Evaluation of the stabilization ability of sludge from the municipal wastewater treatment system through the application of an aerobic process combined with alkalization

University of Science and Technology, The University of Danang, Danang, Vietnam

^* Corresponding author: vdnkhoi@dut.udn.vn

Abstract

The study compares the stabilization potential of secondary sludge from an municipal wastewater treatment system at a laboratory scale, based on two aerobic stabilization experiments: one conducted without an alkaline supplement (T1) and the other with an alkaline supplement (T2). Factors such as temperature, dissolved oxygen (DO), oxidation-reduction potential (ORP), pH, and alkalinity were continuously monitored to maintain optimal environmental conditions for the sludge stabilization process. Experimental results indicated that sludge volume, as measured by MLVSS, decreased by 21% in the T1 experiment and 25% in the T2 experiment, corresponding to sludge decomposition rates of 0.013 g/g/day and 0.06 g/g/day, respectively. Furthermore, organic matter conversion efficiency in the T2 experiment, as measured by COD, increased to 22%, and as measured by BOD5, reached 32% compared to the T1 experiment. Additionally, under controlled alkaline conditions in T2, the oxidation of ammonium compounds was more stable than in T1, with an approximately 5% difference in conversion efficiency from N-NH₄⁺ to N-NO₃^-. Stabilized sludge from both experiments (T1 and T2) demonstrated an organic matter reduction efficiency, based on COD, ranging from 74-80% in urban wastewater treatment trials. This finding suggests the potential for regenerating and reusing secondary sludge to enhance the operational efficiency of urban wastewater treatment systems.