Abstract: A system for controlling the amount of a liquid carbon source released to a constructed wetland, includes: a carbon source pool, a carbon source pipe, a peristaltic pump, a programmable logic controller (PLC), a computer, a first flow meter, a first chemical oxygen demand (COD) sensor, a first total nitrogen (TN) sensor, a second TN sensor, a second COD sensor, an inlet pipe, and an outlet pipe. The first flow meter, the first COD sensor, and the TN sensor are disposed on the inlet pipe; the second COD sensor and the second TN sensor are disposed on the outlet pipe; the inlet pipe and the outlet pipe are connected to the constructed wetland; the carbon source pipe is connected to the carbon source pool via the peristaltic pump; the computer, the peristaltic pump, the first flow meter, and all sensors are connected to the PLC controller.

Abstract: A subsurface flow constructed wetland (SFCW) includes a sand layer having a ventilation property of 90 mL/(cm·s) and a permeation rate of less than 0.3 kg/m2/h under a two-meter-high pressure head, a filter layer disposed on the sand layer, and a gabion module disposed on the filter layer. The filter layer includes fine sand with a particle size of 0.25-0.35 cm. The gabion module includes a gabion box including a plant layer and a filler layer, and the filler layer is disposed on the plant layer.

Abstract: A subsurface flow constructed wetland (SFCW) includes a sand layer having a ventilation property of 90 mL/(cm·s) and a permeation rate of less than 0.3 kg/m2/h under a two-meter-high pressure head, a filter layer disposed on the sand layer, and a gabion module disposed on the filter layer. The filter layer includes fine sand with a particle size of 0.25-0.35 cm. The gabion module includes a gabion box including a plant layer and a filler layer, and the filler layer is disposed on the plant layer.