1G.B. Kataganova, 2A.A. Gulakhmadzoda
Annotation:
This article examines the chemical composition of activated sludge from the Dushanbe wastewater treatment plant. The concentrations of macroelements (K, Ca, Mg) and microelements—including heavy metals (Cr, Pb, Hg, Cd, Cu, Ni, Zn, and As)— were evaluated using statistical metrics, scatter plots, and correlation analysis. The findings were compared against international standards, including those set by the EPA, the European Union’s Directive 86/278/EEC, and the People’s Republic of China’s standard GB 18918-2002. While the concentrations of most heavy metals were found to be below the maximum permissible limits, relatively high levels of copper, zinc, and arsenic were recorded. Given the growing challenges in wastewater treatment and the ongoing search for sustainable agricultural practices, the use of activated sludge presents a promising solution. This study covers the composition of activated sludge, its impact on soil fertility and crop growth and yield, as well as the potential risks associated with its use as a fertilizer. The results are intended to inform the development of recommendations for the safe and effective application of activated sludge in agriculture.
Keywords: activated sludge, wastewater, chemical composition, heavy metals, macro-elements, micro-elements, concentration, enrichment factor (EF), correlation analysis, EPA standards, Directive 86/278/EEC, environmental assessment, reuse, Dushanbe.