Nutrient removal in hybrid constructed wetlands: spatial-seasonal variation and the effect of vegetation

2019 ◽  
Vol 79 (10) ◽  
pp. 1985-1994 ◽  
Author(s):  
Haq Nawaz Abbasi ◽  
Jing Xie ◽  
Syed Ikhlaq Hussain ◽  
Xiwu Lu
Keyword(s):  
Constructed Wetlands ◽  
Water Depth ◽  
Nutrient Removal ◽  
Plant Root ◽  
Pilot Scale ◽  
Treatment Wetlands ◽  
Opposite Trend ◽  
Number Of Factors ◽  
Plant Root System ◽  
Floating Treatment Wetlands

Abstract Constructed wetlands (CWs) are an aesthetic and sustainable form to treat wastewater, however, their performance can be increased by improving a number of factors. The pilot-scale hybrid constructed wetland (CW) system was the combination of constructed floating treatment wetlands (CFWs) and horizontal subsurface flow constructed wetlands (HSFCWs); operated for a year and covered all seasons. The research was conducted to investigate the performance of the CW system regarding water depth, spatial, and seasonal removal of pollutants. Nine economical plants species were selected and divided into four groups to grow in CW-I to CW-IV, respectively. Removal increased along the bed and most of the total phosphorus (TP) removal occurred in the second bed, whereas total nitrogen (TN) and ammonium (NH4) removal were associated with the plant root system and biomass. Optimum removal of nutrients with respect to water depth was at 35 cm. TN and NH4 removal patterns were similar in different CWs. TN and NH4 removal were higher during summer compared to winter; only CW-IV showed the opposite trend.

Effects of operation parameters on nutrient removal from wastewater and high-protein biomass production in a duckweed-based (Lemma aequinoctialis) pilot-scale system

2014 ◽  
Vol 70 (7) ◽  
pp. 1195-1204 ◽  
Author(s):  
Yonggui Zhao ◽  
Yang Fang ◽  
Yanling Jin ◽  
Jun Huang ◽  
Shu Bao ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Biomass Production ◽  
Water Depth ◽  
Nutrient Removal ◽  
Removal Rate ◽  
Pilot Scale ◽  
Coverage Rate ◽  
High Protein ◽  
Dianchi Lake ◽  
Operation Conditions

The effects of water depth, coverage rate and harvest regime on nutrient removal from wastewater and high-protein biomass production were assessed in a duckweed-based (Lemna aequinoctialis) pilot-scale wastewater treatment system (10 basins × 12 m2) that is located near Dianchi Lake in China. The results indicated that a water depth of 50 cm, a coverage rate of 150% and a harvest regime of 4 days were preferable conditions, under which excellent records of high-protein duckweed (dry matter production of 6.65 g/m2/d with crude protein content of 36.16% and phosphorus content of 1.46%) were obtained at a temperature of 12–21 °C. At the same time, the system achieved a removal efficiency of 66.16, 23.1, 48.3 and 76.52% for NH4+-N, TN, TP and turbidity, respectively, with the considerable removal rate of 0.465 g/m2/d for TN and 0.134 g/m2/d for TP at a hydraulic retention time of 6 days. In additionally, it was found that a lower duckweed density could lead to higher dissolved oxygen in the water and then a higher removal percentage of NH4+-N by nitrobacteria. This study obtains the preferable operation conditions for wastewater treatment and high-protein biomass production in a duckweed-based pilot-scale system, supplying an important reference for further large-scale applications of duckweed.

scholarly journals Wetland Technologies for Nursery and Greenhouse Compliance with Nutrient Regulations

HortScience ◽  
2013 ◽  
Vol 48 (9) ◽  
pp. 1103-1108 ◽  
Author(s):  
Sarah A. White
Keyword(s):  
Constructed Wetlands ◽  
Constructed Wetland ◽  
Public Awareness ◽  
Subsurface Flow ◽  
Agricultural Runoff ◽  
Surface Flow ◽  
Treatment Wetlands ◽  
Treatment Technology ◽  
Subsurface Flow Constructed Wetlands ◽  
Floating Treatment Wetlands

The need to protect our water resources and increasing public awareness of the importance of cleaner water for ecological and human health reasons are driving regulations limiting nutrient release from traditionally exempt, non-point source agricultural contributors. Modification of production practices alone may not be adequate to meet regulated nutrient criterion limits for irrigation and stormwater runoff entering surface waters. Three constructed wetland technologies are well suited to help agricultural producers meet current and future regulations. The first two technologies, surface- and subsurface-flow constructed wetlands, have been in use for over 40 years to cleanse various types of wastewater, whereas floating treatment wetlands are an emerging remediation technology with potential for both stormwater and agricultural runoff treatment applications. The mechanisms driving removal of both nitrogen (N) and phosphorus (P) in constructed wetland systems are discussed. Surface-flow constructed wetlands remediate N contaminants from both container nursery and greenhouse production wastewater, whereas P remediation is variable and tied most closely to active plant growth as the constructed wetland ages. Subsurface-flow constructed wetlands effectively remediate N from production wastewater and can be tailored to increase consistency of P remediation through selection of P-sorbing root-bed substrates. Floating treatment wetlands effectively remediate both N and P with a designed surface area of a pond covered depending on the target effluent concentration or regulated total maximum daily load. The choice of treatment technology applied by growers to meet regulated water quality targets should be based on both economic and site-specific considerations.

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