Vertical flow constructed wetlands: kinetics of nutrient and organic matter removal

Abstract

The kinetics of organic matter and nutrient removal in a pilot vertical subsurface wetland with red ferralitic soil as substrate were evaluated. The wetland (20 m(2)) was planted with Cyperus alternifolius. The domestic wastewater that was treated in the wetland had undergone a primary treatment consisting of a septic moat and a buffer tank. From the sixth week of operation, the performance of the wetland stabilized, and a significant reduction in pollutant concentration of the effluent wastewater was obtained. Also a significant increase of dissolved oxygen (5 mg/l) was obtained. The organic matter removal efficiency was greater than 85% and the nutrient removal efficiency was greater than 75% in the vertical subsurface wetland. Nitrogen and biochemical oxygen demand (BOD) removal could be described by a first-order model. The kinetic constants were 3.64 and 3.27 d(-1) for BOD and for total nitrogen, respectively. Data on the removal of phosphorus were adapted to a second-order model. The kinetic constant was 0.96 (mg/l)(-1) d(-1). The results demonstrated the potential of vertical flow constructed wetlands to clean treated domestic wastewater before discharge into the environment.

A Study on Mechanism of Organic Matter Removal in a Three-step Series Constructed Rapid Infiltration System Used for Domestic Wastewater Treatment

“…A correlation coefficient r of 0.97 was observed between the CoD removal percentages and the abundances of aerobic bacteria in the three-step series CRi system, indicating that the correlation was very obvious. This also indicated that microbes were playing a key role in the removal of organic matter, which was in agreement with some previous studies [10][11][12][13][14][15].…”

Ibuprofen and iohexol removal in saturated constructed wetland mesocosms

“…Regarding pharmaceuticals, however, the more commonly used model is the first-order kinetic model (Matamoros and Bayona, 2006). However, zero-order and second-order kinetic models have also been used in CWs (Mitchell and McNevin, 2001;Pérez et al, 2014). Studies on pharmaceutical degradation kinetics in CWs are scarce, and previous research has mainly focused on the effects of single factors, such as plant species, season etc., while the potential synergy between factors has been neglected.…”

Bacterial Biomass Effect on Performance Improving of Vertical Flow Constructed Wetlands for Domestic Wastewater Treatment

“…Finally, the difference of pH observed between the planted beds is due to the physiological speci cities of the plants used. On the other hand, the increase of OD in the bed ltrates would result from the aeration of the raw water during its application to the beds of the vertical ow wetlands and the oxygen released at the apex of the rootlets of the plants (Pérez et al 2014).…”