scholarly journals Effect of C/N Ratio on the Removal of Nitrogen and Microbial Characteristics in the Water Saturated Denitrifying Section of a Two-Stage Constructed Rapid Infiltration System

2018 ◽  
Vol 15 (7) ◽  
pp. 1469 ◽  
Author(s):  
Qinglin Fang ◽  
Wenlai Xu ◽  
Gonghan Xia ◽  
Zhicheng Pan
Keyword(s):  
Extracellular Polymeric Substances ◽  
Oxygen Demand ◽  
Denitrifying Bacteria ◽  
Major Constituent ◽  
Two Stage ◽  
Second Stage ◽  
Microbial Characteristics ◽  
The Mean ◽  
Water Saturated ◽  
Nitrogen Pollutants

The aim of this study was to improve the removal of nitrogen pollutants from artificial sewage by a modeled two-stage constructed rapid infiltration (CRI) system. The C/N ratio of the second stage influent was elevated by addition of glucose. When the C/N ratio was increased to 5, the mean removal efficiency of total nitrogen (TN) reached up to 75.4%. Under this condition, the number of denitrifying bacteria in the permanently submerged denitrifying section (the second stage) was 22 times higher than that in the control experiment without added glucose. Elevation of the C/N ratio resulted in lower concentrations of nitrate and TN in the second stage effluent, without impairment of chemical oxygen demand removal. The concentration of nitrate and TN in effluent decreased as the abundance of denitrifying bacteria increased. Moreover, the bacterial biofilms that had formed in the sand of the second stage container were analyzed. The secretion of extracellular polymeric substances, a major constituent of biofilms, was enhanced as a result of the elevated C/N ratio, which lead to the improved protection of the bacteria and enhanced the removal of pollutants.

A Two-Stage Combination Model for Wind Power Forecasting

2015 ◽  
Vol 737 ◽  
pp. 9-13
Author(s):  
Jun Zhang ◽  
Yuan Hao Wang ◽  
Ying Yi Li ◽  
Feng Guo
Keyword(s):  
Neural Network ◽  
Bp Neural Network ◽  
Wind Farm ◽  
General Trend ◽  
Two Stage ◽  
Combination Model ◽  
Second Stage ◽  
Combination Forecasting ◽  
The Mean ◽  
Power Sequence

With the wind farm data from the southeast coast this paper builds a two-stage combination forecasting model of output power based on data preprocessing which include filling up missing data and pre-decomposition. The first stage is a composite prediction of decomposed power sequence in which a time series and optimized BP neural network predict the general trend and the correlation of various factors respectively. The second stage is BP neural network with its input is the results of first stage. The effectiveness and accuracy of the two-stage combination model are verified by comparing the mean square error of the combination model and other models.

scholarly journals Comparison of estimators in one-phase two-stage Poisson sampling in forest inventories

2012 ◽  
Vol 42 (10) ◽  
pp. 1865-1871 ◽  
Author(s):  
Daniel Mandallaz ◽  
Alexander Massey
Keyword(s):  
Small Area ◽  
Two Stage ◽  
Random Sample Size ◽  
Poisson Sampling ◽  
Second Stage ◽  
Forest Inventories ◽  
Unbiased Estimates ◽  
The Mean ◽  
Concentric Circles ◽  
Better Than

In the context of Poisson sampling, numerous adjustments to classical estimators have been proposed that are intended to compensate for inflated variance due to random sample size. However, such adjustments have never been applied to extensive forest inventories. This work investigates the performances of four estimators for the timber volume in one-phase two-stage forest inventories, where trees in the first stage are selected, at the plot level, by concentric circles or angle-count methods and a subset thereof are selected by Poisson sampling for further measurements to get a better estimation. The original two-stage estimator is the sum of two components: the first is the mean of Horwitz–Thompson estimators using simple volume approximations, based on diameter and species alone, of all first-stage trees in each inventory plot, and the second is the mean of Horwitz–Thompson estimators based on the differences between the simple volume approximations and refined volume determinations based on further diameter and height measurements on the second-stage trees within each inventory plot. This two-stage estimator is particularly useful because it provides unbiased estimates even if the simple prediction model is not correct, which is particularly important for small area estimation. The other three estimators rely on adjustments of the second component of the original estimator that are adapted from estimators proposed in the literature by L.R. Grosenbaugh and C.-E. Särndal. It turns out that these adjustments introduce a negligible bias and that the original simple estimator performs just as well or even better than the new estimators with respect to the variance.

