Hypochlorite efficiency on greensand for iron and manganese removal as potassium permanganate alternative in ground water treatment
摘要
Iron and manganese contamination in groundwater necessitates effective treatment. Greensand filter, commonly regenerated with potassium permanganate (KMnO4), faces challenges due to KMnO4’s high cost and stringent handling. This study investigates the feasibility of using sodium hypochlorite (NaOCl) as a cost-effective and readily available alternative for greensand regeneration in the Middle Nile Delta, Egypt. Field trials at six locations evaluated the performance of NaOCl compared to KMnO4 in removing iron and manganese. NaOCl achieved iron removal efficiencies ranging from 27.06 to 84.5% and manganese removal efficiencies between 60 and 98%. While KMnO4 exhibited higher iron removal (75–96%) and manganese removal efficiencies from 40 to 94.08%. NaOCl increases the regeneration cycle, from two or three days for KMnO4 to weekly or bi-weekly intervals. The optimum regeneration time by NaOCl was 40 min according to the experimental procedure, where iron and manganese concentration after regeneration was 0.1 mg/L ± 0.002 and 0.2 mg/L ± 0.009 respectively. NaOCl demonstrated comparable or superior manganese removal in several cases. Chlorite and chlorate concentrations using Ion chromatography ranged from non-detectable to 0.6 mg/L ± 0.06, total organic carbon (TOC) ranged between 0.8 mg/l ± 0.1 and 1.6 mg/l ± 0.2 and Trihalomethanes (THMs) were non-detected using gas chromatography in all six locations. This study, the first of its kind in the region, provides valuable insights into the efficacy of NaOCl for large-scale greensand regeneration. The findings demonstrate NaOCl's potential as a viable and sustainable alternative to KMnO4, offering significant economic and operational benefits for water treatment facilities in Egypt.