Multilayer calcium alginate beads containing Diatom Biosilica and Bacillus subtilis as microecologics for sewage treatment

Organic matter pollution and heavy metal pollution have become one of the main problems in water recycling, and the strategy to simultaneously remove soluble organic matter and metal ions is crucial for sewage treatment. In this study, multilayer calcium Alginate beads (n-Alg-DBs-Bas) containing Diatom Biosilica (DBs) and Bacillus subtilis (Bas) were designed as microecologics for sewage treatment. The introduction of DBs in beads and the multilayer structure could promote Bas growth, prolong the stability of the beads, and enhance the adsorption of beads, further improve the sewage treatment efficiency. The organic matter degradation of 3 layered Alg-DBs-Bas reached to 68.23 ± 0.95 % of COD and 58.88 ± 0.84 % of NH4+-N, and the metal ion adsorption was up to 119.31 mg/g for Fe3+, 110.81 mg/g for Zn2+ and 141.34 mg/g for Cu2+. The prepared multilayer calcium alginate beads combined organic matter degradation and metal ions absorption, which is significant for environmental applications.