1 The Effect of Operating Method and Configuration of Soil Trench System on NH3-N and NO3-N Nitrogen Removal: Computer Simulation Results

Many studies have confirmed the efficiency of soil trench systems; however, few studies have focused systematically on finding the optimal operating condition and configuration of these systems. In this study, a computer simulation was performed to find the optimal operating condition and configuration of a soil trench, based on the efficiency of ammonium and nitrate nitrogen removal. To achieve this goal, CHAIN_2D—a previous version of Hydrus-2D—was modified to incorporate the effect of soil moisture content and temperature on the nitrification and denitrification reaction rates; it was then used to simulate the dynamics of nitrogen in the soil trench system under 12 different operating conditions and configurations. Based on the result, daily intermittent wastewater application method, configuration with 100 cm depth and 100 cm influent pipe distance and fine-textured soil such as clay loam should be the relative optimal, respectively. This result will be used to design, construct, and operate an improved soil trench system set in a closed container