Microalgae can remove nutrients and organic contaminants from municipal wastewater reverse osmosis concentrate (ROC) and enable resource recovery via biomass production. Two cationic starch flocculants (starch-graft-poly cationic moiety 2-methacryloyloxyethyl trimethyl ammonium chloride (St-g-PDMC) and starch-graft-poly cationic moiety 2,3-epoxypropyl trimethyl ammonium chloride (St-GTA)) were synthesized and tested as potential greener and lower cost alternatives to conventional chemical flocculants for harvesting Chlorella vulgaris and Nannochloropsis salina from the algae-treated ROC. St-GTA achieved up to 97% separation (based on optical density) for both algal species at the dosage of 5–10 mg g⁻¹ dry cell weight (DWC) compared to alum (69% at 10 mg g⁻¹ DWC) and PolyDADMAC (93% at 35 mg g⁻¹ DWC). The overall better performance of St-GTA was attributed to its higher intrinsic viscosity, positive surface charge, and solubility. The harvesting efficiency was influenced by algal growth phases, which led to differences in the levels of negative charge and functional groups on the algal surfaces. The effectiveness of the flocculants was primarily associated with their respective level of positive surface charge (R² = 0.87) that facilitated charge neutralization as indicated by apparent surface charge of the algal flocs (R² = 0.97). Flocculation using St-GTA removed 40% TP, 25% TN, and 20% DOC from the residual contaminants of the algae-treated ROC. Overall, the study indicated that cationic starch could be an environmentally benign and cost-effective approach for harvesting microalgae from the treated ROC, and beneficial to the subsequent utilization of the harvested biomass.

微藻可以从市政废水反渗透浓缩液（ROC）中去除营养物和有机污染物，并通过生物质生产实现资源回收。合成了两种阳离子淀粉絮凝剂（淀粉接枝聚阳离子部分2-甲基丙烯酰氧基乙基三甲基氯化铵（St-g-PDMC）和淀粉接枝聚阳离子部分2,3-环氧丙基三甲基氯化铵（St-GTA）），经测试可作为从藻类处理过的ROC中收获小球藻和拟南芥盐藻的常规化学絮凝剂的潜在绿色环保方法和低成本替代品。与明矾相比，St-GTA在5–10 mg g ^-1干细胞重量（DWC）的剂量下，两种藻类的分离率高达97％（基于光密度），而明矾（10 mg g时达到69％）^-1 DWC）和PolyDADMAC（35 mg g ^-1 DWC时为93％）。St-GTA总体上更好的性能归因于其更高的特性粘度，正表面电荷和溶解度。收获效率受到藻类生长期的影响，这导致藻类表面上负电荷和官能团的含量差异。絮凝剂的有效性主要与它们各自的正表面电荷水平（R ²  = 0.87）有关，这有助于电荷中和，如藻类絮凝物的表观表面电荷（R ² = 0.97）。使用St-GTA的絮凝从藻类处理过的ROC的残留污染物中去除了40％TP，25％TN和20％DOC。总体而言，研究表明，阳离子淀粉可能是一种环境友好且具有成本效益的方法，用于从处理过的ROC中收获微藻，并且有利于随后利用收获的生物质。