Wastewater treatment in developing countries remains inadequate due to limited awareness of its environmental and health impacts, coupled with the high costs of available treatment technologies. Therefore, developing cost-effective, accessible, and efficient treatment solutions is crucial for protecting public health and the environment. This study evaluates the chemical oxygen demand (COD) removal efficiency of a novel combined pre-treatment process followed by adsorption using Noug sawdust activated carbon (NSDAC), a low-cost and sustainable adsorbent. A laboratory-based study was conducted to optimize COD removal efficiency through sequential pre-treatment steps as screening, sedimentation, and filtration followed by adsorption with NSDAC. The adsorbent was chemically activated using sulfuric acid (H₂SO₄) and thoroughly characterized to assess its physicochemical properties. Batch adsorption experiments examined the influence of pH, adsorbent dose, contact time, and agitation speed on COD removal efficiency. A central composite design was employed to evaluate process interactions and optimize conditions using Design Expert version 13.0.5.0 software. ANOVA and a quadratic logistic regression model were used to assess the statistical significance of process parameters. The highest COD removal efficiency (90.53%) was achieved at a pH of 6.05, an adsorbent dose of 10.87 g/L, a contact time of 86.94 min, and an agitation speed of 190.31 rpm. When applied to real wastewater, the integrated pre-treatment and NSDAC adsorption system achieved a COD removal efficiency of 97.50%, demonstrating superior performance. Adsorption data best fit the Langmuir isotherm model (R² = 0.9993) and followed pseudo-second-order kinetics (R² = 0.9936), indicating monolayer adsorption and chemisorption as the dominant mechanism. This study highlights the potential of NSDAC as a sustainable alternative to conventional adsorbents, contributing to the development of cost-effective wastewater treatment technologies. Future research should focus on optimizing large-scale applications, assessing the economic feasibility of widespread NSDAC adoption, and investigating its regeneration and reusability to improve long-term sustainability.
Anteneh et al. (Thu,) studied this question.