Combination of magnetic activated carbon and activated sludge for methylene blue and nickel(II) ions removal in aerobic biological treatment

The treatment of dyes and heavy metals in aqueous solutions is a major environmental concern, and many methods have been developed to address this problem. However, most of these methods focus on treating either dyes or heavy metals and have their own limitations. Therefore, treatment process that can simultaneously remove both dyes and heavy metals on large scale is essentially required. In this study, we synthesized magnetic activated carbon (MAC) derived from Litsea glutinosa seeds, which was applied to eliminate methylene blue and nickel ions in the aeration tank of the biological treatment system. Structural characteristics and adsorption properties of MAC were studied. The obtained results revealed that the removal efficiency of these pollutants significantly improved as a combination of MAC and activated sludge, especially in the case of nickel ions removal. Furthermore, using MAC in the biological treatment system markedly enhanced the COD removal in compared with that treated without MAC or activated sludge. The advantage of treatment process with MAC addition was also clearly observed by accelerating the settling of activated sludge. Moreover, the obtained results confirmed that wastewater after being treated was assessed as non-toxic to living organisms by using bioassay.