Simulation-based Design of Fluidized Bed Reactors for Wastewater Treatment

对于加拿大和世界各地的市政当局来说，最大限度地减少废水排放到环境中是一个越来越重要的考虑因素。进入溪流、河流和湖泊的磷排放是这些水体富营养化的主要驱动因素之一，在这些水体中，高水平的生物营养物质的存在导致植物和藻类的生长增加。这种增加随后导致水体中氧气水平的枯竭，这对鱼类和水生生态系统中的所有生物多样性都有毁灭性的影响。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。Ostara养分回收公司(Ostara)开发了能够从废水中回收磷的技术，以便回收的含磷固体(鸟粪石)可以用作缓释肥料。Ostara的核心技术是PEARL®沸腾床反应器，能够从废水处理厂回收高达50%的磷，并以可供分配的形式(从该过程中)输出富磷肥料生产。这项技术的核心是一个复杂的多相流态化结晶过程，多分散的(鸟粪石)固体颗粒分散在多组分的液体(废水)中。进一步发展Ostara的珍珠反应堆技术需要进行多相CFD模拟，以解决内部多相流体动力学问题，同时解决发生在固/液界面的结晶过程产生的传质问题。这项研究涉及使用两相流模型的“谱”，以便为Ostara独特的多分散流态化反应器确定最准确的模型。

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.