Increasing nitrogen removal efficiency by intermittent aeration in partial areas of laboratory-scale vertical flow constructed wetlands

2020 ◽  
Vol 71 (12) ◽  
pp. 1686
Author(s):  
Chen Chen ◽  
Nannan Zhang ◽  
Zhe Liu ◽  
Shuqing An ◽  
Dehua Zhao
Keyword(s):  
Removal Efficiency ◽  
Constructed Wetlands ◽  
Nitrogen Removal ◽  
Amoa Gene ◽  
Laboratory Scale ◽  
Vertical Flow ◽  
Intermittent Aeration ◽  
Nitrate Reductase Gene ◽  
Partial Area ◽  
Reductase Gene

Intermittent aeration (IA) has been widely used in constructed wetlands (CWs) because it is economical and results in high nitrogen removal efficiency (RE). The aim of this study was to identify whether IA (4hday–1; the recommended frequency according to previous studies) in a partial area (PIA) can improve nitrogen RE compared with IA applied throughout the CW (TIA). Three types of laboratory-scale vertical flow CWs were constructed: PIA, TIA and non-aerated (NA). PIA achieved a higher RE of total nitrogen than TIA and NA (mean RE 60.6 v. 45.2 and 37.4% respectively). In the PIA, the ammonia mono-oxygenase subunit A (amoA) gene was abundant in aerated areas, whereas the nitrate reductase gene narG and nitrite reductase genes nirK and nirS were abundant in anaerobic areas. The results of this study suggest that PIA is an effective strategy for nitrogen removal when applying aeration in CWs because it preserves a constant anaerobic area for denitrification.

scholarly journals Effects of salinity on the treatment of synthetic petroleum-industry wastewater in pilot vertical flow constructed wetlands under simulated hot arid climatic conditions

2020 ◽  
Vol 28 (2) ◽  
pp. 2172-2181
Author(s):  
Thomas V. Wagner ◽  
Fatma Al-Manji ◽  
Jie Xue ◽  
Koen Wetser ◽  
Vinnie de Wilde ◽  
...  
Keyword(s):  
Benzoic Acid ◽  
Removal Efficiency ◽  
Constructed Wetlands ◽  
Membrane Fouling ◽  
Plant Defence ◽  
Petroleum Industry ◽  
Vertical Flow ◽  
Treated Effluent ◽  
The Impact ◽  
Industry Wastewater

AbstractPetroleum-industry wastewater (PI-WW) is a potential source of water that can be reused in areas suffering from water stress. This water contains various fractions that need to be removed before reuse, such as light hydrocarbons, heavy metals and conditioning chemicals. Constructed wetlands (CWs) can remove these fractions, but the range of PI-WW salinities that can be treated in CWs and the influence of an increasing salinity on the CW removal efficiency for abovementioned fractions is unknown. Therefore, the impact of an increasing salinity on the removal of conditioning chemicals benzotriazole, aromatic hydrocarbon benzoic acid, and heavy metal zinc in lab-scale unplanted and Phragmites australis and Typha latifolia planted vertical-flow CWs was tested in the present study. P. australis was less sensitive than T. latifolia to increasing salinities and survived with a NaCl concentration of 12 g/L. The decay of T. latifolia was accompanied by a decrease in the removal efficiency for benzotriazole and benzoic acid, indicating that living vegetation enhanced the removal of these chemicals. Increased salinities resulted in the leaching of zinc from the planted CWs, probably as a result of active plant defence mechanisms against salt shocks that solubilized zinc. Plant growth also resulted in substantial evapotranspiration, leading to an increased salinity of the CW treated effluent. A too high salinity limits the reuse of the CW treated water. Therefore, CW treatment should be followed by desalination technologies to obtain salinities suitable for reuse. In this technology train, CWs enhance the efficiency of physicochemical desalination technologies by removing organics that induce membrane fouling. Hence, P. australis planted CWs are a suitable option for the treatment of water with a salinity below 12 g/L before further treatment or direct reuse in water scarce areas worldwide, where CWs may also boost the local biodiversity.

Nutrient removal efficiency and resource economics of vertical flow and horizontal flow constructed wetlands

2001 ◽  
Vol 18 (2) ◽  
pp. 157-171 ◽  
Author(s):  
Volker Luederitz ◽  
Elke Eckert ◽  
Martina Lange-Weber ◽  
Andreas Lange ◽  
Richard M Gersberg
Keyword(s):  
Removal Efficiency ◽  
Constructed Wetlands ◽  
Nutrient Removal ◽  
Resource Economics ◽  
Horizontal Flow ◽  
Vertical Flow ◽  
Nutrient Removal Efficiency

scholarly journals Start-Up and Aeration Strategies for a Completely Autotrophic Nitrogen Removal Process in an SBR

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Xiaoling Zhang ◽  
Fan Zhang ◽  
Yanhong Zhao ◽  
Zhengqun Li
Keyword(s):  
Removal Efficiency ◽  
Total Nitrogen ◽  
Nitrogen Removal ◽  
Tap Water ◽  
Granular Sludge ◽  
Anammox Bacteria ◽  
Intermittent Aeration ◽  
Start Up ◽  
Canon Process ◽  
Autotrophic Nitrogen Removal

The start-up and performance of the completely autotrophic nitrogen removal via nitrite (CANON) process were examined in a sequencing batch reactor (SBR) with intermittent aeration. Initially, partial nitrification was established, and then the DO concentration was lowered further, surplus water in the SBR with high nitrite was replaced with tap water, and continuous aeration mode was turned into intermittent aeration mode, while the removal of total nitrogen was still weak. However, the total nitrogen (TN) removal efficiency and nitrogen removal loading reached 83.07% and 0.422 kgN/(m3·d), respectively, 14 days after inoculating 0.15 g of CANON biofilm biomass into the SBR. The aggregates formed in SBR were the mixture of activated sludge and granular sludge; the volume ratio of floc and granular sludge was 7 : 3. DNA analysis showed that Planctomycetes-like anammox bacteria and Nitrosomonas-like aerobic ammonium oxidization bacteria were dominant bacteria in the reactor. The influence of aeration strategies on CANON process was investigated using batch tests. The result showed that the strategy of alternating aeration (1 h) and nonaeration (1 h) was optimum, which can obtain almost the same TN removal efficiency as continuous aeration while reducing the energy consumption, inhibiting the activity of NOB, and enhancing the activity of AAOB.

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