Microalgae-based systems have been increasingly considered to remediate wastewater, while producing valued biomass. While microalgal monocultures are difficult to maintain in wastewater, mixed cultures have the potential to offer improved system stability and robustness. This research aims to provide a detailed comparison of microalgal monoculture and mixed culture photobioreactors (PBRs) in terms of microalgae growth, biomass harvesting potential, nutrient removal and organic characteristics. Some of the PBRs were further tested for their responses to the presence of wastewater-derived bacteria. Monocultures (containing species from Chlorophyta, Cyanophyta and Eustigmatophyta, respectively) and mixed cultures (mixing two or three species) were evaluated using advanced characterisation techniques including flow cytometry, liquid chromatography – organic carbon detection and excitation−emission matrix fluorescence spectroscopy. The impact of bacteria on system performance was explored by co-culturing some of the cultures with activated sludge. In general, mixed culture systems showed more stable biomass growth and improved nutrient removal uptake (by 20%), as compared to monocultures. However, overyielding (higher biomass production) was not observed in the mixed cultures. Mixing different microalgae tended to increase the concentrations of soluble extracellular materials (e.g. biopolymers) that were able to retain water within the biomass, leading to a lower biomass harvesting potential, as indicated by the capillary suction time. Adding activate sludge significantly increased reduction of measurable dissolved organic carbon concentration (particularly biopolymers and low molecular weight compounds) and nitrogen by >250%. However, wastewater-derived bacteria reduced the yield of all the cultures substantially (by 63–76%) and lowered the dewaterability of the cultures.

人们越来越多地考虑了基于微藻的系统在产生有价值的生物质的同时对废水进行补救。虽然微藻单培养很难在废水中维持，但混合培养具有改善系统稳定性和耐用性的潜力。这项研究旨在提供微藻单培养和混合培养光生物反应器（PBR）在微藻生长，生物量收集潜力，营养去除和有机特性方面的详细比较。进一步测试了某些PBR对废水衍生细菌的反应。使用先进的鉴定技术（包括流式细胞仪）评估了单一培养物（分别包含绿藻，蓝藻和洋桔梗的物种）和混合培养物（混合两种或三种物种），液相色谱法–有机碳检测和激发发射矩阵荧光光谱法。通过将某些培养物与活性污泥共同培养，探索了细菌对系统性能的影响。一般而言，与单一培养相比，混合培养系统显示出更稳定的生物量生长和改善的营养去除吸收（提高20％）。然而，在混合培养物中未观察到过高的产量（更高的生物量产生）。混合不同的微藻往往会增加能够将水保留在生物质中的可溶性细胞外物质（例如生物聚合物）的浓度，从而导致较低的生物质收获潜力（如毛细管抽吸时间所示）。添加活性污泥可显着增加可测量的溶解有机碳浓度（尤其是生物聚合物和低分子量化合物）和氮的减少量> 250％。但是，废水中的细菌会大大降低所有培养物的产量（降低63–76％），并降低培养物的脱水能力。