Biofiltration conceptions applied to pre-treatment of supply water to remove emerging contaminants

ABSTRACT

Due to the increasing susceptibility of water bodies used as sources for public supply to various contaminants and the limited efficiency of conventional water treatment, there is a need to investigate complementary and/or alternative treatment techniques. The aim of this study was to evaluate the efficiency of different biofiltration conceptions, on a bench scale, for the removal/biodegradation of diuron and microcystins, in concentrations of the order of 1000 μg·L⁻¹ of diuron and 50 μg·L⁻¹ of microcystins, in the granular materials slow filter sand, rapid filter sand and granular activated carbon in a laboratory filter. The study was carried out in two distinct experimental phases: with natural biological activation (Phase 1) and with specific biological activation, with the addition of a bacterial culture proven to be active for the degradation of microcystins Sphingosinicella microcystinivorans — B9 (Phase 2). Natural activation showed greater efficiency in relation to the removal of diuron and microcystins, as well as the complementary parameters for all granular media. Specific activation with B9 bacteria proved to be complex in relation of controlling its activity and interfered negatively in the removal of diuron and microcystins when compared to natural activation, including in the granular activated carbon filter. For sand filters, the use of coarser granulometry, such as the rapid filter sand, may be promising because it presents easier handling and cleaning, slower clogging and lower cleaning frequency, in addition to a similar performance to the filter with slow filter sand in relation to the removal of diuron and microcystins.

Keywords:
biofiltration; diuron; microcystins; biological activation; B9 bacteria