UNSW Water Research Centre, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia; Centre for Advanced Macromolecular Design, School of Chemical Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
Monash Institute of Pharmaceutical Sciences (MIPS), Monash University, IVC 3052, Australia.
Water Res. 2014 Sep 15;61:253-62. doi: 10.1016/j.watres.2014.05.032. Epub 2014 Jun 2.
Dissolved air flotation (DAF), an effective treatment method for clarifying algae/cyanobacteria-laden water, is highly dependent on coagulation-flocculation. Treatment of algae can be problematic due to unpredictable coagulant demand during blooms. To eliminate the need for coagulation-flocculation, the use of commercial polymers or surfactants to alter bubble charge in DAF has shown potential, termed the PosiDAF process. When using surfactants, poor removal was obtained but good bubble adherence was observed. Conversely, when using polymers, effective cell removal was obtained, attributed to polymer bridging, but polymers did not adhere well to the bubble surface, resulting in a cationic clarified effluent that was indicative of high polymer concentrations. In order to combine the attributes of both polymers (bridging ability) and surfactants (hydrophobicity), in this study, a commercially-available cationic polymer, poly(dimethylaminoethyl methacrylate) (polyDMAEMA), was functionalised with hydrophobic pendant groups of various carbon chain lengths to improve adherence of polymer to a bubble surface. Its performance in PosiDAF was contrasted against commercially-available poly(diallyl dimethyl ammonium chloride) (polyDADMAC). All synthesised polymers used for bubble surface modification were found to produce positively charged bubbles. When applying these cationic micro-bubbles in PosiDAF, in the absence of coagulation-flocculation, cell removals in excess of 90% were obtained, reaching a maximum of 99% cell removal and thus demonstrating process viability. Of the synthesised polymers, the polymer containing the largest hydrophobic functionality resulted in highly anionic treated effluent, suggesting stronger adherence of polymers to bubble surfaces and reduced residual polymer concentrations.
气浮（DAF）是一种澄清富藻/蓝藻水的有效处理方法，高度依赖于混凝-絮凝。由于在水华期间不可预测的混凝剂需求，处理藻类可能会出现问题。为了消除混凝-絮凝的需要，已经证明使用商业聚合物或表面活性剂来改变 DAF 中的气泡荷电具有潜力，称为 PosiDAF 工艺。使用表面活性剂时，去除效果不佳，但观察到良好的气泡附着。相反，使用聚合物时，可以有效地去除细胞，这归因于聚合物桥接，但聚合物不易附着在气泡表面，导致阳离子澄清出水，表明聚合物浓度高。为了结合聚合物（桥接能力）和表面活性剂（疏水性）的特性，在本研究中，用具有各种碳链长度的疏水侧基对商业阳离子聚合物聚（二甲基氨基乙基甲基丙烯酸酯）（polyDMAEMA）进行功能化，以提高聚合物对气泡表面的附着性。其在 PosiDAF 中的性能与商业上可用的聚二烯丙基二甲基氯化铵（polyDADMAC）进行了对比。用于气泡表面改性的所有合成聚合物都被发现产生带正电荷的气泡。在没有混凝-絮凝的情况下，将这些阳离子微气泡应用于 PosiDAF 中，可获得超过 90%的细胞去除率，最高达到 99%的细胞去除率，从而证明了该工艺的可行性。在所合成的聚合物中，含有最大疏水性官能团的聚合物导致处理后的废水呈高度阴离子性，这表明聚合物与气泡表面的附着更强，残留聚合物浓度更低。
