Performance of intermittent aeration reactor on NH4-N removal from groundwater resources

2010 ◽  
Vol 61 (12) ◽  
pp. 3061-3069 ◽  
Author(s):  
W. Khanitchaidecha ◽  
T. Nakamura ◽  
T. Sumino ◽  
F. Kazama
Keyword(s):  
Removal Rate ◽  
Groundwater Resources ◽  
Ammonium Nitrogen ◽  
Total Carbon ◽  
Intermittent Aeration ◽  
Reactor Performance ◽  
Total Carbon Content ◽  
Term Operation ◽  
N Removal ◽  
Synthetic Groundwater

To study the effect of intermittent aeration period on ammonium–nitrogen (NH4-N) removal from groundwater resources, synthetic groundwater was prepared and three reactors were operated under different conditions – “reactor A” under continuous aeration, “reactor B” under 6 h intermittent aeration, and “reactor C” under 2 h intermittent aeration. To facilitate denitrification simultaneously with nitrification, “acetate” was added as an external carbon source with step-wise increase from 0.5 to 1.5 C/N ratio, where C stands for total carbon content in the system, and N for NH4-N concentration in the synthetic groundwater. Results show that complete NH4-N removal was obtained in “reactor B” and “reactor C” at 1.3 and 1.5 C/N ratio respectively; and partial NH4-N removal in “reactor A”. These results suggest that intermittent aeration at longer interval could enhance the reactor performance on NH4-N removal in terms of efficiency and low external carbon requirement. Because of consumption of internal carbon by the process, less amount of external carbon is required. Further increase in carbon in a form of acetate (1.5 to 2.5 C/N ratios) increases removal rate (represented by reaction rate coefficient (k) of kinetic equation) as well as occurrence of free cells. It suggests that the operating condition at reactor B with 1.3 C/N ratio is more appropriate for long-term operation at a pilot-scale.

scholarly journals Nitrogen removal from ammonium-contaminated groundwater using dropping nitrification–cotton-based denitrification reactor

2021 ◽  
Author(s):  
A. K. Maharjan ◽  
K. Mori ◽  
K. Nishida ◽  
T. Toyama
Keyword(s):  
Nitrogen Removal ◽  
Removal Rate ◽  
Denitrifying Bacteria ◽  
Electron Donors ◽  
Nitrifying Bacteria ◽  
Contaminated Groundwater ◽  
Total N ◽  
N Removal ◽  
Denitrification Reactor ◽  
Synthetic Groundwater

Abstract A novel dropping nitrification–cotton-based denitrification reactor was developed for total nitrogen (N) removal from ammonium (NH4+)-contaminated groundwater. The nitrogen removal ability of the reactor was evaluated for 91 days. A 1 m-long dropping nitrification unit was fed with synthetic groundwater containing 30 mg-NH4+-N/L at a flow rate of 2.16 L/d. The outlet of the dropping nitrification unit was connected to the cotton-based denitrification unit. The NH4+ present in the groundwater was completely oxidized (>90% nitrification efficiency) by nitrifying bacteria to nitrite (NO2–) and nitrate (NO3–) in the dropping nitrification unit. Subsequently, the generated NO2– and NO3– were denitrified (96%–98% denitrification efficiency) by denitrifying bacteria in the cotton-based denitrification unit under anoxic conditions. Organic carbons released from the cotton presumably acted as electron donors for heterotrophic denitrification. Nitrifying and denitrifying bacteria were colonized in higher abundance in the dropping nitrification and cotton-based denitrification units, respectively. The total N removal rate and efficiency of the dropping nitrification–cotton-based denitrification reactor for 91 days were 58.1–66.9 mg-N/d and 96%–98%, respectively. Therefore, the dropping nitrification–cotton-based denitrification reactor will be an efficient, sustainable, and promising option for total N removal from NH4+-contaminated groundwater.

scholarly journals Ammonium-Nitrogen (NH4+-N) Removal from Groundwater by a Dropping Nitrification Reactor: Characterization of NH4+-N Transformation and Bacterial Community in the Reactor