scholarly journals Evidence for a two-stage model of microbial infection

1968 ◽  
Vol 66 (2) ◽  
pp. 273-280 ◽  
Author(s):  
G. G. Meynell ◽  
Joan Maw
Keyword(s):  
Standard Error ◽  
Stage Model ◽  
Microbial Infection ◽  
Two Stage ◽  
Second Stage ◽  
Initial Stage ◽  
The Mean ◽  
Pass Through

SUMMARYColony counts on mice given the same number ofSalmonellaalways differ considerably. However, the standard error of the mean log count does not increase after the first 1·5 hr. of infection until the 8th or 10th day. These infections therefore appear to pass through an initial stage lasting a few hours, in which a varying proportion of the inoculum is killed, followed by a prolonged second stage in which the scatter in individual colony counts remains constant.

scholarly journals Inequitable wages and tax evasion

2020 ◽  
Author(s):  
Linda Dezső ◽  
James Alm ◽  
Erich Kirchler
Keyword(s):  
Tax Evasion ◽  
Tax Compliance ◽  
Lab Experiment ◽  
Two Stage ◽  
Second Stage ◽  
Human Choice ◽  
Income Ratio ◽  
Group Members ◽  
The Mean ◽  
Per Se

In a two-stage, preregistered lab experiment (aspredcited.com #36099), weexamine whether wage inequity has a greater impact on tax compliance and onthe beliefs about prevailing compliance norms among the wronged when it results from intentional human choice versus a random mechanism. Subjects areorganized into groups of six. In the ?the first stage, we perform a wage inequity manipulation by assigning equitable or inequitable wages to subjects as remuneration for a trivial, real-e?ort task. In the second stage, subjects are prompted to report their incomes, of which a certain percent is deducted but not redistributedbetween them. Next, subjects state their incentivized beliefs about the mean ofthe declared-to-true income ratio among their group members. We ?nd that taxcompliance and beliefs about the prevailing compliance norms are eroded whenwage inequity stems from intentional human choice but not when the same wageis randomly chosen. Consequently, it is not the wage inequity per se that reducestax compliance and corrupts beliefs about the norms, but rather the inequity dueto human choice. Our results demonstrate that incidental unfairness in the formof intentional wage inequity adversely spills over onto tax compliance and beliefsabout the prevailing compliance norms. In conclusion, intentional wage inequitycan be harmful for the society as a whole.

scholarly journals Tips and Tricks in surgical reduction of the posterior column of AO/OTA C3 pilon fractures

2022 ◽  
Vol 23 (1) ◽  
Author(s):  
Moran Huang ◽  
Qiuke Wang ◽  
Junjie Guan ◽  
Kexin Liu ◽  
Yunfeng Chen ◽  
...  
Keyword(s):  
Posterior Column ◽  
Posterolateral Approach ◽  
Foot And Ankle ◽  
Two Stage ◽  
Aofas Score ◽  
Second Stage ◽  
Controversial Topic ◽  
The Mean ◽  
Ankle Function ◽  
Pilon Fractures

Abstract Background Accurate posterior column reduction remains a challenging and controversial topic in the management of complex pilon fractures (AO/OTA C3). We aim to report the outcomes of surgical treatment for 22 AO/OTA C3 pilon fracture cases between January 2015 and May 2017 and highlight some traps and tips. Methods Three patients underwent two-stage early plating on the posterior column through a posterolateral approach. The remaining 19 patients were treated with two-stage delayed plating on the posterior column: 11 patients were treated with a posterolateral approach, five patients with a modified posteromedial approach, and three patients with a single anterior approach. The reduction of the posterior column was evaluated according to the Burwell-Charnley’s radiographic criteria, and functional outcomes were assessed using the American Orthopedic Foot and Ankle Society (AOFAS) scores. Results Posterior column malreduction occurred in five cases, including in one case that was re-adjusted immediately and in another case that was re-adjusted during a two-staged delayed operation. According to Burwell-Charnley’s criteria, the satisfactory rate of fracture reduction was 81.8%. After 1 year, the mean AOFAS score was 81.9 (81.9 ± 9.9); the outcome was excellent in three (20.0%), good in nine (60.0%), and fair in three (20.0%). Excellent or good outcomes were noted in 12 patients (80.0%). Conclusions The combined anterior and posterior approach is suggested in the second stage of plating so that the posterior column fragments can be re-adjusted intraoperatively, if necessary. Following these procedures, satisfactory reduction and recovery of good ankle function can be anticipated.

