Batch Mode Research Articles

Online boxplot derived outlier detection

AbstractOutlier detection is a widely used technique for identifying anomalous or exceptional events across various contexts. It has proven to be valuable in applications like fault detection, fraud detection, and real-time monitoring systems. Detecting outliers in real time is crucial in several industries, such as financial fraud detection and quality control in manufacturing processes. In the context of big data, the amount of data generated is enormous, and traditional batch mode methods are not practical since the entire dataset is not available. The limited computational resources further compound this issue. Boxplot is a widely used batch mode algorithm for outlier detection that involves several derivations. However, the lack of an incremental closed form for statistical calculations during boxplot construction poses considerable challenges for its application within the realm of big data. We propose an incremental/online version of the boxplot algorithm to address these challenges. Our proposed algorithm is based on an approximation approach that involves numerical integration of the histogram and calculation of the cumulative distribution function. This approach is independent of the dataset’s distribution, making it effective for all types of distributions, whether skewed or not. To assess the efficacy of the proposed algorithm, we conducted tests using simulated datasets featuring varying degrees of skewness. Additionally, we applied the algorithm to a real-world dataset concerning software fault detection, which posed a considerable challenge. The experimental results underscored the robust performance of our proposed algorithm, highlighting its efficacy comparable to batch mode methods that access the entire dataset. Our online boxplot method, leveraging dataset distribution to define whiskers, consistently achieved exceptional outlier detection results. Notably, our algorithm demonstrated computational efficiency, maintaining constant memory usage with minimal hyperparameter tuning.

New Solutions in Single-Cell Protein Production from Methane: Construction of Glycogen-Deficient Mutants of Methylococcus capsulatus MIR

The biotechnology of converting methane to single-cell protein (SCP) implies using fast-growing thermotolerant aerobic methanotrophic bacteria. Among the latter, members of the genus Methylococcus received significant research attention and are used in operating commercial plants. Methylococcus capsulatus MIR is a recently discovered member of this genus with the potential to be used for the purpose of SCP production. Like other Methylococcus species, this bacterium stores carbon and energy in the form of glycogen, particularly when grown under nitrogen-limiting conditions. The genome of strain MIR encodes two glycogen synthases, GlgA1 and GlgA2, which are only moderately related to each other. To obtain glycogen-free cell biomass of this methanotroph, glycogen synthase mutants, ΔglgA1, ΔglgA2, and ΔglgA1ΔglgA2, were constructed. The mutant lacking both glycogen synthases exhibited a glycogen-deficient phenotype, whereas the intracellular glycogen content was not reduced in strains defective in either GlgA1 or GlgA2, thus suggesting functional redundancy of these enzymes. Inactivation of the glk gene encoding glucokinase also resulted in a sharp decrease in glycogen content and accumulation of free glucose in cells. Wild-type strain MIR and the mutant strain ΔglgA1ΔglgA2 were also grown in a bioreactor operated in batch and continuous modes. Cell biomass of ΔglgA1ΔglgA2 mutant obtained during batch cultivation displayed high protein content (71% of dry cell weight (DCW) compared to 54% DCW in wild-type strain) as well as a strong reduction in glycogen content (10.8 mg/g DCW compared to 187.5 mg/g DCW in wild-type strain). The difference in protein and glycogen contents in biomass of these strains produced during continuous cultivation was less pronounced, yet biomass characteristics relevant to SCP production were slightly better for ΔglgA1ΔglgA2 mutant. Genome analysis revealed the presence of glgA1-like genes in all methanotrophs of the Gammaproteobacteria and Verrucomicrobia, while only a very few methanotrophic representatives of the Alphaproteobacteria possessed these determinants of glycogen biosynthesis. The glgA2-like genes were present only in genomes of gammaproteobacterial methanotrophs with predominantly halo- and thermotolerant phenotypes. The role of glycogen in terms of energy reserve is discussed.