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 599 ◽  
Author(s):  
Amit Kumar Maharjan ◽  
Tatsuru Kamei ◽  
Iswar Man Amatya ◽  
Kazuhiro Mori ◽  
Futaba Kazama ◽  
...  
Keyword(s):  
Atmospheric Oxygen ◽  
Low Cost ◽  
Ammonium Nitrogen ◽  
Nitrogen Transformation ◽  
Contaminated Groundwater ◽  
Nylon Thread ◽  
N Removal ◽  
Functional Bacteria ◽  
Synthetic Groundwater

A dropping nitrification reactor was proposed as a low-cost and energy-saving option for the removal of NH4+-N from contaminated groundwater. The objectives of this study were to investigate NH4+-N removal performance and the nitrogen removal pathway and to characterize the microbial communities in the reactor. Polyolefin sponge cubes (10 mm × 10 mm × 10 mm) were connected diagonally in a nylon thread to produce 1 m long dropping nitrification units. Synthetic groundwater containing 50 mg L−1 NH4+-N was added from the top of the hanging units at a flow rate of 4.32 L day−1 for 56 days. Nitrogen-oxidizing microorganisms in the reactor removed 50.8–68.7% of the NH4+-N in the groundwater, which was aerated with atmospheric oxygen as it flowed downwards through the sponge units. Nitrogen transformation and the functional bacteria contributing to it were stratified in the sponge units. Nitrosomonadales-like AOB predominated and transformed NH4+-N to NO2−-N in the upper part of the reactor. Nitrospirales-like NOB predominated and transformed NO2−-N to NO3−-N in the lower part of the reactor. The dropping nitrification reactor could be a promising technology for oxidizing NH4+-N in groundwater and other similar contaminated wastewaters.

Optimum backwashing conditions and ammonium-nitrogen treatment efficiency of iron oxide modified sands coated in biofilm

2015 ◽  
Vol 16 (2) ◽  
pp. 418-427
Author(s):  
Dongmei Li ◽  
Jieman Lin ◽  
Yizhi Wang ◽  
Wen Zhang ◽  
Shaoxiu Li
Keyword(s):  
Iron Oxide ◽  
Removal Rate ◽  
Ammonium Nitrogen ◽  
Head Loss ◽  
Absorption Capacity ◽  
Morphological Properties ◽  
Treatment Efficiency ◽  
N Removal ◽  
Quartz Sands ◽  
Nitrogen Treatment

In this study, iron oxide modified sands with nano-pores (IOMSNP) were enveloped in biofilm (B-IOMSNP) in order to treat the ammonium-nitrogen (NH4+-N) in micro-polluted raw water. The biomass, optimum backwashing conditions, treatment efficiency, and surface morphological properties of the B-IOMSNP were investigated via bio-filtration experiments. The raw quartz sands (RQS) and IOMSNP exhibited biomass levels of 24.32 nmol-P/(g-sand) and 83.71 nmol-P/(g-sand), respectively. The B-IOMSNP filter exhibited a lower swelling ratio, smaller initial head loss, and longer filtration period when water and air were used alternately for backwashing rather than water alone. In addition, the B-IOMSNP was most effective when air alone (at a strength of qair,I = 7 L/(s·m2) for tair,I = 6 min), a combination of air and water (at strengths of qair,II = 7 L/(s·m2) and qwater,II = 5 L/(s·m2) for tair-water,II = 6 min, respectively), and water alone (at a strength of qwater,III = 7 L/(s·m2) for twater,III = 4 min) were used alternately for flushing. The results indicated that the proposed B-IOMSNP could efficiently resist the shock induced by high NH4+-N concentrations (4 mg/L). The ripening period of the B-IOMSNP column was equal to 30 minutes. Furthermore, the B-IOMSNP reduced the turbidity of the water to values of less than 0.2 NTU for 72 hours and exhibited an NH4+-N removal rate of up to 96% and a head loss of 132 cm. In contrast, the biofilm-coated RQS exhibited an NH4+-N removal rate varying from 60% to 82%, a filtration period of 16 hours, and a terminal head loss of 58 cm. Due to its nano-pores and rough surface, the IOMSNP exhibited a specific surface area 39 times greater than that of the RQS, resulting in a higher filtration performance and absorption capacity.

