Rising Air Bubbles Research Articles

Enhancing sludge thickening in continuous treatment using polymeric bubbles with cationic polymer P2900 and cocamidopropyl betaine.

Sludge thickening is a fundamental stage of treatment. This study investigated the application, in continuous treatment, of polymeric bubbles produced with cationic polymer P2900 and cocamidopropyl betaine (CAPB), a zwitterionic surfactant. The proposed reagent combination aims to form aerated flakes, solid waste structures, and rapidly rising air bubbles, ideal for treatments in compact units. Using this combination, it was possible to achieve a total solids concentration of 45% with the modified bubbles and 25% with the conventional water treatment. This level of thickening occurred under the following operating conditions: initial total solids (TS) concentration of 10g L-1, a flow rate of 5 L min-1, saturation pressure (psat) of 3atm, and polymer dosage of 10mg (gTS)-1. The suggested mechanism of action involves the adhesion of P2900 molecules to CAPB at the air/water interface, forming a lining on the bubble surface. Additionally, polymerized species form due to the residual aluminum (Al) in the sludge, which would occur during flocculation in the helical tubular flocculator (HTF), adsorbing the micelles and bubbles of CAPB. The critical micellar concentration (CMC) of CAPB was 0.26mmol L-1. Polymeric bubble technology can provide an efficient and cost-effective approach to sludge thickening in continuous treatment.

Simulating the Rising Air Bubbles Stream through Heavy Fuel Oil Residue Bubble Column Reactor using COMSOL

Several industrial operations rely on the rise of air bubbles through heavy fuel oil residue (HFOr), including oil recovery and wastewater treatment. In order to increase efficiency and decrease expenses, it is necessary to understand the peculiarities of this process. With the help of COMSOL Multiphysics, we numerically simulate the ascent of a single air bubble via HFOr in this article. The dimensions of the container used in the simulations were (100) mm in diameter and (200) mm in height, with an air bubble diameter of 4.5 mm. For an air bubble ascending through an HFOr column, the predicted numerical outcomes are contrasted with nine experimental versions. As the bubble rose higher, the region with the greatest number of vortices was located on its side. The remaining vortex is contained inside the bubble. In addition, since drag decreases the flow, a lighter fluid usually exhibits a region of strong vortex and low pressure. Because of the oscillation effect, the results reveal that the rising velocity initially rises and then gradually falls between 0.6 and 0.65 s. The air bubbles' wavy motion is caused by the high fluid density, which becomes worse as the air velocity gets higher. The values of the drag coefficient rise sharply with decreasing air extrusion speed. It turns out that the height of the fluid has an inverse relationship with the pressure.

Hydrodynamics and shape reconstruction of single rising air bubbles in water using high-speed tomographic particle tracking velocimetry and 3D geometric reconstruction

Time-resolved tomographic particle tracking velocimetry (TR-3D-PTV), also called 4D-PTV, is used here to obtain the instantaneous 3D liquid flow field information in the wake of a single rising bubble in water. Simultaneously, the bubble shape, size and velocity are determined by tomographic reconstruction of the 3D bubble shape. Both, tracer particles for PTV and bubbles, are imaged in a shadow mode with background illumination. The Lagrangian method used in this paper, especially combined with the shake the box algorithm, has big advantages compared to particle image velocimetry, in situations, where only low particle per pixel values can be obtained. In this research, single air bubbles of different sizes, with diameters of around 2.4 mm, 4.0 mm, 6.0 mm and 9.6 mm, were injected into stagnant de-ionized water. Their shape was reconstructed in 3D, and an equivalent bubble diameter was determined from this reconstruction. Compared to conventionally used 2D shadow imaging, this diameter is about 13% smaller. The 3D bubble trajectory can be analysed and decomposed into a sinusoidal function curve lateral projection and an ellipsoidal shape vertical projection. As the bubble diameter increases, the radius of the spiral trajectory is decreasing as well as the amplitude of vertical sinusoidal oscillation. The wake structure in the liquid behind the bubbles is also changing with bubble size: from simple vortex pairs for smaller bubbles to an intertwined structure of several twisted vortices for the bigger ones.Graphical abstractThree-dimensional bubble reconstruction (grey surface) and liquid stream lines coloured with velocity magnitude around an ascending air bubble in de-ionized water.

