as underground inflow at the ‘upper gate’, is 1.33?×?105 m3/year. The total annual groundwater recharge is 2.06?×?106 m3. The annual discharge through underground outflow at the ‘lower gate’ (through which groundwater flows onto the coastal plain) is 3.29?×?105 m3/year. Groundwater discharge due to pumping from Khor Arbaat basin is 4.38?×?106 m3/year on average. The total annual groundwater discharge is about 4.7?×?106 m3. A deficit of 2.6?×?106 m3/year is calculated. Although the total annual discharge is twice the estimated annual recharge, additional groundwater flow from the fractured basement probably balances the annual groundwater budget since no decline is observed in the piezometric levels.  相似文献   

7.
In low-lying areas of urban and suburban regions in Asia, the use of landfill has allowed urban land use to encroach onto watery landforms, such as back marshes, which were formerly used as rice fields. To improve understanding of the associations between land-use patterns and landfill development, we carried out a case study in the urban fringe of Metro Manila in the Philippines. We examined landfill volume derived from land-use change using GIS, and field surveyed qualitative aspects of the landfill used. We calculated the rate of application of landfill in low-lying housing development areas to be 5.0 × 103 m3 km?2 year?1, most of which consisted of offsite disposal of construction waste or crushed rock produced by urban development and renewal on the adjoining uplands. The flow of fill material from offsite sources to onsite landfill development areas was on the basis of individual agreements between suppliers and developers.  相似文献   

8.
 This paper presents the results of field tests of hydrologic parameters in a landfill and the results of numerical simulation to find the efficiency of the pumping method to reduce leachate levels in the landfill. The field hydraulic conductivity and storativity of waste and buried cover soils in the landfill are measured by pumping and slug tests. The hydrologic condition inside the landfill is first calibrated using the drawdown-time curve obtained from the pumping test, and the flow behavior of leachate during pumping in the landfill, when various layers of waste and buried cover soil exist, is analyzed through three-dimensional numerical simulation of flow. The results of the field investigation show that the buried cover soil of low hydraulic conductivity forms an impermeable layer preventing the downward flow of leachate and upward flow of landfill gas. The hydraulic conductivities of the pumping test and slug tests were quite close on the same order of magnitude. It was also possible to match the drawdown-time data of the field tests with those of the model using input data close to the hydrologic property obtained from the field tests. The numerical flow analysis showed that pumping was possible up to 120 tons/day for a single well without a drain, while the pumping rate could be increased to 300 tons/day for the same well with the drain. From the vertical section of the flow vector with a horizontal drain, the barrier role of buried cover soil is identified, which was proposed by examining the water contents of the disposed cover soil and waste in the field. Received: 15 May 1998 · Accepted: 4 January 1999  相似文献   

9.
Landfilled wastes manifest slow decomposition, producing emanation of gases, and outflow of leachate. Waste mass shows various chemical reactions and complex evolutions that occur under the influence of natural agents, as rain and microorganisms. These reactions lead to biological, physical, and chemical transformations of wastes. The intensity of the phenomenon is related to the air and the humidity. These factors originate from the initial composition of the solid waste, the operating mode of the landfill, and the geological and hydrogeological conditions. Leachate is considered a major source of groundwater pollution. It has a complex nature; it typically contains high concentrations of chemical hazardous including heavy metals, chemical compounds that may severely pollute the environment. These challenges are faced all over the world by environment protection agencies and waste management bodies. The challenge differs according to the specific situation of the site, the climatic, environmental, and geological factors. The international literature is rich with studies in this concern. Each country or region of the world has its own legislation and laws governing waste management, e.g., the European Commission Legislation, the US Environmental Agency, and so forth. The main objective of this study is to shed light on the environmental consequences of a landfill site located in the southeast of Riyadh City, Saudi Arabia. It constitutes a peculiar case because of its situation, its exploitation mode, and nature of buried wastes. The study made use of satellite MSS, TM, ETM and SPOT image 2007, and Digital Elevation Model (DEM), respectively. Geological, morphological, hydrological, hydrochemical, and detailed drainage analyses were performed. Records of meteorological stations were also used in this study. The satellite images illustrate the evolution of the site through time since its start in the 1990s of the twentieth century. The main geological units outcropping in the area are the Sulaiy Formation, the Yamama Formation, Khabra deposits, floodplain deposits, alluvium, and sheet gravel. Drainage analyses shows a dendritic nature for the network, a total area of 2,113 km2, basin slope of 0.016, perimeter of 430?×?103, and a mean elevation of 635 m. Annual rainfall is around 100 mm, evapotranspiration is about 2,900 mm, wind speed averages at 5.1 km/h, and runoff peak is within 2.7–4.7 m3/s. A plume of total dissolved solids and nitrates was observed to initiate from the landfill site. Heavy metal concentration confirms the same result. Planners, environmentalists, decision makers, and other interest groups can use the findings of this study for environmental management of the landfill and protection of the downstream part of the Sulaiy tributary from leachate contamination. The results indicate the importance of monitoring landfills through the combined use of ground and satellite monitoring.  相似文献   

