Microbial Removal Using Layered Double Hydroxides
and Iron (Hydr)oxides Immobilized on Granular Media |
Jeong-Ann Park, Chang-Gu Lee, Seong-Jik Park, Jae-Hyeon Kim, and Song-Bae Kim† |
Environmental Biocolloid Engineering Laboratory, Department of Rural Systems Engineering, Seoul National University, Seoul 151-921, Korea |
Corresponding Author:
Song-Bae Kim ,Tel: +82-2-880-4587, Fax: +82-2-873-2087, Email: songbkim@snu.ac.kr |
Received: March 21, 2010; Accepted: August 12, 2010. |
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ABSTRACT |
The objective of this study was to investigate microbial removal using layered double hydroxides (LDHs) and iron (hydr)oxides (IHs)
immobilized onto granular media. Column experiments were performed using calcium alginate beads (CA beads), LDHs entrapped in
CA beads (LDH beads), quartz sand (QS), iron hydroxide-coated sand (IHCS) and hematite-coated sand (HCS). Microbial breakthrough
curves were obtained by monitoring the effluent, with the percentage of microbial removal and collector efficiency then quantified
from these curves. The results showed that the LDH beads were ineffective for the removal of the negatively-charged microbes (27.7%
at 1 mM solution), even though the positively-charged LDHs were contained on the beads. The above could be related to the immobilization
method, where LDH powders were immobilized inside CA beads with nano-sized pores (about 10 nm); therefore, micro-sized
microbes (E. coli = 1.21 μm) could not diffuse through the pores to come into contact with the LDHs in the beads, but adhere only to the
exterior surface of the beads via polymeric interaction. IHCS was the most effective in the microbial removal (86.0% at 1 mM solution),
which could be attributed to the iron hydroxide coated onto the exterior surface of QS had a positive surface charge and, therefore,
effectively attracted the negatively-charged microbes via electrostatic interactions. Meanwhile, HCS was far less effective (35.6% at 1
mM solution) than IHCS because the hematite coated onto the external surface of QS is a crystallized iron oxide with a negative surface
charge. This study has helped to improve our knowledge on the potential application of functional granular media for microbial
removal. |
Keywords:
Microbial removal | Layered double hydroxides | Iron (hydr)oxides | Calcium alginate bead | Iron hydr(oxide)-coated sand |
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