Hollow Fiber Membrane Bioreactor Research Articles

A critical Review on Advanced Membrane Bioreactors for Wastewater Treatment: Fouling Reduction and Energy Demand

Objectives:Rapid industrialization has highlighted the importance of addressing environmental issues and the increasing demand for water supply. As a result, innovative solutions to improve water circulation management in both public and industrial sectors have been proposed, one of which is the introduction of Membrane Bioreactor (MBR) technology. This study aims to understand the mechanisms and characteristics of membrane fouling in MBR processes and compare the associated energy consumption, with the goal of improving process efficiency and energy performance.Methods:In this study, various factors influencing the MBR process were considered to analyze the mechanisms and characteristics of membrane fouling. The impact of fouling on the process was assessed, and energy consumption was compared. Specifically, the power consumption of flat-sheet and hollow-fiber MBRs was analyzed, focusing on the proportion of energy used for microbial treatment and membrane cleaning. The Specific Energy Demand (SED) was calculated to evaluate the energy consumption efficiency of different fouling control methods in MBRs.Results and Discussion:In typical MBR processes, 68.0% (flat-sheet) and 53.0% (hollow-fiber) of the power consumption is attributed to air scouring for microbial treatment and membrane cleaning. Notably, 57.0% (flat-sheet) and 36.0% (hollow-fiber) of the power is consumed to supply air for detaching adhered foulants to maintain filtration performance. These results indicate that aeration is a major energy consumer in MBR processes. SED is a critical indicator for assessing the energy consumption of specific fouling control methods, with typical MBR processes having an SED of 0.2-0.3kWh/m3. In contrast, using a non-aerated membrane module with reciprocating inertial force for fouling control reduces SED to 0.005-0.01 kWh/m3, representing a 20-60 fold decrease in energy consumption, highlighting the need for energy reduction.Conclusion:This study provides insights into fouling reduction characteristics in MBR processes, suggesting a new paradigm for enhancing the economic feasibility of MBR technology. Applying non-aerated membrane modules to reduce energy consumption can significantly improve MBR efficiency, contributing to energy reduction and environmentally friendly technology development. Therefore, strategies to maximize energy efficiency and minimize environmental impact in MBR processes are essential.

Enhancing the membrane bioreactor efficiency: The impact of rotating membrane modules and aeration strategies on the transmembrane pressure.

The study analyses the performance of a pilot plant using a rotating hollow fibre (HF) membrane bioreactor system. The experiments evaluated the effect of operational parameters such as rotational speed, aeration strategies, and maintenance cleaning (MC) procedures on the efficiency of the system, in particular transmembrane pressure (TMP) and filtrate quality. The results indicate that the rotating membrane module reduces TMP increase and can operate for 48 days with satisfactory performance, even without aeration. This has the potential to significantly improve efficiency, resulting in significant energy savings. In addition, two MC methods, clean in air and clean in place, were tested and found to be efficient for weekly MC. It was observed that operating without aeration during colder seasons may not be effective. Therefore, adaptive strategies are needed to address seasonal temperature variations.

Feammox bacterial biofilm formation in HFMB

Nitrogen pollution has been increasing with the development of industrialization. Consequently, the excessive deposition of reactive nitrogen in the environment has generated the loss of biodiversity and eutrophication of different ecosystems. In 2005, a Feammox process was discovered that anaerobically metabolizes ammonium. Feammox with the use of hollow fiber membrane bioreactors (HFMB), based on the formation of biofilms of bacterial communities, has emerged as a possible efficient and sustainable method for ammonium removal in environments with high iron concentrations. This work sought to study the possibility of implementing, at laboratory scale, an efficient method by evaluating the use of HFMB. Samples from an internal circulation reactor (IC) incubated in culture media for Feammox bacteria. The cultures were enriched in a batch reactor to evaluate growth conditions. Next, HFMB assembly was performed, and Feammox parameters were monitored. Also, conventional PCR and scanning electron microscopy (SEM) analysis were performed to characterize the bacterial communities associated with biofilm formation. The use of sodium acetate presented the best performance for Feammox activity. The HFMB operation showed an ammonium (NH4+) removal of 50%. SEM analysis of the fibers illustrated the formation of biofilm networks formed by bacteria, which were identified as Albidiferax ferrireducens, Geobacter spp, Ferrovum myxofaciens, Shewanella spp., and Anammox. Functional genes Archaea/Bacteria ammonia monooxygenase, nrxA, hzsB, nirS and nosZ were also identified. The implementation of HFMB Feammox could be used as a sustainable tool for the removal of ammonium from wastewater produced because of anthropogenic activities.

