scholarly journals Reduction in Nitrogen Exports from Stormflow after Conversion of a Dry Detention Basin to a Stormwater Wetland

2020 ◽  
Vol 10 (24) ◽  
pp. 9024
Author(s):  
Charles P. Humphrey ◽  
Guy Iverson
Keyword(s):  
Urban Runoff ◽  
Control Measures ◽  
Hydraulic Residence Time ◽  
Detention Basin ◽  
Dissolved Nitrogen ◽  
Total Dissolved Nitrogen ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Before And After ◽  
Detention Basins

Stormwater control measures such as dry detention basins and wetlands are often used to reduce the discharge of urban runoff and nutrients to streams, but differences in nutrient treatment may vary between practices. The goal of this study was to compare the nitrogen treatment efficiency of a dry detention basin before and after it was converted into a stormwater wetland. Inflow and outflow from a detention basin in Greenville, North Carolina was sampled during 13 storms and the stormwater wetland was sampled during 10 storms. Total dissolved nitrogen (TDN), NO3−, NH4+, chloride, dissolved organic carbon (DOC), and physicochemical properties were evaluated. Inflow and outflow from the detention basin had identical median concentrations of TDN (0.47 mg L−1). The median TDN concentration for wetland outflow (0.18 mg L−1) was 63% lower relative to inflow (0.49 mg L−1). The hydraulic residence time of stormwater in the wetland was more than 10 times greater relative to the dry basin. There was a significant (p < 0.001) reduction in dissolved oxygen and oxidation reduction potential and an increase in median DOC concentrations in wetland outflow relative to inflow. Most of the reduction in TDN within the wetland was attributed to loss of NO3− (80% reduction), possibly due to denitrification. Conversion of dry detention basins to wetlands may provide significant benefits with regards to reducing TDN transport associated with urban runoff.

scholarly journals Further micro-injection studies on the oxidation-reduction potential of the cell-interior

1926 ◽  
Vol 99 (698) ◽  
pp. 383-397 ◽  
Keyword(s):  
Reduction Potential ◽  
Chemical Properties ◽  
Ion Concentration ◽  
Egg Cell ◽  
Cell Interior ◽  
Hydrogen Ion Concentration ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Physico Chemical ◽  
Before And After

In previous communications on this subject (20, 21, 22) we described the results obtained when coloured indicators of known physico-chemical properties were injected into individual living cells. Using a modification of the micromanipulator of Chambers (4), we have worked with various unicellular protozoa and egg-cells, and have been able to draw definite conclusions as to the average hydrogen-ion concentration and the average oxidation-reduction potential of the cell interior. Our first communication dealt with the amœba, and we showed that its internal p H was probably in the neighbourhood of 7.6, while its internal r H (oxidation-reduction potential, 5) was between 17 and 19. Both values are near neutrality, so that this cell could be said to be slightly alkaline and slightly on the electronegative or reducing side of oxidation-reduction neutrality. We next extended our investigation to several types of marine egg-cells before and after fertilisation, and during the early cleavage stages. The changes which the internal p H and r H undergo during these ontogenetic events are very small indeed, and the phylogenetic differences, for example, as between the ovum of the polychsete worm and that of the starfish are correspondingly slight. The egg-cell, then, appeared to have a of about 6.6 and an r H of the order of 21 or 22. It was therefore a little on the acid side of acidbase neutrality and a little on the electropositive side of oxidation-reduction neutrality, differing on both these counts from the amœba. The amœba, therefore, has a higher intensity of reduction than the egg-cell.

scholarly journals The hydrogen-ion concentration and oxidation-reduction potential of the cell-interior before and after fertilisation and cleavage: A micro-injection study on marine eggs

1926 ◽  
Vol 99 (695) ◽  
pp. 173-199 ◽  
Keyword(s):  
Single Cells ◽  
Biological Data ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Reduction Potentials ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Before And After ◽  
Egg Membrane ◽  
The Moment

In our previous communications on this subject we have described experiments dealing with the micro-injection of indicators into single cells. In the conclusion to our paper (10 a ) on the p H. and r H of the Amœba, we said, “It is hoped that other biological data will soon be available . . . such problems as the . . . oxidation-reduction potentials of egg-cells before and after fertilisation at once present themselves.” The present paper is devoted to these problems. Warburg (17) and Meyerhof (8), and afterwards other workers, observed an enormous increase in the oxygen-consumption of the egg to take place on fertilisation. Shearer (12) found that this occurred at the moment of contact of the spermatozoon with the egg membrane. In view of the fact that the increase was about 2000 per cent., it was clearly a matter of great interest to determine whether the r H changed at the same time. We have attempted to follow the changes in r H by micro-injection experiments and by staining. The two methods failed to give concordant results for reasons which are discussed in the text.

