Abstract
Sulphate (SO 4 2- ) in wastewater should be reduced before discharge because high concentration of SO 4 2- could cause pollution problems to surrounding environment. In present study, the modified rice straw as anionic sorbent was used to prepare expanded- and fixed-bed columns for sulphate removal. The breakthrough curves were analyzed by Thomas model to investigate the column adsorption performance. The results showed that, for expanded-bed operation, the expansion ratio linearly increased with upflow volecity. The maximum expansion ratio of less than 25% was recommended because the breakthrough time and column adsorption amount both decreased with the rise of expansion ratio. For fixed-bed operation, either increase of influent sulphate concentration or flow rate would shorten the breakthrough time. However, with the increase of of height-diameter ratio of the column, the fixed-bed service time was extended. Under experimental flow rate, expanded-bed provided better adsorption of sulphate than fixed-bed. Additionally, 0.1 mol/L NaOH solution was the most appropriate regeneration agent under experimental conditions.
Published Version
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