scholarly journals Influence of dissolved oxygen on nitrification kinetics in a circulating bed reactor

1998 ◽  
Vol 37 (4-5) ◽  
pp. 189-193 ◽  
Author(s):  
V. Lazarova ◽  
R. Nogueira ◽  
J. Manem ◽  
L. Melo
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Municipal Wastewater ◽  
Ammonia Concentration ◽  
Pilot Scale ◽  
Biofilm Reactor ◽  
Laboratory Scale ◽  
Nitrification Rate ◽  
Nitrification Kinetics ◽  
Laboratory Scale Reactor

The influence of dissolved oxygen concentration in nitrification kinetics was studied in a new biofilm reactor, the circulating bed reactor (CBR). The study was carried out partly at laboratory scale with synthetic water containing inorganic carbon and nitrogen compounds, and partly at pilot scale for secondary and tertiary nitrification of municipal wastewater. The experimental results showed that either the ammonia or the oxygen concentration could be limiting for the nitrification rate. The transition from ammonia to oxygen limiting conditions occurred for an oxygen to ammonia concentration ratio of about 1.5 - 2 gO2/gN-NH4+ for both laboratory- and pilot-scale reactors. The nitrification kinetics of the laboratory-scale reactor was close to a half order function of the oxygen concentration, when oxygen was the rate limiting substrate.

Nonlinear and set-point control of the dissolved oxygen concentration in an activated sludge process

1996 ◽  
Vol 34 (3-4) ◽  
pp. 135-142 ◽  
Author(s):  
Carl-Fredrik Lindberg ◽  
Bengt Carlsson
Keyword(s):  
Dissolved Oxygen ◽  
Activated Sludge ◽  
Oxygen Concentration ◽  
Controller Design ◽  
Ammonia Concentration ◽  
Pilot Scale ◽  
Process Efficiency ◽  
Activated Sludge Process ◽  
Dissolved Oxygen Concentration ◽  
Set Point

Control of the dissolved oxygen concentration (DO) in an activated sludge process is of considerable importance because of economy and process efficiency. A strategy for designing a nonlinear DO controller was developed. The basic idea was to take the nonlinear oxygen transfer function into account in the controller design. Simulations illustrated that a nonlinear DO controller outperforms a standard PI controller. This was also confirmed in a pilot-scale plant experiment. A supervision (set-point) controller for the DO is also outlined. Initial simulations showed promising results where the aeration system is used more efficiently and the effluent ammonia concentration could be maintained low.

Effect of Physicochemical Variables on Algal Autoflotation

1992 ◽  
Vol 26 (7-8) ◽  
pp. 1769-1778 ◽  
Author(s):  
S.-I. Lee ◽  
B. Koopman ◽  
E. P. Lincoln
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Retention Time ◽  
Contact Time ◽  
Pilot Scale ◽  
Dissolved Oxygen Concentration ◽  
Physicochemical Variables ◽  
Rise Rate ◽  
Mixing Intensity ◽  
Maximum Rise

Combined chemical flocculation and autoflotation were examined using pilot scale process with chitosan and alum as flocculants. Positive correlation was observed between dissolved oxygen concentration and rise rate. Rise rate depended entirely on the autoflotation parameters: mixing intensity, retention time, and flocculant contact time. Also, rise rate was influenced by the type of flocculant used. The maximum rise rate with alum was observed to be 70 m/h, whereas that with chitosan was approximately 420 m/h. The efficiency of the flocculation-autoflotation process was superior to that of the flocculation-sedimentation process.

