Department of Civil & Environmental Engineering, University of California Davis, Davis, CA 95616, USA.
Department of Anatomy, Physiology, and Cell Biology, School of Veterinary Medicine, University of California Davis, Davis, CA 95616, USA.
Toxins (Basel). 2021 Jan 29;13(2):99. doi: 10.3390/toxins13020099.
Cyanobacterial blooms and the associated release of cyanotoxins pose problems for many conventional water treatment plants due to their limited removal by typical unit operations. In this study, a conventional water treatment process consisting of coagulation, flocculation, sedimentation, filtration, and sludge dewatering was assessed in lab-scale experiments to measure the removal of microcystin-LR and cells using liquid chromatography with mass spectrometer (LC-MS) and a hemacytometer, respectively. The overall goal was to determine the effect of recycling cyanotoxin-laden dewatered sludge supernatant on treated water quality. The lab-scale experimental system was able to maintain the effluent water quality below relevant the United States Environmental Protection Agency (US EPA) and World Health Organisation (WHO) standards for every parameter analyzed at influent concentrations of above 10 cells/mL. However, substantial increases of 0.171 NTU (Nephelometric Turbidity Unit), 7 × 10 cells/L, and 0.26 µg/L in turbidity, cyanobacteria cell counts, and microcystin-LR concentration were observed at the time of dewatered supernatant injection. Microcystin-LR concentrations of 1.55 µg/L and 0.25 µg/L were still observed in the dewatering process over 24 and 48 h, respectively, after the initial addition of cells, suggesting the possibility that a single cyanobacterial bloom may affect the filtered water quality long after the bloom has dissipated when sludge supernatant recycling is practiced.
蓝藻水华及其相关的藻毒素释放对许多常规水处理厂造成了问题，因为它们通过典型的单元操作的去除效果有限。在这项研究中，在实验室规模实验中评估了包括混凝、絮凝、沉淀、过滤和污泥脱水的常规水处理工艺，以分别使用液相色谱-质谱联用仪 (LC-MS) 和血球计数器测量微囊藻毒素-LR 和细胞的去除率。总体目标是确定回收含藻毒素的脱水污泥上清液对处理后水质的影响。实验室规模的实验系统能够将出水水质维持在相关的美国环保署 (US EPA) 和世界卫生组织 (WHO) 标准以下，分析的每个参数在进水浓度为 10 个细胞/毫升以上时都达到了标准。然而，在脱水上清液注入时，浊度、蓝藻细胞计数和微囊藻毒素-LR 浓度分别大幅增加了 0.171 NTU（浊度单位）、7×10 个细胞/L 和 0.26 µg/L。在最初添加 10 个细胞后的 24 和 48 小时，仍分别观察到脱水过程中的微囊藻毒素-LR 浓度为 1.55 µg/L 和 0.25 µg/L，这表明当实施污泥上清液循环利用时，单个蓝藻水华可能会在水华消散后很长时间内影响过滤后的水质。
