Role of plant uptake on nitrogen removal in constructed wetlands located in the tropics

1997 ◽  
Vol 36 (12) ◽  
pp. 1-8 ◽  
Author(s):  
Thammarat Koottatep ◽  
Chongrak Polprasert
Keyword(s):  
Constructed Wetlands ◽  
Constructed Wetland ◽  
Plant Uptake ◽  
Aquatic Vegetation ◽  
Initial Density ◽  
Free Water ◽  
N Removal ◽  
N Assimilation ◽  
Removal Efficiencies

Major interactive components of the constructed wetlands such as aquatic vegetation, substratum, water, microorganisms and animals play significant roles in the treatment of wastewaters. For nitrogen (N) removal, a sequential nitrification/denitrification reaction and plant uptake are two major treatment mechanisms, while NH3 volatilization is considered to be insignificant under the liquid pH lower than 8. In this research, both laboratory- and pilot-scale constructed wetlands were operated in the free water surface (FWS) mode. In order to investigate the role of plant uptake of N, narrow-leave cattails (Typha augustifolia) were planted at the initial density of 35 rhizomes/m2. Based on N mass balance, approximately 50% of the total nitrogen (TN) loaded into the constructed wetlands, operating at the hydraulic retention time (HRT) of 2–10 days, was accounted for by the amount of N assimilation into the plant tissues, resulting in the total kjeldahl nitrogen (TKN) and chemical oxygen demand (COD) removal efficiencies of 40–70% and 71–83%, respectively. To further investigate the role of plant uptake, the cattail plants harvested at the intervals of 2, 4, 8, and 12 weeks of operation resulted in the TN removal efficiencies of 73, 78, 86 and 80%, respectively. The constructed wetland unit having the plant harvesting interval of 8 weeks yielded the N plant uptake of 7.1–7.5 kg/(ha.day) amounting to 66–71% of the TN input. Some biogeochemical parameters such as oxidation-reduction potential (Eh) and dissolved oxygen (DO) in the constructed wetland beds suggested the occurrence of anoxic and reduced conditions which were favorable for the N removal processes such as plant uptake, ammonification, and nitrification/denitrification.

Septage dewatering in vertical-flow constructed wetlands located in the tropics

2001 ◽  
Vol 44 (2-3) ◽  
pp. 181-188 ◽  
Author(s):  
T. Koottatep ◽  
C. Polprasert ◽  
N. T.K. Oanh ◽  
U. Heinss ◽  
A. Montangero ◽  
...  
Keyword(s):  
Constructed Wetlands ◽  
Low Cost ◽  
Drainage System ◽  
Oxygen Demand ◽  
Free Water ◽  
Total Solid ◽  
Solid Loading ◽  
Flow Mode ◽  
Vertical Flow ◽  
N Removal

Constructed wetlands (CWs) have been proven to be an effective low-cost treatment system, which utilizes the interactions of emergent plants and microorganisms in the removal of pollutants. CWs for wastewater treatment are normally designed and operated in horizontal-flow patterns, namely, free-water surface or subsurface flow, while a vertical-flow operation is normally used to treat sludge or septage having high solid contents. In this study, three pilot-scale CW beds, each with a surface area of 25 m2, having 65 cm sand-gravel substrata, supported by ventilated-drainage system and planting with narrow-leave cattails (Typha augustifolia), were fed with septage collected from Bangkok city, Thailand. To operate in a vertical-flow mode, the septage was uniformly distributed on the surface of the CW units. During the first year of operation, the CWs were operated at the solid loading rates (SLR) and application frequencies of, respectively, 80-500 kg total solid (TS)/m2.yr and 1-2 times weekly. It was found that the SLR of 250 kg TS/m2.yr resulted in the highest TS, total chemical oxygen demand (TCOD) and total Kjeldahl nitrogen (TKN) removal of 80, 96 and 92%, respectively. The TS contents of the dewatered septage on the CW beds were increased from 1-2% to 30-60% within an operation cycle. Because of the vertical-flow mode of operation and with the effectiveness of the ventilation pipes, there were high degrees of nitrification occurring in the CW beds. The nitrate (NO3) contents in the CW percolate were 180-250 mg/L, while the raw septage had NO3 contents less than 10 mg/L. Due to rapid flow-through of the percolates, there was little liquid retained in the CW beds, causing the cattail plants to wilt, especially during the dry season. To reduce the wilting effects, the operating strategies in the second year were modified by ponding the percolate in the CW beds for periods of 2 and 6 days prior to discharge. This operating strategy was found beneficial not only for mitigating plant wilting, but also for increasing N removal through enhanced denitrification activities in the CW beds. During these 2 year operations, the dewatered septage was not removed from the CW beds and no adverse effects on the septage dewatering efficiency were observed.

