scholarly journals Enhanced Sediment Denitrification for Nitrogen Removal by Manipulating Water Level in the Lakeshore Zone

Water ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 3323
Author(s):  
Yangfang Gao ◽  
Mingming Wang ◽  
Jun Wei ◽  
Lingwei Kong ◽  
Hui Xu ◽  
...  
Keyword(s):  
Water Level ◽  
Nitrogen Removal ◽  
Lake Taihu ◽  
Denitrification Rate ◽  
Sediment Layer ◽  
Shore Zone ◽  
Simulation Experiments ◽  
Strong Positive Relationship ◽  
Underlying Mechanisms ◽  
Sediment Denitrification

Denitrification of sediments is an important way to remove reactive nitrogen in lakeshore zones. In this work, we analyzed sediment denitrification patterns across the shore zone of Lake Taihu and explored their underlying mechanisms using flooding simulation experiments. The results showed that denitrification mainly occurred in the upper sediment layer (0–10 cm) and the denitrification rate was highest at the land–water interface (6.2 mg N/m2h), where there was a frequent rise and fall in the water level. Denitrification was weaker in the lakebed sediments (4.6 mg N/m2h), which were inundated long-term, and in the sediments of the near-shore zone (2.3 mg N/m2h), which were dried out for extended periods. Flooding simulation experiments further indicated a strong positive relationship between sediment denitrification rate and flooding frequency. When the flooding occurred once every 3, 6, 9, 12, or 15 days, the denitrification rate reached 7.6, 5.7, 2.8, 0.9, and 0.6 mg N/m2h, respectively. Frequent flooding caused alternating anoxic and aerobic conditions in sediments, accelerating nitrogen substrate supply and promoting the growth and activity of denitrifying bacteria. Based on these findings, we propose a possible strategy for enhancing sediment denitrification by manipulating the water level, which can help guide nitrogen removal in lakeshore zones.

Effects of the combination of aeration and biofilm technology on transformation of nitrogen in black-odor river

2016 ◽  
Vol 74 (3) ◽  
pp. 655-662 ◽  
Author(s):  
Mei Pan ◽  
Jun Zhao ◽  
Shucong Zhen ◽  
Sheng Heng ◽  
Jie Wu
Keyword(s):  
Enzyme Activity ◽  
Nitrogen Removal ◽  
Removal Rate ◽  
River Networks ◽  
Water Tank ◽  
Simulation Experiments ◽  
Overlying Water ◽  
Combined Process ◽  
Polluted Rivers ◽  
Laboratory Water

Excess nitrogen in urban river networks leading to eutrophication has become one of the most urgent environmental problems. Combinations of different aeration and biofilm techniques was designed to remove nitrogen from rivers. In laboratory water tank simulation experiments, we assessed the removal efficiency of nitrogen in both the overlying water and sediments by using the combination of the aeration and biofilm techniques, and then analyzed the transformation of nitrogen during the experiments. Aeration (especially sediment aeration) combined with the biofilms techniques was proved efficient in removing nitrogen from polluted rivers. Results indicated that the combination of sediment aeration and biofilms, with the highest nitrogen removal rate from the overlying water and sediments, was the most effective combined process, which especially inhibited the potential release of nitrogen from sediments by reducing the enzyme activity. It was found that the content of dissolved oxygen in water could be restored on the basis of the application of aeration techniques ahead, and the biofilm technique would be effective in purifying water in black-odor rivers.

scholarly journals Response of Submerged Aquatic Vegetation to Water Depth in a Large Shallow Lake after an Extreme Rainfall Event

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2412 ◽  
Author(s):  
Jinge Zhu ◽  
Jiancai Deng ◽  
Yihui Zhang ◽  
Zhaoliang Peng ◽  
Weiping Hu
Keyword(s):  
Water Level ◽  
Water Depth ◽  
Submerged Aquatic Vegetation ◽  
Community Dynamics ◽  
Aquatic Vegetation ◽  
Lake Taihu ◽  
Extreme Rainfall ◽  
Rainfall Event ◽  
Cumulative Probability ◽  
Extreme Rainfall Event

Submerged aquatic vegetation (SAV) is an important part of lake ecosystems, and a proper SAV community structure is the key factor in keeping a clear-water state. Although the response of SAV to water depth has been widely studied in different aquatic environments, little is known about the response of the SAV community to changes in water depth of a large lake after an extreme rainfall event. To examine this question, 780 samples were collected from Lake Taihu, China, between 2013 and 2017 to analyze the variations in SAV and water depth. The water level of the lake ranged from 2.75 to 4.87 m, and the water depth at sampling sites ranged from 1.07 to 3.31 m. The SAV biomass at the sampling sites ranged from 0 to 17.61 kg/m2. The influence of water depth on SAV biomass and frequency of occurrence differed by seasons and by species. The adaptation of SAV species to increasing water depth is a key element for community dynamics, which in turn contributes to water level regulation. A new method was proposed to identify the optimal water depth for SAV biomass accumulation based on calculation of the cumulative probability and probability density.