Whey utilization in a two-stage fermentation process

2017 ◽  
Vol 2 (1) ◽  
pp. 17-20 ◽  
Author(s):  
Aladár Vidra ◽  
Áron Németh
Keyword(s):  
Lactic Acid ◽  
Propionic Acid ◽  
Fermentation Process ◽  
Oxygen Demand ◽  
Lactobacillus Species ◽  
Mineral Salts ◽  
Two Stage ◽  
Propionibacterium Acidipropionici ◽  
Second Stage ◽  
Feasible Option

Abstract Whey is a major by-product of the cheese and dairy industry and has valuable nutritional constituents, however poses a major environmental risk if disposed of without prior treatment. The main components of whey except of water are lactose, lactic acid, soluble proteins, lipids, vitamins and mineral salts which give a very high biochemical oxygen demand (BOD) and chemical oxygen demand (COD) load (30,000 - 50,000 ppm and 60.000 - 80,000 ppm, respectively) to the whey. This composition provides adequate nitrogen and carbon source to be utilized by microorganisms. The aim of this study was to examine the whey utilization in a two-stage fermentation process using Lactobacillus species and Propionibacterium acidipropionici. In the first stage Lactobacillus species utilise the main part of the nitrogen source while covert lactose content to lactic acid. In the second stage Propionibacterium acidipropionici utilize lactic acid and produce propionic acid. This two-stage fermentation process can be a feasible option, both for bioremediation of whey and production of propionic acid from waste sources. High lactose conversion (>90%) to lactic acid was achieved at the first stage, but its conversion to propionic acid during the second stage was insufficient (~30%). The COD was successfully decreased during the fermentations.

Treatment of corn ethanol distillery wastewater using two-stage anaerobic digestion

2016 ◽  
Vol 74 (2) ◽  
pp. 431-437 ◽  
Author(s):  
B. Ráduly ◽  
L. Gyenge ◽  
Sz. Szilveszter ◽  
A. Kedves ◽  
S. Crognale
Keyword(s):  
Anaerobic Digestion ◽  
Methane Production ◽  
Oxygen Demand ◽  
Continuous Phase ◽  
Methane Content ◽  
Microbial Consortia ◽  
Two Stage ◽  
Second Stage ◽  
Conversion Rates ◽  
Distillery Wastewater

In this study the mesophilic two-stage anaerobic digestion (AD) of corn bioethanol distillery wastewater is investigated in laboratory-scale reactors. Two-stage AD technology separates the different sub-processes of the AD in two distinct reactors, enabling the use of optimal conditions for the different microbial consortia involved in the different process phases, and thus allowing for higher applicable organic loading rates (OLRs), shorter hydraulic retention times (HRTs) and better conversion rates of the organic matter, as well as higher methane content of the produced biogas. In our experiments the reactors have been operated in semi-continuous phase-separated mode. A specific methane production of 1,092 mL/(L·d) has been reached at an OLR of 6.5 g TCOD/(L·d) (TCOD: total chemical oxygen demand) and a total HRT of 21 days (5.7 days in the first-stage, and 15.3 days in the second-stage reactor). Nonetheless the methane concentration in the second-stage reactor was very high (78.9%); the two-stage AD outperformed the reference single-stage AD (conducted at the same reactor loading rate and retention time) by only a small margin in terms of volumetric methane production rate. This makes questionable whether the higher methane content of the biogas counterbalances the added complexity of the two-stage digestion.

Anaerobic/aerobic biodegradation of pentachlorophenol using GAC fluidized bed reactors: optimization of the empty bed contact time

1997 ◽  
Vol 36 (6-7) ◽  
pp. 107-115 ◽  
Author(s):  
Gregory J. Wilson ◽  
Amid P. Khodadoust ◽  
Makram T. Suidan ◽  
Richard C. Brenner
Keyword(s):  
Fluidized Bed ◽  
Oxygen Demand ◽  
Aerobic Biodegradation ◽  
Fluidized Bed Reactors ◽  
Reactor Performance ◽  
Reactor Operation ◽  
Significant Cost ◽  
Second Stage ◽  
Primary Substrate ◽  
Chlorinated Phenolic Compounds

