Reactive settling is the process of sedimentation of small solid particles in a fluid with simultaneous reactions between the components of the solid and liquid phases. This process is important in sequencing batch reactors (SBRs) in wastewater treatment plants. In that application the particles are biomass (bacteria; activated sludge) and the liquid contains substrates (nitrogen, phosphorus) to be removed through reactions with the biomass. The operation of an SBR in cycles of consecutive fill, react, settle, draw, and idle stages is modeled by a system of spatially one-dimensional, nonlinear, strongly degenerate parabolic convection-diffusion-reaction equations. This system is coupled via conditions of mass conservation to transport equations on a half line, whose origin is located at a moving boundary and that model the effluent pipe. A monotone and invariant-region-preserving finite difference scheme is proposed and applied to simulate operating cycles and the denitrification process within an SBR.
翻译:固态小粒子在液体中沉积的过程是固体和液体阶段各组成部分同时反应的液体中小固态粒子沉积的过程。这一过程对于废水处理厂的批量反应堆(SBRs)的排序十分重要。在这一应用中,颗粒是生物量(细菌;活性淤泥),液体含有通过生物量反应清除的子strates(氮、磷);在连续填充、反应、沉淀、绘图和闲置阶段的循环中,SBR的操作由空间单维、非线性、严重降解的parblic-coption-difiction-rection-reaction等方程式系统模拟。这个系统通过大规模保护条件结合到半线上的传输方程式,该方程式的起源在移动边界上,并以此为废水管道的模型。一个单体和不变区域-区域-保留有限差异方案被提议并应用于模拟操作周期和SRBR内脱硝化过程。