scholarly journals Removal of perchlorate by a lab-scale constructed wetland using achira (Canna indica L.)

2021 ◽  
Author(s):  
Dongqin Li ◽  
Haishuo Gao ◽  
Xinyu Du ◽  
Junhao Qin ◽  
Huashou Li ◽  
...  
Keyword(s):  
Constructed Wetlands ◽  
Microbial Degradation ◽  
Constructed Wetland ◽  
Plant Uptake ◽  
Soil Microorganism ◽  
Removal Mechanism ◽  
Mass Balance Calculation ◽  
Canna Indica ◽  
Rhizosphere Environment ◽  
Aerial Stem

Abstract Achira (Canna indica L.) has not yet been tested for its potential in removing perchlorate (ClO4−) from wastewater. In this study, constructed wetlands with and without achira were used to investigate the removal efficiency and removal mechanism of perchlorate. The results showed that more ClO4− was removed by the wetlands with achira relative to those without. Perchlorate removal in the wetlands without achira decreased with time, whereas perchlorate in the wetlands with achira was stably removed. In terms of ClO4− content, the achira tissues were in the descending order of: leaf > aerial stem > flower or rhizome > root. Perchlorate was concentrated in leaves (more than 55.8%) rather than in root (less than 0.67%). Mass balance calculation showed that plant uptake accounted for 5.81–7.34% of initial ClO4− input, while microbial degradation accounted for 29.39–62.48%. The wetlands with achira were favorable for soil microorganism growth and proliferation and in turn ClO4− biodegradation. Furthermore, the effluent pH increased in achira wetland columns and in turn promoting ClO4− removal. The results indicating that the wetlands with achira promote ClO4− removal by improving the rhizosphere environment.

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.

Research Development on Constructed Wetlands

2014 ◽  
Vol 535 ◽  
pp. 388-393
Author(s):  
Lu Mei Qin ◽  
Hong Hu Zeng ◽  
Yan Peng Liang
Keyword(s):  
Wastewater Treatment ◽  
Constructed Wetlands ◽  
Constructed Wetland ◽  
Influential Factors ◽  
Research Development ◽  
Removal Mechanism ◽  
The World ◽  
Effective System ◽  
Mechanism Function ◽  
Combined Technique

Constructed wetland is a mode of economical and highly effective system applied in wastewater treatment with special removal mechanism function, which has drawn much attention over the world constantly. On the basis of study from abroad, this article makes the brief induction of removal mechanism, influential factors and combined technique of constructed wetlands, for the further research works were also put forward in the next future.

Enhancement of nitrogen removal in subsurface flow constructed wetlands employing a 2-stage configuration, an unsaturated zone, and recirculation

1995 ◽  
Vol 32 (3) ◽  
pp. 59-67 ◽  
Author(s):  
Kevin D. White
Keyword(s):  
Constructed Wetlands ◽  
Nitrogen Removal ◽  
Constructed Wetland ◽  
Subsurface Flow ◽  
Great Promise ◽  
Effluent Recirculation ◽  
Wetland Treatment ◽  
Subsurface Flow Constructed Wetlands ◽  
Inlet Zone ◽  
Bod Removal

Constructed wetland technology is currently evolving into an acceptable, economically competitive alternative for many wastewater treatment applications. Although showing great promise for removing carbonaceous materials from wastewater, wetland systems have not been as successful at nitrification. This is primarily due to oxygen limitations. Nitrification does occur in conventional wetland treatment systems, but typically requires long hydraulic retention times. This paper describes a study that first evaluated the capability of subsurface flow constructed wetlands to treat a high strength seafood processor wastewater and then evaluated passive aeration configurations and effluent recirculation with respect to nitrogen treatment efficiency. The first stage of a 2-stage wetland treatment system exhibited a relatively short hydraulic retention time and was designed for BOD removal only. The second stage wetland employed an unsaturated inlet zone and effluent recirculation to enhance nitrification. Results indicate that organic loading, and thus BOD removal, in the first stage wetland is key to optimal nitrification. Passive aeration through an unsaturated inlet zone and recirculation achieved up to 65-70 per cent ammonia nitrogen removal at hydraulic retention times of about 3.5 days. Inlet zone configuration and effluent recirculation is shown to enhance the nitrogen removal capability of constructed wetland treatment systems.

scholarly journals Variation of Bacterial and Archaeal Community Structures in a Full-Scale Constructed Wetlands for Wastewater Treatment