Rainfall Data for the Design of Detention Basins

1984 ◽  
Vol 16 (8-9) ◽  
pp. 255-270
Author(s):  
Viktor Arnell
Keyword(s):  
Urban Runoff ◽  
Rainfall Data ◽  
Correct Result ◽  
Detention Basin ◽  
Design Storm ◽  
Local Coefficients ◽  
Detention Basins ◽  
Runoff Model ◽  
Selection Of

This paper decribes the selection of rainfall data for design of detention basins. The use of design storms (the uniform intensity design storm, the Chicago design storm and the Sifalda design storm) were compared with the use of historical storms where the historical storms were assumed to give the most correct result. Historical storms were selected from an 18-year rainfall record and local coefficients were estimated from the same record. Three test catchments were used and detention basins were located at the outlet of each basin. For the runoff simulations were used the CTH-Urban Runoff Model which also includes a detention basin submodel. The results show the importance of the design storms having total volumes that correspond to the volumes of the historical storms. The use of the uniform intensity design storm and the Chicago design storm resulted in underestimated detention basin volumes. The Sifalda design storm caused overestimated basin volumes which can be reduced after an improvement of the storm.

Mercury and lead profiles and burdens in soils of Quebec (Canada) before and after flooding

1995 ◽  
Vol 52 (11) ◽  
pp. 2493-2506 ◽  
Author(s):  
Agnès Grondin ◽  
Marc Lucotte ◽  
Benoit Fortin ◽  
Alfonso Mucci
Keyword(s):  
Reduction Potential ◽  
Atmospheric Transport ◽  
Organic Layer ◽  
Organic C ◽  
Partial Redistribution ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Before And After ◽  
Apparent Decrease ◽  
Poorly Drained Soils

Forest soils and their flooded equivalents were sampled in the Cabonga (southern Quebec) and La Grande (northern Quebec) hydroelectric complexes and analyzed at 1-cm intervals for organic C, N, Fe, Mn, Hg, and Pb. In the La Grande region, thin Cladina sp. podzols and thicker Pleurozium sp. podzols are characterized by lower Hg burdens (2500 and 5100 μg∙m−2, respectively) than the thicker but less dense soils typical of wetter environments (6000 to 8000 μg∙m−2). These differences suggest that a fraction of Hg is leached downslope from uplands (podzols) and partially accumulates in poorly drained soils (wetlands) below. Unlike Pb, Hg showed no apparent decrease in atmospheric transport over 1000 km from south to north, away from the industrialized regions. Upon inundation, the oxidation–reduction potential drops rapidly but there was no noticeable decrease in the organic C burden, with the exception of flooded podzols where the surficial organic layer may undergo erosion. In flooded wetland soils, Hg, Pb, and Fe display a partial redistribution towards the sediment–water interface, but the Hg burdens of these soils remain comparable to those of their unflooded equivalents. In contrast, the surficial erosion of the flooded podzols may represent one pathway for Hg to enter organisms in the reservoir.

Automatic Regulation of Activated Sludge Aeration – Single-Tank Nitrification-Denitrification

1993 ◽  
Vol 28 (10) ◽  
pp. 289-298 ◽  
Author(s):  
F. Lefevre ◽  
J. M. Audic ◽  
B. Bujon
Keyword(s):  
Activated Sludge ◽  
Nitrogen Concentration ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Automatic Regulation ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Before And After ◽  
User Friendly ◽  
Activated Sludge Processes

Several activated sludge processes using intermittent aeration were developed during the last decade to improve nitrogen removal. Timers, oxidation-reduction or oxygen probes are often used to switch aeration on and off at preset times or by upper and lower limits. These regulation systems cannot adjust the oxygen supply to the biological oxygen demand and cannot realize the supply when “requested” by the influent. A new controller/regulator system (OGAR: Optimized manaGement of Aeration by Redox) based on the variation with time of the oxidation reduction potential was developed : EH = f(time). This OGAR system controls the aeration periods and therefore optimizes the nitrification and denitrification reactions in the sludge processes. The operation of the OGAR programmable controller can be summarized by three functions: It is a true diagnostic tool and a decision making aid. Its simple design enables it to be adapted easily to any site and to be highly user-friendly. OGAR was applied to an existing wastewater treatment plant located at Nezel-la-Falaise near Paris (west suburb). Overall performance of the plant before and after implementation of automatic aeration control by OGAR yields the following conclusions:removal of COD was improved by 45 % reduction in COD from 100 mg/l to 55 mg/lammonia nitrogen concentration was reduced from 42 mg.l-1 to 2mg.1-1 and nitrate nitrogen concentration was reduced to less than 5 mg.1-1

scholarly journals Influence of thermal hydrolysis treatment on chemical speciation and bioleaching behavior of heavy metals in the sewage sludge

2020 ◽  
Author(s):  
Jinxin Zheng ◽  
Chunsheng Qiu ◽  
Chenchen Wang ◽  
Jiaqi Zhao ◽  
Dong Wang ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Chemical Speciation ◽  
Ph Value ◽  
Thermal Hydrolysis ◽  
Bcr Method ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Before And After ◽  
Reducible Fraction ◽  
Oxidizable Fraction