Novel biofilm reactor for denitrification of municipal wastewater

2018 ◽  
Vol 78 (7) ◽  
pp. 1566-1575 ◽  
Author(s):  
S. S. Rathnaweera ◽  
B. Rusten ◽  
K. Korczyk ◽  
B. Helland ◽  
E. Rismyhr
Keyword(s):  
Carbon Source ◽  
Municipal Wastewater ◽  
Low Cost ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Biofilm Reactor ◽  
Treated Wastewater ◽  
Removal Rates ◽  
Good Filter ◽  
Solids Removal

Abstract A pilot-scale CFIC® (continuous flow intermittent cleaning) reactor was run in anoxic conditions to study denitrification of wastewater. The CFIC process has already proven its capabilities for biological oxygen demand removal with a small footprint, less energy consumption and low cost. The present study focused on the applicability for denitrification. Both pre-denitrification (pre-DN) and post-denitrification (post-DN) were tested. A mixture of primary treated wastewater and nitrified wastewater was used for pre-DN and nitrified wastewater with ethanol as a carbon source was used for post-DN. The pre-DN process was carbon limited and removal rates of only 0.16 to 0.74 g NOx-N/m²-d were obtained. With post-DN and an external carbon source, 0.68 to 2.2 g NO3-Neq/m²-d removal rates were obtained. The carrier bed functioned as a good filter for both the larger particles coming with influent water and the bio-solids produced in the reactor. Total suspended solids removal in the reactor varied from 20% to 78% (average 45%) during post-DN testing period and 9% to 70% (average 29%) for pre-DN. The results showed that the forward flow washing improves both the DN function and filtration ability of the reactor.

scholarly journals Enhancing Nitrate Removal from Waters with Low Organic Carbon Concentration Using a Bioelectrochemical System—A Pilot-Scale Study

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 516 ◽  
Author(s):  
Rauno Lust ◽  
Jaak Nerut ◽  
Kuno Kasak ◽  
Ülo Mander
Keyword(s):  
Organic Carbon ◽  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Power Efficiency ◽  
Municipal Wastewater ◽  
Nitrate Removal ◽  
Treatment Plant ◽  
Municipal Wastewater Treatment ◽  
Dissolved Oxygen Concentration ◽  
Organic Carbon Concentration

Assessments of groundwater aquifers made around the world show that in many cases, nitrate concentrations exceed the safe drinking water threshold. This study assessed how bioelectrochemical systems could be used to enhance nitrate removal from waters with low organic carbon concentrations. A two-chamber microbial electrosynthesis cell (MES) was constructed and operated for 45 days with inoculum that was taken from a municipal wastewater treatment plant. A study showed that MES can be used to enhance nitrate removal efficiency from 3.66% day−1 in a control reactor to 8.54% day−1 in the MES reactor, if a cathode is able to act as an electron donor for autotrophic denitrifying bacteria or there is reducing oxygen in a cathodic chamber to favor denitrification. In the MES, greenhouse gas emissions were also lower compared to the control. Nitrous oxide average fluxes were −639.59 and −9.15 µg N m−2 h−1 for the MES and control, respectively, and the average carbon dioxide fluxes were −5.28 and 43.80 mg C m−2 h−1, respectively. The current density correlated significantly with the dissolved oxygen concentration, indicating that it is essential to keep the dissolved oxygen concentration in the cathode chamber as low as possible, not only to suppress oxygen’s inhibiting effect on denitrification but also to achieve better power efficiency.

Transformation of Azo Dye AO-7 by Wastewater Biofilms

1992 ◽  
Vol 26 (3-4) ◽  
pp. 627-636 ◽  
Author(s):  
C. Harmer ◽  
P. Bishop
Keyword(s):  
Dissolved Oxygen ◽  
Azo Dye ◽  
Municipal Wastewater ◽  
Bond Cleavage ◽  
Biofilm Reactor ◽  
Cod Removal ◽  
Bulk Phase ◽  
Acid Orange 7 ◽  
Low Dissolved Oxygen ◽  
The Impact

Azo dyes are common contaminants in wastewater. Many are poorly removed by most typical municipal treatment processes. Those which are partially degraded may form toxic intermediates, particularly under anaerobic conditions. Acid Orange 7 (AO-7) is a simple azo dye which is biotransformable. In this study, bulk-phase factors affecting azo bond cleavage of AO-7 in a synthetic municipal wastewater were investigated using lab-scale, rotating drum biofilm reactors. A series of statistically designed experiments were used to characterize the response of the pseudo-steady state biofilms. A variety of microorganisms from the activated sludge seed for the biofilm were found to be capable of transforming the AO-7. Biofilm removals of AO-7 ranged from 18 to 97%. Two maxima of AO-7 transformation rates were found-one at high bulk-phase dissolved oxygen and low COD removal flux, and another at low dissolved oxygen and high COD flux. No 1-amino 2-naphthol intermediate was detected. The sulfanilic acid intermediate was present at low dissolved oxygen levels. Suspended-phase COD removal was inhibited by AO-7, but the effect was not detected in the biofilm reactor system. AO-7 transformation and biological nitrification interact, but the impact is small.