Ammonium removal in constructed wetlands with recirculating subsurface flow: removal rates and mechanisms

1995 ◽  
Vol 32 (3) ◽  
pp. 193-202 ◽  
Author(s):  
F. J. Sikora ◽  
Tong Zhu ◽  
L. L. Behrends ◽  
S. L. Steinberg ◽  
H. S. Coonrod
Keyword(s):  
Constructed Wetlands ◽  
Constructed Wetland ◽  
Removal Rate ◽  
N Uptake ◽  
Subsurface Flow ◽  
N Removal ◽  
Air Water Interface ◽  
Scirpus Cyperinus ◽  
Macrophyte Growth ◽  
Discernible Difference

From June 1993 through February 1994, the removal of NH4-N was evaluated in constructed wetlands at the TVA constructed wetland research facility in Muscle Shoals, AL. The objectives were to determine rates for NH4-N removal and speculate on potential mechanisms for removal. Nine constructed wetland cells were used with approximate dimensions of 9.1 × 6.1 × 0.6 m3 and a recirculating subsurface flow system in a gravel base. Treatments consisted of an unplanted (WO=control) and two polycultural planting schemes (P1=Scirpus acutus, Phragmites communis and Phalaris arundinacea; P2=Typha sp., Scirpus atrovirens georgianus and Scirpus cyperinus) replicated 3 times. Salt solutions were added and recirculated in each cell resulting in initial concentrations of 50 and 300 mg l−1 of NH4-N and COD, respectively, when fully diluted with wetland water. Salts were added to wetlands approximately every 6 weeks with the first addition on June 1, 1993 and the last addition on February 9, 1994 for a total of 6 time periods (times I, II, III, IV, V and VI). The COD of the waters was removed at rates ranging from 5.5 to 10 g/m2/d during times I through IV with no discernible difference amongst the planting treatments. Wetland cells with P1 were more efficient at removing NH4-N (1.1 g/m2/d) than P2 (0.6 g/m2/d) or WO (0.5 g/m2/d) at time I with differences decreasing by time IV (0.3 to 0.7 g/m2/d). During the winter (times V and VI), there were no differences in NH4-N removal amongst planting treatments with an average removal rate of 0.35 g/m2/d. There was a seasonal change in NH4-N removal in all the treatments, with the change most noticeable in the planted cells. The removal of NH4-N in WO was speculated to be due to a combination of sorption onto gravel, microbial assimilation, and nitrification at the air-water interface. The extra NH4-N removal in the planted cells diminished in the winter because the removal was most likely due to a combination of enhanced nitrification from O2 transport and NH4-N uptake mediated by seasonal macrophyte growth.

scholarly journals VERTICAL SUBSURFACE FLOW AND FREE SURFACE FLOW CONSTRUCTED WETLANDS FOR SUSTAINABLE POWER GENERATION AND REAL WASTEWATER SELECTIVE POLLUTANTS REMOVAL

2020 ◽  
Vol 24 (06) ◽  
pp. 91-102
Author(s):  
Zahraa S. Aswad ◽  
◽  
Ahmed H. Ali ◽  
Nadia M. Al-Mhana ◽  
◽  
...  
Keyword(s):  
Power Generation ◽  
Free Surface ◽  
Constructed Wetlands ◽  
Constructed Wetland ◽  
Suspended Solids ◽  
Subsurface Flow ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Removal Efficiencies ◽  
Better Than

A vertical subsurface flow constructed wetland (VSSFCW) and a free surface flow constructed wetland (FSFCW) were set for the objective of comparison the performance of two systems in order to make a decision of the better one for future installation of wastewater treatment system and power generation. Both of the constructed wetlands were planted with Cyperus Alternifolius. During the observation period (19 days or 456 hours), environmental conditions such as pH, temperature, total chemical oxygen demand (COD), phosphate (PO4), nitrate (NO3) ,total suspended solids (TSS), total dissolved solids (TDS), Pb, Cu, and Cd removal efficiencies of the systems were determined. According to the results, final removal efficiencies for the VSSF and FWSF, respectively, were: COD (94.3% and 94.3%),PO4 (84.3% and 75.3%), NO3 (100% and 100%), TSS (96.8% and 85.6%), Pb (65.8% and 81.4%), Cu (more than 94.7% and 89.4%), Cd (85.7% and 88%). The treatment performances of the VSSF were better than that of the FWSF with regard to the removal of suspended solids and nutrients. In FWSF systems, electricity generation performed better than VSSF of 31.4 mV especially with batch system during one wastewater feed is loaded among all of the nineteen days with maximum voltage of 33.7 mV and decreased gradually as oxygen depletion in cathode chamber and less metabolism processes has occurred.

