Department of Civil, Architectural and Environmental Engineering , The University of Texas at Austin , Austin , Texas 78712 , United States.
Environ Sci Technol. 2019 Oct 15;53(20):11694-11703. doi: 10.1021/acs.est.5b05255. Epub 2019 Oct 4.
The role of calcite heterogeneous nucleation was studied in a particle-coagulation treatment process for removing microalgae from water. Batch experiments were conducted with sp. and sp. in the presence and absence of carbonate and in the presence and absence of magnesium to delineate the role of CaCO nucleation on microalgae removal. The results indicate that effective algae coagulation (e.g., up to 81% algae removal efficiency) can be achieved via heterogeneous nucleation with CaCO; however, supersaturation ratios between 120 and 200 are required to achieve at least 50% algae removal, depending on ion concentrations. Algae removal was attributed to the adsorption of Ca onto the cell surface, which provides nucleation sites for CaCO precipitation. Bridging of calcite particles between the algal cells led to rapid aggregation and formation of larger flocs. However, at higher supersaturation conditions, algae removal was diminished due to the dominance of homogeneous nucleation of CaCO. The removal of algae in the presence of Ca and Mg required higher supersaturation values; however, the shift from heteronucleation to homonucleation with increasing supersaturation was still evident. The results suggest that water chemistry, pH, ionic strength, alkalinity, and Ca concentration can be optimized for algae removal via coagulation and sedimentation.
在去除水中微藻的颗粒凝聚处理过程中，研究了方解石异质成核的作用。在存在和不存在碳酸盐以及存在和不存在镁的情况下，进行了 sp. 和 sp. 的分批实验，以描绘 CaCO 成核对微藻去除的作用。结果表明，通过 CaCO 的异质成核可以实现有效的藻类凝聚（例如，高达 81%的藻类去除效率）；然而，取决于离子浓度，至少需要达到 50%的藻类去除所需的过饱和度比为 120 至 200。藻类去除归因于 Ca 在细胞表面的吸附，这为 CaCO 沉淀提供了成核位点。方解石颗粒在藻细胞之间的桥接导致快速聚集和形成更大的絮体。然而，在较高的过饱和度条件下，由于 CaCO 的均相成核占主导地位，藻类去除减少。在 Ca 和 Mg 存在的情况下去除藻类需要更高的过饱和度值；然而，随着过饱和度的增加，从异质成核到均相成核的转变仍然明显。结果表明，可以通过凝聚和沉淀优化水化学、pH 值、离子强度、碱度和 Ca 浓度以去除藻类。
