An integrated model of substrate clogging in vertical flow constructed wetlands

This paper presents an integrated model of substrate clogging in a vertical flow constructed wetland (VFCW). The model simulates the reduction of pore space in the wetland substrate due to combined influences of various physical, biogeochemical and plant-related processes. A series of experiments based on laboratory-scale VFCWs were conducted to examine and measure key parameters related to clogging of the wetland substrate during operation under different conditions. The model was then validated using data collected from the experiments. The results showed that the model was able to replicate the clogging phenomenon as observed in the experiments, in particular, the characteristic clogging time. The model also predicted well individual contributions to clogging by accumulated inert suspended solids, microbial biomass and plant root materials during the wetland operation. Although the validation was based on the laboratory data, the results indicated that the model describes well the processes underlying the clogging and has the potential to become a tool for assessing the performance of prototype CWs in relation to clogging at both the design and operation stages. ► This paper presents an integrated model for substrate clogging in a VFCW. ► The model includes physical, biogeochemical and plant-related processes. ► Key parameters related to clogging in this model have been measured and validated. ► The model describes well the contribution of individual process to clogging. ► The model has the potential to become a tool for assessing the performance of CWs.