Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kgs, Lyngby, Denmark; Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220, Aalborg, Denmark.
Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kgs, Lyngby, Denmark.
Chemosphere. 2021 Jan;262:127939. doi: 10.1016/j.chemosphere.2020.127939. Epub 2020 Aug 13.
Species specific nitrogen-to-phosphorus molar ratio (NPR) has been suggested for green microalgae. Algae can store nitrogen and phosphorus, suggesting that the optimum feed concentration dynamically changes as function of the nutrient storage. We assessed the effect of varying influent NPR on microalgal cultivation in terms of microbial community stability, effluent quality and biokinetics. Mixed green microalgae (Chlorella sorokiniana and Scenedesmus sp.) and a monoculture of Chlorella sp. were cultivated in continuous laboratory-scale reactors treating used water. An innovative image analysis tool, developed in this study, was used to track microbial community changes. Diatoms proliferated as influent NPR decreased, and were outcompeted once cultivation conditions were restored to the optimal NPR range. Low NPR operation resulted in decrease in phosphorus removal, biomass concentration and effluent nitrogen concentration. ASM-A kinetic model simulation results agreed well with operational data in the absence of diatoms. The failure to predict operational data in the presence of diatoms suggest differences in microbial activity that can significantly influence nutrient recovery in photobioreactors (PBR). No contamination occurred during Chlorella sp. monoculture cultivation with varying NPRs. Low NPR operation resulted in decrease in biomass concentration, effluent nitrogen concentration and nitrogen quota. The ASM-A model was calibrated for the monoculture and the simulations could predict the experimental data in continuous operation using a single parameter subset, suggesting stable biokinetics under the different NPR conditions. Results show that controlling the influent NPR is effective to maintain the algal community composition in PBR, thereby ensuring effective nutrients uptake.
已建议使用特定于物种的氮磷摩尔比（NPR）来培养绿色微藻。藻类可以储存氮和磷，这表明最佳饲料浓度会随着养分储存的动态变化而变化。我们评估了变应 NPR 对微藻培养的影响，包括微生物群落稳定性、出水质量和生物动力学。混合绿藻（Chlorella sorokiniana 和 Scenedesmus sp.）和 Chlorella sp. 的单培养物在处理废水的连续实验室规模反应器中进行培养。本研究开发了一种创新的图像分析工具，用于跟踪微生物群落变化。当进水 NPR 降低时，硅藻大量繁殖，一旦恢复到最佳 NPR 范围，就会被淘汰。低 NPR 操作会导致磷去除率、生物量浓度和出水氮浓度降低。ASM-A 动力学模型模拟结果与无硅藻存在时的运行数据吻合较好。在存在硅藻的情况下，未能预测运行数据表明微生物活性存在差异，这会显著影响光生物反应器（PBR）中的养分回收。在不同 NPR 下进行 Chlorella sp. 单培养时，没有发生污染。低 NPR 操作会导致生物量浓度、出水氮浓度和氮定额降低。对单培养物进行了 ASM-A 模型校准，并且可以使用单个参数子集来模拟连续运行中的实验数据，这表明在不同 NPR 条件下具有稳定的生物动力学。结果表明，控制进水 NPR 可有效维持 PBR 中的藻类群落组成，从而确保有效吸收养分。