Algal-Based Hollow Fiber Membrane Bioreactors for Efficient Wastewater Treatment: A Comprehensive Review

The treatment of living organisms is a critical aspect of various environmental and industrial applications, ranging from wastewater treatment to aquaculture. In recent years, algal-based hollow fiber membrane bioreactors (AHFMBRs) have emerged as a promising technology for the sustainable and efficient treatment of living organisms. This review provides a comprehensive examination of AHFMBRs, exploring their integration with algae and hollow fiber membrane systems for diverse applications. It also examines the applications of AHFMBRs in various areas, such as nutrient removal, wastewater treatment, bioremediation, and removal of pharmaceuticals and personal care products. The paper discusses the advantages and challenges associated with AHFMBRs, highlights their performance assessment and optimization strategies, and investigates their environmental impacts and sustainability considerations. The study emphasizes the potential of AHFMBRs in achieving enhanced nutrient removal, bioremediation, and pharmaceutical removal while also addressing important considerations such as energy consumption, resource efficiency, and ecological implications. Additionally, it identifies key challenges and offers insights into future research directions. Through a systematic analysis of relevant studies, this review aims to contribute to the understanding and advancement of algal-based hollow fiber membrane bioreactors as a viable solution for the treatment of living organisms.

Optimal metabolite transport in hollow fibre membrane bioreactors

Hollow fibre membrane bioreactors provide a fast and efficient method for engineering functional tissue for use in medical treatments. Flow is utilised to overcome mass transport limitations by perfusing a nutrient-rich culture medium through the fibre lumen, which can then transport along the fibre lumen or across the porous membrane wall. Cells seeded at the outer membrane wall consume the nutrient and subsequently produce waste metabolites, which are transported away through an external extra-capillary space (ECS) along with excess nutrient. We present and investigate a two-dimensional axisymmetric model for fluid flow and solute transport through a single-fibre bioreactor configuration, with cells seeded to the external fibre wall. Fluid flow is modelled by steady lubrication and Darcy equations, which are coupled to the solute transport problem modelled by a system of advection–diffusion equations, supplemented with a reaction term to model the cell layer. Our model analysis reveals how spatially varying wall permeability distributions can be utilised to provide uniform nutrient delivery to a spatially uniform, homogeneous cell population. We also reveal how maximising the transmural pressure drop across the membrane wall is the dominant mechanism for waste removal rather than traditional experimental methods of flushing the ECS.

The impact of solid/floc holdup on oxygen transfer in a rotating hollow fiber membrane bioreactor under endogenous conditions.

A set of oxygen transfer experiments in clean water and three different activated sludge concentrations were conducted with fine and coarse bubble aeration in a rotating hollow fiber membrane bioreactor to observe the impact of different rotational speeds on the oxygen transfer rate. The results showed that with increasing membrane rotational speed, the oxygen transfer coefficient enhanced while the α-factor showed similar values at comparable sludge concentrations and solid/floc holdups. The highest improvement rates occurred during the experiments with coarse bubble aeration at 50 rpm and the lowest specific airflow rate. The solid/floc holdup appears to universally impact oxygen transfer depletion regardless of what reactor type, diffuser setup and membrane rotational speed were used in the wastewater experiments.

