Sewage Sludge and Sediment Analyses as Indicators of Regional Heavy-Metal Pollution: A Case Study in El-Harrach, Algeria

This study examines pollution in the El-Harrach region in northern Algeria by analyzing concentrations of heavy metals and trace elements in sewage sludge and sediments. Three locations were sampled: upstream, within the Baraki wastewater treatment plant (WWTP), and downstream. To identify the major mineralogical components and pollutant composition, chemical analyses were performed using advanced methods, including X-ray diffraction (XRD), X-ray fluorescence (XRF), Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Atomic Emission Spectroscopy (ICP-AES), and total organic carbon (TOC) analysis. Sediments were heavily enriched in heavy metals, particularly at the WWTP. This location yielded concentrations of 2200 ppm copper (Cu), 1160 ppm chromium (Cr), 1590 ppm zinc (Zn), and 320 ppm nickel (Ni). In the downstream areas, lead (Pb) and arsenic (As) were present at 330 ppm and 60 ppm, respectively. The upstream samples showed lower levels, with 410 ppm Cu, 680 ppm Cr, and 100 ppm Ni. Pollution level indicators, including the contamination factor (CF) and enrichment factor (EF), indicated extreme signs of pollution, primarily due to Cu, Zn, Cr, and As, resulting from the influence of industrial effluent and WWTPs. These findings indicate the need for continued environmental monitoring and implementation of effective remediation programs to mitigate these environmental and public health risks in the region.