scholarly journals CASE STUDY ON NITRIFICATION RATES IN A NON-STIRRED MEMBRANE-AERATED BIOFILM REACTOR OPERATED UNDER LAMINAR REGIME

2018 ◽  
pp. 193-201
Author(s):  
Judith Molina-Burgos ◽  
Juan A. Jácome-Burgos ◽  
Joaquín Suárez-López
Keyword(s):  
Oxygen Transfer ◽  
Control Method ◽  
Oxygen Transfer Rate ◽  
Conductivity Measurement ◽  
Biofilm Reactor ◽  
Synthetic Wastewater ◽  
Ammonium Concentration ◽  
Significant Drop ◽  
Ammonium Removal

A lab-scale non-stirred membrane-aerated biofilm reactor with a volume of 14.2 L was operated under laminar flow regime with inorganic synthetic wastewater to assess tertiary nitrification rates. Nitrifying counter-diffusive biofilm grown over microporous polypropylene tubular membranes supplied with atmospheric air at low pressure (3.45 kPa). The reactor was operated at very low water-velocities (in cm/s): from 2.3×10-4 to 2.3 × 10-3. In all runs, the influent ammonium concentration was kept constant ( 26 mg-N/L). By changing the volumetric inflow, the membrane-aerated biofilm (MAB) was tested at seven different ammonium applied loads (range: 0.57 - 6.04 g-N/m2 d). The corresponding ammonium removal rates ranged 0.56 to 3.02 g-N/(m2 d). The percentage of biological ammonium removal presented a range from 50% to 98%. As expected, due to passive experimental dynamic conditions to achieve an ammonium removal percentage greater than 80% a hydraulic retention time of 19 h was required. Clean membrane oxygen transfer rate was evaluated. The nitrifying MAB was found to enhance the oxygen transfer across the membrane when the surface nitrification rates were high. A significant drop in electrical conductivity that is proportional to the ammonium removed was observed. Thus, conductivity measurement can be used as a simple control method of ammonium removal extent. Effluent suspended solids were not detected, therefore a sedimentation process was unnecessary.

Removal of ammonium from aqueous solutions using the residue obtained from struvite pyrogenation

2011 ◽  
Vol 64 (12) ◽  
pp. 2508-2514 ◽  
Author(s):  
Haiming Huang ◽  
Qianwu Song ◽  
Chunlian Xu
Keyword(s):  
Aqueous Solutions ◽  
Experimental Results ◽  
Synthetic Wastewater ◽  
Ammonium Concentration ◽  
Ammonium Removal ◽  
Optimum Ph ◽  
Series Of Experiments ◽  
Release Ratio ◽  
Phosphate Source ◽  
The Cost

This paper reports the results of laboratory studies on the removal of ammonium from aqueous solutions using struvite pyrogenation residues. A series of experiments were conducted to examine the effects of the pyrogenation temperature (90–210 °C) and time (0.5–4 h) on the ammonium release of struvite. In addition, the pyrolysate of struvite produced at different pyrogenation temperatures and times was recycled for ammonium removal from aqueous solutions. The experimental results indicated that the ammonium release ratio of struvite increased with an increase in the pyrogenation temperature and time, and the struvite pyrolysate used as magnesium and phosphate source for ammonium removal was produced at the optimal condition of pyrogenation temperature of 150 °C for 1 h. Furthermore, experimental results showed that the optimum pH and pyrolysate dosage for ammonium removal from 100 ml synthetic wastewater (1,350 mg ammonium/L) were at pH 9 and 2.4 g of struvite pyrolysate, respectively, and initial ammonium concentration played a significant role in the ammonium removal by the struvite pyrolysate. In order to further reduce the cost of struvite precipitation, the struvite pyrolysate was repeatedly used for four cycles. The results of economic analysis showed that recycling struvite for three process cycles should be reasonable for ammonium removal, with ammonium removal efficiencies of over 50% and a reduction of 40% in the removal cost per kg NH4+.

scholarly journals Test of Membrane Aerated Biofilm Reactors for Nitrogen Removal in Wastewater Treatment

2022 ◽  
Vol 2152 (1) ◽  
pp. 012039
Author(s):  
Cheng Chen
Keyword(s):  
Wastewater Treatment ◽  
Dissolved Oxygen ◽  
Oxygen Transfer ◽  
Removal Rate ◽  
Oxygen Transfer Rate ◽  
Ammonia Removal ◽  
Biofilm Reactor ◽  
Nitrification Rate ◽  
Permeable Membrane ◽  
Biofilm Reactors

