Evaluation of trace metals in sewage sludge from a wastewater treatment plant with perspective of valorisation

Abstract

The increasing quantities of sewage sludge from wastewater ‎treatment plants are a great source of worry especially concerning ‎their impact on the environment. Managing such sludge is the ‎basis for a successful general sanitation scheme.‎ The present work subject matter is the evaluation of pollutants ‎present in the sewage sludge recovered from urban wastewater ‎treatment plant of the town of Boumerdès, Algeria, which is treated ‎wastewater from three (03) towns: Boumerdes – Corso – ‎Tidjelabine. For this study, we followed the evolution of some ‎physical and chemical parameters such as the concentration of ‎trace metals which we have analysed mineralogically through the ‎use of X-ray fluorescence and then compared to the French ‎standard NF U 44-041. The NF U 44-041 standard concerns the ‎reuse of sewage sludge as fertilizer in land application. Several ‎sewage sludge samples have been analysed in the present work.‎ The analysis of the sewage sludge physical properties has revealed ‎a low percentage of dry matter (total solids) and a high ‎percentage of organic matter. The chemical characterization of the ‎sludge helped to evaluate their pH and polluting power. Overall ‎the pH level of the sludge was approaching neutrality and their ‎concentration in trace metals was below the thresholds defined by ‎the NF U 44-041 standard. Thus, municipal sewage sludge does ‎not represent any danger to the environment that thus can safely ‎be used in agriculture