地下水人工回注污染物迁移转化饱和流模型

Modeling of contaminant transportduring groundwater recharge withsecondary effluent

利用污水处理厂二级出水进行的人工地下回注伴随有污染物迁移转化的地质化学及生物化学过程,现存的商业化软件无法模拟。该文以饱和流模型为基础,结合对流-扩散过程、吸附过程及可能的生物降解过程,建立了一个针对地下水人工回注的数学模型。采用有限体积差分并对水浸深度不同的网格采取不同的离散措施,保证在地下水面处的连续性。应用算子分裂技术并设计了一种特殊的迎风差分格式,使得模型求解速度加快。该模型已应用于北京市高碑店污水处理厂人工地下水回注示范工程。

Groundwater recharge with secondary effluent from waste water treat plants is accompanied by geochemical and biochemical processes of contaminants. Existing commercial softwares cannot simulate these processes. A numerical model based on saturated flow was developed to describe groundwater recharge by secondary effluents taking into account convection-dispersion, adsorption and biodegradation. The finite volume method was used to model the varying water table. Operator-splitting techniques were used for the reactive transport model with an implicit upwind finite difference scheme to solve the convection-dispersion equations. The model was used to analyze the groundwater recharge demonstration project with secondary effluent at the Gaobeidian wastewater treatment plant in Beijing.