Mass Balance Study on Phosphorus Removal in Constructed Wetland Microcosms Treating Polluted River Water

Abstract

A number of studies have showed that the mass removal rates of phosphorus (P) in different constructed wetlands (CWs) varied significantly, and it is essential to quantify the contributions of major P removal processes in order to improve system design. The objective of this study was to investigate the effects of vegetation, hydraulic retention time (HRT), and water temperature on P removal from polluted river water and to quantify the contributions of different P removal pathways in surface CWs. Results showed that the average total P removal rates ranged between 2.69 and 20.84 mg/(m2 day) in different seasons and were influenced significantly by vegetation, HRT, and water temperature. According to the mass balance approach, plant uptake removed 4.81–22.33% of P input, while media storage contributed 36.16–49.66%. Other P removal processes such as microbiota uptake removed around 0.26–4.13%. Media storage and plant uptake were identified as the main P removal processes in surface CWs treating polluted river water. This illustrated the importance of selecting media and plants in CWs for future practical application.

Research on Phosphorus Removal in Artificial Wetlands by Plants and Their Photosynthesis

“…The results indicate that during the process of artificial wetlands removing P-pollutants, phosphorus removed by other means like substrates and microorganisms cover most proportion of wetlands removing phosphorus. Similar to researches of many scholars, Gagnon V et al [8] verified that Ppollutants are mainly distributed in substrates and wetland system with plants has higher efficiency in removing total phosphorus; Chung A K C et al [9] figured out that removal rate of total phosphorus by artificial wetlands is 52 while Paccumulation in plant body is not 5% enough; Wu H et al [10] also believed that efficiency of artificial wetlands removing P-pollutants is 67% and maximum P-removing efficiency of plants reaches 34.17%. All of which may be related to multiple factors like different plants and substrate types and different pollutant concentrations, Konnerup D et al [11] found that the lower content of total phosphorus in sewage is, the more obvious the P-removing effect by artificial wetlands will be.…”

Watershed-Scale Phosphorus Balance Evaluation Using a Mass Balance Method

“…We used a mass balance method [8,11,12] in this study to calculate P balance of the watershed which was regarded as a whole in this study and the lake itself in one year (2010). The watershed boundary is the natural catchment area, not including the watershed form where water is channeled.…”

Effect of Plant Harvesting on the Performance of Constructed Wetlands during Summer

“…It contained: the amounts of nitrogen imported and exported from the microcosm systems; the amounts of nitrogen assimilated by plants; the amounts of nitrogen absorbed by the substrate; other losses, including ammonia volatilization, N2O and N2 emission [19]. The calculative pattern for the nitrogen mass balance is shown below [20]:…”