10.
The River Gash Basin is filled by the Quaternary alluvial deposits, unconformably overlying the basement rocks. The alluvial deposits are composed mainly of unconsolidated layers of gravel, sand, silt, and clays. The aquifer is unconfined and is laterally bounded by the impermeable Neogene clays. The methods used in this study include the carry out of pumping tests and the analysis of well inventory data in addition to the river discharge rates and other meteorological data. The average annual discharge of the River Gash is estimated to be 1,056?×?106 m3 at El Gera gage station (upstream) and 587?×?106 m3 at Salam-Alikum gage station (downstream). The annual loss mounts up to 40% of the total discharge. The water loss is attributed to infiltration and evapotranspiration. The present study proofs that the hydraulic conductivity ranges from 36 to 105 m/day, whereas the transmissivity ranges from 328 to 1,677 m2/day. The monitoring of groundwater level measurements indicates that the water table rises during the rainy season by 9 m in the upstream and 6 m in the midstream areas. The storage capacity of the upper and middle parts of the River Gash Basin is calculated as 502?×?106 m3. The groundwater input reach 386.11?×?106 m3/year, while the groundwater output is calculated as 365.98?×?106 m3/year. The estimated difference between the input and output water quantities in the upper and middle parts of the River Gash Basin demonstrates a positive groundwater budget by about 20?×?106 m3/year  相似文献   

11.
Low-flow indices have been determined from long-term daily streamflow data for 13 catchments in Dongjiang Basin in southern China. The Brutsaert-Nieber method was applied to estimate catchment-scale effective groundwater parameters; representative values were 4.5?×?10?4 m2 s?1 for the hydraulic diffusivity; 3.19?×?10?5 m2 s?1/2 for the hydraulic desorptivity; 2.27?×?10?4 m s?1 for the hydraulic conductivity; and 0.2617 for the drainable porosity. The response constants correlate well with the total stream length and catchment area. Solutions of the linearised Boussinesq equation were used to guide the development of regional multivariate regression models for estimating low-flow indices from the catchment-scale effective parameters. Results showed that these catchments exhibit similar low-flow characteristics. The 7-day lowest average streamflows with return periods of 10 and 2 years (7Q10 and 7Q2) are highly correlated with the catchment-scale response constants. The low-flow ratio Q95/Q50 (ratio of daily streamflow exceeded 95 and 50% of the time, respectively) varied between 0.3 and 0.5, indicating a high proportion of groundwater in the streamflow. The advantage of the regional regression model is its conceptual basis and use of the catchment-scale effective parameters. The method has the potential to be applied to ungauged catchments for estimating low-flow statistics from stream length and catchment area.  相似文献   

12.
碎块石土由于块石含量较高,块石粒径较大,其水力学参数的确定具有一定困难。首先,采用双套环法对三峡库区泄滩滑坡的滑体碎块石土饱和渗透系数进行了原位试验,并根据土层孔隙率、颗粒级配等因素采用相关经验公式对试验结果进行了分析。其次,结合使用张力计和体积含水率仪对其土水特征曲线进行了现场模拟试验,并采用Fredlund模型对试验结果进行了拟合分析。最后,根据土水特征曲线和饱和渗透系数,采用经验公式估算了其非饱和渗透系数。试验及分析表明,该滑坡的碎块石土层的饱和渗透系数为(1.78～3.2)×10-2 cm/s,为强渗透性;材料的细颗粒含量越少,有效粒径及控制粒径越大,不均匀系数越小,相应的渗透系数越大。相关研究成果可以为泄滩滑坡非饱和非稳定渗透计算提供参数依据,并对同类型土体非饱和水力学参数的确定具有一定的借鉴意义。  相似文献   