scholarly journals Denitrification of Permeable Sand Sediment in a Headwater River Is Mainly Influenced by Water Chemistry, Rather Than Sediment Particle Size and Heterogeneity

2021 ◽  
Vol 9 (11) ◽  
pp. 2202
Author(s):  
Weibo Wang ◽  
Xu Wang ◽  
Xiao Shu ◽  
Baoru Wang ◽  
Hongran Li ◽  
...  
Keyword(s):  
Particle Size ◽  
Water Chemistry ◽  
Denitrification Rate ◽  
Sediment Particle ◽  
Permeable Sediment ◽  
Permeable Sediments ◽  
Sediment Particle Size ◽  
The Impact ◽  
Sediment Denitrification ◽  
Material Exchange

Sediment particle size and heterogeneity play an important role in sediment denitrification through direct and indirect effects on, for example, the material exchange rate, environmental gradients, microbial biomass, and grazing pressure. However, these effects have mostly been observed in impermeable sediments. On the other hand, the material exchange of permeable sediments is dominated by advection instead of diffusion, with the exchange or transport rates exceeding those of diffusion by two orders of magnitude relative to impermeable sediments. The impact of permeable sediment particle size and heterogeneity on denitrification remains poorly understood, especially at the millimeter scale. Here, we conducted an in situ control experiment in which we sorted sand sediment into four homogeneous-particle-sizes treatments and four heterogeneous treatments. Each treatment was deployed, in replicate, within the riffle in three different river reaches with contrasting physicochemical characteristics. After incubating for three months, sediment denitrifier communities (nirS, nirK, nosZ), denitrification gene abundances (nirS, nirK, nosZ), and denitrification rates in all treatments were measured. We found that most of the denitrifying microbes in permeable sediments were unclassified denitrifying microbes, and particle size and heterogeneity were not significantly correlated with the functional gene abundances or denitrification rates. Water chemistry was the key controlling factor for the denitrification of permeable sediments. Water NO3−-N directly regulated the denitrification rate of permeable sediments, instead of indirectly regulating the denitrification rate of sediments by affecting the chemical characteristics of the sediments. Our study fills a knowledge gap of denitrification in permeable sediment in a headwater river and highlights that particle size and heterogeneity are less important for permeable sediment denitrification.

Denitrification in Constructed Wastewater Wetlands Receiving High Concentrations of Nitrate

1994 ◽  
Vol 29 (4) ◽  
pp. 7-14 ◽  
Author(s):  
A. J. van Oostrom ◽  
J. M. Russell
Keyword(s):  
Organic Carbon ◽  
Nitrogen Removal ◽  
Plant Material ◽  
Pilot Scale ◽  
Surface Flow ◽  
Denitrification Rate ◽  
Biomass Carbon ◽  
Meat Processing ◽  
Wetland Plant ◽  
High Concentrations

Nitrogen removal in constructed wetlands receiving nitrified wastewaters can be limited by insufficient organic carbon for denitrification. Experiments were undertaken to determine the importance of decaying plant material, in a floating mat of the wetland plant Glyceria maxima, as a source of organic carbon and anoxic sites for denitrification in surface-flow wetlands. In the laboratory, a mat of G. maxima floating on a nitrified meat processing effluent (87 g m−3 NO3-N) promoted a denitrification rate of 3.8 g m−2 day−1 at 20°C. Under strictly anoxic conditions, and where G. maxima leaves were the sole carbon source for denitrification, about 2.1 g of the biomass carbon was consumed for every gram of NO3−N removed. The biomass carbon produced by G. maxima growing on meat processing effluent has the potential to sustain a denitrification rate of 2.4 - 4.8 g m−2 day−1. In a pilot-scale wetland completely covered with G. maxima and receiving a nitrified meat processing effluent, nitrogen removal rates ranged from 0.6 g m−2 day−1 in winter to 3.0 g m−2 day−1 in summer. The floating plant mat and the sediment are the most active denitrification sites in the wetland. Nitrogen removal may potentially be enhanced by improving the contact between the wastewater and the decaying plant material.