Archaea ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Xiu-lu Lang ◽  
Xiang Chen ◽  
Ai-ling Xu ◽  
Zhi-wen Song ◽  
Xin Wang ◽  
...  
Keyword(s):  
Microbial Community ◽  
Constructed Wetlands ◽  
Relative Abundance ◽  
Constructed Wetland ◽  
Free Surface Flow ◽  
Archaeal Community ◽  
Illumina Miseq ◽  
Surface Flow ◽  
Community Structures ◽  
Soil And Water

Microorganisms play important roles in the reduction of organic and inorganic pollutants in constructed wetlands used for the treatment of wastewater. However, the diversity and structure of microbial community in constructed wetland system remain poorly known. In this study, the Illumina MiSeq Sequencing of 16S rDNA was used to analyze the bacterial and archaeal microbial community structures of soil and water in a free surface flow constructed wetland, and the differences of bacterial communities and archaeal compositions between soil and water were compared. The results showed that the Proteobacteria were the dominant bacteria, making up 35.38%~48.66% relative abundance. Euryarchaeotic were the absolute dominant archaea in the influent sample with the relative abundance of 93.29%, while Thaumarchaeota showed dominance in the other three samples, making up 50.58%~75.70%. The relative abundances of different species showed great changes in bacteria and archaea, and the number of dominant species in bacteria was much higher than that in archaea. Compared to archaea, the community compositions of bacteria were more abundant and the changes were more significant. Meanwhile, bacteria and archaea had large differences in compositions between water and soil. The microbial richness in water was significantly higher than that in soil. Simultaneously, soil had a significant enrichment effect on some microbial flora.

Enhancement of the performance of constructed wetlands for wastewater treatment in winter: the effect of Tubifex tubifex

RSC Advances ◽  
2016 ◽  
Vol 6 (41) ◽  
pp. 34841-34848 ◽  
Author(s):  
Yan Kang ◽  
Jian Zhang ◽  
Huijun Xie ◽  
Zizhang Guo ◽  
Pengfei Li ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Constructed Wetlands ◽  
Constructed Wetland ◽  
Water Purification ◽  
Tubifex Tubifex ◽  
Batch Systems ◽  
Potential Use

An improved constructed wetland (CW) with the addition ofTubifex tubifexin winter was studied in laboratory batch systems. The outcomes of this study indicate that the potential use ofTubifex tubifexcould improve the ecosystem and water purification by CWs in winter.

scholarly journals Effects of Supplemental Cations on Growth and Nitrogen Accumulation in Canna indica L.

2021 ◽  
Vol 20 (4) ◽  
Author(s):  
Manutsawan Manokieng ◽  
◽  
Arunothai Jampeetong ◽  
Keyword(s):  
Plant Growth ◽  
Constructed Wetlands ◽  
Nitrate Removal ◽  
Nitrogen Accumulation ◽  
Total Biomass ◽  
Canna Indica ◽  
Whole Plant ◽  
Stimulate Plant Growth ◽  
Plant Level ◽  
Mineral Accumulation

Abstract The effects of supplemental cations on growth, nitrogen, and mineral accumulation were assessed in Canna indica L. Similar sized 45 days-old plants were grown on a nutrient solution modified from Hoagland and Arnon (1950). The different cations were added to generate 6 treatments (n=4): (i) control (no cation added), (ii) 2.5 mM K+, (iii) 2.5 mM Ca2+, (iv) 75 mM Na+, (v) 1.25 mM K+ + 1.25 mM Ca2+ and (vi) 2.5 mM Ca2+ + 75 mM Na+, respectively. An experiment was carried out in the greenhouse for 49 days. The study found that supplemental K+ and K++ Ca2+ increased plant growth and total biomass. The highest SER was found in plants receiving supplemental K+. In contrast, SERs, leaf areas, and total biomass decreased in Na+ or Na++Ca2+ supplemented plants. The accumulated NO3- concentration (at the whole plant level) was also highest in the plants with supplemental K+ and K++Ca2+. The total nitrogen accumulation was higher in the K+, Ca2+, and K++Ca2+ supplemented plants than in the control plants. The results suggest that supplemental cations particularly K+ can enhance plant growth and nitrogen accumulation in C. indica. Therefore, cation supplementation could be an alternative technique to stimulate plant growth and improve nitrate removal in constructed wetlands. Keywords: Constructed wetland, Nitrate removal, Potassium, Tropical wetland plants

