Environmental fate of heavy metals and hydrocarbons in ash from mukah power generation plant

Azzudin, Shebli (2014) Environmental fate of heavy metals and hydrocarbons in ash from mukah power generation plant. Masters thesis, Universiti Malaysia Sarawak.

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Abstract

Coal power generation plant emits several pollutants linked to the environmental problems. Ash produced during coal combustion is partitioned into bottom ash and flyash. A study has been undertaken to investigate the environmental fate of heavy metals and hydrocarbons in ash from Mukah Power Generation Plant (MPG). Soil and sediment samples collected from seven sampling locations at the vicinity of MPG were analysed for aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and heavy metals. The hydrocarbons were extracted from core samples by Soxhlet extraction method and analysed using gas chromatography equipped with flame ionisation detector (GC-FID). Heavy metals were extracted by digestion with aqua regia solution and analysed on the inductively coupled plasma optical emission spectrometer (ICP-OES). The total concentrations of total aliphatic hydrocarbons (TAHs) and PAHs in core samples ranged between 2512.4 to 6566.0 mg/kg and 518.0 to 1210.4 mg/kg dry weight, respectively. Relatively elevated concentration of the hydrocarbons and heavy metals concentrations were found at sampling sites located near to the plant and at the top layers of sample cores suggesting of anthropogenic inputs. Molecular indices and distribution patterns of hydrocarbons were used to predict the sources of hydrocarbons. The diagnostic indices showed the hydrocarbons are petrogenic (fossil fuel) and pyrogenic in characters. The hydrocarbons were resulted from incomplete combustion of coal from the plant. Total organic carb influence the concentration of hydrocarbons in soils. The concentration of T AHs and total PAHs in the core samples of MPG found to be significantly correlated with the Toe of soil. The distribution patterns of heavy metals in the study area were also used to predicting their sources. The dominant heavy metals in core samples were Mn, Zn, V and Pb. The fate and dispersal pathways of hydrocarbons and heavy metals in the sample from study area were predicted using simple correlation analysis. High correlation of both hydrocarbons and heavy metals with fly ash suggests the fly ash is the pollution source. Spatial distribution trend of the hydrocarbons and heavy metals showed the meteorological condition have influenced the pollutants distribution in the study area. The pollution index values (PI) for most sampling sites within vicinity of MPG area showed the study area was contaminated with aliphatic hydrocarbons, PAHs and heavy metals from the plant discharge. The results of this study can be used as baseline data in health risks assessment associated with coal-fired power plant impacts toward environment.

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