scholarly journals Polishing of Chemical Oxygen Demand (COD) Using Moving Bed Bio-Reactor

2015 ◽  
Vol 773-774 ◽  
pp. 1281-1285
Author(s):  
Jamal Ali Kawan ◽  
Rakmi Abd-Rahman ◽  
Othman bin Jaafar ◽  
Fatihah Suja
Keyword(s):  
Chemical Oxygen Demand ◽  
Municipal Wastewater ◽  
Removal Rate ◽  
Research Work ◽  
Real Life ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Biofilm Reactor ◽  
Moving Bed ◽  
Building Engineering

The pilot-scale experiment in moving bed biofilm reactor (MBBR) with a capacity of 433 L was carried out for this study with real life situations, it was decided that the complete research work must be done under as realistic conditions as possible,i.e.with real municipal wastewater, chemical free and with local commercially available products such as carriers for biofilm reactor. The reactor was start-up in 30/9/2013 up to date, Effluent from clarifier of STP used as influence of MBBR for polishing. MBBR is using continues down flow to polish effluent municipal wastewater from a faculty of new building engineering community in UKM to get the water free from main pollutant parameters, for reuse in the irrigation or discharge to the river. Laboratory experiments will conduct with different hydraulic retention time (HRT), filling ratio of plastic (Enviro Multi Media) in the MBBR about 5%. Aerobic reactors used the majority of the decaying organic material. An average removal rate of 41.75%, 32.85%, 24.80% and 35.77% of initial chemical oxygen demand (COD) were achieved under a HRT of 24hr, 12hr, 6hr and 2hr, respectively. The model simulated results showed good agreements with experimental results. The model could be employed in the design of a full-scale MBBR process for simultaneous removal of organic carbon from effluent STP.

A pilot-scale study on PVA gel beads based integrated fixed film activated sludge (IFAS) plant for municipal wastewater treatment

2015 ◽  
Vol 73 (1) ◽  
pp. 113-123 ◽  
Author(s):  
Nitin Kumar Singh ◽  
Jasdeep Singh ◽  
Aakansha Bhatia ◽  
A. A. Kazmi
Keyword(s):  
Activated Sludge ◽  
Pilot Plant ◽  
Municipal Wastewater ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Biofilm Reactor ◽  
16S Rrna Genes ◽  
Volume Index ◽  
Rrna Genes ◽  
Gel Beads

In the present study, a pilot-scale reactor incorporating polyvinyl alcohol gel beads as biomass carrier and operating in biological activated sludge mode (a combination of moving bed biofilm reactor (MBBR) and activated sludge) was investigated for the treatment of actual municipal wastewater. The results, during a monitoring period of 4 months, showed effective removal of chemical oxygen demand (COD), biological oxygen demand (BOD) and NH3-N at optimum conditions with 91%, ∼92% and ∼90% removal efficiencies, respectively. Sludge volume index (SVI) values of activated sludge varied in the range of 25–72 mL/g, indicating appreciable settling characteristics. Furthermore, soluble COD and BOD in the effluent of the pilot plant were reduced to levels well below discharge limits of the Punjab Pollution Control Board, India. A culture dependent method was used to enrich and isolate abundant heterotrophic bacteria in activated sludge. In addition to this, 16S rRNA genes analysis was performed to identify diverse dominant bacterial species in suspended and attached biomass. Results revealed that Escherichia coli, Pseudomonas sp. and Nitrosomonas communis played a significant role in biomass carrier, while Acinetobactor sp. were dominant in activated sludge of the pilot plant. Identification of ciliated protozoa populations rendered six species of ciliates in the plant, among which Vorticella was the most dominant.

