Encapsulation is a promising technology to retain and protect autotrophs for biological nitrogen removal. One-dimensional biofilm models have been used to describe encapsulated systems; they do not, however, incorporate chemical sorption to the encapsulant nor do they adequately describe cell growth and distribution within the encapsulant. In this research we developed a new model to describe encapsulated growth and activity of Nitrosomonas europaea, incorporating ammonium sorption to the alginate encapsulant. Batch and continuous flow reactors were used to verify the simulation results. Quantitative PCR and cross-section fluorescence in situ hybridization were used to analyze the growth and spatial distribution of the encapsulated cells within alginate. Preferential growth of Nitrosomonas near the surface of the encapsulant was predicted by the model and confirmed by experiments. The modeling and experimental results also suggested that smaller encapsulants with a larger surface area to volume ratio would improve ammonia oxidation. Excessive aeration caused the breakage of the encapsulant, resulting in unpredicted microbial release and washout. Overall, our modeling approach is flexible and can be used to engineer and optimize encapsulated systems for enhanced biological nitrogen removal. Similar modeling approaches can be used to incorporate sorption of additional species within an encapsulant, additional nitrogen-converting microorganisms, and the use of other encapsulation materials.

封装是一种很有前途的技术，可以保留和保护自养生物以进行生物脱氮。一维生物膜模型已被用于描述封装系统；然而，它们没有将化学吸附结合到密封剂中，也没有充分描述密封剂内的细胞生长和分布。在这项研究中，我们开发了一种新模型来描述亚硝化单胞菌的封装生长和活性，将铵吸附结合到藻酸盐封装剂中。使用间歇式和连续流反应器来验证模拟结果。定量 PCR 和横截面荧光原位杂交用于分析藻酸盐内包封细胞的生长和空间分布。优先增长模型预测了封装材料表面附近的亚硝化单胞菌，并通过实验证实了这一点。建模和实验结果还表明，具有较大表面积与体积比的较小密封剂将改善氨氧化。过度曝气导致密封剂破裂，导致不可预测的微生物释放和冲刷。总的来说，我们的建模方法是灵活的，可用于设计和优化封装系统以增强生物脱氮。类似的建模方法可用于将额外物种的吸附结合到封装剂、额外的氮转化微生物以及其他封装材料的使用中。