Dynamics of single bubble ascension in stagnant liquid: An investigation into multiphase flow effects on hydrodynamic characteristics using computational simulation

Industrial operations often involve multiphase flows, where the motion of bubbles plays a crucial role in determining hydrodynamic properties. In the context of modern practices, advanced computational solvers are increasingly employed to simulate the interactions and trajectories of bubbles within complex flows. This study stands out in its unique examination of the computational software COMSOL's capability to accurately simulate the upward motion of a single bubble within quiescent water, akin to a liquid-like environment. The novelty lies in the comprehensive coverage of various container diameters (ranging from 10 to 80 mm) and heights (from 25 to 300 mm) relative to the air bubble diameter (ranging from 0.5 to 8 mm). Through meticulous comparisons between nine empirical formulas and numerically projected bubble ascent through a water column, a remarkable level of agreement emerges, underscoring the precision and consistency of the simulations. These simulations unveil intriguing findings, shedding light on the intricate interplay of forces governing bubble behavior. Notably, variations in drag forces induce changes in bubble shapes as a function of diameter, while the ascent of bubbles is accompanied by distinctive vortices, resulting in fascinating asymmetry. Furthermore, vorticity concentrates within the bubble, particularly in lighter fluid regions characterized by reduced pressure. The study also unveils how larger aspect ratios minimize flow drag, consequently boosting ascent velocities, and demonstrates the influence of container diameter on the rising velocity. Gravitational forces are found to reduce ascent velocities at greater column heights, while the rate of air bubble rise escalates with its size. This meticulous exploration of bubble dynamics in multiphase flows yields invaluable insights for diverse industrial applications, ultimately enhancing our understanding of this complex phenomenon. The strong alignment observed between empirical formulations and numerical simulations within the COMSOL framework underscores the utility of such computational tools for the study and design of multiphase flows' intricate dynamics.

Nanoscale Investigation into Dynamics of Thin Liquid Films during Bouncing and Attachment of Rising Air Bubbles on Hydrophilic and Hydrophobic Surfaces.

Investigations on bouncing and attachment of free-rising air bubbles on hydrophobic surfaces have been limited to side-view, high-speed photography of the bubble-plate attachment process. In this work, an investigation of the dynamics as well as stability of thin liquid films (TLFs) between free-rising air bubbles and quartz surfaces was performed using a newly developed multiple-wavelength synchronized reflection interferometry microscopy (SRIM) technique. The effect of surface hydrophobicity on both the stability and critical rupture thickness of TLFs was investigated. Results showed that the TLF ruptured at a critical rupture thickness of 100-1000 nm or beyond during bubble's impact on hydrophobic quartz surfaces. The critical rupture thicknesses varied depending on the surface hydrophobicity as well as surface asperity. A higher surface hydrophobicity, in general, contributed to a higher critical rupture thickness. In addition, the effect of n-octanol on the stability of the TLFs was investigated. Results showed that film stability increased with increasing the concentration of n-octanol, which was accompanied by a significant decrease in the critical rupture thickness. The present result illustrates, for the first time, the dynamics of TLFs on hydrophobic surfaces under a dynamic condition compared with previous studies under a quasi-equilibrium condition. The information revealed from the present work has a significant implication to many industrial applications, including froth flotation and other biological and semiconductor applications.

Effect of different co-foaming agents on PFAS removal from the environment by foam fractionation

Per- and poly-fluoroalkyl substances (PFAS) are recalcitrant, synthetic chemicals that are ubiquitous in the environment because of their widespread use in a variety of consumer and industrial products. PFAS contamination has become an increasing issue in recent years, which needs to be urgently addressed. Foam fractionation is emerging as a potential remediation option that removes PFAS by adsorption to the surface of rising air bubbles which are removed from the system as a foam. PFAS concentrations in the environment are often not sufficient to allow for formation of a foam by itself and often a co-foaming agent is required to be added to enhance the foamability of the solution. In this study, the effect of different classes of co-foaming agents, anionic, non-ionic, zwitterionic and cationic surfactants on the removal of PFAS with varying fluorocarbon chain length from 3 to 8 in a foam fractionation process have been investigated. Evaluation of the air-water interface partitioning coefficient (k’) in addition with surface tension and PFAS removal results support the contention that using a co-foaming agent with the opposite charge to the PFAS in question significantly facilitates the adsorption of PFAS to the air-water interface, enhancing the efficiency of the process. Using the non-ionic surfactant (no headgroup electrostatic interaction with PFAS), as a reference, it was observed, in terms of PFAS separation and rate of PFAS removal, that anionic co-surfactant performed worst, zwitterionic was better, and cationic co-surfactant performed best. All of the PFAS species were able to be removed below the limit of detection (0.05 µg/L) after 45 minutes of foaming time with the cationic surfactant.

