Evaluating centrifuged water treatment plant sludge as an adsorbent for nutrients, microorganisms, and heavy metals removal from wastewater

Abstract

Achieving universal access to clean water, as mandated by SDG 6 – Clean Water and Sanitation, is crucial for supporting human health and environmental sustainability. Water treatment plants generate a by-product known as Water Treatment Plant Sludge (WTPS), comprising organic and inorganic substances. Traditionally, the disposal of WTPS poses environmental risks, including nutrient runoff and heavy metal contamination. This study investigates using centrifuged WTPS, without prior treatment, as an adsorbent to remove contaminants from treated wastewater, offering a sustainable waste management solution. Through comprehensive characterization using Scanning Electron Microscopy, Thermogravimetric Analysis, Fourier Transform Infrared Spectroscopy, and geo-environmental parameter assessment, the research evaluates the adsorption efficacy of WTPS. A factorial design methodology facilitated the systematic examination of adsorption tests. Findings indicate that WTPS exhibits adsorption capacities for phosphorus (q = 0.2 mg g-1), Chemical Oxygen Demand (q = 1.1 mg g-1), and metals under specific conditions. Maximum removal efficiencies for total coliforms and Escherichia coli were achieved with extended contact times, showcasing WTPS's potential as a robust adsorbent. The research demonstrates that centrifuged WTPS can significantly reduce concentrations of metals such as Pb, Co, and Ni (100%), Al (96%), Cu (95%), and Fe (93%) in treated wastewater, presenting a promising approach for enhancing wastewater quality. However, the interaction between WTPS and wastewater resulted in an increased concentration of Mn in the effluent, highlighting the complex dynamics of adsorption processes. In conclusion, centrifuged WTPS emerges as a viable, cost-effective adsorbent, aligning with sustainable waste management practices and circular economy principles.