A highly efficient laccase-immobilized bioreactor prepared by radiation induced graft polymerization for removal of persistent pollutants

Radiation induced graft polymerization (RIGP) is an excellent tool for functionalization of polymers, allowing the preparation of high density polymer brushes suitable for enzyme immobilization. Herein, we report on a hollow fiber membrane bioreactor prepared using RIGP to host laccase which is an efficient enzyme for removal of phenolic compounds. Polymer brushes were functionalized with aldehyde moieties to allow covalent bonds in between the polymer and the enzyme for immobilization. Moisture retention was also greatly improved after functionalization. As a result, after optimization of immobilization and reaction conditions, the bioreactor showed high stability in organic media and efficient biodegradation of an organic phenolic pollutant (bisphenol A).

Feammox Bacterial Biofilms as an Alternative Biological Process for the Removal of Nitrogen from Agricultural Wastewater

The excessive deposition of ammonium (reactive nitrogen) in the environment has led to losses of biodiversity and the eutrophication of ecosystems. Anthropogenic sources contribute twice the natural rate of terrestrial reactive nitrogen and provide about 45% of the total amount of it produced annually on Earth. Recently, a biological process that anaerobically metabolizes ammonium and facilitates iron reduction, termed Feammox, was discovered. The use of Feammox activity together with hollow fiber membrane bioreactors (HFMB), for which the latter are based on the formation of biofilms of bacterial communities, constitutes an efficient and sustainable method for the removal of ammonium from agriculturally derived wastewater. To implement the use of HFMB with Feammox activity, the formation of Feammox bacterial biofilms from wastewater sludge samples from a brewery was evaluated. The cultures were enriched with two different carbon sources, namely, sodium acetate and sodium bicarbonate; then, ferrous iron and ammonium concentrations, which were used as indicators of reactive nitrogen removal, were measured. The measurements revealed that the ammonium removal level reaches 20.4% when sodium acetate is used as carbon source. Moreover, an increase in the ferrous iron concentration of +Δ84.6 mg/L was observed, indicating that Feammox activity had been generated. Biofilm formation was observed under Feammox conditions on the hollow fibers. These results showed that Feammox bacteria can form biofilms and efficiently remove ammonium from wastewater, constituting an essential feature with which to scale up the process to HFMBs. Overall, these results contribute to a better understanding of the Feammox process that can be used to implement these processes in agriculture and thus progress towards a more sustainable industry.

Membrane Applications in Autologous Cell Therapy.

Stem cell and cell therapies, particularly autologous cell therapies, are becoming a common practice. However, in order for these technologies to achieve wide-scale clinical application, the prohibitively high cost associated with these therapies must be addressed through creative engineering. Membranes can be a disruptive technology to reshape the bioprocessing and manufacture of cellular products and significantly reduce the cost of autologous cell therapies. Examples of successful membrane applications include expansions of CAR-T cells, various human stem cells, and production of extracellular vesicles (EVs) using hollow fibre membrane bioreactors. Novel membranes with tailored functions and surface properties and novel membrane modules that can accommodate the changing needs for surface area and transport properties are to be developed to fulfil this key role.

Simultaneous removal of H2S and NH3 from raw biogas in hollow fibre membrane bioreactors