Ideal gas law and fluid dynamics simulation: characterizing an air bubble rising from the bottom of a lake

The use of animations, simulations, and remote lab experiments has taken a new turn during the pandemic. When teaching introductory-level physics courses, the simulations and animations play an important role. Carefully designed simulations assist students visualize real-life situations and help understand complex physics concepts behind them. Some of these simulations guide students to understand the problem itself and encourage them to adjust variables and observe the changes. Not to mention, both students and instructors can benefit from these simulations in any environment, remote, or in-person. We designed a simulation to demonstrate the rise of an air bubble from a certain depth of a lake. Assuming the gas trapped inside the air bubble to be ideal, using Ideal Gas Law, we designed the simulation to show how the volume of the bubble expands as it ascends. To solve for volume as it reaches the surface, we employed knowledge from fluid dynamics. We incorporated equations to account for the pressure variations with the depth. Unlike in other simulations, here we share a link with the user, permitting them to alter the program. This gives users an opportunity to understand the coding of the simulation, if they are interested in creating similar animations in the future.

Improved Wake Velocity Distribution Behind a Rising Bubble for Isothermal and Thermally Stratified Liquid Layers

Abstract This paper aims at (a) improving the vertical velocity distribution in the wake of a rising isolated bubble for isothermal water layers and (b) evaluating the proposed distribution for thermally stratified therminol layers before and after the initiation of vortex shedding. To address these objectives, numerical investigations are performed, for the rise of an isolated bubble in isothermal and thermally stratified liquid layers, with a combination of the monotonic upwind scheme for conservation laws and pressure implicit with splitting of operators numerical scheme. The analysis revealed that the vertical velocity in the wake of a rising isolated bubble, for isothermal and thermally stratified liquid layers, differs remarkably from the Gaussian distribution. Based on the detailed investigations, region-wise wake velocity distribution comprising a linear superposition of Gaussian approximation with Burr distribution is proposed. Furthermore, this distribution is utilized to predict the rise velocity for a chain of bubbles having different frequencies of departure. Thus, the findings will be useful for the design of heat exchangers or cooling devices, which rely on the heat transfer augmentation with rising air bubbles from a heated surface for isothermal (buoyancy suppressed) and thermally stratified (buoyancy assisted) liquid layers.

Hydrodynamics of Rising Air Bubbles in Mixture of Proteins with Non-Ionic Surfactants to Declare their Interaction at the Air-Water Interface

Evaluation of behaviour of adsorbed layers of protein-surfactant mixture at the air-water interfaces have recently received great attention due to their wide applications in food and pharmaceutical industries. In this research, qualitative study of surface activity of two kinds of proteins, Beta- Lactoglobulin (BLG) and Beta-Casein (BCS), nonioinic surfactant of C10DMPO, and the mixtures of them in different concentrations at the air-water interface is investigated using rising bubble method. The similarity between measured local velocity profiles can be due to the fact that all mentioned materials are surface-active one and could create the Marangoni effect and develop a dynamic adsorption layer. As there is no significant interaction between the protein and surfactant molecules, stable complex structures cannot be formed in the protein-C10DMPO mixture. The mixture velocity profile is more similar to that of the surfactant which is a result of replacement of protein molecules or complexes with free surfactant at the bubble interface. It is found that the mixture of non-ionic surfactant with BCS has a bit synergetic effect while for its mixture with BLG, a negative synergy is observed which is resulted from the shape of protein.

Bubble size distribution and gas holdup in bubble columns employing non‐Newtonian liquids: A CFD study

AbstractThe hydrodynamics involved with the rise of air bubbles in shear‐thinning non‐Newtonian liquids in bubble columns was investigated using computational fluid dynamics (CFD). In bubble columns, the bubble size distribution (BSD) and gas holdup significantly affect the mass transfer rates and the reactor design. Consequently, the influence of superficial gas velocity, flow index, consistency index, sparger bubble size, and yield stress were analyzed on a local and global scale. The bubble sizes and the coalescence and breakage phenomena were incorporated using the homogeneous discrete method of the population balance model (PBM). The bubbles underwent coalescence during ascent and exhibited bimodal distribution. The radial homogeneity of the gas phase increased axially. Moreover, the zones of low liquid dynamic viscosity produced zones of a high gas holdup. Though the dual effect of viscosity on gas holdup was non‐existent, the gas holdup surged after 35.1 mPa s at the mid‐zone and remained constant thereafter. The noteworthy differences in simulation results put further emphasis upon the importance of sparger bubble size in CFD modelling. A decrease in the overall gas holdup and the axial air velocity with yield stress was observed. CFD simulation proved capable of providing results in reasonable agreement with experiments.

