fly ash landfills under continuous

Overview

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and utilization rates. In China, coal is the predominant source of power, accounting for over 73% of the country’s
life2,7,8 (Zhao 2018; Hassett D J 1994; Locatelli L 2019). Additionally, around 50% of China’s coal-fired power
both within and between years. Since 1956,The mean annual precipitation is 419.8 mm, with a maximum of
718.0 mm (1988) and a minimum of 260.7 mm (1997). The mean annual precipitation days are 73.6, with
Initial moisture content (%) (g/cm3) silt content (%) (%) (%) (%)
Table 1. The basic physical indexs of CFA.
Table 2. Ion contents in fly Ash and bottom Ash (mg/kg). ① The average content of soil in North China.
The basic physical indexs of the coal fly ash are shown in Table 1.
The ion contents in fly ash and bottom ash are shown in Table 2.
Color (%) (g/cm3) (%) (%) (%) (%) >0.05 mm 0.005 mm < 0.005 mm classification
Table 3. The basic physical indicators of undisturbed Ma’lan soil.
study. The basic properties of the undisturbed Ma’lan loess are shown in Table 3. The elements or compounds
hole, and slag yard had a moisture content of 0%, while the sample from the ash storage yard had a moisture
content of 0.05%. Based on the determined moisture content, 100 g (dry weight) of each sample was accurately
moisture content of approximately 15% was estimated using the plastic limit of Ma’lan loess. Six moisture
gradients (11, 13, 15, 17, 19, and 21%) were then selected experimentally. Three kilograms of air-dried soil
Table 6. Values of contaminant ions concentration in the model.
column tests was taken as the pollutants concentrations, as shown as the Table 6.
Where θ is the volumetric water content, C0 is initial solute concentration (mg/L), Ct is solute concentration
the results of previous studies, the results is shown as Table 7. The longitudinal dispersion coefficient was
values, with the fitting error falling within the permissible range(Supplemental Figure S-1). It shows that the
Ion concentration of the leachate from four fly ash samples is shown as Table 8. Based on a comparison of
moisture content of 13% after 20 manual compaction blows, resulting in a value of 1.781 g/cm³. The compaction
For coal fly ash, the optimal moisture content is 32%, which corresponds to a dry density of 1.054 g/cm³.
The compaction curves of CFA is shown Fig. 6. Fly ash exhibits a stable internal structure when it is near its
The main physical properties of compacted remodeled Ma’lan loess and CFA are shown as Tables 9 and 10,
for each of the soil column was shown as Table 11.
Table 8. Ion Concentration in Leachate from fly Ash and bottom Ash (mg/L). Bold value represents ion
Table 9. The main physical properties of compacted remodeled Ma’lan loess.
Table 10. The main physical properties of compacted CFA.
Cd having the largest decrease. After a period of leaching, concentrations of Ni, Cr, Cd, Pb all reduced to 0 mg/L.
The information about discharge and outflow times of leachate for the five ash columns is shown as Table 12.
outlined in the Groundwater Quality Standard (GB/T 14848 − 2017), as presented in Table 13.
Table 12. The information of leachate outflows of ash columns.
National standard on drinking water quality (mg/l) ≤ 250 ≤ 1.0 ≤ 0.05 ≤ 0.05 ≤ 0.01 ≤ 0.05
of 56 cm, not yet exceeds the current design range for the bottom loess isolation layer in our country. Integrating

Methods (brief)

Fly ash and bottom ash samples and characterization
Sample collection and pretreatment
To comprehensively assess the pollutant content in pulverised fuel ash from the power plant, this study sampled
fly ash and bottom ash based on their respective collection locations. Fly ash samples were collected randomly
from the fly ash outlet and storage yard, while bottom ash samples were taken randomly from the tap hole and
slag dump. The sample locations is shown in Fig. 1. The samples were labelled as ash 1, ash 2, slag 1, and slag 2,
respectively. After screening with a 3 mm Teflon-coated sieve mesh, the four samples with the same weight were
The analysis of the ash samples included particle size distribution, maximum dry density, optimum moisture
The chemical composition of the ash samples was analyzed, focusing on six elements of prime environmental
Atomic Absorption Spectrometry with Aqua Regia Digestion (NY/T 1613–2008). Fluoride and chloride were
loess surrounding the ash storage field. The sample weighed 100 kg. Tap water was used instead of meteoric
The leaching procedure for the fly ash and bottom ash samples was conducted according to the Solidwaste-
the following steps: First, 20 g of each of the four ash samples were placed in pre-dried, constant-weight, covered
hole, and slag yard had a moisture content of 0%, while the sample from the ash storage yard had a moisture
content of 0.05%. Based on the determined moisture content, 100 g (dry weight) of each sample was accurately
weighed and placed in 2 L glass wide-mouth bottles. Ultra-pure water was added to each sample to achieve
a frequency of 110 oscillations per minute and an amplitude of 40 mm. The samples were shaken at room
(ρdmax) and optimum moisture contents was determined. Compaction tests were performed on Ma’lan loess and

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Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised