Nitrate removal by an ultra-compact biofilm reactor

2000 ◽  
Vol 42 (3-4) ◽  
pp. 181-186 ◽  
Author(s):  
S.L. Ong ◽  
W.J. Ng ◽  
L.Y. Lee ◽  
J. Yu ◽  
J. Y. Hu
Keyword(s):  
Conversion Rate ◽  
Nitrate Removal ◽  
Biomass Concentration ◽  
Growth Yield ◽  
Biofilm Reactor ◽  
Yield Coefficient ◽  
Nitrate N ◽  
Density And Biomass ◽  
Stage 1 ◽  
Two Stages

This study consisted of two stages. The first stage was to cultivate denitrifying biofilm with a simplified UCBR while the second stage was to investigate the performance of a standard UCBR for nitrate removal. The volumetric nitrate-N conversion rate increased steadily from less than 0.5 kg/m3.d to about 2.5 kg/m3.d towards the end of Stage 1. Reactor instability and poor biofilm morphology had led to a relatively low nitrate-N conversion rate during stage 1 of operation. In Stage 2, the conversion rate increased rapidly to 6.5 kg/m3.d within 4 days and increased steadily to 10.5 kg/m3.d, thereafter. The biofilm formation in Stage 2 was better than that attained in Stage 1. Biofilm density and biomass concentration in the reactor were in the range of 20.5 to 29.0 g/L and 1 to 3 g/L, respectively. The specific growth rate of the denitrifiers (μ) and the observed biomass growth yield coefficient (Yobs) in the reactor varied within the ranges of 1.5-4.2 d-1 and 0.20-0.65 g biomass/g nitrate-N, respectively. The specific nitrate-N conversion rate (γ) was within the range of 1.8-3.8 g nitrate-N/g biomass.d.

scholarly journals Performance of an autotrophic denitrification process with mixed electron donors and a functional microbial community

2018 ◽  
Vol 19 (2) ◽  
pp. 434-443 ◽  
Author(s):  
Xianxin Luo ◽  
Junfeng Su ◽  
Han Liu ◽  
Tinglin Huang ◽  
Li Wei ◽  
...  
Keyword(s):  
High Throughput Sequencing ◽  
Accumulation Rate ◽  
Nitrate Removal ◽  
Biofilm Reactor ◽  
Electron Donors ◽  
Molar Ratio ◽  
Groundwater Treatment ◽  
N Accumulation ◽  
Nitrate N ◽  
N Removal

Abstract A moving bed biofilm reactor (MBBR) using Mn(II) and Fe(II) as mixed electron donors was designed for nitrate removal. The optimal state, as determined by response surface methodology, was an Fe(II):Mn(II) molar ratio of 0.62, electron donor:electron acceptor molar ratio of 2.62 and hydraulic retention time of 10.88 h. Subsequently, the MBBR was applied to groundwater treatment and demonstrated a final nitrate-N removal efficiency of 99.5% with a nitrite-N accumulation rate of 0.0706 mg-N·L−1·h−1. Furthermore, high-throughput sequencing was employed to characterize bacterial communities in the MBBR. Results showed that the genera of Pseudomonas and Acinetobacter may make a contribution to the nitrate removal.

scholarly journals Effect of 2CaO·SiO2 particles addition on dephosphorization behavior

2020 ◽  
Vol 39 (1) ◽  
pp. 219-227
Author(s):  
Aijun Deng ◽  
Yunjin Xia ◽  
Jie Li ◽  
Dingdong Fan
Keyword(s):  
Liquid Slag ◽  
Solid Phase ◽  
Solid Particles ◽  
Hot Metal ◽  
Liquid Silicate ◽  
Phase Complex ◽  
Dephosphorization Slag ◽  
Stage 1 ◽  
Two Stages ◽  
Complex Liquid

