scholarly journals Effects of Partial Saturation on Nitrogen Removal and Bacterial Community in Vertical-Flow Constructed Wetlands

2021 ◽  
Author(s):  
Khadija kraiem ◽  
Hamadi Kallali ◽  
Rim Werheni Ammeri ◽  
salma Bessadok ◽  
Naceur Jedidi
Keyword(s):  
Constructed Wetlands ◽  
Nitrogen Removal ◽  
Constructed Wetland ◽  
Removal Rate ◽  
Vertical Flow ◽  
Partial Saturation ◽  
Denitrifying Bacterium ◽  
Saturation Condition ◽  
Vertical Flow Constructed Wetland ◽  
Kjeldahl Nitrogen

Abstract The laboratory-scale pilot of constructed wetlands has been in operation for six months; (1) an unsaturated vertical flow constructed wetland (UVF-CW), this system was used to represent the classic vertical constructed wetlands, (2) a saturated vertical flow constructed wetland (SVF-CW), to evaluate the effects of the saturated condition on nitrogen removal and composition of the microbial community. The results showed that the saturation condition positiveley influenced the removal efficiencies of the nitrogen,, the aeverage removal rate of the total kjeldahl nitrogen increased from 56% in unsaturated vertical flow constructed wetland (UVF-CW) to 63% in saturated vertical flow constructed wetland ( SVF-CW). In addition, the microbial communities also was affected by the saturation condition, the relative abundances of nitrifying bacterium in UVF-CW are 13.8% (Nitrosomonas), 7.2% (Nitrosospira), 18.1% (Nitrospira) and 15.3% (Nitrobacter). In contrast, in SVF-CW, Nitrosomonas, Nitrosospira, Nitrospira and Nitrobacter only accounted for 6.8%, 5.6%, 7.4% and 10.6% respectively. However, the saturation condition seemed to increase denitrifying bacterium more than three times, in unsaturated vertical flow constructed wetland, only Pseudomonas (6.5%) and Paracoccus (4.85%) were detected, but in saturated vertical flow constructed wetland (SVF-CW), the abundance of Pseudomonas (13.08%) and Paracoccus (9.74%) were increased, and three other groups of denitrifying bacteria were also detected as Zoogloea (3.32%), Thauera (5.41%) and Thiobacillus (3).

Nitrogen Removal Capacity in Horizon Subsurface Flow and Vertical Flow Constructed Wetland in Relation to Operational Mode

2011 ◽  
Vol 374-377 ◽  
pp. 118-121
Author(s):  
Tian Xie ◽  
Zong Lian She ◽  
En Shi ◽  
Lei Lei Li ◽  
Ying Jie Zhu
Keyword(s):  
Nitrogen Removal ◽  
Constructed Wetland ◽  
Removal Rate ◽  
Nitrate Removal ◽  
Subsurface Flow ◽  
Vertical Flow ◽  
Operational Mode ◽  
Removal Capacity ◽  
Vertical Flow Constructed Wetland ◽  
Operational Modes

Two laboratory scale constructed wetlands were designed as horizon subsurface flow constructed wetland (HFCW) and vertical flow constructed wetland (VFCW) and were utilized to study the treatment capacity to reduce nitrogen. According to different inflow concentration and height of water surface, HFCW was analyzed in two operational modes and VFCW in four operational modes. The semi-submerged VFCW had the best capacity to remove nitrogen and the total nitrogen removal rate reached to 92% and the removal rate of HFCW was 90%. Moreover, the un-submerged VFCW could reduce 93% ammonia but nitrate removal rate just was 9%. And the removal rates of NH4+-N, NO3--N and TN respectively were 85%, 80% and 81% in submerged VFCW.

Effects of a saturated layer and recirculation on nitrogen treatment performances of a single stage Vertical Flow Constructed Wetland (VFCW)

2013 ◽  
Vol 68 (7) ◽  
pp. 1461-1467 ◽  
Author(s):  
S. Prigent ◽  
J. Paing ◽  
Y. Andres ◽  
F. Chazarenc
Keyword(s):  
Constructed Wetland ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Single Stage ◽  
Vertical Flow ◽  
Saturated Layer ◽  
Vertical Flow Constructed Wetland ◽  
Hydraulic Load ◽  
Nitrogen Concentrations ◽  
Kjeldahl Nitrogen

Upgrades to enhance nitrogen removal were tested in a 2 year old pilot vertical flow constructed wetland in spring and summer periods. The effects of a saturated layer and of recirculation were tested in particular. Two pilots (L = 2 m, W = 1.25 m, H = 1.2 m), filled with expanded schist (Mayennite®), were designed with hydraulic saturated layers of 20 and 40 cm at the bottom. Each pilot was fed with raw domestic wastewater under field conditions according to a hydraulic load of 15–38 cm d−1 (i.e. 158–401 g COD (chemical oxygen demand) m−2 d−1) and to recirculation rates ranging from 0% up to 150%. The initial load during the first 2 years of operation resulted in an incomplete mineralized accumulated sludge leading to total suspended solids (TSS), COD and biochemical oxygen demand (BOD5) release. A 40 cm hydraulic saturated layer enabled an increase of 5–10% total nitrogen (TN) removal compared to a 20 cm saturated layer. Recirculation allowed the dilution of raw wastewater and enhanced nitrification in a single stage. A design of 1.8 m² pe−1 (48 cm d−1, 191 g COD m−2 d−1) with a 40 cm saturated layer and 100% recirculation enabled the French standard D4 (35 mg TSS L−1, 125 mg COD L−1, 25 mg BOD5 L−1), nitrogen concentrations below 20 mg TKN (total Kjeldahl nitrogen) L−1 and 50 mg TN L−1, to be met.

