Modeling Subsurface Upflow Wetlands Systems for Wastewater Effluent Treatment

Abstract

Constructed wetlands have been popular in ecological engineering regime; yet, modeling the physical, chemical, and biological processes within these wetlands is a long-standing challenge in the past decades. In concert with our field-scale pilot testing of a new-generation subsurface upflow wetland (SUW) system, this article highlights an advancement of modeling the SUW system with a layer-structured compartmental simulation model. This is the first wetland model of its kind to address the complexity between plant nutrient uptake and medium sorption. Such a system dynamics model using STELLA Ò as a means for a graphical formulation was applied to illustrate the essential mechanism of the nitrification and denitrification processes within a sorption mediumbased SUW system, which can be recognized as one of the major passive on-site wastewater treatment technologies in this decade. Model calibration and validation received fairly good R-squared values of 0.9998 and 0.9644, respectively. Such good agreement with the measured data confirms that the developed system dynamics model may provide a reliable tool for designing this particular type of constructed wetland. This work also entails the significant movement of linking green building with green infrastructure as part of the urbanization for nature.

A tracer study for assessing the interactions between hydraulic retention time and transport processes in a wetland system for nutrient removal

“…In our case, the height to length (h:l) ratio might be more important than the length to width (l:w) ratio, which should be highlighted as a new considerable parameter for future SUW design. A shorter length (i.e., a smaller l:w ratio) can be applied for the future design, which also supports the conclusion in our previous modeling work [24]. Thus, we suggest that a shorter length and a larger depth of the SUW system can be the nextgeneration SUW for both fixed and mobilized modules in real-world applications.…”

Unsteady state series CSTR modeling of removal of ammonia nitrogen from domestic wastewater treated in a vertical flow constructed wetland

“…It is dependent on dissolved oxygen, pH and temperature. The nitrification rate is significantly affected by DO and pH, whereas temperature has a lower effect [16]. Aeration significantly enhances nitrification, whereas low oxygen concentration and temperature have a decreasing effect [27,28].…”

System Dynamics Modeling of Nitrogen Removal in a Stormwater Infiltration Basin with Biosorption‐Activated Media

“…Coupled feedback loops, stocks, and flows are used to structure interactions among variables and to demonstrate the dynamic behavior of the whole system over time. The model was originally developed during the mid-1950s (Forrester, 1971) and has been extensively used to address a wide variety of environmental and ecological studies, including tree growth (Pan and Raynal, 1995), lake eutrophication assessment (Vezjak et al, 1998), bioavailability of metals in wetlands (Wood and Shelley, 1999), groundwater recharge (Abbott and Stanley, 1999), waste management (Dyson and Chang, 2005), water reallocation (Elmahdi et al, 2007), and wastewater treatment (Xuan et al, 2010(Xuan et al, , 2011). Thus, system dynamics modeling is well suited for studying N transformations due to the cycling and feedback feature of N species in stormwater management, although few studies have been performed for such purposes.…”

“…In addition to this main loop, a variety of reverse reactions produce internal loops among different compounds, such as N uptake (NH 4 + to ON), dissimilatory nitrate reduction to ammonium (NO 3 to NH 4 + ) (Canfield et al, 2010), and volatilization (NH 4 + to NH 3 ). To better recognize such a dynamic complex system involving various circular, interlocking relationships among its compounds, system dynamics modeling has been recently applied to "visualize" the nutrient removal process in some semi-enclosed subsurface treatment facilities (Xuan et al, 2010(Xuan et al, , 2011.…”

“…As a prolific type of recycled material, tire crumb has proven harmless to the environment, with no DNA and chromosome‐damaging chemicals present (Birkholz et al, 2003) and no acute toxicity (Shin et al, 1999; Wanielista, 2008). Additionally, tire crumb has proven effective for nutrient reduction (Hossain et al, 2010; Lisi et al, 2004; Smith et al, 2008), leading to its application on green roof installations (Wanielista and Hardin, 2006) and constructed wetlands (Xuan et al, 2009). Most recently, the effectiveness of a soil amendment media known as biosorption‐activated media (BAM) for nutrient reduction was confirmed by O'Reilly et al (2012c) in a regional‐scale stormwater infiltration basin.…”