Explorative Evaluation of the Adsorptive Potential of Quercus robur and Quercus rugosa for Lake Water Treatment

This study assessed and compared the effects of Quercus robur (QRO) and Quercus rugosa (QRU) seed extracts as natural coagulants on the physicochemical properties of lake water in Johannesburg. Jar test experiments were conducted using dosage concentrations of 15, 20, and 25 mL, with settling times of 30, 60, and 90 min. The treatments led to 100% turbidity removal across all tested dosages within 90 min. Dissolved oxygen significantly improved, increasing from 1.65 ± 0.02 mg/L in raw lake water to 2.39 ± 0.01 mg/L and 2.33 ± 0.01 mg/L after treatments with QRU and QRO, respectively. Conversely, pH levels decreased from 7.42 ± 0.03 to 7.06 ± 0.02 with QRO and 7.16 ± 0.04 with QRU. Total dissolved solids were reduced from 97.67 ± 1.53 mg/L to 70.33 ± 0.58 mg/L with QRO and 71.33 ± 0.58 mg/L using QRU. A corresponding decline in conductivity was observed, from 192.0 ± 1.0 µS/cm to 141.33 ± 0.58 µS/cm with QRO and 142.33 ± 0.58 µS/cm with QRU. Principal Component Analysis (PCA) highlighted clear distinctions between treated samples and raw lake water, with the treated samples clustering away from untreated water and aligning with improved physicochemical indicators. The findings demonstrate the efficacy of Q. robur and Q. rugosa seed extracts in enhancing water quality and their suitability as low-cost, natural alternatives to conventional coagulants. Post-treatment values for all key parameters met the World Health Organization's recommended limits for drinking water, underscoring the potential of these materials for sustainable water purification.