Nitrate removal from aquaculture effluents using woodchip bioreactors improved by adding sulfur granules and crushed seashells

2018 ◽  
Vol 77 (9) ◽  
pp. 2301-2310 ◽  
Author(s):  
Mathis von Ahnen ◽  
Per Bovbjerg Pedersen ◽  
Johanne Dalsgaard
Keyword(s):  
Removal Rate ◽  
Nitrate Removal ◽  
Response Surfaces ◽  
Reactor Performance ◽  
Total N ◽  
Mixture Ratio ◽  
Aquaculture Effluents ◽  
N Removal ◽  
Sulfur Granules ◽  
Central Composite

Abstract This study examined the effects on nitrate removal when adding sulfur granules and crushed seashells to a woodchip bioreactor treating aquaculture effluents. Using a central composite design, the two components were added at three levels (0.000, 0.125 and 0.250 m3/m3 bioreactor volume) to 13 laboratory-scale woodchip bioreactors, and a response surface method was applied to find and model the optimal mixture ratios with respect to reactor performance. Adding 0.125 m3/m3 sulfur granules improved the total N removal rate from 3.27 ± 0.38 to 8.12 ± 0.49 g N/m3/d compared to pure woodchips. Furthermore, the inclusion of crushed seashells together with sulfur granules helped to maintain the pH above 7.4 and prevent a production (i.e., release) of nitrite. According to the modeled response surfaces, a sulfur granule:crushed seashell:woodchip mixture ratio containing about 0.2 m3 sulfur granules and 0.1 m3 crushed seashells per m3 reactor volume would give the best results with respect to high N removal and minimal nitrite release. In conclusion, the study showed that N removal in woodchip bioreactors may be improved by adding sulfur granules and seashells, contributing to the optimization of woodchip performance in treating aquaculture effluents.

scholarly journals Influence of Particle Size of River Sand on the Decontamination Process in the Slow Sand Filter Treatment of Micro-Polluted Water

Water ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 100
Author(s):  
Xuemei Ji ◽  
Cui Zhao ◽  
Yufeng Lv ◽  
Jifu Yang ◽  
Bin Li
Keyword(s):  
Particle Size ◽  
Rural Areas ◽  
Size Range ◽  
Removal Rate ◽  
Polluted Water ◽  
Adsorption Model ◽  
Particle Size Range ◽  
River Sand ◽  
Term Operation ◽  
N Removal

Slow sand filters (SSFs) have been widely used in the construction of water plants in rural areas. It is necessary to find river sand of suitable particle size to improve SSF treatment of micro-polluted water so as to ensure the effective and long-term operation of these plants. In this study, SSF1# (particle size of 0.1–0.5 mm), SSF2# (particle size of 0.5–1 mm), and SSF3# (particle size of 1–1.5 mm) were selected. The physical absorption, CODMn and NH4+-N removal effect, and microbial community were analyzed. According to Langmuir and Freundlich adsorption model fitting, the smaller the particle size of the river sand, the more pollutants are adsorbed under the same conditions. SSF1# has the shortest membrane-forming time, highest CODMn and NH4+-N removal rate, and highest Shannon estimator, indicating that there are more abundant microbial species in the biofilm. Mesorhizobium, Pannonibacter, Pseudoxanthomonas, Aquabacterium, Devosia, and other bacteria have different proportions in each system, each forming its own stable biological chain system. The effluent quality of the three SSFs can meet drinking water standards. However, river sand with a particle size range of 0.1–0.5 mm is easily blocked, and thus the recommended size range for SSF is 0.5–1 mm.

