Selenate (SeO₄²⁻) and sulfate (SO₄²⁻) are frequently present together with chromate (CrO₄²⁻) in certain industrial wastewaters. SeO₄²⁻ and CrO₄²⁻ are required to be reduced while SO₄²⁻ reduction should be minimized to avoid the production of toxic sulfide. In this study, a modified biofilm model was employed to investigate the interactions between CrO₄²⁻, SeO₄²⁻ and SO₄²⁻ bioreduction in a methane (CH₄)-based membrane biofilm reactor (MBfR). The model was calibrated using steady-state experimental data of two reported CH₄-based MBfRs reducing these oxyanions. The modeling results suggested that the majority of methanotrophs (>80%) were located in the outer layer of the biofilm, while the oxyanions-reducing bacteria preferred to grow close to the membrane. The introduction of SeO₄²⁻ or SO₄²⁻ enriched selenate/sulfate-reducing bacteria (SeRB/SRB) but decreased the abundance of chromate-reducing bacteria (CRB). A biofilm thickness of >300 μm, an HRT of higher than 4 h and an influent dissolved oxygen concentration of 0.3 mg /L were favorable for simultaneous high-level CrO₄²⁻ and SeO₄²⁻ removal. A two-stage MBfR system with optimized operational conditions showed promise in retaining high-purity (>98%) selenium nanoparticles when treating both CrO₄²⁻ and SeO₄²⁻ impacted wastewaters. Moreover, the model indicated that efficient CrO₄²⁻ removal (>90%) along with minor SO₄²⁻ reduction (<10%) could be realized via maintaining appropriate biofilm thickness (200-250 μm) and influent dissolved oxygen (0.7–0.8 mg /L) in a single MBfR. These findings offer insights for the design and operation of CH₄-based technology for remediating CrO₄²⁻ contaminated industrial wastewaters.

在某些工业废水中，硒酸盐 (SeO ₄ ^2- ) 和硫酸盐 (SO ₄ ^2- ) 经常与铬酸盐 (CrO ₄ ^2- )一起存在。SeO ₄ ^2-和CrO ₄ ^2-需要被还原，而SO ₄ ^{2- 的}还原应尽量减少以避免产生有毒的硫化物。在这项研究中，经修饰的生物膜模型，用于研究的CrO之间的相互作用₄ ^2-，SEO ₄ ^2-和SO ₄ ^2-中甲烷生物还原（CH ₄) 为基础的膜生物膜反应器 (MBfR)。使用两个报告的减少这些氧阴离子的基于CH ₄的 MBfR 的稳态实验数据校准该模型。建模结果表明，大多数甲烷氧化菌 (>80%) 位于生物膜的外层，而氧阴离子还原菌更喜欢在膜附近生长。引入SeO ₄ ^2-或 SO ₄ ^2-富硒酸盐/硫酸盐还原菌 (SeRB/SRB) 但降低了铬酸盐还原菌 (CRB) 的丰度。大于 300 μm 的生物膜厚度、高于 4 h 的 HRT 和 0.3 mg /L 的进水溶解氧浓度有利于同时高水平 CrO ₄ ^2-和 SeO₄ ²⁻去除。具有优化操作条件的两级 MBfR 系统在处理受 CrO ₄ ^2-和 SeO ₄ ^2-影响的废水时，有望保留高纯度 (>98%) 的硒纳米颗粒。此外，该模型表明，有效的CrO ₄ ^2-轻微SO沿去除（> 90％）₄ ^2-减少（<10％）可能被通过保持适当的生物膜的厚度（200-250微米）和进水溶解氧实现（0.7 –0.8 mg /L）在单个 MBfR 中。这些发现为基于CH ₄的技术用于修复 CrO ₄ ^2-污染的工业废水的设计和操作提供了见解。