Municipal Wastewater Quality Control: Heavy Metal Comparative Analysis—Case Study

Abstract

A comparative analysis was conducted on raw and treated wastewater and the concentrations of heavy metals in sewage sludge from a wastewater treatment plant (WWTP). The research aimed to demonstrate improved efficiency in reducing heavy metal levels as a part of municipal and industrial waste management, with a specific emphasis on minimising the overall environmental impact. In this study, we presented the results of a repeated measures analysis of variance and assessed compliance with heavy metal content standards in sewage sludge from municipal treatment using a one-sample t-test against a reference norm. The analysis included measurements conducted between 2004 and 2015. We conducted an analysis of heavy metals, including zinc (Zn), lead (Pb), cadmium (Cd), copper (Cu), chromium (Cr), and nickel (Ni), manganese (Mn) and mercury (Hg). High Zn concentration that we observed in pre-treatment wastewater raised important questions. Leakages in sewage networks can result in contaminants infiltrating the wastewater, thereby increasing pollutant concentrations. Elevated concentrations can stem from industrial activities, where Zn and pollutants are discharged into wastewater as byproducts of industrial operations. The study illustrated the attainment of the highest sanitary standards, ensuring that treatment processes effectively eliminate harmful toxic substances, ultimately guaranteeing that the final product is safe for further reclamation processes.