Removal of contaminants of emerging concern from pig manure in different operation stages of a thin-layer cascade photobioreactor. Relationship with concentrations in microalgae and manure.

The performance of a pilot-scale thin-layer cascade photobioreactor, operated in semicontinuous mode, for the removal of veterinary drug residues and other contaminants of emerging concern (CECs) from pig manure has been assessed in six operation stages. Chlorella sp. (70–90%), Scenedesmus sp. (10–25%) and Diatomea (<5%) comprise the microalgae species present during the stages. The global performance to remove the total CEC content in the photobioreactor effluent varied from 62 to 86% on each stage, while an CEC mean amount close to 8% was accumulated in the photobioreactor biomass. A relation with weather conditions was not observed. Elimination ratio was not related to the concentration in the influent which reached up to 8000 ng L−1 for some CECs. As expected, the concentrations of veterinary drugs were higher than those of non-veterinary CECs. The concentrations accumulated in the grown biomass were relative low, lower than 10 ng per fresh g excepting for a few cases. However, statistical data suggested that the linkage of CECs to microalgae biomass boosted their removal from the influent. Furthermore, it was observed that the manure liquid phase contained higher amounts of CECs than the solid phase.

本研究依托六个运行阶段，评估了半连续运行的中试规模薄层级联光生物反应器对猪粪中兽药残留及其他新兴污染物（contaminants of emerging concern, CECs）的去除性能。各阶段的微藻群落由小球藻属（Chlorella sp.，占比70%~90%）、栅藻属（Scenedesmus sp.，占比10%~25%）以及硅藻（Diatomea，占比<5%）组成。该光生物反应器对进水中总CECs的整体去除率在各阶段介于62%~86%之间，而光生物反应器生物质中累积的CECs平均含量接近8%。未观察到该处理系统的性能与气象条件存在关联，且CECs去除率与进水浓度无关，部分CECs的进水浓度最高可达8000 ng·L⁻¹。正如预期，兽药类CECs的浓度高于非兽药类CECs。生长的微藻生物质中累积的CECs浓度相对较低，仅少数案例中浓度超过每鲜重克10 ng。然而统计数据表明，CECs与微藻生物质的结合可促进其从进水中的去除。此外，研究发现猪粪液相中的CECs含量显著高于固相。