AbstractThe effect of the addition of 2CaO·SiO2 solid particles on dephosphorization behavior in carbon-saturated hot metal was investigated. The research results showed that the addition of 2CaO·SiO2 particles have little influence on desilication and demanganization, and the removal of [Si] and [Mn] occurred in the first 5 min with different conditions where the contents of 2CaO·SiO2 particles addition for the conditions 1, 2, 3, 4, and 5 are 0, 2.2, 6.4, 8.6, and 13.0 g, respectively. The final dephosphorization ratios for the conditions 1, 2, 3, 4, and 5 are 61.2%, 66.9%, 79.6%, 63.0%, and 78.1%, respectively. The dephosphorization ratio decreases with the increase of 2CaO·SiO2 particles in the first 3 min. The reason for this is that the dephosphorization process between hot metal and slag containing C2S phase consisted of two stages: Stage 1, [P] transfers from hot metal to liquid slag and Stage 2, the dephosphorization production (3CaO·P2O5) in liquid slag reacts with 2CaO·SiO2 to form C2S–C3P solid solution. The increase of 2CaO·SiO2 particles increases the viscosity of slag and weakens the dephosphorization ability of the stage 1. The SEM and XRD analyses show that the phase of dephosphorization slag with the addition of different 2CaO·SiO2 particles is composed of white RO phase, complex liquid silicate phase, and black solid phase (C2S or C2S–C3P). Because the contents of C2S–C3P and 2CaO·SiO2 in slag and the dephosphorization ability of the two stages are different, the dephosphorization ability with different conditions is different.

Determination of the Maintenance Requirements of Activated Sludge

1993 ◽  
Vol 28 (7) ◽  
pp. 139-142 ◽  
Author(s):  
J. Chang ◽  
P. Chudoba ◽  
B. Capdeville
Keyword(s):  
Wastewater Treatment ◽  
Process Development ◽  
Biomass Concentration ◽  
Growth Yield ◽  
Kinetic Studies ◽  
Initial Biomass Concentration ◽  
Aerobic Wastewater Treatment ◽  
Initial Substrate ◽  
Maintenance Requirements ◽  
The Cost

Maintenance energy plays an important role both in basic kinetic studies and in process development. Numerous studies have been devoted to the maintenance concept in various microbial fields but very few in biological wastewater treatment. Using a fermenter coupled to a mass spectrometer, we investigated the influence of the ratio So/Xo (ratio between initial substrate concentration and initial biomass concentration) on the observed sludge growth yield of an oxic-settling anaerobic (OSA) system. By measuring the substrate removed, the oxygen consumed and the carbon dioxide produced, we were able to estimate the substrate fraction used for maintenance purposes. The results indicate that at a high So/Xo ratio, a greater proportion of the substrate is devoted to maintenance thus significantly decreasing the observed growth yield. These findings are of particular importance in view of the cost associated with the disposal of excess sludge in aerobic wastewater treatment processes.

scholarly journals Archaeological studies In theIlmeny state reserve, South Urals

2020 ◽  
pp. 112-122
Author(s):  
V.S. Mosin
Keyword(s):  
Bronze Age ◽  
Iron Age ◽  
Early Iron Age ◽  
South Urals ◽  
Stone Age ◽  
Stage 1 ◽  
Two Stages

The paper describes two stages of archeological studies at the territory of the Ilmeny State Reserve. Stage 1 is related to expedition of L.Ya. Krizhevskaya in 1961–1970, which resulted in fn-ding of more than 40 settlements and sites of the Stone Age, Bronze Age and Early Iron Age. Seven settlements were excavated. Stage 2 studies began in 2010 and are continued at present. These works allowed us to fnd about 40 sites and settlements of the Stone Age and to excavate of the Stone Age sites and Bronze Ages burials.

scholarly journals Apical Debris Extrusion by Adaptive Root Canal Instrumentation in Oval Canals: Full-Sequence SAF System vs. the XP-Endo Shaper Plus Sequence

2020 ◽  
Vol 10 (16) ◽  
pp. 5684 ◽  
Author(s):  
Ajinkya M. Pawar ◽  
Bhaggyashri A. Pawar ◽  
Anuj Bhardwaj ◽  
Alexander Maniangat Luke ◽  
Zvi Metzger ◽  
...  
Keyword(s):  
Root Canal ◽  
Significance Level ◽  
Full Sequence ◽  
Apical Extrusion ◽  
Significant Difference ◽  
Group A ◽  
Group B ◽  
Stage 1 ◽  
Two Stages ◽  
Root Canal Instrumentation

Apical extrusion of debris (AED) by the full sequence of the self-adjusting file (SAF) system was compared with that of the XP-endo shaper plus sequence. Sixty permanent mandibular incisors were randomly assigned to two groups (n = 30) for root canal instrumentation: Group A: Stage 1—pre-SAF OS, pre-SAF 1 and pre-SAF 2 files, followed by Stage 2—1.5 mm SAF; and Group B: Stage 1— hand K-file 15/0.02, followed by Stage 2—XP-endo shaper and Stage 3—XP-endo finisher. The AED produced during instrumentation at each stage was collected in pre-weighed Eppendorf tubes. The weights of AED by the two methods were compared using t tests with significance level set at 5%. Group A produced significantly less total AED than Group B (p < 0.001), with no significant difference in debris extrusion between the two stages (p = 0.3014). Conversely, in Group B, a significant difference was noted between Stage 1 and Stages 2 and 3 (p < 0.01), with no significant difference between Stages 2 and 3 (p = 0.488). Both sequences resulted in measurable amounts of AED. Each phase, in either procedure, made its own contribution to the extrusion of debris.

scholarly journals Qualitative Interviewing: Testing Health Surveys Among Vietnam War Veterans at the Age of 70 Years

SAGE Open ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 215824401983269
Author(s):  
April S. Fales ◽  
Yasmin S. Cypel ◽  
Marsha E. Dunn ◽  
Ann L. Truelove ◽  
Erick K. Ishii ◽  
...  
Keyword(s):  
Qualitative Research ◽  
Vietnam War ◽  
Questionnaire Development ◽  
Usability Testing ◽  
Cognitive Interviewing ◽  
Item Recall ◽  
Subject Recruitment ◽  
Vietnam Era ◽  
Stage 1 ◽  
Two Stages

The Vietnam Era Health Retrospective Observational Study (VE-HEROeS) is a nationwide study designed to compare the health of U.S. Vietnam era veterans to age- and sex-matched U.S. residents. Two self-administered mail questionnaires, one for veterans and the other for the U.S. nonmilitary population, were developed using already validated and newly developed items. A pretest was conducted to evaluate item recall and comprehension, new-item response validity, and the overall survey experience (usability of survey materials including the screener questionnaire for nonveterans). Subject recruitment was completed using convenience sampling and a $50 incentive. Cognitive interviewing and usability interviewing, two qualitative research methods, were implemented. Interviews were conducted in two stages (Stage 1, cognitive interviewing, n = 12; Stage 2, usability testing, n = 8) by three experienced methodologists. Concurrent probing techniques, unscripted probes, and retroactive probing were used to elicit response from 14 veterans and six nonveterans (mostly male, White, and aged 65-70 years). Information about the overall survey process was also obtained through observation during usability testing. Results signify that qualitative research is an important part of questionnaire development targeting older veterans due to issues involving comprehension, interpretability, and recall.

Efficient two-stage sequential arrays of proof of concept studies for pharmaceutical portfolios

2020 ◽  
pp. 096228022095817
Author(s):  
Linchen He ◽  
Linqiu Du ◽  
Zoran Antonijevic ◽  
Martin Posch ◽  
Valeriy R Korostyshevskiy ◽  
...  
Keyword(s):  
Cost Effectiveness ◽  
Cost Benefit ◽  
Cost Effective ◽  
Cost Ratio ◽  
Proof Of Concept ◽  
Type Iii ◽  
Benefit Cost Ratio ◽  
Stage 1 ◽  
Two Stages ◽  
Benefit Cost

Previous work has shown that individual randomized “proof-of-concept” (PoC) studies may be designed to maximize cost-effectiveness, subject to an overall PoC budget constraint. Maximizing cost-effectiveness has also been considered for arrays of simultaneously executed PoC studies. Defining Type III error as the opportunity cost of not performing a PoC study, we evaluate the common pharmaceutical practice of allocating PoC study funds in two stages. Stage 1, or the first wave of PoC studies, screens drugs to identify those to be permitted additional PoC studies in Stage 2. We investigate if this strategy significantly improves efficiency, despite slowing development. We quantify the benefit, cost, benefit-cost ratio, and Type III error given the number of Stage 1 PoC studies. Relative to a single stage PoC strategy, significant cost-effective gains are seen when at least one of the drugs has a low probability of success (10%) and especially when there are either few drugs (2) with a large number of indications allowed per drug (10) or a large portfolio of drugs (4). In these cases, the recommended number of Stage 1 PoC studies ranges from 2 to 4, tracking approximately with an inflection point in the minimization curve of Type III error.

scholarly journals Determining Ergonomic Smartphone Forms With High Grip Comfort and Attractive Design

2018 ◽  
Vol 61 (1) ◽  
pp. 90-104 ◽  
Author(s):  
Songil Lee ◽  
Gyouhyung Kyung ◽  
Jihhyeon Yi ◽  
Donghee Choi ◽  
Sungryul Park ◽  
...  
Keyword(s):  
Potential Effect ◽  
Hand Length ◽  
Stage 1 ◽  
Two Stages