scholarly journals Role of different plants on nitrogen and phosphorus removal at low temperature in lab-scale constructed wetlands

2019 ◽  
Vol 118 ◽  
pp. 01023 ◽  
Author(s):  
Liwei Xiao ◽  
Hong Jiang ◽  
Chao Shen ◽  
Ke Li ◽  
Lei Hu
Keyword(s):  
Constructed Wetlands ◽  
Nutrient Removal ◽  
Phosphorus Removal ◽  
Sichuan Basin ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Relative Growth ◽  
Stems And Leaves ◽  
Removal Efficiencies

In this study, plant growth and nitrogen and phosphorus removal efficiency in lab-scale CWs by five plants (H. vulgaris, N. peltatum, N. tetragona, N. pumilum, S. trifolia) in winter in Sichuan basin was evaluated. H. vulgaris and N. tetragona would well adapt to the winter wetland environment, and the relative growth at the end of the experiment was 89.83% and 66.85%, respectively. In winter, H. vulgaris kept growing with accumulated stems and leaves, while growth of N. tetragona was mainly caused by the growth of roots and stems underwater. In addition, during the winter, removal efficiencies were 66.29%, 57.47%, 54.78%, 55.47%, 41.66% of TN and 62.40%, 69.75%, 69.97%, 65.65%, 76.55% of TP for each planted CWs respectively. The results indicated that the removal of nitrogen and phosphorus from CWs was mainly achieved by substrate, while a small portion was attributed by plant. However, plants like H. vulgaris and N. tetragona, in the CWs in winter can play the role of landscaping. Thus, H. vulgaris could be considered as a suitable and effective nutrient removal plant for treatment of nitrogen and phosphorus water in winter wetlands in Sichuan basin.

Evaluation of constructed wetlands by wastewater purification ability and greenhouse gas emissions

2007 ◽  
Vol 56 (3) ◽  
pp. 49-55 ◽  
Author(s):  
P. Gui ◽  
R. Inamori ◽  
M. Matsumura ◽  
Y. Inamori
Keyword(s):  
Plant Growth ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Constructed Wetlands ◽  
Constructed Wetland ◽  
Seasonal Changes ◽  
Free Water ◽  
Domestic Wastewater ◽  
Pollutant Removal ◽  
Gas Emissions

Domestic wastewater is a significant source of nitrogen and phosphorus, which cause lake eutrophication. Among the wastewater treatment technologies, constructed wetlands are a promising low-cost means of treating point and diffuse sources of domestic wastewater in rural areas. However, the sustainable operation of constructed wetland treatment systems depends upon a high rate conversion of organic and nitrogenous loading into their metabolic gaseous end products, such as N2O and CH4. In this study, we examined and compared the performance of three typical types of constructed wetlands: Free Water Surface (FWS), Subsurface Flow (SF) and Vertical Flow (VF) wetlands. Pollutant removal efficiency and N2O and CH4 emissions were assessed as measures of performance. We found that the pollutant removal rates and gas emissions measured in the wetlands exhibited clear seasonal changes, and these changes were closely associated with plant growth. VF wetlands exhibited stable removal of organic pollutants and NH3-N throughout the experiment regardless of season and showed great potential for CH4 adsorption. SF wetlands showed preferable T-N removal performance and a lower risk of greenhouse gas emissions than FWS wetlands. Soil oxidation reduction potential (ORP) analysis revealed that water flow structure and plant growth influenced constructed wetland oxygen transfer, and these variations resulted in seasonal changes of ORP distribution inside wetlands that were accompanied by fluctuations in pollutant removal and greenhouse gas emissions.

Treatment of laboratory wastewater in a tropical constructed wetland comparing surface and subsurface flow

2001 ◽  
Vol 44 (11-12) ◽  
pp. 499-506 ◽  
Author(s):  
A.A. Meutia
Keyword(s):  
Removal Efficiency ◽  
Constructed Wetland ◽  
Rainy Season ◽  
Transition Period ◽  
Subsurface Flow ◽  
Dry Season ◽  
Surface Flow ◽  
Cod Removal ◽  
N Removal ◽  
Removal Efficiencies