scholarly journals Effect of the Influent Substrate Concentration on Nitrogen Removal from Summer to Winter in Field Pilot-Scale Multistage Constructed Wetland–Pond Systems for Treating Low-C/N River Water

2021 ◽  
Vol 13 (22) ◽  
pp. 12456
Author(s):  
Tao Wang ◽  
Liping Xiao ◽  
Hongbin Lu ◽  
Shaoyong Lu ◽  
Xiaoliang Zhao ◽  
...  
Keyword(s):  
River Water ◽  
Constructed Wetlands ◽  
Nitrogen Removal ◽  
Constructed Wetland ◽  
Substrate Concentration ◽  
Removal Rate ◽  
Carbon Sources ◽  
River Estuary ◽  
Pilot Scale ◽  
Surface Flow

The quality of micropolluted water is unstable and its substrate concentration fluctuates greatly. The goal is to predict the concentration effect on the treatment of nitrogen in a river with an actual low C/N ratio for the proposed full-scale Xiaoyi River estuary wetland, so that the wetland project can operate stably and perform the water purification function effectively in the long term. Two pilot-scale multistage constructed wetland–pond (MCWP) systems (S1 and S2, respectively) based on actual engineering with the same “front ecological oxidation ponds, two-stage horizontal subsurface flow constructed wetlands and surface flow constructed wetlands (SFCWs) as the core and postsubmerged plant ponds” as the planned process were constructed to investigate the effect of different influent permanganate indexes (CODMn) and total nitrogen (TN) contents on nitrogen removal from micropolluted river water with a fixed C/N ratio from summer to winter in the field. The results indicate that the TN removal rate in the S1 and S2 systems was significant (19.56% and 34.84%, respectively). During the process of treating this micropolluted water with a fixed C/N ratio, the influent of S2 with a higher CODMn concentration was conducive to the removal of TN. The TN removal rate in S2 was significantly affected by the daily highest temperature. There was significant nitrogen removal efficiency in the SFCWs. The C/N ratio was a major determinant influencing the nitrogen removal rate in the SFCWs. The organic matter release phenomenon in SFCWs with high-density planting played an essential role in alleviating the lack of carbon sources in the influent. This research strongly supports the rule that there is seasonal nitrogen removal in the MCWPs under different influent substrate concentrations, which is of guiding significance for practical engineering.

Correlation Studies of Dissolved Oxygen in the IVCW System Changes and Removal of Nitrogen

2012 ◽  
Vol 610-613 ◽  
pp. 417-421
Author(s):  
Ji Ku Zhang ◽  
Yue Lang ◽  
Ming Jie Li
Keyword(s):  
Dissolved Oxygen ◽  
Constructed Wetlands ◽  
Total Nitrogen ◽  
Constructed Wetland ◽  
Flow Direction ◽  
Vertical Flow ◽  
Correlation Studies ◽  
Vertical Flow Constructed Wetlands ◽  
Vertical Flow Constructed Wetland ◽  
System Changes

Experiment simulates the integrated vertical flow constructed wetland (IVCW) operation of the system, discusses the trend of Dissolved Oxygen (DO) within the system and the relativity of DO and removing nitrogen. The results show that NH4+-N, NO3—-N and DO decrease along the flow direction in the integrated vertical flow constructed wetlands; NO3—-N increased and then decreased along the process; because of the DO of upstream pool is low, so the Total Nitrogen (TN) removing process occurs mainly in the downstream pool.

High-rate nitrogen removal in a two-stage subsurface vertical flow constructed wetland

Desalination ◽  
2009 ◽  
Vol 246 (1-3) ◽  
pp. 55-68 ◽  
Author(s):  
Guenter Langergraber ◽  
Klaus Leroch ◽  
Alexander Pressl ◽  
Kirsten Sleytr ◽  
Roland Rohrhofer ◽  
...  
Keyword(s):  
Nitrogen Removal ◽  
Constructed Wetland ◽  
High Rate ◽  
Vertical Flow ◽  
Two Stage ◽  
Vertical Flow Constructed Wetland

Reversing Clogging in Vertical-Flow Constructed Wetlands by Backwashing Treatment

2010 ◽  
Vol 129-131 ◽  
pp. 1064-1068
Author(s):  
Fei Ma ◽  
Li Jiang ◽  
Ting Zeng
Keyword(s):  
Waste Water ◽  
Hydraulic Conductivity ◽  
Constructed Wetlands ◽  
Constructed Wetland ◽  
Removal Rate ◽  
Pollutant Removal ◽  
Vertical Flow ◽  
Vertical Flow Constructed Wetlands ◽  
The World ◽  
Design Guidance

More and more constructed wetland CW) were used to treat waste water in the world for its advantage on cheaper and efficiency. CW would clog for improper design or imperfect management, so application for it was limited. The purpose of this paper is that using backwashing method resolve filter media clogging problem which is an intractable matter in constructed wetlands project. The effects of the backwashing treatment on pollutant removal, as well as the influence on characteristics of hydraulics of wetlands, were studied. The experimental results indicate that CW hydraulic conductivity, hydraulic resistance time and removal rate of COD increased after backwashing. This paper confirmed that backwashing method can reverse clogging in vertical-flow constructed wetlands, and provided design guidance for applying backwashing method to treat clogging vertical-flow constructed wetlands.

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