Abstract
Volcanic ash soil heated with ferrous sulfate (VASHF) has a large specific surface area and is porous. VASHF particles have a rough surface and contain micropores with a diameter in the range of 0.003-100 μm. Pores having a diameter larger than 5 μm account for 41.6% of micropores. Moreover, VASHF also has a positive charge. The ability of VASHF to remove algae was examined in terms of the particle size of VASHF, line velocity and the thickness of VASHF. It was shown that VASHF can remove algae from water. The algal removal mechanism of VASHF is considered to be a result of the retention of algae due to the number of pores among particles, the irregularity of the surface and the micropores diameter of the particles, and also of the adsorption of algae due to the particles having a positive charge. Moreover, H2SO4 treatment is the most effective method of recycling used VASHF that contains adsorbed algae. This allows VASHF to be reused.
