Breakthrough Column Studies for Iron(II) Removal from Water by Wooden Charcoal and Sand: A low cost approach

Abstract

Ground water is the major source of drinking water in rural and semi-urban areas of Assam. It contains an excessive amount of iron (1 to 10 mg/L). People living in rural and semi-urban areas of Assam uses indigenous household iron filter units – developed using community prepared wooden charcoal (CPWC) and river sand (RS) as filter media. CPWC and RS processed and respectively termed as processed wooden charcoal (PWC) and processed sand (PS). The present work evaluates adsorptive capacity of PWC and PS for dissolved iron removal through continuous mode column studies. The experiments were carried out using synthetic water containing Fe(II) at a fixed pH of 5.5 and zero dissolved oxygen levels. The adsorption breakthrough curves obtained at different bed depths indicate increase of breakthrough time with increase in bed depths, while the uptake of Fe(II) ions onto the adsorbent decreases when the linear flow rate through the bed increases. A rise in the inlet Fe(II) concentration reduces the volume treated before the packed bed gets saturated. PWC shows higher affinity for Fe(II) as compared to PS under the experimental conditions of this study. On comparison of up-scaled columns and indigenous unit models of same bed heights and flow rate, the up-scaled columns perform better than indigenous unit models and yield higher breakthrough throughputs. Among up-scaled columns, the column with PWC at top and PS at bottom yielded higher breakthrough throughput for initial Fe(II) concentration of 5 mg/L. The up-scaled columns perform reasonably well with actual groundwater containing various other ionic species and indicate its ability to remove fluoride, turbidity, sulfate and alkalinity at breakthrough point of Fe(II).