Bubble's rise characteristics in shear-thinning xanthan gum solution: a numerical analysis

The rise of gaseous bubbles in shear-thinning liquid is a fundamental issue in fluid physics, particularly the bubbles rise dynamics in water-soluble xanthan gum concentration have a strong link for enhancing the stability of foams that have been encountered extensively in oil recovery, methane hydrate formation processing, froth flotation, and food and beverage industries. Here, air bubble rise behavior in xanthan gum solution (XGs) was investigated by using a coupled volume of fluid with the level set approach in CFD (computational fluid dynamics) modelling. The Carreau-Yasuda rheological model was adopted to define the viscous properties of the XGs and the continuum surface force model was used to track the interface between bubble and XGs. Additionally, ANN (artificial neural network) modeling was demonstrated for estimating the outputs of CFD. Our estimated CFD results for different bubble terminal velocities in water and experimental data obtained from the literature showed that there was a maximum relative error of 4.51%. Then, the CFD setup was utilized to investigate the effect of different concentrations of XGs and liquid flow index (N) on bubble rise dynamics within the bubble Reynolds number (Reb) range up to 10.05 and Eotvos number (Eo) range up to 3.47. For a fixed bubble size, the dimensionless bubble terminal velocity decreased in increased flow index and concentration of XGs, which led to decrease Reb and increase Eo. For a given XGs, the dimensionless bubble terminal velocity significantly depends on Reb and Eo. It was found that XGs and flow index significantly affect the distribution of dimensionless liquid viscosity than that of the dimensionless liquid velocity close to the bubble's underneath region. In a comparison with the rheological power-law model, the Carreau-Yasuda model showed to predict more accurate results. The estimated drag coefficient showed a deviation from the empirical equation reported in the literature, in contrast, a more accurate estimation in drag coefficient was obtained based on modified Reynolds number and Archimedes number. ANN modelling outputs agreed with CFD results and indicated that the training and testing of ANN have great efficiency to predict unknown values.

Investigation of antibiotic surface activity by tracking hydrodynamic of a rising bubble

Improving the performance of many industries as well as traditional and modern processes necessitates knowledge of interfacial phenomena. Nowadays, due to the widespread use of antibiotics, it is crucial to improve their function, optimize their synthesis process and explore their removal method from aquatic environment. For the first time, the adsorption kinetic of Amoxicillin and Ampicillin is measured by pendant drop and their surface activity is investigated by rising bubble method. From adsorption kinetics, it is obvious that Ampicillin is surface active at air–water interface. While Ampicillin shows a drastic surface activity even at 500 ppm, i.e. surface pressure around 2.5 mN/m. From local velocity profiles of single rising air bubble, defiantly the Amoxicillin is not surface active. It is concluded from both results, that presence of Ampicillin and Amoxicillin in water will change the molecular structure in the bulk and at the interface. As expected, the sensitivity of the rising bubble method to the impurity compared to others like pendant drop method is undeniable.

Hydrodynamics of single bubble rising through water column using volume of fluid (VOF) method

The importance of air bubble dynamics in liquid is in some phenomena like chemical and biochemical processes in refinery units. The 2D Volume of Fluid (VOF) method together with the CFD technique were employed for simulating. The dynamic meshing technique is used to simulate the hydrodynamics of rising air bubble in liquid water column via the User Defined Function (UDF) code in the C++ environment was developed to evaluate bubble rising through the water column. The rising of air bubble through a stagnant water column has been considered and the influence of column dimension, bubble size, and aspect ratio on the rising velocity characterized is investigated. The obtained results showed that the bubble rising velocity increase with the bubble size and its shapes was transformed from ellipsoidalto-ellipsoidal cap shape. The rising velocity of air bubbles was affected by the column diameter. It was observed that the air bubble moving toward the top of the water column with oscillation for all cases. A good agreement was obtained between the rising velocity predicted in the simulation with that obtained from the literature.