H 2 S and NH 3 are toxic, corrosive and odorous gases that often co-exist in gas streams emitted from industrial processes, including biogas produced in anaerobic digestion plants. A hollow fibre membrane bioreactor (HFMB) was tested for simultaneous biological removal of H 2 S and NH 3 from raw biogas. The HFMB achieved a removal efficiency (RE) > 99% for treating up to 1850, 915 and 1200 ppm v of H 2 S at an empty bed residence time (EBRT) of 187, 92 and 46 s, respectively. The RE of NH 3 was > 99% when the inlet NH 3 concentrations were up to 460, 355 and 750 ppm v at an EBRT of 187, 92 and 46 s, respectively. At an EBRT of 46 s, the RE of H 2 S and NH 3 was in the range of 85–97 and 73–95%, respectively, for inlet biogas laden with 1200–1700 ppm v of H 2 S and 750–1050 ppm v of NH 3 . The critical loading rates of H 2 S and NH 3 were about 150 and 40 g m −3 h −1 , respectively. S 0 (52%), SO 4 2 − (48%) and N 2 (92%) were the end products of the H 2 S and NH 3 bioconversion. Different sulfide oxidizers including aerobic (e.g. Smithella sp., Sulfuricurvum sp. and Thiomonas sp.) and anoxic (e.g. Rhodanobacter sp., Sulfuritalea sp. and Thiobacillus sp.) chemolithotrophs contributed to the H 2 S bioconversion. Aerobic (e.g. Pseudomonas sp., Stenotrophomonas sp. and Nitrosospira sp.) and Fe(III) dependent anaerobic (e.g. Clostridium_sensu_stricto_12 sp., Rhodoferax sp. and Dechloromonas sp.) ammonium oxidizers contributed to the NH 3 bioconversion. Denitrifiers including denitrifying phosphorus accumulating organisms (e.g Candidatus_Contendobacter sp.) contributed to the denitrification process. • Hydrophilic polyethersulfone HFMB simultaneously treated H 2 S and NH 3 from raw biogas. • Maximum H 2 S and NH 3 flux through membrane module was 1.94 and 0.55 g m -2 day -1 , respectively. • The critical loading rate of H 2 S and NH 3 was close to 150 and 40 g m -3 h -1 , respectively, at an EBRT of 46 s. • Outlet/inlet CH 4 ratio ( ∼ 0.99) confirmed low ( < 1%) biogas dilution in the HFMB. • Both aerobic and anoxic processes contributed to H 2 S and NH 3 bioconversion in the HFMB.

Development of operating process for continuous production of biomass by Tetradesmus obliquus (MT188616.1) in a hollow fiber membrane photobioreactor

An effective prototype of photobioreactor namely hollow fiber membrane bioreactor is employed to produce algal biomass for biofuel production. The effect of two-stage cultivation system on the biomass productivity and lipid production is studied using freshwater green microalga Tetradesmus obliquus MT188616.1. The hybrid system combines exponential biomass production in hollow fiber membrane photobioreactor (HFMPBr) and a coordinated high-lipid stimulation phase in nitrogen-deprived medium by the shake flask method. This work is proposed to examine the usefulness of HFMPBr module to enhance the microalgal growth rate through the effective mass transfer by standardizing the culture medium re-circulation flow rates (5 – 45 mL min−1) through the hollow fiber membranes. Cultivation is carried out at continuous mode in HFMPBr containing polysulfone fabricated membranes at fixed light intensity of 50 µmol m−2 s−1 and temperature at 28 °C. Biomass productivity and specific growth rate obtained are 0.44 g L−1d−1 and 1.61 µ d−1 with a lipid yield of 0.1 g L− 1. The key operating parameter i.e., liquid flow rate is optimized based on biomass production. The highest biomass concentration is produced at the flow rate of 45 mL min−1. The results showed that HFMPBr module is a better choice for the algal-cultivation to obtain higher biomass yield.

Resilience of hollow fibre membrane bioreactors for treating H2S under steady state and transient conditions

H2S removal performance by hollow fibre membrane bioreactors (HFMBs) was investigated for 271 days at ambient (20 ± 2 °C) temperature employing an inlet H2S concentrations up to 3600 ppmv and empty bed residence time (EBRT) of 187, 92 and 62 s. Different operating conditions including pH control (with or without), famine period, shock loads (4–72 h) and different biomass types (presence or absence of suspended biomass) were investigated. The H2S flux and mass-transfer coefficient were significantly higher for the biotic HFMBs (R1 and R2) compared to the abiotic control (R3) at all employed EBRTs. Significant differences in H2S removal efficiency (RE) and elimination capacity (EC) were noted for different inlet H2S concentrations, EBRTs, pH and biomass type. The HFMB achieved >99% RE at steady-state for biotic operation with an EC of 33.8, 30.0 and 30.9 g m−3 h−1 at an EBRT of 187, 92 and 62 s, respectively. Sulfate (92–93%) was the main sulfur species in the H2S bioconversion process. The HFMB showed a good resilience to shock loads and showed quick recovery (<24 h) after withdrawal of the shock loads. The HFMB had a critical loading rate of H2S about 135 g m−3 h−1 under transient-state.

Evaluation of using a porous medium approach to simulate flat-sheet membrane bioreactors

Abstract The porous medium approach has been applied by others to study the global hydrodynamics in hollow-fiber (HF) membrane bioreactors (MBR). This study explores the usability of the porous medium approach for flat-sheet (FS) MBR and introduces a CFD-based numerical calibration of the porous parameters. Two key modeling strategies are suggested to ensure the pressure prediction accuracy: (1) use SST turbulence model incorporated with an intermittency transition model (SSIT); (2) considerate two-phase flow during the calibration. The results showed that SSIT significantly improved the pressure prediction of the flow between two sheets. Also, unlike HF MBR, the gas phase was observed to be non-negligible during the calibration for FS MBR. The numerically calibrated porous parameters were then applied in a three-dimensional simplified model (SPM), where multiple membrane sheets were treated as one porous zone. The SPM was compared with a realistic model (RM), where all membrane sheets were simulated directly. A similar pressure distribution was observed in both models; however, local flow characteristics (i.e., the acceleration of the flow entering the module zone) were not reflected in the SPM. Hence, it is recommended to use the porous medium approach for global hydrodynamics investigation when the local flow characteristics are not of interest.

Towards the biomimetic design of hollow fiber membrane bioreactors for bioartificial organs and tissue engineering: A micro-computed tomography (μCT) approach

Hollow fiber membrane bioreactors (HFMBs) with cells cultured in the extracapillary space (ECS) have been proposed for bioartificial organs, to assist patients with failing organs, or to produce in vitro engineered biological substitutes of tissues and organs. They have not gained clinical acceptance yet. One factor limiting therapeutic application is the irregular membrane distribution in the HFMB shell, often considered a typical feature of clinical-scale HFMBs. Such distribution does not permit good control of shell spaces, prevents from offering cells a template structure mimicking the tissue-specific extracellular matrix (ECM) and an adequate supply of oxygen and nutrients, and limits control over cell migration, organization, and differentiation in the ECS. In this study, micro-computed tomography and image analysis techniques were used to characterize the space distribution in the shell of HFMBs varying for membrane packing density and bundling technique, and to investigate whether and how it is possible to manufacture HFMBs in which the distribution of intermembrane spaces in the ECS is uniform and biomimetic. Results suggest that the arrangement in HFMBs of hollow fiber membranes bundled in rolled cross-woven mats at high packing density permits to obtain a uniform shell-side membrane distribution with pore size distribution favoring cells migration around the membranes, and mimicking the ECM structure of bone tissue. • HFMBs were equipped with membranes in loose bundles or in cross-woven mats at varying packing density in the ECS. • Voids distribution in ECS was characterized by μCT and image analysis and was compared to natural bone and a synthetic bone substitute. • Results show that in HFMBs with densely packed membranes in cross-woven mats voids distribution is uniform and mimics bone ECM.