An integrated reactor system has been developed to remediate pentachlorophenol (PCP) containing wastes using sequential anaerobic and aerobic biodegradation. Anaerobically, PCP was degraded to predominately equimolar concentrations (>99%) of monochlorophenol (MCP) in two GAC fluidized bed reactors at Empty Bed Contact Times (EBCTs) ranging from 18.6 to 1.15 hours. However, at lower EBCTs, MCP concentrations decreased to less than 10% of the influent PCP concentration suggesting mineralization. The optimal EBCT was determined to be 2.3 hours based on PCP conversion to MCPs and stable reactor operation. Decreasing the EBCT fourfold did not inhibit degradation of PCP and its intermediates, thus allowing removal of PCP at much lower detention time and resulting in a significant cost advantage. Analytical grade PCP was fed via syringe pumps into two fluidized bed reactors at influent concentrations of 100 mg/l and 200 mg/l, respectively. Acting as the primary substrate, ethanol was also fed into the reactors at concentrations of 697 and 1388 mg/l. Effluent PCP and chlorinated phenolic compounds were analyzed weekly to evaluate reactor performance. Biodegradation pathways were also identified. 3-chlorophenol (CP) was the predominant MCP and varied simultaneously with 3,5-dichlorophenol (DCP) concentrations. Likewise, 4-CP concentrations varied simultaneously with 3,4-DCP concentrations. A second stage aerobic GAC fluidized bed reactor was added after the anaerobic reactor to completely mineralize the remaining MCP and phenols. Data show no presence of phenol and MCP in the effluent or on the GAC. Overall, the chemical oxygen demand (COD) fed to the system was reduced from 75 g/d in the influent to less than 1.5 g/d in the effluent.

An Enhanced Two Stage MMSE Equalizer for Coded FBMC/OQAM Systems

2019 ◽  
Vol 10 (1) ◽  
pp. 69-82 ◽  
Author(s):  
Mohammad Rizk Assaf ◽  
Abdel-Nasser Assimi
Keyword(s):  
Error Propagation ◽  
Channel Model ◽  
Error Correcting Codes ◽  
Two Stage ◽  
Probability Of Error ◽  
Second Stage ◽  
Different Types ◽  
Mmse Equalizer ◽  
And Performance ◽  
Ici Cancellation

In this article, the authors investigate the enhanced two stage MMSE (TS-MMSE) equalizer in bit-interleaved coded FBMC/OQAM system which gives a tradeoff between complexity and performance, since error correcting codes limits error propagation, so this allows the equalizer to remove not only ICI but also ISI in the second stage. The proposed equalizer has shown less design complexity compared to the other MMSE equalizers. The obtained results show that the probability of error is improved where SNR gain reaches 2 dB measured at BER compared with ICI cancellation for different types of modulation schemes and ITU Vehicular B channel model. Some simulation results are provided to illustrate the effectiveness of the proposed equalizer.

Advanced Treatment of Coking Wastewater by Oxidation Process Using Pyrite and Hydrogen Peroxide

2013 ◽  
Vol 726-731 ◽  
pp. 2521-2525
Author(s):  
Zhi Yong Zhang ◽  
De Li Wu
Keyword(s):  
Hydrogen Peroxide ◽  
Oxidation Process ◽  
Low Cost ◽  
Oxygen Demand ◽  
Utilization Efficiency ◽  
Advanced Treatment ◽  
Coking Wastewater ◽  
Second Stage ◽  
Potential Alternative ◽  
High Utilization

Coking wastewater is a kind of recalcitrant wastewater including complicate compositions. Advanced treatment of coking wastewater by Fenton-Like reaction using pyrite as catalyst was investigated in this paper. The results show that the chemical oxygen demand (COD) of coking wastewater decreased significantly by method of coagulation combined with two-stage oxidation reaction. COD of wastewater can decrease from 250mg/l to 45mg/l after treatment, when 2g/L pyrite was used in each stage oxidation and the dosage of hydrogen peroxide (H2O2) is 0.2ml/l for first stage treatment, 0.1ml/l for second stage treatment respectively. The pyrite is effective to promote Fenton-Like reaction with low cost due to high utilization efficiency of H2O2, moreover, catalyst could be easily recovered and reused. The Fenton-Like reaction might be used as a potential alternative to advanced treatment of recalcitrant wastewater.

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