Wastewater treatment by constructed wetland is an appropriate technology for tropical developing countries like Indonesia because it is inexpensive, easily maintained, and has environmentally friendly and sustainable characteristics. The aim of the research is to examine the capability of constructed wetlands for treating laboratory wastewater at our Center, to investigate the suitable flow for treatment, namely vertical subsurface or horizontal surface flow, and to study the effect of the seasons. The constructed wetland is composed of three chambered unplanted sedimentation tanks followed by the first and second beds, containing gravel and sand, planted with Typha sp.; the third bed planted with floating plant Lemna sp.; and a clarifier with two chambers. The results showed that the subsurface flow in the dry season removed 95% organic carbon (COD) and total phosphorus (T-P) respectively, and 82% total nitrogen (T-N). In the transition period from the dry season to the rainy season, COD removal efficiency decreased to 73%, T-N increased to 89%, and T-P was almost the same as that in the dry season. In the rainy season COD and T-N removal efficiencies increased again to 95% respectively, while T-P remained unchanged. In the dry season, COD and T-P concentrations in the surface flow showed that the removal efficiencies were a bit lower than those in the subsurface flow. Moreover, T-N removal efficiency was only half as much as that in the subsurface flow. However, in the transition period, COD removal efficiency decreased to 29%, while T-N increased to 74% and T-P was still constant, around 93%. In the rainy season, COD and T-N removal efficiencies increased again to almost 95%. On the other hand, T-P decreased to 76%. The results show that the constructed wetland is capable of treating the laboratory wastewater. The subsurface flow is more suitable for treatment than the surface flow, and the seasonal changes have effects on the removal efficiency.

Plant uptake of diclofenac in a mesocosm-scale free water surface constructed wetland by Cyperus alternifolius

2016 ◽  
Vol 73 (12) ◽  
pp. 3008-3016 ◽  
Author(s):  
Jun Zhai ◽  
Md. Hasibur Rahaman ◽  
Jiucui Ji ◽  
Zhiyoung Luo ◽  
Quanfeng Wang ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Constructed Wetland ◽  
Plant Uptake ◽  
Water Surface ◽  
Free Water ◽  
Root Surface ◽  
Plant Tissues ◽  
Scale Free ◽  
Free Water Surface ◽  
Cyperus Alternifolius

Abstract This study aimed to assess the uptake of diclofenac, a widely used nonsteroidal anti-inflammatory pharmaceutical, by a macrophyte Cyperus alternifolius in a mesocosm-scale free water surface (FWS) constructed wetland. Quantitative analysis of diclofenac concentrations in water solution and plant tissues was conducted by high performance liquid chromatography analysis after sample pre-treatment with solid-phase extraction and liquid extraction, respectively. The FWS with Cyperus alternifolius obtained a maximum 69.3% diclofenac removal efficiency, while a control system without plant only had a removal efficiency of 2.7% at the end of the experiment period of 70 days. Based on mass balance study of the experimental system, it was estimated that plant uptake and in-plant conversion of diclofenac contributed about 21.4% of the total diclofenac removal in the mesocosm while the remaining 78.6% diclofenac was eliminated through biotic and abiotic conversion of diclofenac in the water phase. Diclofenac on the root surface and in roots, stems and leaves of Cyperus alternifolius was found at the concentrations of 0.15–2.59 μg/g, 0.21–2.66 μg/g, 0.06–0.53 μg/g, and 0.005–0.02 μg/g of fresh weight of plant tissues, respectively. The maximum bioaccumulation factor of diclofenac was calculated in roots (21.04) followed by root surface (20.49), stems (4.19), and leaves (0.16), respectively. Diclofenac translocation potentiality from root to stem was found below 0.5, suggesting a slow and passive translocation process of diclofenac. Current study demonstrated high potential of Cyperus alternifolius for phytoremediation of diclofenac in FWS and can be applied in other engineered ecosystems.

Application of Constructed Wetland to Rural Domestic Wastewater Treatment in China

2014 ◽  
Vol 1073-1076 ◽  
pp. 1011-1014
Author(s):  
Fang Chen ◽  
Qiang Yao
Keyword(s):  
Wastewater Treatment ◽  
Constructed Wetlands ◽  
Constructed Wetland ◽  
Rural Economy ◽  
Domestic Wastewater ◽  
Treatment Technology ◽  
Domestic Wastewater Treatment ◽  
The One ◽  
Low Nitrogen

Constructed wetland is a new wastewater treatment technology. It not only is more effective in wastewater treatment, but also has good eco-landscapes value. According to the characteristics of domestic wastewater discharge in rural, constructed wetlands is a key technology to solving this problem in China. Application of constructed wetland to Chinese rural domestic wastewater treatment was reviewed in this paper. On this basis, the issues in the application of constructed wetland encountered, and future trends are discussed. On the one hand, constructed wetlands were prone to clogging and low nitrogen removal efficiency. On the other hand, some existing constructed wetlands were abandoned due to poor maintenance and management. Therefore, in order to play better the role of wastewater treatment, anti-blocking ability and denitrification efficiency of constructed wetlands should be improved. Meanwhile, the maintenance and management of constructed wetlands should be strengthened. Application of constructed wetlands in the rural area provides a strong guarantee for sustainable development of rural economy.

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