Biosorption studies on arsenic (III) removal from industrial wastewater by using fixed and fluidized bed operation

Abstract

Previously, activated carbon was used as adsorbent for the removal of heavy metals at batch scale and the reported removal efficiency was up to 25 % (while in our technique the efficiency is up to 75%). The large industries operate with continuous processes and discharge large amount of wastewater containing heavy metals. No research was published for continuous operation using fluidized bed adsorption column till now. The novelty of this study is on the mode of operation (continuous operation at large scale under fixed and fluidized bed conditions), Biosorbent activated carbon (AC), and maximum efficiency of arsenic removal (i.e. 75 %). The Biosorbent activated carbon prepared from waste agriculture material. Industrial wastewater consists of many inorganic and organic pollutants which are discharged into water bodies resulting the serious health problems. Now a days, concentration of arsenic has much increased as compared to the permissive concentration level (25mg/L). Therefore, there is need to reduce this concentration up to threshold value (10μg/L). The use of biosorbents for arsenic removal from wastewater has global significance due to its widespread availability and low cost. Biosorption of Arsenic strongly depends on the initial metal concentration, contact time, speed of stirring, pH and temperature. The maximum arsenic as (III) removed at pH-7.5 is 70%, it was improved to 83% by agitation in batch experiments. While in continuous mode experiments (Fixed bed) the bed height and flow rates were varied. At the Fluidized bed experiments, the maximum As (III) removed was 75%. The effects of several factors such as pH, initial solute concentration, biosorbents dose, has been revaluated in this paper. The low cost, easily available biosorbent AC is recommended for removal of arsenic from contaminated wastewaters to bring them in compliance.