es400793x_si_001.pdf (735.2 kB)
Flocculation of Microcystis aeruginosa Using Modified Larch Tannin
journal contribution
posted on 2016-02-19, 07:27 authored by Li Wang, Wenyan Liang, Jian Yu, Zhixia Liang, Lingling Ruan, Yuanchun ZhangTo
flocculate the cyanobacterium Microcystis aeruginosa from water, larch tannin, a natural polymer, was modified by Mannich reaction to obtain a flocculant, named A-TN, which
was then quaternized to yield another flocculant, named Q-TN. A-TN
and Q-TN were characterized by Fourier transform infrared spectra
(FTIR) and zeta potential analysis. The effects of the flocculation
parameters, e.g., dosage, pH, cell density, culture time, and extracellular
organic materials, were studied. The results showed that Q-TN was
effective under a wider range of pH values than A-TN and could work
under a pH of 9.0, whereas A-TN could work only under a pH of 7.0.
For algal samples with densities from 1 × 108 to 5
× 109 cells/L, the optimum dosages of Q-TN to achieve
more than 90% removal efficiency ranged from 0.5 to 20 mg/L, and the
optimum dosages had a good linear relationship with cell density.
Furthermore, the required dosage of Q-TN clearly increased along with
the algae culture time, most of which was consumed by the extracellular
organic materials (EOM) excreted from the cells. The spectra of the
three-dimensional excitation–emission matrix showed that 100%
of simple aromatic proteins and 78.8% of protein-like substances in
the EOM could be removed by Q-TN. However, Q-TN was less effective
in humic/fulvic-like substance flocculation. Q-TN functioned to settle
the algae cells and a large amount of their metabolites effectively.