Effectiveness of Moringa oleifera, chitosan, and alum as adsorbents in lake water treatment

Abstract

This study evaluated the effects of Moringa oleifera (MO), chitosan, and alum as adsorbents on the physicochemical properties of water collected from Lake Florida in Johannesburg, South Africa. The lake water was subjected to three different treatments using jar tests at concentration dosages of 25, 30, and 35 mL and settling times of 30, 60, and 90 min. The water treated with adsorbents significantly reduced turbidity (p < 0.05) with removal efficiencies of 99.33% for MO (30 mL, 30 min), 99.22% for chitosan (35 mL, 60 min), and 99.60% for alum (25 mL, 60 min). Dissolved oxygen increased significantly (p < 0.05) from 2.06 ± 0.02 mg/L to 3.24 ± 0.01 mg/L with chitosan (25 mL, 90 min) and MO (35 mL, 90 min), and to 3.15 ± 0.01 mg/L with alum (25 mL, 60 min). Sulfate levels increased with MO from 65.00 ± 1.00 mg/L to 200.67 ± 0.58 mg/L (35 mL, 90 min), while alum caused an initial decrease to 49.67 ± 0.58 mg/L (25 mL, 30 min), followed by an increase to 71.33 ± 0.58 mg/L. Furthermore, total dissolved solids and conductivity increased with MO, whereas chitosan and alum caused no significant changes. However, a slight pH reduction was noted, with no significant nitrate alteration. Based on principal component analysis, the key factors driving water quality variations in the dataset were treatment type and retention time, with parameters such as pH, conductivity, and sulfate being strong indicators of treatment efficiency. Dissolved oxygen and nitrate were more dependent on treatment time. These findings provide insights into the performance of different adsorbents and their impacts on lake water quality.