Abstract
Widely-used denitrification biofilter (DNBF) is facing the challenge towards the simultaneous removal of steroid estrogens (SEs) and total nitrogen (TN) from secondary effluent. Herein, slow-release calcium peroxide (SR-nCP) was firstly introduced into DNBF to construct SR-nCP/biofilter to in-situ enhance the removal of SEs and TN from low carbon to nitrogen (C/N) ratio wastewater. Results showed that the SEs removal rate could reach >95 % and the effluent TN maintained <15 mg/L. Under hydraulic retention time (HRT) = 3 h, 17α-ethinyl estradiol (EE2) removal increased by 22.0 %–27.0 %, and the denitrification load increased by 123.5 % to reach (60.8 ± 4.8) g·N (m3·d)−1. Moreover, SR-nCP/biofilter improved the reduction of both endocrine disrupting and acute toxicity, and the enhancement effect was more prominent under the low HRT condition. Furthermore, Sediminibacterium and Steroidobacter were identified as core aerobic bacterium that acted on SEs degradation and anaerobic bacterium that was responsible for simultaneous removal of SEs and TN, respectively. The presented strategy exhibited a synergistic effect of oxygen and organic carbon from SR-nCP and confirmed the feasibility of the SR-nCP/biofilter for the removal of SEs and TN from low C/N wastewater, highlighting a promising in-situ enhancement method for upgrading the function of current DNBF in advanced wastewater purification.
Published Version
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