Dataset associated to publication: "High-rate biological selenate reduction in a sequencing batch reactor for recovery of hexagonal selenium"

Results belonging to paper "High-rate biological selenate reduction in a sequencing batch reactor for recovery of hexagonal selenium".Recovery of selenium (Se) from wastewater provides a solution for both securing Se supply and preventing Se pollution. Here, we developed a high-rate process for biological selenate reduction to elemental selenium. Distinctive from other studies, we aimed for a process with selenate as the main biological electron sink, with minimal formation of methane or sulfide. A sequencing batch reactor, fed with an influent containing 120 mgSe L^-1 selenate and ethanol as electron donor and carbon source, was operated for 495 days. The high rates (419 ± 17 mgSe L^-1 day^-1) were recorded between day 446 and day 495 for a hydraulic retention time of 6h. The maximum conversion efficiency of selenate amounted to 96% with a volumetric conversion rate of 444 mgSe L^-1 day^-1, which is 6 times higher than the rates reported in the literature thus far. At the end of the experiment, a highly enriched selenate reducing biomass had developed, with a specific activity of 856±26 mgSe^-1day^-1g_biomass^-1, which was nearly 1000-fold higher than that of the inoculum. No evidence was found for the formation of methane, sulfide, or volatile reduced selenium compounds like dimethyl-selenide or H₂Se, revealing a high selectivity. Ethanol was incompletely oxidized to acetate. The produced elemental selenium partially accumulated in the reactor as pure (≥80% Se of the total mixture of biomass sludge flocs and flaky aggregates, and ~100% of the specific flaky aggregates) selenium black hexagonal needles, with cluster sizes between 20-200 µm. The new process may serve as the basis for a high-rate technology to remove and recover pure selenium from wastewater or process streams with high selectivity.<br>

本研究结果源自论文《序批式反应器中用于回收六方硒的高速率生物硒酸盐还原工艺》。从废水中回收硒（Se），兼具保障硒资源供给与防控硒污染的双重价值。本研究开发了一种可将硒酸盐生物还原为单质硒的高速率工艺。与现有同类研究不同，本工艺以硒酸盐作为主要生物电子受体，旨在最大限度抑制甲烷与硫化物的生成。本研究采用以乙醇作为电子供体与碳源、进水硒酸盐浓度为120 mgSe·L⁻¹的序批式反应器（sequencing batch reactor），连续运行495天。在水力停留时间为6小时的工况下，第446天至第495天期间，系统实现了419±17 mgSe·L⁻¹·d⁻¹的高还原速率。硒酸盐的最大转化效率可达96%，对应容积转化速率为444 mgSe·L⁻¹·d⁻¹，为现有文献报道同类速率的6倍。实验结束时，系统中已富集得到高活性的硒酸盐还原菌群，其比活性可达856±26 mgSe·d⁻¹·g_生物质⁻¹，约为接种污泥的1000倍。未检测到甲烷、硫化物以及二甲基硒醚、硒化氢（H₂Se）等挥发性还原硒化合物的生成，证明本工艺具有优异的反应选择性。乙醇未被完全氧化，最终代谢产物为乙酸盐。生成的单质硒部分以高纯度形式在反应器内富集：在生物质污泥絮体与片状聚集体的总混合物中，硒占比≥80%；在特定片状聚集体中，硒占比接近100%。产物为黑色六方针状硒单质，团簇尺寸介于20~200 μm之间。该新工艺可为开发高选择性、高速率的废水及工艺流中纯硒脱除与回收技术提供核心支撑。