Constructed wetland for water quality improvement: a case study from Taiwan

2010 ◽  
Vol 62 (10) ◽  
pp. 2408-2418 ◽  
Author(s):  
C. Y. Wu ◽  
J. K. Liu ◽  
S. H. Cheng ◽  
D. E. Surampalli ◽  
C. W. Chen ◽  
...  
Keyword(s):  
Water Quality ◽  
Wastewater Treatment ◽  
Constructed Wetlands ◽  
Constructed Wetland ◽  
Water Reuse ◽  
Oxygen Demand ◽  
Sediment Oxygen Demand ◽  
Nucleotide Sequence Analysis ◽  
Sediment Samples ◽  
Wetland System

In Taiwan, more than 20% of the major rivers are mildly to heavily polluted by domestic, industrial, and agricultural wastewaters due to the low percentage of sewers connected to wastewater treatment plants. Thus, constructed or engineered wetlands have been adopted as the major alternatives to clean up polluted rivers. Constructed wetlands are also applied as the tertiary wastewater treatment systems for the wastewater polishment to meet water reuse standards with lower operational costs. The studied Kaoping River Rail Bridge Constructed Wetland (KRRBCW) is the largest constructed wetland in Taiwan. It is a multi-function wetland and is used for polluted creek water purification and secondary wastewater polishment before it is discharged into the Kaoping River. Although constructed wetlands are feasible for contaminated water treatment, wetland sediments are usually the sinks for organics and metals. In this study, water and sediment samples were collected from the major wetland basins in KRRBCW. The investigation results show that more than 97% of total coliforms (TC), 55% of biochemical oxygen demand (BOD), and 30% of nutrients [e.g. total nitrogen (TN), total phosphorus (TP)] were removed via the constructed wetland system. However, results from the sediment analyses show that wetland sediments contained high concentrations of metals (e.g. Cu, Fe, Zn, Cr, and Mn), organic contents (sediment oxygen demand = 1.7 to 7.6 g O2/m2 d), and nutrients (up to 18.7 g/kg of TN and 1.22 g/kg of TN). Thus, sediments should be excavated periodically to prevent the release the pollutants into the wetland system and causing the deterioration of wetland water quality. Results of polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE), and nucleotide sequence analysis reveal that a variation in microbial diversity in the wetland systems was observed. Results from the DGGE analysis indicate that all sediment samples contained significant amounts of microbial ribospecies, which might contribute to the carbon degradation and nitrogen removal. Gradual disappearance of E. coli was also observed along the flow courses through natural attenuation mechanisms.

scholarly journals Effect of hydraulic retention time on chemical oxygen demand and total nitrogen removal in intermittently aerated constructed wetlands

2020 ◽  
Vol 15 (3) ◽  
pp. 1 ◽  
Author(s):  
Isabela Pires da Silva ◽  
Gabriela Barbosa da Costa ◽  
João Gabriel Thomaz Queluz ◽  
Marcelo Loureiro Garcia
Keyword(s):  
Chemical Oxygen Demand ◽  
Constructed Wetlands ◽  
Total Nitrogen ◽  
Total Phosphorus ◽  
Constructed Wetland ◽  
Retention Time ◽  
Hydraulic Retention Time ◽  
Subsurface Flow ◽  
Oxygen Demand ◽  
Intermittent Aeration

   This study evaluated the effect of hydraulic retention time on chemical oxygen demand (COD) and total nitrogen (TN) removal in an intermittently aerated constructed wetlands. Two horizontal subsurface-flow constructed wetlands were used: one without aeration and the other aerated intermittently (1 hour with aeration/7 hours without aeration). Both systems were evaluated treating domestic wastewater produced synthetically. The flow rate into the two CWs was 8.6 L day-1 having a hydraulic retention time of 3 days. The results show that the intermittently aerated constructed wetland were highly efficient in removing COD (98.25%), TN (83.60%) and total phosphorus (78.10%), while the non-aerated constructed wetland showed lower efficiencies in the removal of COD (93.89%), TN (48.60%) and total phosphorus (58.66). These results indicate, therefore, that intermittent aeration allows the simultaneous occurrence of nitrification and denitrification processes, improving the removal of TN in horizontal subsurface-flow constructed wetlands. In addition, the use of intermittent aeration also improves the performance of constructed wetlands in removing COD and total phosphorus.

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