Author(s): T. D. M. Hai; Tran Thuy Anh; Tran Duc Ha
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Abstract: Because of the large amount of drainage sludge in the upcoming years, Yen So landfill, which receives all of the sludge from inner city of Hanoi, may face the risk of overload and environmental contamination. This study aims to clarify the characteristics and to assess the hazardous level and reusability of sewage sludge and river sediment from To Lich River (TLR) basin. Sewage sludge from two sewers in the old and new urban areas were analyzed in consideration of physical features, chemical components both in dry and rainy seasons. After that, these concentrations were compared with national environmental regulations for hazards and aquatic life preservation, land use purposes. Concentrations of heavy metals in the river sediment at seven sample sites along the upstream were also examined. Although heavy metals in sewage sludge and river sediment exceeds national standards for sediment to protect fresh aquatic life and several land use purposes, they are below standards for hazardous wastes. Sewage sludge has high humidity and inorganic content both in two seasons. However, sewage sludge in dry seasons contains higher concentrations of heavy metals than in rainy seasons, thus, unsuitable for all of land use purposes. Sewage sludge in rainy season and sediment are not suitable for agricultural purpose due to high concentrations of Zn, and Cr, respectively. Those characteristics allows sewage sludge and TLR sediment to be reused as industrial, commercial, and service land. In case the sludge is reused as fertilizer or agricultural soil, heavy metal concentration should be lessened.
Year: 2018