Construction of Magnetic Composite Bacterial Carrier and Application in 17β-Estradiol Degradation

Abstract

Estrogen contamination is widespread and microbial degradation is a promising removal method; however, unfavorable environments can hinder microbial function. In this study, a natural estrogen 17β-estradiol (E2) was introduced as a degradation target, and a new combination of bacterial carrier was investigated. We found the best combination of polyvinyl alcohol (PVA) and sodium alginate (SA) was 4% total concentration, PVA:SA = 5:5, with nano-Fe3O4 at 2%, and maltose and glycine added to promote degradation, for which the optimal concentrations were 5 g·L−1 and 10 g·L−1, respectively. Based on the above exploration, the bacterial carrier was made, and the degradation efficiency of the immobilized bacteria reached 92.3% in 5 days. The immobilized bacteria were reused for three cycles, and the degradation efficiency of each round could exceed 94%. Immobilization showed advantages at pH 5, pH 11, 10 °C, 40 °C, and 40 g·L−1 NaCl, and the degradation efficiency of the immobilized bacteria was higher than 90%. In the wastewater, the immobilized bacteria could degrade E2 to about 1 mg·L−1 on the 5th day. This study constructed a bacterial immobilization carrier using a new combination, explored the application potential of the carrier, and provided a new choice of bacterial immobilization carrier.

Development and assessment of an immobilized bacterial alliance that efficiently degrades tylosin in wastewater

“…Activated carbon (AC) was washed three times with deionized water and dried at 65˚C. The bacterial alliance was immobilized with 2% SA+2% PVA (SA and PVA ratios were based on [26] with various concentrations of AC (0, 0.5, 1, 1.5, and 2%). First, PVA was dissolved by heating and SA added, with mixing by a magnetic stirrer.…”

“…As microorganisms can be affected by unfavorable environments, functional microorganisms can be immobilized on carriers [26], thereby reducing external environment influences [27,28]. Various materials are used as immobilization carriers, including inorganic materials, natural organic polymers, and synthetic organic polymers [29].…”