Environmental Degradation of Tire-Wear Particles

1980 ◽  
Vol 53 (4) ◽  
pp. 903-914 ◽  
Author(s):  
S. H. Cadle ◽  
R. L. Williams
Keyword(s):  
Environmental Degradation ◽  
Removal Rate ◽  
Atmospheric Oxygen ◽  
Oxidative Degradation ◽  
Total Carbon ◽  
Water Runoff ◽  
Wear Particles ◽  
Total Removal ◽  
Total Carbon Content ◽  
Tire Wear

Abstract Each of the three analysis methods contributes to an understanding of the degradation processes which occur in environmentally exposed tire-wear particles. Extraction-pyrolysis-GC is the most reliable method since it treats the whole sample rather than a few particles. In 16 months, 52% of the polymer in tread-wear particulate was degraded in soil samples. In glass beads, only 36% of the polymer in tread-wear particulate degraded, perhaps because soil microorganisms were not available to degrade sulfur linkages in the vulcanized portion of the polymer. Fresh tread particles of the same size showed no degradation. The pyrolysis-GC results showed wider scatter, presumably because only a few rubber particles could be analyzed and all the particles did not degrade at the same rate. However, this method showed that the unsaturated bonds of polybutadiene undergo oxidative degradation more rapidly than do the aromatic bonds of styrene units. These results strongly suggest that one important mode of degradation of tread-wear paniculate is atmospheric oxidation. The TGA results showed that biodegradation did not reduce the total carbon content of the tread-wear particulate in this 16-month study. However, more than half of the extender oil was oxidized sufficiently to increase its vaporization temperature to the polymer temperature range. Biooxidation may have detoxified some of the polynuclear aromatic hydrocarbon portion of the oil. Overall, these results suggest that microbial attack of tread-wear particulate is less significant than attack by-atmospheric oxygen. To match the amount of rubber observed at the California freeway site, the removal rate by all mechanisms must be 0.67% per day. For this high removal rate, the amount of rubber at the roadside would reach a steady-state value within the first two years of a freeway's use at a level equivalent to five months of tire-wear. The rate of environmental degradation found in this study is 0.15 per day, or 22% of the total removal rate found in the California study. Wind erosion and water runoff probably also contribute to the total removal rate. Most importantly, we have shown that tread-wear particles degrade at a faster rate than tread-rubber itself, and that environmental degradation plays an important role in the fate of tire-wear particulate.

Transport of soluble organic and inorganic carbon in sandy soils under nitrogen fertilization

1999 ◽  
Vol 79 (2) ◽  
pp. 303-310 ◽  
Author(s):  
F. L. Wang ◽  
A. K. Alva
Keyword(s):  
Nitrogen Fertilization ◽  
Inorganic Carbon ◽  
Average Rate ◽  
Sandy Soils ◽  
Water Soluble ◽  
Total Carbon ◽  
Total Carbon Content ◽  
Water Soluble Organic Carbon ◽  
Isobutylidene Diurea ◽  
Leaching Condition

Leaching of water soluble soil carbon plays an important role in downward transport of soil nutrients and pollutants and may be influenced by soil and management factors. We examined the leaching of water soluble carbon from two sandy soils under nitrogen fertilization by adapting an intermittent leaching-incubation technique using packed soil columns (94 × 10 cm). After 30 d, cumulative amounts of water-soluble organic carbon (SOC) leached from the Candler and Wabasso sand for various treatments in mg C column−1 were: 77 and 302 (NH4NO3), 64 and 265 (control), and 45 and 239 (isobutylidene diurea, IBDU), respectively. The IBDU and NH4NO3 treatments increased the leaching of water-soluble inorganic carbon (SIC), which ranged from 2 to 38 mg C column−1 over 30 d. At the end of eight cycles of leaching/incubation, the total carbon content increased at depth (control and NH4NO3 treatment) in the Candler sand, but decreased in the Wabasso sand. In the first leaching event, the average rate of SOC leaching from the Wabasso sand was 26 mg C column−1 d−1 which dropped rapidly to about 5 mg C column−1 d−1 towards the end of the experiment. The rate of SOC leaching from the Candler sand was much lower (<8 mg C column−1 d−1) than the rate of SOC leaching from the Wabasso sand. Compared with the unamended treatments, application of NH4NO3 increased and IBDU decreased the leaching of SOC in both soils. These effects of N application were considerable during the initial two to three leaching events only. Our results suggest that the initial rainfalls that follow a dry period may be critical for transporting SOC from the upper layer of these sandy soils. Key words: C leaching, sandy soil, intermittent leaching condition, isobutylidene

scholarly journals Characteristics of Liparis loeselii (L.) Rich. populations in selected Natura 2000 areas in eastern Poland