Highly efficient lattice Boltzmann multiphase simulations of immiscible fluids at high-density ratios on CPUs and GPUs through code generation

A high-performance implementation of a multiphase lattice Boltzmann method based on the conservative Allen-Cahn model supporting high-density ratios and high Reynolds numbers is presented. Meta-programming techniques are used to generate optimized code for CPUs and GPUs automatically. The coupled model is specified in a high-level symbolic description and optimized through automatic transformations. The memory footprint of the resulting algorithm is reduced through the fusion of compute kernels. A roofline analysis demonstrates the excellent efficiency of the generated code on a single GPU. The resulting single GPU code has been integrated into the multiphysics framework waLBerla to run massively parallel simulations on large domains. Communication hiding and GPUDirect-enabled MPI yield near-perfect scaling behavior. Scaling experiments are conducted on the Piz Daint supercomputer with up to 2048 GPUs, simulating several hundred fully resolved bubbles. Further, validation of the implementation is shown in a physically relevant scenario—a three-dimensional rising air bubble in water.

Passage of a rising bubble through a liquid‐liquid interface: A flow map for different regimes

AbstractThe passage of a rising air bubble through a stratified horizontal interface between two Newtonian liquids is studied numerically. A ternary phase‐field model has been utilized for capturing the interface between three immiscible fluids. According to the previous studies, the density, viscosity, and surface tension of the two liquids, in addition to the bubble diameter, are the effective parameters of bubble interaction with the interface. By changing these variables, three main flow patterns are identified in numerical simulations. Penetration flow regime is observed when the bubble enters the upper liquid alone and does not raise the lower liquid. Entrainment flow regime occurs when the bubble lifts some of the heavier liquid to the lighter liquid but still rises alone. If the bubble holds a film of the denser liquid when it rises in the upper liquid, envelopment flow regime takes place. A flow regime map is represented to distinguish the aforementioned flow patterns using Weber and Morton numbers and determine regime transition criteria based on these two dimensionless parameters. For Weber numbers lower than 30, or Morton numbers higher than 1.7 × 10−2, the penetration regime is observed. On the contrary, when the Weber number is higher than 65 and the Morton number is lower than 7 × 10−5, the envelopment regime occurs. The entrainment pattern happens between these ranges and two additional limiting relations of 320Mo0.18 < We < 1500Mo0.23.

Motor oil removal from water by continuous froth flotation: The influence of surfactant structure on interfacial adsorption and foam properties

The influence of the chemical structure of three surfactants, anionic extended surfactant Alfoterra® C145–8PO (ALF), anionic methyl ester sulfonate (MES), and cationic cetyltrimethyl ammonium bromide (CTAB), on the adsorption and foam characteristics relating to effectiveness at reduction of motor oil in a continuous froth flotation system. All surfactants were chosen based on having the similar number of carbon atoms in alkyl chain. So the effects of the different head group and the existence of a polypropylene oxide in the ALF’s structure on the surface activity and motor oil removal could be elaborated. The results demonstrated that CTAB, having strongest positively charged head group with the shortest tail length, provided the highest diffusivity, foamability, and foam stability, leading to the highest enrichment ratios of motor oil and surfactant. Conversely, ALF, having the largest molecular size and the longest tail length, gave the lowest diffusivity and foam properties. Hence, it exhibited the highest motor oil removal and surfactant recovery with the lowest enrichment ratios of both motor oil and ALF. The added packing media with 50% packing volume augmented the residence time of the rising air bubbles, enhancing the motor oil removal by about 16%, 15%, and 24% for the ALF, MES, and CTAB, respectively.

Immobilization and growth of clonal tissue fragments from the macrophytic red alga Gracilaria vermiculophylla on porous mesh panels

New approaches are needed to automate and intensify the cultivation of commercially important red macroalgae. For example, cultivation of Gracilaria vermiculophylla on vertically stacked panels, deployed in raceway circulation tanks or in the open ocean, may enable process intensification. A scalable process for panel inoculation is a first step toward this end. Clonal plantlets of G. vermiculophylla were mechanically blended (1000 rpm, 5 s) into tissue fragments of 2 cm nominal size, deposited on a 3-mm polypropylene mesh sheet, and then sprayed with a pressurized water jet at 4.5 bar in 0.1 s bursts with average velocity of 13 m s−1. The force of the water jet pushed the 1 mm diameter thallus tissue fragments into the mesh openings, securing the plantlet to the mesh support. Gracilaria vermiculophylla test panels (7 cm per side) were placed in an upright orientation, with rising air bubbles providing fluid motion over the panel surface. During cultivation at saturation light intensity in nutrient-replete medium, near-exponential growth was sustained over 42 days at a specific growth rate of 8–9% per day, identical to the freely suspended thallus tissues. The tissue fragments proliferated over the panel surface and extended outward from the panel surface, ultimately creating a loose mat of tissue nearly 8–10 cm in thickness and biomass loadings exceeding 3000 g FW per m2 of panel surface. The steps used to prepare the G. vermiculophylla panels can be automated, and dense arrays of stationary G. vermiculophylla panels cultivated under defined current flow offer future potential for process intensification.