Adaptive predictive control of dissolved oxygen concentration in a laboratory-scale bioreactor

1995 ◽  
Vol 43 (1) ◽  
pp. 21-32 ◽  
Author(s):  
Constantino Diaz ◽  
Pierre Dieu ◽  
Claude Feuillerat ◽  
Philippe Lelong ◽  
Marc Salome
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Predictive Control ◽  
Laboratory Scale ◽  
Dissolved Oxygen Concentration ◽  
Adaptive Predictive Control

scholarly journals La Alcalinidad Y La Nitrificación En Una Laguna Aireada A Escala Piloto

2016 ◽  
Vol 12 (36) ◽  
pp. 89
Author(s):  
Agustín Leiva Pérez ◽  
Edison Macías Andrade ◽  
Joffre A. Andrade Candell ◽  
Ana M. Aveiga Ortiz ◽  
Sergio S. Alcívar Pinargote
Keyword(s):  
Calcium Carbonate ◽  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Ammonium Phosphate ◽  
Pilot Scale ◽  
Process Efficiency ◽  
Dissolved Oxygen Concentration ◽  
Initial Concentration ◽  
Nitrification Process ◽  
The Relationship

It was studied the relationship among means alkalinity concentration as calcium carbonate, and the nitrification process in an aerated oxidation lagoon in batch and pilot scale (1,72 m3 as total volume and 1,46 m3 as effective one) working on a residual synthetic liquid, elaborated with base in sucrose, sulfate and ammonium phosphate. The results demonstrated that when being increased the initial alkalinity in the range from 120 to 360 mg CaCO3/dm3, the nitrification process efficiency increased significantly until the surroundings of the 86%, decreasing when being this with smaller and bigger values that said range. The dissolved oxygen concentration stayed around 4,3 mg/dm3, belonging together with the aerobic character of the microorganisms for nitrification (Nitrosomona and Nitrobacter). The initial concentration of total nitrogen in each one of the 14 processes batch was 38 mg/dm3 and the same one went down to minimum values around 4,56 mg/dm3.

scholarly journals High-Rate Nitrification at Low pH in Suspended- and Attached-Biomass Reactors

2004 ◽  
Vol 70 (11) ◽  
pp. 6481-6487 ◽  
Author(s):  
Sheldon Tarre ◽  
Michal Green
Keyword(s):  
Ammonia Concentration ◽  
Low Ph ◽  
Biofilm Reactor ◽  
High Rate ◽  
Ammonium Uptake ◽  
Nitrifying Bacteria ◽  
Nitrification Rate ◽  
Uptake System ◽  
Chemolithotrophic Bacteria ◽  
Suspended Biomass

ABSTRACT This article reports on high-rate nitrification at low pH in biofilm and suspended-biomass reactors by known chemolithotrophic bacteria. In the biofilm reactor, at low pH (4.3 � 0.1) and low bulk ammonium concentrations (9.3 � 3.3 mg � liter−1), a very high nitrification rate of 5.6 g of N oxidized � liter−1 � day−1 was achieved. The specific nitrification rate (0.55 g of N � g of biomass−1 � day−1) was similar to values reported for nitrifying reactors at optimal pH. In the suspended-biomass reactor, the average pH was significantly lower than that in the biofilm reactor (pH 3.8 � 0.3), and values as low as pH 3.2 were found. In addition, measurements in the suspended-biomass reactor, using isotope-labeled ammonium (15N), showed that in spite of the very low pH, biomass growth occurred with a yield of 0.1 g of biomass � g of N oxidized−1. Fluorescence in situ hybridization using existing rRNA-targeted oligonucleotide probes showed that the nitrifying bacteria were from the monophyletic genus Nitrosomonas, suggesting that autotrophic nitrification at low pH is more widespread than previously thought. The results presented in this paper clearly show that autotrophic nitrifying bacteria have the ability to nitrify at a high rate at low pH and in the presence of only a negligible free ammonia concentration, suggesting the presence of an efficient ammonium uptake system and the means to cope with low pH.

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