Removal of estrone, 17β-estradiol, and estriol from sewage and cow dung by immobilized Novosphingobium sp. ARI-1

ABSTRACT

Immobilized bacterial agents (IBA) can increase the cell density and improve the environmental adaptability of bacteria. An estrogen-degrading bacterium, Novosphingobium sp. ARI-1, was immobilized in calcium alginate (CA) using an embedding method and applied to the removal of estrogens from natural sewage and cow dung. The optimum immobilization conditions were as follows: sodium alginate (SA) and CaCl₂·2H₂O concentrations of 5% (m/v) and 4% (m/v), respectively; a bacterial suspension to SA ratio of 1:2; and cross-linking for 6 h at 4°C. Immobilized strain ARI-1 mediated the biodegradation of estrone (E1), 17β-estradiol (E2), and estriol (E3) either individually or in combination and was tolerant of various temperatures and pH values. Immobilized ARI-1 removed 80.43%, 94.76%, and 100% of E1, E2, and E3 from sewage containing 1.75, 0.71, and 1.52 μg L⁻¹ of the three test estrogens within seven days, respectively. In cow dung containing initial E1, E2, and E3 concentrations of 0.71, 0.64, and 0.66 mg kg⁻¹, respectively, E1 and E2 concentrations were below the limit of detection, and 1.09% of E3 remained after incubation with immobilized ARI-1 for seven days. These results confirmed the utility of immobilized strain ARI-1 for the removal of estrogens from environmental matrices.

KEYWORDS:

• Immobilization
• estrogens
• degradation
• sewage
• cow dung

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Jiangsu Provincial Key Research and Development Plan, China [grant numbers BE2015682, BE2017718], the Natural Science Foundation of Jiangsu Province [grant number BK20161454], the Fundamental Research Funds for the Central Universities [grant number KYZ201516], the National Natural Science Foundation of China [grant number 41371307], the National Key R&D Plan Key Projects [grant number 2016YFD0800203], and the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).