Environmental Impact and Physicochemical Assessment of Pond Ash for its Potential Application as a Fill Material

Abstract

Thermal power plants (TPPs) produce a large quantity of coal ash, whose disposal is a big environmental issue. A major portion of coal ash is dumped as pond ash in ash pond near TPPs. Properties of pond ash vary from TPP to TPP and also within the same ash pond at inflow and outflow point. To assess the feasibility of pond ash as a fill material, pond ash samples were collected from inflow and outflow points of three TPPs in Haryana. This paper presents a detailed characterization study on the physicochemical, mineralogical and morphological properties of pond ash samples. Leaching study was also carried out to assess the potential contamination of ground water from coal ash fills. Results reveal that all inflow and outflow pond ashes have low specific gravity (2.03-2.27) as compared to soil (2.6-2.7), i.e. natural fill material, low amount of unburned carbon content (1.79-3.49 %) and the values of maximum dry density and optimum moisture content are within the permissible limits as per design standards of embankment construction. The results of leaching study indicate that concentration of lead (Pb) and chromium (Cr) are quite high from standard land disposal limit, prescribed by Ministry of Environment and Forest in all pond ash samples. So it can be effectively used as construction fill materials for low-lying areas and as embankment materials etc., with caution to protect ground water from contamination due to the high concentration of lead (Pb) and chromium (Cr).

Performance Evaluation of Pavement Geomaterials Stabilized with Pond Ash and Brick Kiln Dust Using Advanced Cyclic Triaxial Testing

“…Both pond ash and brick kiln dust are primarily composed of quartz, alumina, and iron oxide, along with a minute amount of oxides of calcium, titanium, magnesium, phosphorous, potassium, sulphur, sodium and manganese. These findings were in coherence with the literature [42][43][44][45][46][47][48]. Brick kiln dust comprises higher iron content and lower quartz content than pond ash.…”

“…The peaks of quartz were noticed at 20.9 positions. These findings were in coherence with the XRD diffractograms of pond ash reported in literature [44,45].…”

“…Further at higher magnifications, the micrographic observations indicate an agglomeration of variable sized granules with scattered empty spaces. These findings were in coherence with the SEM micrographs of brick kiln dust reported in the literature [44,45].…”

“…This behaviour could be attributed to the presence of cenospheres in the wastes [42]. Higher specific gravity of brick kiln dust than pond ash could be due to coarser particle size and higher iron content in brick kiln dust [43,44]. The grain size distribution curves of pond ash and brick kiln dust samples have been reported in the Figure 1.…”

Research Progress on Separation and Detection Methods of Microplastics in Soil Environment

“…And the density difference between microplastics and microplastics soil samples is the separation essence of density separation method. The density of is generally 0.8~1.4 g/cm3 [13], but the density of soil samples is generally 2.6~2.7 g/cm3 [14]. Because of the adsorption effect of soil aggregates and the large specific surface area of microplastics, microplastics and soil aggregates combine in different limits, which increases the difficulty of separating microplastics in soil environment [15] and reduces the extraction efficiency of density separation method in soil environment.…”