13.
The generation of massive volume of slimes from sand mining industry ascertains the need for effective waste treatment. The application of slimes in landfill barrier construction works has been identified as one of the processes that can be used to reduce their volume, enabling in this way the rehabilitation of dangerous sites. This article presents a modified triaxial cell specially built to investigate high water content soils and discusses the results obtained from the investigation of the hydraulic properties of two slimes. The results of laboratory filter cake tests show that the slimes have reasonably good sealing capacities due to the formation of a cake layer on other porous materials upon draining. A relatively low hydraulic conductivity (1.5–3 × 10−9 m/s) was achieved, once the cake layer was formed. This is close to the prescribed 1 × 10−9 m/s required by the local environmental governmental authority for a landfill hydraulic barrier material, indicating their potential suitability as landfill barrier.  相似文献   

14.
Landfilling is a common practice worldwide for solid waste management. The leachate generated at landfill sites contains various organic and inorganic pollutants while it should be treated properly. In this study, the electrocoagulation (EC) process was recognized for its simplicity and effectiveness which was used for the treatment of leachate from the Djebel Chakir landfill site in northern Tunisia. In addition, we investigated the effect of microorganisms (e.g., bacteria, fungi, spore) on sludge production by the application of autoclaving treatment on raw leachate. The application of low current density (15 mA/cm2) within 2 h of treatment and using Al-Al electrodes revealed significant improvement of performance when autoclaving was applied. The chemical oxygen demand (COD) and nitrogen removal increased from 39 to 64% and from 13 to 30%, respectively. The sludge volume was reduced from 40 to 10%, and thus, its handling and disposal costs would be significantly decreased. The energy consumption rate was stable after 40 min of treatment at about 0.8 kWh/kg COD removed. Our study shows that removal of microorganisms by autoclaving prior to the EC process is promising for landfill leachate treatment. However, since autoclaving is far from being practical and cost-effective at full-scale plant, research on coupling EC with an alternative disinfecting process might be of great interest.  相似文献   

15.
An extensive use of solid-waste landfills for disposal of municipal and industrial wastes have prompted increased attention to groundwater pollution caused by leachate generated in such landfills. The potential for groundwater contamination by leachate has necessitated engineering designs for landfills. The quantity of leachate generated from the solid waste and the movement of water through the solid waste depends on water input and the solid-waste characteristics. This paper dealt with the experimental investigations using the laboratory solid-waste leaching column to estimate the total leachate volume/leachate flow for unsaturated and saturated conditions. The hydraulic properties of the solid waste like initial moisture content, field capacity, permanent wilting point, saturation moisture content, effective void ratio, saturation hydraulic conductivity and saturation suction pressure were determined from the small-scale laboratory experiments, which are the input for analytical model study of leachate flow/total leachate volume for both unsaturated and saturated conditions. The result of analytical model study was compared with the results of experimental investigations. Comparisons of measured and computed total leachate volume/leachate flow using Darcy’s law showed reasonable agreement.  相似文献   

16.
A workflow is described to estimate specific storage (S s) and hydraulic conductivity (K) from a profile of vibrating wire piezometers embedded into a regional aquitard in Australia. The loading efficiency, compressibility and S s were estimated from pore pressure response to atmospheric pressure changes, and K was estimated from the earliest part of the measurement record following grouting. Results indicate that S s and K were, respectively, 8.8?×?10?6 to 1.2?×?10?5 m?1 and 2?×?10?12 m s?1 for a claystone/siltstone, and 4.3?×?10?6 to 9.6?×?10?6 m?1 and 1?×?10?12 to 5?×?10?12 m s?1 for a thick mudstone. K estimates from the pore pressure response are within one order of magnitude when compared to direct measurement in a laboratory and inverse modelled flux rates determined from natural tracer profiles. Further analysis of the evolution and longevity of the properties of borehole grout (e.g. thermal and chemical effects) may help refine the estimation of formation hydraulic properties using this workflow. However, the convergence of K values illustrates the benefit of multiple lines of evidence to support aquitard characterization. An additional benefit of in situ pore pressure measurement is the generation of long-term data to constrain groundwater flow models, which provides a link between laboratory scale data and the formation scale.  相似文献   

