Clogging Simulation of Horizontal Subsurface-Flow Constructed Wetland

摘要

Clogging of constructed wetlands commonly occurs; however, clogging of horizontal subsurface-flow constructed wetlands (HSSFCW) has not been successfully simulated using mathematical models. This study established a mathematical model by coupling one-dimensional mass transfer model with multicomponent biochemical reactions by using Constructed Wetland Model No. 1 to simulate clogging during treatment of domestic sewage with HSSFCW. Complex relations among porosity, hydraulic conductivity, and retention capability of particles were dodged dexterously in the new model by using total particle concentration within interstitial space as indicator of clogging. Introducing particulate component release ratio, which controlled the transmission of particles within substrates, and using substrate porosity as constant simplified the simulation and saved computation time. Clogging degree can be easily identified by comparing total particle concentration in the interstitial space with the concentration threshold of clogging, such as biofilm density. The value of particulate component release ratio was determined, and the model was calibrated using measured data from the literature. Results showed that the proposed model can successfully simulate clogging and explain the underlying mechanism of HSSFCW. The new model supplied a simple method for predicting the clogging of HSSFCW.