Abstract Membrane aerated biofilm reactor, as a biological wastewater treatment technology, has been nearly mature on a commercial scale. It uses bubble-free aeration to provide oxygen for biological nitrification and wastewater degradation. A novel oxygen-permeable hollow fiber membrane (Zeelung cord) specifically designed for use in a membrane aerated biofilm reactors (MABR). These fibers are organized into bundles, which are wrapped around the reinforcing core to increase strength. This permeable membrane allows oxygen to diffuse into the attached biofilm, which directly leads to the biological oxidation of pollutants in the wastewater. This study aimed to determine the nitrification and oxygen transfer capacity of Zeelung fibers used in the MABR system. The effects of various C/N ratios (in the range of 1.0 to 3.0) on the membrane modules were studied using three laboratory-scale reactors over the course of 165 days. In this test, the average removal efficiency of COD can reach 74% under selected conditions, up to 90%. Meanwhile, the average nitrification rate is 3.9 g/d/m2, the average ammonia removal rate is 90%, and the maximum value can reach 99%. In addition, the oxygen transfer rate of the fiber in the liquid phase was 19.65 g/d/m2. The experiment also indicated that the nitrification rate is directly proportional to the transfer flux of oxygen and is related to the content of dissolved oxygen in the water. The nitrification rate can be controlled by controlling the concentration of dissolved oxygen in water, thus affecting the removal rate of ammonia nitrogen.

scholarly journals Performance of thin film composite membranes for ammonium removal and reuse of ammonium-enriched solution for plant growth

2020 ◽  
Author(s):  
Marcus Ze Yuan Lim ◽  
Woon Chan Chong ◽  
Woei Jye Lau ◽  
Chai Hoon Koo
Keyword(s):  
Thin Film ◽  
Plant Growth ◽  
Membrane Filtration ◽  
Composite Membranes ◽  
Domestic Sewage ◽  
Synthetic Wastewater ◽  
Ammonium Concentration ◽  
Film Composite ◽  
Ammonium Removal ◽  
Thin Film Composite

Abstract Ammonium is known to be one of the most significant pollutants in water bodies. The presence of ammonium in water is mainly originated from agricultural activities, domestic sewage and industrial effluent. This study evaluates the performance of two commercial thin film composite (TFC) membranes, i.e., NF270 and XLE from FilmTec™ for ammonium removal using synthetic wastewater and domestic sewage. The filtration experiment was conducted at different feed ammonium concentrations, humic acid concentrations, pHs and pressure. Results showed that the membrane rejection against ammonium increased dramatically with increasing ammonium concentration. However, the membrane flux was slightly compromised at higher ammonium concentration. With respect to pH, highest ammonium removal rate was able to be achieved at an optimum pH of 10. Besides, the permeation flux increased gradually with increasing feed pressure. From the results, the XLE membrane outperformed the NF270 membrane in terms of ammonium rejection. The retentate of XLE membrane filtration process was found to be useful as liquid fertiliser for plant growth. The results indicated that the TFC membrane process is not only able to produce permeate with an ammonium concentration below the acceptable limit of 10 mg/L but also able to produce retentate with enriched ammonium for plant growth.

DISTRIBUTION OF OXYGEN TRANSFER RATE IN STIRRED BIOREACTORS WITH SIMULATED BROTHS

2008 ◽  
Vol 7 (3) ◽  
pp. 199-211 ◽  
Author(s):  
Dan Cascaval ◽  
Anca-Irina Galaction ◽  
Stefanica Camarut ◽  
Radu Z. Tudose
Keyword(s):  
Oxygen Transfer ◽  
Transfer Rate ◽  
Oxygen Transfer Rate ◽  
Stirred Bioreactors

Estimation of oxygen transfer rate in sequencing batch reactor

1996 ◽  
Vol 34 (3-4) ◽  
pp. 413-420
Author(s):  
Y. C. Liao ◽  
D. J. Lee
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Transfer ◽  
Transfer Rate ◽  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
Oxygen Transfer Rate ◽  
Intermittent Aeration ◽  
Transient Effects ◽  
Operational Parameters ◽  
Transient Model

Transient model of oxygen transfer rate in a sequencing batch reactor is derived and solved numerically. The dissolved oxygen response under several conditions is analyzed. Effects of operational parameters and liquid bath height are studied. When with short, intermittent aeration periods, the transient effects on oxygen transfer rate may be substantial and should be taken into considerations. An example considering bioreaction is also given.

scholarly journals Two-Phase Flow Mass Transfer Analysis of Airlift Pump for Aquaculture Applications

Fluids ◽  
2021 ◽  
Vol 6 (6) ◽  
pp. 226
Author(s):  
Rashal Abed ◽  
Mohamed M. Hussein ◽  
Wael H. Ahmed ◽  
Sherif Abdou
Keyword(s):  
Mass Transfer ◽  
Oxygen Transfer ◽  
Transfer Rate ◽  
Two Phase Flow ◽  
Oxygen Transfer Rate ◽  
Flow Patterns ◽  
Oxygen Mass Transfer ◽  
Phase Flow ◽  
Two Phase ◽  
Airlift Pump

