Construction of heterotrophic-sulfur autotrophic integrated fluidized bed reactor for simultaneous and efficient removal of compound pollution of perchlorate and nitrate in water
2022
Wan, Dongjin | Cao, Yang | Shi, Yahui | Li, Qi | Li, Ying | Zhang, Zhixiang | Han, Xinze | Gao, Yafei
A heterotrophic sulfur autotrophic integrated fluidized bed reactor was established for simultaneous and efficient removal of ClO₄⁻ and NO₃⁻ from water. The optimum operating conditions forecasted through the response surface method (RSM) were the hydraulic retention time (HRT) of 0.50 h, the influent acetate (CH₃COO⁻) concentration of 55 mg/L and the reflux ratio of 14, contributing to ClO₄⁻ and NO₃⁻ removal of 98.99% and 99.96%, respectively, without secondary pollution caused by residual carbon (NPOC <3.89 mg/L). Meanwhile, the effluent pH fluctuated in a range of 6.70–8.02 and sulfur-containing by-products (i.e., SO₄²⁻ and S²⁻) could be controlled by adjusting operation conditions throughout the experimental stage. The increase of the influent CH₃COO⁻ concentration reduced the load borne by autotrophic reduction process and further reduced SO₄²⁻ production. Shortening HRT, increasing the influent CH₃COO⁻ concentration and decreasing the reflux ratio could all reduce alkalinity consumption. Shortening HRT and decreasing the reflux ratio could shorten contact time between sulfur and water and thus inhibit S⁰ disproportionation. High-throughput sequencing result showed that Proteobacteria and Chlorobi were the dominant bacteria. Sulfurovum, Sulfuricurvum and Ignavibacterium were the major heterotrophic denitrifying bacteria (DB)/perchlorate reducing bacteria (PRB), Ferritrophicum and Geothrix were DB, and Chlorobaculum was S⁰ disproportionation bacteria.
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