17.
Magnetic properties and heavy metal content of landfill leachate sludge samples from two municipal solid waste disposal sites near Bandung, West Java, Indonesia, and their correlation with heavy metals are studied in the present work. Leachate was found to be sufficiently magnetic with mass-specific magnetic susceptibility that varies from 64.8 to 349.0 × 10−8 m3 kg−1. It is, however, less magnetic than the soils around the landfill sites. The magnetic minerals are predominantly pseudo-single domain and multidomain magnetite. Leachate samples from the older but inactive disposal site, Jelekong, are found to be more magnetic than that from Sarimukti, the younger and active site. The enhancement of leachate due to the soil-derived ferrimagnetic particles is possibly the same for both Sarimukti and Jelekong. The fact that strong correlation between magnetic parameters and heavy metals is observed in Jelekong but is absent in Sarimukti suggests that the use of magnetic measurement as a proxy measurement for heavy metal content in leachate is plausible provided that the magnetic susceptibility exceeds certain threshold value. Moreover, the accumulation of magnetic minerals and heavy metals in leachate might depend on the activity and the age of landfill site.  相似文献   

18.
There is an urgent need for characterization of leachate arising from waste disposal to ensure a corresponding effective leachate management policy. Field and laboratory studies have been carried out to investigate the impact of municipal landfill leachate on the underlying groundwater at a site in West Malaysia. The solid waste was disposed of directly onto an unprotected natural soil formation. This situation was made worse by the shallow water table. The hydrochemical composition of groundwater in the vicinity of the site (background) is a dilute mixed cation, bicarbonate water. The high ionic balance error of ~13.5% reveals that the groundwater body underneath the site was a highly contaminated leachate rather than contaminated groundwater. Elevated concentration of chloride (355.48 mg/L), nitrate (10.40 mg/L as NO3), nitrite (14.59 mg/L), ammoniacal-N (11.61 mg/L), sodium (227.56 mg/L), iron (0.97 mg/L), and lead (0.32 mg/L) measured downgradient indicate that the contamination plume has migrated further away from the site. In most cases, the concentration of these contamination indicators, together with the ranges of sodium percentage (66.3–89.9%) and sodium adsorption ratio (10.1–19.7%), were found to be considerably higher than the limit values of safe water for both domestic and irrigation purposes, respectively.  相似文献   

19.
Soil–water characteristics are necessary for water quality monitoring, solute migration and plant growth. Soil–water characteristic curve (SWCC) is a relationship between suction and water content or degree of saturation. However, little information is available concerning the impacts of grazing exclusion management on soil–water characteristics. Here, the soil–water characteristics of grasslands, which were excluded grazing for 5 (GE5) and 15 years (GE15), were studied. The saturated hydraulic conductivity (K s), SWCC, particle composition, field capacity and some other indexes were determined. Results showed that the clay content and K s of grassland soil were higher for GE15 than GE5. For both treatments, in low suction condition (≤100 kPa), the water holding capacity of 0–10 cm soil was the best. Water holding capacity of topsoil decreased gradually with the increasing of suction, and it reached the strongest when the suction reached 600 kPa. In all soil water suction, the water holding capacity of subsoil was the weakest. The van Genuchten expression was applicable for most of the samples, except 20–30 cm of GE5 and 10–20 cm of GE15. Dual porosity equation was applicable for all the samples. The soil–water capability and soil structure of which was fenced for 15 years is superior to that of 5 years. This study suggests that the enclosure management improved the soil structure and soil–water capability.  相似文献   

20.
Estuaries are important subcomponents of the coastal ocean, but knowledge about the temporal and spatial variability of their carbonate chemistry, as well as their contribution to coastal and global carbon fluxes, are limited. In the present study, we measured the temporal and spatial variability of biogeochemical parameters in a saltmarsh estuary in Southern California, the San Dieguito Lagoon (SDL). We also estimated the flux of dissolved inorganic carbon (DIC) and total organic carbon (TOC) to the adjacent coastal ocean over diel and seasonal timescales. The combined net flux of DIC and TOC (FDIC?+?TOC) to the ocean during outgoing tides ranged from ??1.8±0.5?×?103 to 9.5±0.7?×?103?mol C h?1 during baseline conditions. Based on these fluxes, a rough estimate of the net annual export of DIC and TOC totaled 10±4?×?106?mol C year?1. Following a major rain event (36 mm rain in 3 days), FDIC?+?TOC increased and reached values as high as 29.0 ±?0.7?×?103?mol C h?1. Assuming a hypothetical scenario of three similar storm events in a year, our annual net flux estimate more than doubled to 25 ±?4?×?106?mol C year?1. These findings highlight the importance of assessing coastal carbon fluxes on different timescales and incorporating event scale variations in these assessments. Furthermore, for most of the observations elevated levels of total alkalinity (TA) and pH were observed at the estuary mouth relative to the coastal ocean. This suggests that SDL partly buffers against acidification of adjacent coastal surface waters, although the spatial extent of this buffering is likely small.  相似文献   

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