Objective: The authors aimed to identify ergonomic smartphone forms by investigating the effects of hand length, four major smartphone dimensions (height, width, thickness, and edge roundness), and smartphone mass on grip comfort and design attractiveness. Background: Despite their potential effect on grip comfort and design attractiveness, the dimensions specified above have never been simultaneously considered in a study investigating smartphone gripping. Method: Seventy-two young individuals participated in a three-stage study. Stage 1 determined the ranges of the four smartphone dimensions suitable for grip comfort and identified the strengths of their influences. Stage 2 investigated the effects of width and thickness (determined to have the greatest influence) on grip comfort and design attractiveness. Mock-ups of varying masses were fabricated using the dimensions determined during the first two stages to investigate the effect of mass on grip comfort and design attractiveness in Stage 3. Results: Phone width was found to significantly influence grip comfort and design attractiveness, and the dimensions of 140 × 65 (or 70) × 8 × 2.5 mm (height × width × thickness × edge roundness) provided high grip comfort and design attractiveness. The selected dimensions were fit with a mass of 122 g, with masses in the range of 106–137 g being comparable. Conclusion: The findings of this study contribute to ergonomic smartphone design developments by specifying dimensions and mass that provide high grip comfort and design attractiveness. Application: The dimensions and mass determined in this study should be considered for improving smartphone design grip comfort and attractiveness.

Denitrification with isopropanol as a carbon source in a biofilm system

1994 ◽  
Vol 30 (11) ◽  
pp. 69-78 ◽  
Author(s):  
Yongwoo Hwang ◽  
Hiroshi Sakuma ◽  
Toshihiro Tanaka
Keyword(s):  
Carbon Source ◽  
Nitrate Removal ◽  
Growth Yield ◽  
Pilot Scale ◽  
Denitrification Rate ◽  
Hydrogen Donor ◽  
Microbial Oxidation ◽  
Biological Denitrification ◽  
Batch Tests

Several batch tests and pilot-scale investigations on biological denitrification with isopropanol were performed. Isopropanol was converted to acetone by microbial oxidation during denitrification. Isopropanol itself little contributed to denitrification in practice while the converted acetone played a role of a main hydrogen donor. A larger quantity of nitrite intermediate was formed by using methanol compared to the case of isopropanol. The measured requirement of isopropanol was 2.0 mg mg−1 NO3-N, and was 2/3 of methanol. The oxygen equivalent of isopropanol for nitrate removal was almost the same as that of methanol. The denitrifier net growth yield for isopropanol was greater than for methanol. In order to maximize the denitrification rate, it is essential to convert isopropanol to acetone rapidly by accurate dosing for nitrogen load because the denitrification rate was accelerated by using acetone only. Excessive dose of isopropanol can cause a decrease in the denitrification rate as well as an increase of BOD in the effluent.

Isolation and Physiological Characterization of Thiothrix sp.

1994 ◽  
Vol 29 (7) ◽  
pp. 261-269 ◽  
Author(s):  
V. Tandoi ◽  
N. Caravaglio ◽  
D. Di Dio Balsamo ◽  
M. Majone ◽  
M. C. Tomei
Keyword(s):  
Growth Yield ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Yield Coefficient ◽  
Simultaneous Presence ◽  
Mixotrophic Growth ◽  
Physiological Characterization ◽  
South Italy ◽  
Mixotrophic Conditions

Thiothrix CT3 was isolated in pure culture by micromanipulation technique. The growth of this microorganism was analyzed in autotrophic, heterotrophic and mixotrophic conditions, in a bicarbonate-containing mineral medium supplemented with thiosulphate and/or acetate. Thiothrix CT3 was able to grow in all the conditions examined: the maximum growth rates estimated were 1.8, 2.5 and 2.5 d−1 respectively. The capacity of this organism to grow autotrophically, as supposed by Winogradsky in 1888, is a strong advantage over the other bacteria present in activated sludge, when sulphides are produced or carried by the sewer. Both the maximum growth rate and growth yield coefficient shown during heterotrophic and mixotrophic growth were comparable, indicating that the simultaneous presence of two substrates (acetate and a reduced sulphur compound) does not give it any particular advantage. The strong presence of Thiothrix spp. in many plants located in South Italy can be explained by the wide nutritional versatility of this filamentous bacterium.

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