Simultaneous Nitrification/Denitrification in a Single Reactor using Ciliated Columns Packed with Granular Sulfur

2005 ◽  
Vol 40 (1) ◽  
pp. 91-96 ◽  
Author(s):  
Yong-Woo Hwang ◽  
Chang-Gyun Kim ◽  
In-Jun Choo
Keyword(s):  
Dissolved Oxygen ◽  
Activated Sludge ◽  
Total Nitrogen ◽  
Nitrogen Removal ◽  
Glass Beads ◽  
Denitrification Rate ◽  
The Other ◽  
Simultaneous Nitrification And Denitrification ◽  
Total Nitrogen Removal ◽  
Anoxic Zones

Abstract This study was conducted to assess the possibility of simultaneous nitrification and denitrification in an activated sludge using a cilia media packed with granular sulfur in a single reactor. For the granular sulfur column adopted, the total nitrogen removal was up to 67%. This facilitated the simultaneous decomposition of autotrophic and heterotrophic denitrifiers present at a 5:2 ratio. On the other hand, the control incubation test employing glass beads achieved only 18% denitrification. Regardless of the NH4-N loadings, the use of ciliated granular sulfur columns, made denitrification 1.5 times faster than when cilia was not used. The size of the granular sulfur columns directly contributed to the extent of denitrification, which was correlated to the void sphere of anoxic zones through the columns. Dissolved oxygen (DO) concentrations lower than 4.0 mg/L did not influence the level of denitrification. However, when higher than 4.0 mg/L, the DO began to negatively impact the denitrification rate. The study found that the simple installation of a cilia media packed with granular sulfur in an existing activated sludge could simultaneously achieve an efficient nitrification/denitrification in a single reactor.

The impact of two species of bioturbating shrimp (Callianassa subterranea and Upogebia deltaura) on sediment denitrification

2004 ◽  
Vol 84 (3) ◽  
pp. 629-632 ◽  
Author(s):  
Rebecca L. Howe ◽  
Andrew P. Rees ◽  
Stephen Widdicombe
Keyword(s):  
Solute Transport ◽  
Denitrification Rate ◽  
Mesocosm Experiment ◽  
Water Interface ◽  
Direct Extension ◽  
Isotope Pairing ◽  
The Impact ◽  
Sediment Denitrification ◽  
Callianassa Subterranea ◽  
Stimulation Of

In a benthic mesocosm experiment, the effects of two species of burrowing Thalassinidean shrimps (Callianassa subterranea and Upogebia deltaura) on rates of sediment denitrification were determined using the isotope pairing technique. Denitrification rate (Dtot) and coupled nitrification–denitrification (Dn) were shown to be significantly enhanced by the presence of U. deltaura by 2·9 and 3·3 times respectively, relative to control measurements. For U. deltaura the stimulation of the denitrification rate was found to be significantly related to the size of the animal (F=5·81, P=0·042). No deviation from the rates determined in control cores for either Dtot or Dn was observed for those cores inhabited by C. subterranea. The increase in Dtot with U. deltaura was considered to be the result of a combination of different factors, including; the direct extension of the sediment–water interface and an increase in oxygenation of the sediments and solute transport, as a result of the ventilating activities of the animal itself.

Effects of influent COD/N ratio and internal recycle ratio on nitrogen removal efficiency in the KNR process

2006 ◽  
Vol 53 (9) ◽  
pp. 265-270 ◽  
Author(s):  
C.W. Suh ◽  
S.H. Lee ◽  
H.S. Jeong ◽  
J.C. Kwon ◽  
H.S. Shin
Keyword(s):  
Carbon Source ◽  
Removal Efficiency ◽  
Nitrogen Removal ◽  
Denitrification Rate ◽  
Optimal Operating ◽  
Operating Condition ◽  
Optimal Operating Condition ◽  
External Carbon Source ◽  
Recycle Ratio ◽  
Removal Efficiencies

In this study, with the KNR® process that has many advantages, the nitrogen removal efficiency of KNR was experimentally investigated at various COD/N ratios of influent conditions. The optimal operating condition of internal recycle ratio was evaluated. The TN removal efficiencies were 59.1, 72.5 and 75.9% at the COD/N ratios of 3, 5 and 7, respectively. These high removal efficiencies resulted from high denitrification rate in UMBR with high microorganism concentration. Furthermore, specific endogenous denitrification at MLVSS of 10.3 g/L that is similar to MLVSS in UMBR was over two times higher than that at MLVSS of 2.06 g/L. This result suggests that endogenous denitrification rate in UMBR is so high that the requirement of an external carbon source can be saved. As the internal recycle ratio increased from 100 to 400%, the TN removal efficiency also improved from 69.5 to 82.9%, and the optimal internal recycle ratio was 300%.

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