ABSTRACT
To address questions of water quality and to suggest a local and available treatment
process for iron and manganese removal, ground water samples w ere collected at
4-stations (I, II, III, IV) seasonally during March 2003 - Feb. 2004 and determined
using atomic absorption spectrophotometer (AAS). The results showed that the
concentrations of these ions are higher than the permissible levels. In this concern,
treatment procedure was evaluated using activated carbon prepared by chemical
activation of rice husk using 70 % H3PO4 at 500 °C. Factors affecting adsorption
process (e.g. contact time and sorbent mass) were examined. The results showed
that the percent removal almost reaches ≥ 99 % and in all cases the ion
concentration after treatment is less than the permissible level. Adsorption isotherm
indicates that the monolayer coverage is 0.357 g and 0.625 g of ferrous and
Manganous per gram of sorbent respectively. In dynamic mode, the adsorption
capacity (i.e., Ce/Co = 50 % or Q 0.5 ) was 1 mg/g at flow rate 1liter/min. and the
column recycled at least five times and only needed 1/ 2 ml of KMnO4 (0.06M) for
each regeneration step and no loss in sorbent per cycle should be considered.
Therefore, activated carbon derived from rice husk may be considered as a better
replacement technology for removal of Fe +2 and due to good efficiency in this
application. The possible working adsorption mechanisms are discussed and
confirmed by FTIR.