2020 ◽  
Vol 55 (3) ◽  
pp. 151-162
Author(s):  
Danuta Urban ◽  
Joanna Sender ◽  
Ewelina Tokarz ◽  
Andrzej Różycki
Keyword(s):  
Natura 2000 ◽  
Total Carbon ◽  
Habitat Conditions ◽  
Total Carbon Content ◽  
Poor Fen ◽  
Calcareous Fen ◽  
Liparis Loeselii ◽  
The Individual ◽  
Insight Into

AbstractIn view of the sensitivity of Liparis loeselii to changes in habitat conditions, we carried out a study with the aim to monitor population numbers, identify the individual features of the Liparis loeselii population, analyse habitat conditions, identify threats and propose conservation measures to preserve the species. The investigations were conducted in seven unmanaged objects located in three Natura 2000 areas in eastern Poland. The results of this study provide a new insight into Liparis loeselii ecology. The analysed populations inhabited some habitat types: extremely poor fen, transitional mire, rich fen, calcareous fen, spring-fed fen. The content of nutrients was similar in all the habitats. A CCA analysis revealed that the total carbon content, pH, and redox potential of the substrate determine differences between the habitats analysed. Juvenile individuals represented a maximum of 12% of the analysed populations and were the least abundant group of these plants. The flowering was primarily influenced by hydrological conditions. Based on the long-term observations reported in this article, it can be assumed that the species stands a chance of surviving at the localities analysed, provided that the habitat conditions do not change dramatically.

scholarly journals Archaeal ammonia oxidizers respond to soil factors at smaller spatial scales than the overall archaeal community does in a high Arctic polar oasis

2016 ◽  
Vol 62 (6) ◽  
pp. 485-491 ◽  
Author(s):  
Samiran Banerjee ◽  
Nabla Kennedy ◽  
Alan E. Richardson ◽  
Keith N. Egger ◽  
Steven D. Siciliano
Keyword(s):  
Community Structure ◽  
Spatial Scales ◽  
Archaeal Community ◽  
Diversity Indices ◽  
High Arctic ◽  
Total Carbon ◽  
Spatial Dependency ◽  
Edaphic Factors ◽  
Total Carbon Content ◽  
Arctic Soils

Archaea are ubiquitous and highly abundant in Arctic soils. Because of their oligotrophic nature, archaea play an important role in biogeochemical processes in nutrient-limited Arctic soils. With the existing knowledge of high archaeal abundance and functional potential in Arctic soils, this study employed terminal restriction fragment length polymorphism (t-RFLP) profiling and geostatistical analysis to explore spatial dependency and edaphic determinants of the overall archaeal (ARC) and ammonia-oxidizing archaeal (AOA) communities in a high Arctic polar oasis soil. ARC communities were spatially dependent at the 2–5 m scale (P < 0.05), whereas AOA communities were dependent at the ∼1 m scale (P < 0.0001). Soil moisture, pH, and total carbon content were key edaphic factors driving both the ARC and AOA community structure. However, AOA evenness had simultaneous correlations with dissolved organic nitrogen and mineral nitrogen, indicating a possible niche differentiation for AOA in which dry mineral and wet organic soil microsites support different AOA genotypes. Richness, evenness, and diversity indices of both ARC and AOA communities showed high spatial dependency along the landscape and resembled scaling of edaphic factors. The spatial link between archaeal community structure and soil resources found in this study has implications for predictive understanding of archaea-driven processes in polar oases.

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