Simulating hydraulic capacity of a wastewater land treatment system with DRAINMOD

Land treatment of wastewater is an important approach of treating low quality water and turning it into a valuable resource. However, improper use of wastewater on land has brought up adverse environment impacts, such as offside secondary pollution. Therefore, determining the hydraulic load of a wastewater land treatment system is a prerequisite for proper functioning of such system. In this study, the field hydrology model-DRAINMOD was used to simulate hydraulic capacity of a wastewater land treatment system in Xi'an, China. The model analyses included the impacts of field drainage condition and irrigation scheduling on annual load of wastewater. At same time, the impacts of the fluctuation of water table on wastewater disposal amount were also discussed in the study. The simulation results showed that the surface drainage condition had little effect on the annual load of wastewater; while neglecting the subsurface drainage effect, the predicted annual loading rate is close the recommended value of wastewater irrigation in Xi'an area. The results also showed that a more frequent and less amount irrigation strategy could achieve maximum amount of annual loading with same drainage spacing in the system.