Abstract In this study, the transformation of chemical speciation of Cr, Mn, As and Cd in the sewage sludge before and after thermal hydrolysis treatment was investigated using modified BCR method. The effect of thermal hydrolysis treatment and chemical speciation change on the subsequent bioleaching behavior was also researched. The results showed that the concentrations of Cr, Mn, As and Cd in oxidizable fraction decreased in the sludge treated by thermal hydrolysis. Meanwhile, the proportions of Cr, Mn and As in the mobile fractions (acid-soluble/exchangeable and reducible fraction) all decreased, while Cd was concentrated in the sludge treated by thermal hydrolysis. The final pH value of bioleached sludge treated by thermal hydrolysis was lower than that in the bioleached raw sewage sludge. And faster increase of oxidation-reduction potential (ORP) was also found in the bioleaching process of the sludge treated by thermal hydrolysis. The removal percentage of Mn and Cd increased in the bioleached sludge treated by thermal hydrolysis. Thermal hydrolysis treatment can promote the bioleaching to some extent. Furthermore, the environmental risk of Cr, Mn, As and Cd in the bioleached sludge treated by thermal hydrolysis was all alleviated according to risk assessment analysis compared with the bioleached raw sewage sludge.

scholarly journals Reduction in mobility and COVID-19 transmission

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Pierre Nouvellet ◽  
Sangeeta Bhatia ◽  
Anne Cori ◽  
Kylie E. C. Ainslie ◽  
Marc Baguelin ◽  
...  
Keyword(s):  
Predictive Ability ◽  
Control Measures ◽  
Social Distancing ◽  
Beneficial Effects ◽  
Mobility Data ◽  
Strict Control ◽  
Before And After ◽  
Proxy Measure ◽  
Lower Transmission ◽  
The Relationship

AbstractIn response to the COVID-19 pandemic, countries have sought to control SARS-CoV-2 transmission by restricting population movement through social distancing interventions, thus reducing the number of contacts. Mobility data represent an important proxy measure of social distancing, and here, we characterise the relationship between transmission and mobility for 52 countries around the world. Transmission significantly decreased with the initial reduction in mobility in 73% of the countries analysed, but we found evidence of decoupling of transmission and mobility following the relaxation of strict control measures for 80% of countries. For the majority of countries, mobility explained a substantial proportion of the variation in transmissibility (median adjusted R-squared: 48%, interquartile range - IQR - across countries [27–77%]). Where a change in the relationship occurred, predictive ability decreased after the relaxation; from a median adjusted R-squared of 74% (IQR across countries [49–91%]) pre-relaxation, to a median adjusted R-squared of 30% (IQR across countries [12–48%]) post-relaxation. In countries with a clear relationship between mobility and transmission both before and after strict control measures were relaxed, mobility was associated with lower transmission rates after control measures were relaxed indicating that the beneficial effects of ongoing social distancing behaviours were substantial.

scholarly journals Evaluating the effectiveness of measures to control the novel coronavirus disease 2019 in Jilin Province, China

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Qinglong Zhao ◽  
Yao Wang ◽  
Meng Yang ◽  
Meina Li ◽  
Zeyu Zhao ◽  
...  
Keyword(s):  
Prevention And Control ◽  
Good Control ◽  
Asymptomatic Infection ◽  
Jilin Province ◽  
Control Measures ◽  
First Case ◽  
Before And After ◽  
Novel Coronavirus ◽  
Reported Data ◽  
And Control

Abstract Background Based on differences in populations and prevention and control measures, the spread of new coronary pneumonia in different countries and regions also differs. This study aimed to calculate the transmissibility of coronavirus disease 2019 (COVID-19), and to evaluate the effectiveness of measures to control the disease in Jilin Province, China. Methods The data of reported COVID-19 cases were collected, including imported and local cases from Jilin Province as of March 14, 2019. A Susceptible–Exposed–Infectious–Asymptomatic–Recovered/Removed (SEIAR) model was developed to fit the data, and the effective reproduction number (Reff) was calculated at different stages in the province. Finally, the effectiveness of the measures was assessed. Results A total of 97 COVID-19 infections were reported in Jilin Province, among which 45 were imported infections (including one asymptomatic infection) and 52 were local infections (including three asymptomatic infections). The model fit the reported data well (R2 = 0.593, P < 0.001). The Reff of COVID-19 before and after February 1, 2020 was 1.64 and 0.05, respectively. Without the intervention taken on February 1, 2020, the predicted cases would have reached a peak of 177,011 on October 22, 2020 (284 days from the first case). The projected number of cases until the end of the outbreak (on October 9, 2021) would have been 17,129,367, with a total attack rate of 63.66%. Based on the comparison between the predicted incidence of the model and the actual incidence, the comprehensive intervention measures implemented in Jilin Province on February 1 reduced the incidence of cases by 99.99%. Therefore, according to the current measures and implementation efforts, Jilin Province can achieve good control of the virus’s spread. Conclusions COVID-19 has a moderate transmissibility in Jilin Province, China. The interventions implemented in the province had proven effective; increasing social distancing and a rapid response by the prevention and control system will help control the spread of the disease.

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