Simulation-based Design of Fluidized Bed Reactors for Wastewater Treatment

最大限度地减少从废水流中排放到环境中的磷是加拿大和世界各地市政当局日益重要的考虑因素。向溪流、河流和湖泊排放磷是这些水体富营养化的主要驱动因素之一，其中高水平生物营养物的存在导致植物和藻类的生长加快。这种增加随后导致水体中氧气水平的耗尽，对鱼类和水生生态系统内的整体生物多样性产生破坏性影响。因此，从废水中去除磷是加拿大研究和开发的一个关键领域。奥斯达营养物回收公司（Ostara）已经开发出能够从废水流中回收磷的技术，使回收的含磷固体（鸟粪石）可以用作缓释肥料。Ostara的核心技术是Pearl®流化床反应器，能够从废水处理厂回收高达50%的磷，并（从该过程中）生产富磷肥料，以准备分配的形式。该技术的核心是一个复杂的多相流化结晶过程，其中多分散（鸟粪石）固体颗粒分散在多组分液相（废水）中。Ostara’s Pearl反应器技术的进一步发展需要多相CFD模拟，以实现内部多相流体动力学的解析，同时，在固/液界面发生的结晶过程引起的传质。这项研究涉及使用两相流模型的“谱”，以确定Ostara独特的多分散流化床反应器最准确的模型。

The minimization of phosporous discharge from wastewater streams into the environment is an increasinglyimportant consideration for municipalities in Canada and throughout the world. Phosphorous discharge intostreams, rivers, and lakes is one of the main drivers of eutrophication of these water bodies, where the presenceof high levels of biological nutrients results in increased growth of plants and algae. This increase subsequentlyresults in depletion of oxygen levels in water bodies which has devastating effects on fish and overallbiodiversity within aquatic ecosystems. Removal of phosphorous from wastewater is thus a key area ofresearch and development in CanadaOstara Nutrient Recovery Inc. (Ostara) has developed technologies which enable the recovery of phosphorousfrom wastewater streams in a way such that the recovered phosphorous containing solids (struvite) may be usedas a slow-release fertilizer. Ostara's core technology is the Pearl® fluidized bed reactor, is able to recover up to50% of phosphorous from a wastewater treatment plant and outputs (from the process) phosphorous-richfertilizer production, in a form ready for distribution. At the heart of this technology is a complex multiphasefluidized crystallization process where polydisperse (struvite) solid particles are dispersed in amulti-component liquid phase (wastewater).Further advancement of the Ostara's Pearl reactor technology requires multiphase CFD simulations to enableresolution of the internal multiphase hydrodynamics and, simultaneously, the mass transfer resulting from thecrystallization process occurring at the solid/liquid interface. This research involves the use of the "spectrum"of two-phase flow models in order to determine the most accurate one for Ostara's unique polydispersefluidized bed reactor.