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In order to prepare a new type of landfill covering material for closure, we used industrial calcium-containing waste (construction rubbish, slag, desulfurized gypsum and fly ash) to modify the dredged urban sludge. Shrink, unconfined compression, shear and infiltration tests were performed to obtain the volume shrinkage, compressive strength, shea...
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Context 1
... mixture was then taken out and pressed into a mold with a specified size to prepare a sample of modified sludge with calcium-containing waste. The material proportion of MS1~MS9 modified sludge samples is shown in Table 2. The ratio of the modified sludge was designed by orthogonal experiment. ...Context 2
... can be found from Figure 7 that the XRD crystallization peaks of samples at different depths had little difference, and a large number of porous zeolite and ettringite crystals in the skeleton structure were found in the samples. Quartz (SiO 2 ) 12 (SO 4 ) 32 ·6H 2 O) and typical 11Å structure of tobermorite constitute the main crystalline phases. Abrazite is a hydrated calcium aluminosilicate substance, and ettringite is a crystalline hydrated calcium sulphoaluminate substance produced by the combination of hydration products, C-A-H and SO 4 2− ions. ...Similar publications
In order to prepare a novel landfill liner material, we used industrial calcium-containing waste (slag, fly ash, and desulfurized gypsum) to solidify municipal sludge. The mechanical and permeability properties of the solidified sludge material (SSM) were evaluated using straight shear, uniaxial compression, and permeability tests. The hydration pr...
Management of solid waste and protecting the ecological balance of the region are key challenges that the coal mining industry has to face. This study evaluated the effect of solid waste backfilling mining on the overlying strata movement and surface deformation variation pattern in slice mining. The mechanical characteristics of different cemented...
To explore the strength development characteristics and engineering performance of different coal-based solid waste filling materials cemented into filling body, coal gangue was used as coarse material, fly ash, desulfurization gypsum, gasification slag, and furnace bottom slag as fine material, and cement as a gelling agent. The uniaxial compressi...
Most of the previous studies focused on the mechanical characteristics before the stress peak of solid waste cemented backfill, but in the compression process of a solid waste cemented body, the phenomenon of post-peak stress rebound often occurs. Through the uniaxial compression experiment of a solid waste cemented body composed of coal gangue, fl...
Each year, China produces a substantial amount of municipal sludge, industrial waste (slag, fly ash, and desulfurized gypsum), and construction waste, while its recycling rate is low. If not disposed in a properly and timely manner, this inequity can have serious environmental impacts. This study aimed to prepare a new type of modified sludge mater...
Citations
... With most studies focusing on the hydraulic conductivity and strength properties of the materials [21,22], there is scarce data available on the environmental impact, such as the leaching of hazardous chemicals from the mixtures. A six-month study conducted by the authors of [23] has demonstrated that the hydraulic conductivity of the SS:RG composite can be maintained at 10 −6 cm/s and the leaching of chemicals from the composite is within the regulated limits when flowing distilled water through the composite. ...
This paper examines the environmental impact of the use of compacted sewage sludge: red gypsum (SS:RG) mixture as intermediate landfill cover in terms of yield and quality of leachate as characterised by hydraulic conductivity and leaching behaviour. A series of column tests using the constant head method is carried out by percolating the synthetic leachate through samples that have been compacted at various degrees (60, 70, 75, 80 and 85%). The leachate quality is monitored at
pre-determined days for pH, COD, Cu, Fe and Zn. In general, hydraulic conductivity decreases in three stages, in which the first stage is mainly attributed to the particle rearrangement and hydration of calcium silicate hydrate (CSH). The hydration of CSH increases the pH, which causes the heavy metal to precipitate and be entrapped within the matrices of CSH gel, thereby further reducing the porosity and hydraulic conductivity. A minimum of 75% compaction has shown favourable final
porosity, hydraulic conductivity, and leachate quality, although a minimum of 80% compaction is recommended in order to achieve a satisfactory compressive strength of greater than 345 kPa for a landfill operation.
... Other studies have depicted the significant evolution of MWW, MSS management, and environmental remediation in China [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57]. ...
Municipal sewage sludge is the residual material produced as a waste of municipal wastewater purification. It is a sophisticated multi-component material, hard to handle. For many years, it has been landfilled, incinerated, and widely used in agriculture practice. When unproperly discharged, it is very polluting and unhealthy. The rapidly increasing global amount of municipal sewage sludge produced annually depends on urbanization, degree of development, and lifestyle. Some diffused traditional practices were banned or became economically unfeasible or unacceptable by the communities. In contrast, it has been established that MSS contains valuable resources, which can be utilized as energy and fertilizer. The objective of the review was to prove that resource recovery is beneficially affordable using modern approaches and proper technologies and to estimate the required resources and time. The open sources of information were deeply mined, critically examined, and selected to derive the necessary information regarding each network segment, from the source to the final point, where the municipal sewage sludge is produced and disposed of. We found that developed and some developing countries are involved with ambitious and costly plans for remediation, the modernization of regulations, collecting and purification systems, and beneficial waste management using a modern approach. We also found that the activated sludge process is the leading technology for wastewater purification, and anaerobic digestion is the leading technology for downstream waste. However, biological technologies appear inadequate and hydrothermal carbonization, already applicable at full scale, is the best candidate for playing a significant role in managing municipal sewage sludge produced by big towns and small villages.
