Effects of Vegetation, Season and Temperature on the Removal of Pollutants in Experimental Floating Treatment Wetlands

Abstract

13The research and interest towards the use of constructed floating wetlands for (waste)water 14 treatment is emerging as more treatment opportunities are marked out and the technique is nitrogen, P and COD were respectively 35%, 42%, 22% and 53% for the CFWs, and 3%, 24 15%, 6% and 33% for the control. The pH was significantly lower in the CFWs (7.08 ± 0.21) 25 than in the control (7.48 ± 0.26) after 11 days. The removal efficiencies of NH 4 -N, total 26 nitrogen and COD were significantly higher in the CFWs as the presence of the floating 27 macrophyte mat influenced positively their removal. Total nitrogen, NH 4 -N and P-removal 28 was significantly influenced by temperature with the highest removal between 5 and 15°C. At 29 lower and higher temperatures, removal relapsed. In general, temperature seemed to be the 30 steering factor rather than season. The presence of the floating macrophyte mat restrained the 31 increase of the water temperature when air temperature was >15°C. Although the mat 32 hampered oxygen diffusion from the air towards the water column, the redox potential 33 measured in the rootmat was higher than the value obtained in the control at the same depth, 34indicating that the release of oxygen from the roots could stimulate oxygen consuming 35 reactions within the root mat and root oxygen release was higher than oxygen diffusion from 36 the air. 37

Effect of Stubble Heights and Treatment Duration Time on the Performance of Water Dropwort Floating Treatment Wetlands (FTWS)

“…As mentioned earlier, the FTW plants play a very significant role in the removal of nutrients [10,26]. As indicated from the earlier studies [11], the effect of different plant regimes management on nutrients removal still need to be investigated.…”

“…In the past 30 years, the FTWs have been tested and applied in laboratories and at pilot scales [3][4][5][6][7][8][9]. Characterized by no extra land demand and adaption to a wide range of water depth, FTWs have been widely used in the treatment of domestic wastewater [10], river water [7,11,12], lake water [5,13,14], agricultural runoff [4,15], swine sewage [16], rainfall [17], storm water [18] and urban runoff [19].…”

“…As the nutrient uptake efficiency is important, much work has been done on the floating plant chosen for the treatment of polluted waters [20,21], improvement of the purification capability of FTWs [7,13,17], and analysis of factors influencing the performance of the FTWs [8,10,[22][23][24]. Among studies on FTWs, the purification effect of FTWs on eutrophicated water has been reported from several works [11,13,16,17,25].…”

“…This combined system performed better than the other two floating bed systems using only one of the two, ie either freshwater clams & the plant structure or biofilms & the plant structure, and the removal efficiencies of integrated ecological floating-bed for total nitrogen, ammonium nitrogen and total phosphorus was 52.7, 33.7 and 54.5%, respectively when the water exchange period was 7 days. Moortel et al [10] studied the influence of temperature and season on physicochemical changes and the removal effect of constructed floating wetland in Drongen, Belgium, and found that the removal rates for total nitrogen (TN), ammonium nitrogen N NH 4 − + , and total phosphorus (TP) were significantly influenced by temperature with the highest removal between 5 and 15°C. Thus, temperature seemed to be the determination factor rather than season.…”

Determination of Microbial Activities and Biomass in Biofilm Associated with Treatment Wetlands Compartments to Investigate Active Pollutant Processing Site

“…Despite the potential advantages of FTWs for the treatment of various wastewaters, there has been little information published to date about their design, construction and performance [2] and only few researchers assessed how the system functions [3,4].…”