Simultaneous removal of selenium and microbial contamination from drinking water using modified ferrihydrite-based adsorbent

The ferrihydrite and modified ferrihydrite-based adsorbents were explored in the present study to remove selenate and bacterial contamination from drinking water. All the zinc-modified absorbents show >80 % bacterial count reduction, contrary to the unmodified adsorbents (30-40 % reduction). Ferrihydrite-based adsorbent modified with zinc (FH2-10) was the most efficient for selenate adsorption and exhibited the highest bactericidal activity. Sorption experiments showed that for Se (VI) concentration of 400 mu g L-1, a sorbent dose of 0.5 g L(-1 )was sufficient to meet drinking water guidelines within the first 10 min. The maximum adsorption capacity of 40.984 mg/ g was obtained for FH2-10. The regeneration and reuse studies show that the selenium removal efficiency retained was >85 % even after three consecutive adsorption-desorption cycles. Column adsorption studies were performed to assess the adsorbent's field applicability, which inferred the adsorption capacity of 1.3 mg/ g. The FH2-10 adsorbent also showed >95 % bacterial growth reduction against E. coli. Hence the present detailed studies infer that FH2-10 is an efficient material for the simultaneous removal of selenium and bacterial contamination from drinking water, with potential for field application if the sulfate co-ions are not present in higher concentrations.