The effect of aeration mode on the operational effectiveness and membrane bioreactors for greywater treatment and membrane fouling

This study aims to investigated the effect of aeration mode on membrane bioreactors (MBRs) using a self-designed integrated hollow fiber MBR and flat sheet organic MBR for rural greywater treatment. The pollutant removal efficiency, characteristics of activated sludge and mixed liquor, and mechanisms of membrane fouling were systematically analyzed under intermittent aeration and continuous modes. The results indicate that the permeability of MBRs in intermittent aeration mode is higher than that in the continuous aeration mode when operating at the same aeration rate. Due to the higher extracellular polymeric substance (EPS) and soluble microbial product (SMP) concentrations. The removal rates of TN and TP by both MBRs at the intermittent aeration mode were higher than those in the continuous aeration mode due to the difference in the aeration environment. Compared to the flat-sheet organic membrane, the hollow-fiber membrane surface was more likely to form biofilms, which cause biological fouling.The relative abundance of Thermomonas showed a positive correlation with the EPS concentration, indicating that Thermomonas participates in EPS synthesis. This study provides a theoretical basis for evaluating the influence of aeration modes on MBRs,and would be a useful guide for the better control of membrane fouling and treatment of rural greywater.

Enhanced removal of antibiotics using Eichhornia crassipes root biomass in an aerobic hollow-fiber membrane bioreactor

The impact of water hyacinth (Eichhornia crassipes) root biomass (WHRB) on pharmaceutical wastewater treatment with an aerobic hollow-fiber membrane bioreactor (HF-MBR) was investigated. The performance of the bioreactor was assessed in terms of COD (Chemical Oxygen Demand) and antibiotic removal and membrane biofouling rate. For deeper insight, microbial communities in sludge and biofilm layers were analyzed through Illumina sequencing. The addition of WHRB into the HF-MBR increased the COD (by 6%), as well as antibiotics and transformation products removal efficiency. Removal efficiencies of 97%, 98% and 84% were obtained for removal of erythromycin, sulfamethoxazole, and tetracycline. Furthermore, WHRB modified the biodegradation network, increased the relative abundances of Chloroflexi, Proteobacteria and Nitrospirae and decreased Firmicutes, compared with the control with antibiotics. The addition of WHRB also enriched Actinobacteria and Bacteroidetes while decreasing the phylla Chloroflexi and Saccharibacteria in the biofilm.

Biological removal of gas‐phase H2S in hollow fibre membrane bioreactors

AbstractBACKGROUNDHydrogen sulphide (H2S) must be treated at its emission source to avoid health risks, odour, and corrosion. Conventional physico‐chemical H2S removal technologies (for example, membrane contactors or chemical scrubbers) have several limitations, such as requiring high amounts of absorption chemicals and energy. In contrast, biological H2S removal technologies are environment friendly, easy to operate, and less expensive due to their low energy requirements. In this study, the feasibility of a porous hydrophilic polyethersulfone hollow fibre membrane bioreactor (HFMB) was tested for the biological removal of gas‐phase H2S by employing three lab‐scale reactors (two biotic and one abiotic). The HFMBs were operated at ~20 °C for ~3 months, employing different H2S inlet loading rates (ILR) and an empty bed residence time of 187 s.RESULTSBiotic performance of the HFMBs demonstrated that the removal efficiency (RE) varied between the different inocula and was in the range of 80–100% for the applied H2S ILR of ~5.0–7.5 g m−3 h−1. The RE reached a constant value of ~100% in both biotic reactors at an ILR of ~17.0 g m−3 h−1 when using acclimatized inoculum. The biotic HFMBs demonstrated ~5–9 times higher H2S flux and ~ 20–26 times higher mass transfer compared to the abiotic control. Surface morphology revealed attached microbial growth on the outer surface of the membranes, while the high throughput sequencing confirmed the richness of H2S oxidizing microbial communities on the shell side.CONCLUSIONThe obtained results confirm that the HFMB configuration is suitable for biological treatment of H2S laden waste gas. © 2021 Society of Chemical Industry (SCI).

