The aim of this work was to obtain decay kinetic parameters for bacteria sedimentation–resuspension in water. For that, synthetic water matrices prepared with four particle sizes at 2.5 and 5 g/l, were spiked with Escherichia coli and Enterococcus faecalis, selected as Gram-negative and -positive models, respectively. Matrices with bacteria without solids were used as controls. Turbidity was measured and culturable bacteria decay was evaluated using membrane filtration over time. Also, the persistence of culturable E. faecalis and its DNA (detected by real-time PCR) was compared. When no colonies were detected, water matrices were mixed to re-suspend sediments and surface samples were collected and analysed. Spearman test was applied to find correlation between bacteria and turbidity. A persistence coefficient (PC) was defined and several kinetic parameters (decay rate constants, R², T₉₀) were calculated from experimental data. While culturable E. coli disappeared from the surface of all water matrices with turbidity (p < 0.05), E. faecalis only showed strong and positive correlation in matrices with higher turbidity and smaller particles. E. coli decayed slower when interacting with smallest solids (<44 μm) than with the largest ones (>149 μm), being T₉₀ 3–4 times higher in the former. Also, it reappeared and persisted in the surface of all matrices after resuspension despite solid concentration (PC: 0.5−0.9). Instead, culturable E. faecalis, persisted less (lower PC values) in matrices with 2.5 g/l than with 5 g/l and no logic relation was observed for any rate constant with particle size. E. faecalis DNA remained in suspension for longer periods until the end of the experience as seen through their lower rate constants (k_DNA < 0.05 h⁻¹). Accurate decay kinetic parameters, like the ones obtained here, are crucial for modelling the fate and transport of bacteria in water and to perform a robust and realistic quantitative risk assessment.

这项工作的目的是获得水中细菌沉降-再悬浮的衰变动力学参数。为此，用 2.5 和 5 g/l 的四种粒径制备的合成水基质加入大肠杆菌和粪肠球菌，分别被选为革兰氏阴性和阳性模型。含有不含固体的细菌的基质用作对照。随着时间的推移，使用膜过滤测量浊度并评估可培养细菌的腐烂。此外，可培养的粪肠球菌的持久性并对其DNA（通过实时PCR检测）进行了比较。当没有检测到菌落时，混合水基质以重新悬浮沉积物，并收集和分析表面样品。Spearman检验用于发现细菌和浊度之间的相关性。定义了持久性系数 ( PC )，并根据实验数据计算了几个动力学参数（衰减速率常数、R ²、T _{90 ）。}虽然可培养的大肠杆菌从所有浊度水基质表面消失（p < 0.05），但粪肠球菌仅在浊度较高和颗粒较小的基质中表现出强正相关。大肠杆菌与最小固体（<44 μm）相互作用时衰减比最大固体（>149 μm）慢，前者的T ₉₀高 3-4 倍。此外，尽管有固体浓度（PC：0.5-0.9），但在重新悬浮后，它会重新出现并持续存在于所有基质的表面。相反，可培养的粪肠球菌在 2.5 g/l 的基质中比在 5 g/l 的基质中持续存在更少（较低的PC值），并且没有观察到任何速率常数与颗粒大小的逻辑关系。粪肠球菌DNA 保持悬浮的时间更长，直到体验结束，从它们较低的速率常数 ( k _DNA < 0.05 h ^-1）。准确的衰变动力学参数（如此处获得的参数）对于模拟水中细菌的命运和运输以及执行稳健和现实的定量风险评估至关重要。