Growth and Contaminant Removal Effect of Several Plants in Constructed Wetlands

Abstract

The aim of the present study is to probe the relation between plant growth and its decontamination effect in constructed wetlands. Four species were studied in the small-scale mono-cultured constructed wetlands, which were fed with domestic wastewater. Plant growth indexes were correlated with contaminant removal performance of the constructed wetlands. Wetlands planted with Cyperus flabelliformis Rottb. showed the highest growth indexes such as shoot growth, biomass, root activity, root biomass increment, and the highest contaminant removal rates, whereas wetlands planted with Vetiveria zizanioides L. Nash had the lowest growth indexes and the lowest removal rates. Above-ground biomass and total biomass were significantly correlated with ammonia nitrogen removal, and below-ground biomass with soluble reactive phosphorus removal. Photosynthetic rate had higher correlation with nitrogen removal in these species. Root activity and root biomass increment was more correlated with 5 d biochemical oxygen demand removal. Chemical oxygen demand removal had lower correlations with plant growth indexes. All four species had higher removal rates in summer and autumn. The results suggest that the effect of plant growth on contaminant removal in constructed wetlands were different specifically in plants and contaminants.

Evaluation of Vertical-Flow Constructed Wetlands for Swine Wastewater Treatment

“…(1.7 g plant −1 day −1 ) in the aerial portion of the plant, greater values were found in the experiment performed by Cheng et al (2009): 2.8 g plant −1 day −1 for C. flabelliformis and lower values, between 0.4 and 0.5 g plant −1 day −1 , for the species Acorus calamus, Phragmites australis and Vetiveria zizanioides, planted in horizontal CWs for treatment of domestic sewage under a load of 2.6 gm −2 day −1 of COD. Working with C. involucratus in vertical CWs for treating of synthetic wastewater (300 gm −3 of COD and 300 gm −3 of N T ) under an average load of 13.7 g m −2 day −1 of COD, Kantawanichkul et al (2009) observed a dry matter production rate of 28.7 g m −2 day −1 , greater than that observed for Cyperus sp.…”

“…used in this experiment. Cheng et al (2009), under the previously mentioned conditions, observed that the greatest reductions in pollutants occurred in the CW planted with C. flabelliformis, and the same presented the greatest biomass production and the fastest growth rate. This confirms that the vegetation has a significant influence on removal of pollutants.…”

Plant growth and nutrient removal in constructed monoculture and mixed wetlands related to stubble attributes

“…However, it remains unclear how these nutrient removal differences occur between plants with comparable size and growth form (Brisson & Chazarenc, 2009). Nutrient removal ability of wetland plants is reported to be correlated with biomass (Tanner, 1996), growth speed and growth rhythm (Cheng et al, 2009a), and root morphology and distribution (Sorrell et al, 2000;Lorenzena et al, 2001;Kyambadde et al, 2004;Amon et al, 2007;Cheng et al, 2009b). However, results are still very inconsistent and little generalization has been made to help guide species selection (Brisson & Chazarenc, 2009;Vymazal & Kröpfelová, 2009).…”

“…The roots were washed over a sieve and measured for fresh and dry weights. The root biomass increment was used as an estimate of root growth (Cheng et al, 2009a).…”

Enzyme activities in pilot-scale constructed wetlands for treating urban runoff in China: temporal and spatial variations

“…It is revealed that the plant root biomass was positively related to urease, acid, and alkaline PP activities [38]. This result might be to some extent related to the effect of the higher root respiration rate on the oxygen content in the rhizosphere, since Cheng et al concluded ammonia nitrogen removal was significantly related to the plant aboveground biomass and nitrogen removal highly correlated with the plant photosynthetic rate in micro-scale gravel-bed CWs [39]. In this study, some significant correlations were detected between plant parameters (biomass, root number, leaf number, and height) and enzyme activities (PP and UR) in DFC and UFC, and the maximum activities of NR, UR, and PP occurred during summer or autumn in DFC and UFC when plants were in the vigorous growth stage, which was consistent with a report of Kong et al, who found that many significant positive correlations between soil enzyme activity was positively related to root activity [32].…”