Subsurface Flow Constructed Wetland Models: Review and Prospects

Abstract

Numerical models are recognized nowadays as a powerful tool to increase the understanding of the internals of constructed wetlands and to help improve their design. Over the last decade many models have been developed, and many simulation studies have been published. Despite diversity is generally a positive thing, having so many different models can be confusing for potential users and may also hinder further development of the existing ones. The aim of this paper is to summarize the state of the art of this discipline, focussing the attention on the most feature-rich process-based models for constructed wetlands for urban wastewater treatment. Their description is combined with a feature comparison in a tabular format to facilitate the selection of one or another based on the specific needs of the potential user. Moreover, a discussion is made regarding the advantages of each reviewed model regarding features, licencing and expected evolution of each of them. Later in the document, we describe the essential phenomena, parameters and processes that we believe that future generation of constructed wetlands models should incorporate, to guide further research on this discipline. Although this paper is focused on models used in academic circles, a model developed to optimize the design of combined sewer overflow wetlands is presented as an example of the potential of design-focused wetlands. At the end of the paper we provide an overview of the past, present and future of constructed wetlands models and analyse were we stand and which is the way to go and the main goals in the near future.

Modelación De La Calidad De Las Aguas en Los Humedales Artificiales De Flujo Superficial (Hafs). Aplicación a Los Hafs Del Tancat De La Pipa en l'ALBUFERA De Valencia.

“…Una situación similar se observó en el modelo Retraso-CWM1 (Llorens et al, 2011a), donde los microorganismos no se modelaron como componentes adheridos sobre la superficie sino en flotación y por lo tanto tenían un comportamiento similar al de los componentes solubles. En aquel caso, se introdujo una concentración constante de microorganismos en el influente a tratar, lo cual permitió la modelación de situaciones estacionarias pero no la simulación del crecimiento de las poblaciones microbianas (Samsó et al, 2014).…”

“…Los principales procesos que intervienen en la eliminación de los contaminantes son la sedimentación, la precipitación, la adsorción, la asimilación por las plantas y las transformaciones microbiológicas (Kumar & Zhao, 2011). El estudio de estos procesos permite, por una parte, aumentar el conocimiento sobre el funcionamiento de esta tecnología y por otra parte, optimizar su diseño y gestión (Rivas et al, 2008;Samsó et al, 2014) con el objetivo de maximizar la eliminación de los componentes deseados. Sin embargo, estos mecanismos ocurren a la vez, influyen unos sobre otros y están afectados por diferentes factores, con lo cual dicho estudio no resulta una tarea sencilla.…”

“…Tabla 3.7. Descripción general de los principales modelos aplicados a HHAA (Modificado de Samsó et al (2014)).…”

Numerical modelling of constructed wetlands for wastewater treatment

“…At least 7 review papers have been published in recent times to summarize the state of the art of CWs numerical models (García et al, 2010;Kumar and Zhao, 2011;Langergraber et al, 2009b;Langergraber, 2010Langergraber, , 2008Meyer et al, 2014;Rousseau et al, 2004). These reviews mostly consist of descriptions of the models features and no critical in-depth comparison is made between them (Samsó et al, 2014b).…”

“…However, and due to the diversity and complexity of the physic-chemical and biological processes occurring within CWs, their functioning is far less well understood than that of activated sludge systems. To bridge this knowledge gap, several mathematical models have been developed in recent years to simulate CWs functioning (Meyer et al, 2014;Samsó et al, 2014b).…”