To further unravel the organic fouling behavior of polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes, typical hydrophilic and hydrophobic organic matters sodium alginate (SA) and humic acid (HA) were chosen as model foulants. The adhesion forces of membrane-foulant and foulant-foulant were investigated by atomic force microscopy in conjunction with self-made PVDF probe and foulant-coated probe, respectively. Besides, the removal rate of dissolved organic carbon, fouling experiments with SA, HA and HA/SA mixtures were carried out with PVDF UF membranes. Results show that SA-PVDF and SA-SA interaction forces were stronger than HA-PVDF and HA-HA interaction forces, respectively. This phenomenon, in conjunction with the fact that the flux decline rate and extent of SA-fouled membrane were more serious than that for HA-fouled membrane, suggests that the hydrophilic organic matters were the dominant matters responsible for membrane fouling. The experiments results with HA/SA mixtures show that the fouling behavior of HA/SA mixtures were closely related to the SA percentage in the mixture. Compared with single specie foulant, there were no significant synergistic effects from HA and SA to enhance membrane fouling. Moreover, there was a positive correlation between the removal rate of foulants and corresponding interaction forces and flux decline rate.%为了揭示有机物对PVDF超滤膜的污染行为，选用典型亲/疏水性有机污染物海藻酸(SA)及腐殖酸(HA)，采用原子力显微镜结合自制的PVDF膜材料探针和污染物探针定量测定了PVDF-污染物及污染物-污染物间的作用力，并进行PVDF膜污染试验和污染物去除效果分析.结果表明：亲水性SA-PVDF及SA-SA之间的作用力皆大于疏水性HA-PVDF及HA-HA间的作用力，且SA污染膜的通量衰减速率与衰减幅度明显大于HA污染膜，说明了亲水性有机物是引起PVDF超滤膜污染的优势污染物.HA/SA混合污染物试验表明，膜污染行为与混合污染物中优势污染物的含量密切相关；与单种污染物的膜污染行为相比，混合污染物间不存在明显的协同作用促进膜污染.此外，污染物的去除率与相应微观作用力大小及膜污染速率成正相关关系.
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