Assessment of VoF based numerical scheme for bubble rise in isothermal liquid layer, and some new insight in thermally stratified liquid layers

This paper aims at (a) comparative assessment of the different volume of fluid (VoF) based numerical schemes for a rising, single air bubble in isothermal liquid (water) layers and (b) investigation of bubble rise in thermally stratified liquid (therminol) layers. For numerical investigation of bubble rise in isothermal liquid layers, three available numerical schemes, Upwind, Quadratic Upstream Interpolation for Convective Kinematics (QUICK) and Monotonic Upwind Scheme for Conservation Laws (MUSCL) schemes, combined with the pressure-velocity coupling(p-v) approaches, such as, Pressure Implicit with Splitting of Operators (PISO) and Semi Implicit Method for Pressure-Linked Equations (SIMPLE), are considered. The wake analysis revealed that the region of influence grows beyond 10 times the diameter of the bubble. Moreover, based on the comparative assessment, MUSCL scheme with PISO is selected, for investigating the bubble rise in thermally stratified therminol layers. Based on these investigations, a 3D diagram, describing bubble shape as f (Ra, Eo, Ga), is proposed, and a new insight to the micro-convection, inside the rising bubbles is provided. Furthermore, a time-scale analysis is performed to describe the heat transfer mechanisms, (a) inside air bubble, and (b) between air bubble and the external surrounding liquid. Thus, the findings will be useful for the design of heat exchangers or cooling devices, which rely on the heat transfer augmentation with rising air bubble.

Effect of a single air bubble on the collapse direction and collapse noise of a cavitation bubble

Studying the influence of a single air bubble on the noise intensity of cavitation bubble collapse has great significance for understanding the mechanism of air entrainment to alleviate cavitation in hydraulic engineering. A cavitation bubble is generated by an underwater low-voltage electric discharge device and interacts with a rising air bubble. Only the cases where the cavitation bubble centroid, air bubble centroid, and hydrophone probes are located approximately on the same horizontal line are analyzed. The results show that the roundness, size and distance of an air bubble have a very important effect on the collapse direction and collapse sound pressure of the cavitation bubble. The findings also reveal that the direction of collapse is closely related to the collapse sound pressure, while the dimensionless distance γ and dimensionless radius roundness ratio ε’ are important parameters that determine the collapse direction of the cavitation bubble.

Design of Sequencing Batch Reactor (SBR) Treatment Plant for Abattoir Wastewater (A Case of Apa Mmini Stream)

Aim: The study aimed at designing a wastewater treatment method for removal of (Biological Oxygen Demand) BOD5 using Sequencing batch reactor (SBR).
 Study Design: SBR functions as a fill-and-draw type of activated sludge system involving a single complete-mix reactor where all steps of an activated sludge process take place.
 Methodology: The intermittent nature of slaughterhouse wastewaters favours batch treatment methods like sequence batch reactor (SBR). Attempts to remediate the impact of this BOD5 on the stream, led to the design of a sequence batch reactor which was designed to treat slaughterhouse effluent of 1000 L.
 Results: The oxygen requirement for effective removal of BOD5 to 95% was determined to be 21.10513 kgO2/d, while L:B of 3:1 was considered for the reactor. Also, air mixing pressure for the design was 0.16835 bar, while settling velocity was .
 Conclusion: To ensure proper treatment of BOD5 load of the slaughterhouse, a sequencing Batch reactor of 1000 litre carrying capacity was designed. For effective operation of this design, the pressure exerted by the mixing air was 0.16835 bar which was far greater than the pressure exerted by the reactor content and the nozzle. Settling velocity of 0.0003445 m/s for 0.887 hrs was required for the reactor to be stable and a theoretical air requirement of 1.6884 m³/d was calculated. Hence the power dissipated by the rising air bubbles to ensure efficient mixing of oxygen in the reactor was calculated as 26530003.91 Kilowatts. With these design parameters, the high BOD5 load downstream of the river can be treated to fall below the FMEnv recommended limit of 50 mg/l.