Airlift pumps can be used in the aquaculture industry to provide aeration while concurrently moving water utilizing the dynamics of two-phase flow in the pump riser. The oxygen mass transfer that occurs from the injected compressed air to the water in the aquaculture systems can be experimentally investigated to determine the pump aeration capabilities. The objective of this study is to evaluate the effects of various airflow rates as well as the injection methods on the oxygen transfer rate within a dual injector airlift pump system. Experiments were conducted using an airlift pump connected to a vertical pump riser within a recirculating system. Both two-phase flow patterns and the void fraction measurements were used to evaluate the dissolved oxygen mass transfer mechanism through the airlift pump. A dissolved oxygen (DO) sensor was used to determine the DO levels within the airlift pumping system at different operating conditions required by the pump. Flow visualization imaging and particle image velocimetry (PIV) measurements were performed in order to better understand the effects of the two-phase flow patterns on the aeration performance. It was found that the radial injection method reached the saturation point faster at lower airflow rates, whereas the axial method performed better as the airflow rates were increased. The standard oxygen transfer rate (SOTR) and standard aeration efficiency (SAE) were calculated and were found to strongly depend on the injection method as well as the two-phase flow patterns in the pump riser.

Oxygen Supply Method Using Gas-Permeable Film for Wastewater Treatment

1993 ◽  
Vol 28 (7) ◽  
pp. 243-250 ◽  
Author(s):  
Y. Suzuki ◽  
S. Miyahara ◽  
K. Takeishi
Keyword(s):  
Wastewater Treatment ◽  
Energy Consumption ◽  
Oxygen Transfer ◽  
Transfer Rate ◽  
Oxygen Supply ◽  
Oxygen Transfer Rate ◽  
High Energy ◽  
High Rate ◽  
N Removal ◽  
High Energy Consumption

Gas-permeable film can separate air and water, and at the same time, let oxygen diffuse from the air to the water through the film. An oxygen supply method using this film was investigated for the purpose of reducing energy consumption for wastewater treatment. The oxygen transfer rate was measured for the cases with or without biofilm, which proved the high rate of oxygen transfer in the case with nitrifying biofilm which performed nitrification. When the Gas-permeable film with nitrifying biofilm was applied to the treatment of wastewater, denitrifying biofilm formed on the nitrifying biofilm, and simultaneous nitrification and denitrification occurred, resulting in the high rate of organic matter and T-N removal (7 gTOC/m2/d and 4 gT-N/m2/d, respectively). However, periodic sloughing of the denitrifying biofilm was needed to keep the oxygen transfer rate high. Energy consumption of the process using the film in the form of tubes was estimated to be less than 40% of that of the activated sludge process.

Flow Mixing Enhancement from Balloon Pulsations in an Intravenous Oxygenator

2004 ◽  
Vol 127 (3) ◽  
pp. 400-415 ◽  
Author(s):  
Amador M. Guzmán ◽  
Rodrigo A. Escobar ◽  
Cristina H. Amon
Keyword(s):  
Numerical Simulations ◽  
Oxygen Transfer ◽  
Fiber Bundle ◽  
Transfer Rate ◽  
Oxygen Transfer Rate ◽  
Three Dimensional ◽  
Time Dependent ◽  
Fiber Placement ◽  
Flow Mixing ◽  
Dependent Flow

Computational investigations of flow mixing and oxygen transfer characteristics in an intravenous membrane oxygenator (IMO) are performed by direct numerical simulations of the conservation of mass, momentum, and species equations. Three-dimensional computational models are developed to investigate flow-mixing and oxygen-transfer characteristics for stationary and pulsating balloons, using the spectral element method. For a stationary balloon, the effect of the fiber placement within the fiber bundle and the number of fiber rings is investigated. In a pulsating balloon, the flow mixing characteristics are determined and the oxygen transfer rate is evaluated. For a stationary balloon, numerical simulations show two well-defined flow patterns that depend on the region of the IMO device. Successive increases of the Reynolds number raise the longitudinal velocity without creating secondary flow. This characteristic is not affected by staggered or non-staggered fiber placement within the fiber bundle. For a pulsating balloon, the flow mixing is enhanced by generating a three-dimensional time-dependent flow characterized by oscillatory radial, pulsatile longitudinal, and both oscillatory and random tangential velocities. This three-dimensional flow increases the flow mixing due to an active time-dependent secondary flow, particularly around the fibers. Analytical models show the fiber bundle placement effect on the pressure gradient and flow pattern. The oxygen transport from the fiber surface to the mean flow is due to a dominant radial diffusion mechanism, for the stationary balloon. The oxygen transfer rate reaches an asymptotic behavior at relatively low Reynolds numbers. For a pulsating balloon, the time-dependent oxygen-concentration field resembles the oscillatory and wavy nature of the time-dependent flow. Sherwood number evaluations demonstrate that balloon pulsations enhance the oxygen transfer rate, even for smaller flow rates.

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