Long-term performance, membrane fouling behaviors and microbial community in a hollow fiber anaerobic membrane bioreactor (HF-AnMBR) treating synthetic terephthalic acid-containing wastewater

Purified terephthalic acid (PTA) wastewater with properties of poor biodegradation and high toxicity is produced from refining and synthesis of petrochemical products. In this study, a lab-scale hollow fiber membrane bioreactor (HF-AnMBR) fed with synthetic PTA wastewater was operated over 200 days with stepwise decreased hydraulic retention time (HRT) to investigate the long-term performance, membrane fouling mechanism and microbial community evolution. Results showed that a stable chemical oxygen demand (COD) removal rate of 65.8 ± 4.1% was achieved at organic loading rate of 3.1 ± 0.3 g-COD/L-reactor/d and HRT 24 h, under which the methane production rate reached 0.33 ± 0.02 L/L-reactor/d. Further shortening HRT, however, led to the decreased COD removal efficiency and low methane bioconversion. A mild membrane fouling occurred due to the production of colloidal biopolymers and the interaction between increased colloidal substances secreted/cracked by microorganisms and membrane interface. Further 16S rRNA analysis indicated that microbial diversity and richness had changed with the variation of HRT while Methanosaeta, and Methanolinea species were always the dominant methanogens responsible for methane production. The results verify that HF-AnMBR is an alternative technology for PTA wastewater treatment along with energy harvesting, and provide a new avenue toward sustainable petrochemical wastewater management.

Investigation of fouling of surface modified Polyvinyl chloride hollow fiber membrane bioreactor via Zinc oxide-nanoparticles under coagulant for municipal wastewater treatment

In this study, hollow fiber PVC/ZnO-nanocomposite in an MBR was investigated for municipal wastewater treatment. The following parameter were evaluated: BOD, COD, TSS, NTU, TP, TKN. ZnO nanoparticles caused to decrease the contact angle from 78° to 67° for the neat PVC and 0.5 wt% ZNO-nanocomposite membrane, respectively. The majority of the neat membrane resistance was due to irreversible resistance. Because of the antibacterial properties of zinc oxide nanoparticles, with increasing nanoparticles loading, the resistance of irreversible part compared to the reversible resistance experienced a significant decrease. This confirm that the fabricated nanocomposite membranes did not show affinity toward adsorption of the sludge inside the pores hence substantially limited the membrane fouling. The FTIR results showed the reduction of proteins and polysaccharides onto the surface of the nanoparticle-incorporated membranes, approaching the clean PVC membrane. This was most likely due to the antibacterial properties of ZnO NPs. Nitrogen and phosphor removal for PVC0.5 membrane was 99% and 79% and TSS removal up to 100% was achieved. The findings of this study showed that modification of PVC polymer using ZnO nanoparticles with the presence of ferric chloride coagulant is a very effective technique for municipal wastewater treatment to meet the well-known standard levels.

Effects of Scaffold Pore Morphologies on Glucose Transport Limitations in Hollow Fibre Membrane Bioreactor for Bone Tissue Engineering: Experiments and Numerical Modelling.

In the current research, three electrospun polycaprolactone (PCL) scaffolds with different pore morphology induced by changing the electrospinning parameters, spinning time and rate, have been prepared in order to provide a fundamental understanding on the effects pore morphology have on nutrient transport behaviour in hollow fibre membrane bioreactor (HFMB). After determining the porosity of the scaffolds, they were investigated for glucose diffusivity using cell culture media (CCM) and distilled water in a diffusion cell at 37 °C. The scanning electron microscope (SEM) images of the microstructure of the scaffolds were analysed further using ImageJ software to determine the porosity and glucose diffusivity. A Krogh cylinder model was used to determine the glucose transport profile with dimensionless variables within the HFMB. The paper discusses the roles of various dimensionless numbers (e.g., Péclet and Damköhler numbers) and non-dimensional groups of variables (e.g., non-dimensional fibre radius) on determining glucose concentration profiles, especially in the scaffold region. A negative linear relationship between glucose diffusivities across PCL scaffolds and the minimum glucose concentrations (i.e., concentration on the outer fibre edge on the outlet side (at z = 1 and r = 3.2) was also found. It was shown that the efficiency of glucose consumption improves with scaffolds of higher diffusivities. The results of this study are expected to help in optimizing designs of HFMB as well as carry out more accurate up scaling analyses for the bioreactor.