Sustainable Banana-Waste-Derived Biosorbent for Congo Red Removal from Aqueous Solutions: Kinetics, Equilibrium, and Breakthrough Studies

This study investigates the adsorption of Congo red (CR) dye from wastewater using banana peel biochar (BPBC) in both batch and fixed-bed column modes. BPBC was characterized using FTIR, SEM, XRD, TGA, and BET analysis, revealing a predominantly mesoporous structure with a surface area of 9.65 m2/g. Batch adsorption experiments evaluated the effectiveness of BPBC in removing CR, investigating the influence of the BPBC dosage, initial CR concentration, and solution pH. Results showed optimal CR removal at pH levels below 4, suggesting a favorable electrostatic interaction between the adsorbent and the dye. Furthermore, a pseudo-first-order kinetic model best described the adsorption process. The Freundlich isotherm provided a better fit compared to the Langmuir and Dubinin–Radushkevich (D-R) models, implying a heterogeneous adsorption surface. The calculated maximum adsorption capacity (Qm) from the Langmuir model was 35.46 mg/g. To assess continuous operation, breakthrough curves were obtained in fixed-bed column experiments with varying bed heights (1–3.6 cm). The results demonstrated efficient CR removal by BPBC, highlighting its potential for wastewater treatment. Finally, this study explored the feasibility of BPBC regeneration and reuse through four adsorption–desorption cycles.

Preparation and Characterization of Ferrihydrite: Application in Arsenic Removal from Aqueous Solutions

Arsenic pollution is a public health hazard in Burkina Faso due to its impact on human health and water resources. To mitigate this pollution, ferrihydrite material has been synthesized and characterized to be used as adsorbent for arsenic removal in aqueous solutions. This study aimed to contribute to improve of access to clean drinking water by removing arsenic from water using ferrihydrite. Arsenic species such as As(III) and As(V) were removed through batch adsorption. Experiments were carried out in batch mode using arsenic aqueous solutions. The characterization of ferrihydrite using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDX), X-ray Diffraction (XRD), Infrared (IR), and Brunauer Emmett Teller (BET) showed that an amorphous and microporous 2-line ferrihydrite. The total specific surface area and pH at point of zero charge (pHpzc) were 184.518 m²/g and 9.41, respectively. The optimal adsorbent doses were 4 g/L for As (V) and 8 g/L for As (III). The optimum pH range for the adsorption of As (V) and As (III) was between 2 and 10, The maximum adsorption capacity was 15.07 mg/g for As(V) and 13.01 mg/g for As(III) with increasing concentration between 2 and 16 mg/L. Equilibrium time for As (V) and As (III) on ferrihydrite was found to be 720 min and 960 min, respectively. The adsorption of As(V) and As(III) was consistent with the Langmuir monolayer model on ferrihydrite. Arsenic adsorption was occurred according to spontaneous chemical reaction. Arsenic removal was occurred on a monolayer following the pseudo-second order kinetic.

Production and Characterization of Activated Carbon Derived from Costus Afer Leaves (C. afer) for the Adsorption of Methylene Blue Dye from an Aqueous Solution

In this work, Costus afer leaves (C. after) was utilized as an agricultural waste material for the synthesis of activated carbon (AC) used for the adsorption of methylene blue dye from its aqueous solution. The raw material was prepared, chemically activated using KHCO3 with an impregnation ratio of 1:3, and later carbonized at a temperature of 700℃ in an inert N2 atmosphere for 1hour to produce activated carbon. The proximate analysis of the biomass revealed the percentage of ash content, moisture content, volatile matter, and fixed carbon present in the waste biomass. The raw and activated carbon produced were characterized using various tests such as: Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray (EDX), Fourier Transform Infrared-(FTIR) Spectrometry, X-Ray Fluorescence (XRF), and Brunauer-Emmett-Teller (BET). The results revealed that the SBET of the biomass increased from 400m2/g to 600m2/g after activation. Adsorption studies were carried out in batch mode to determine the influencing factors of adsorption with varying adsorbent dosage, contact time, and pH values. The adsorption experiment revealed high adsorption efficiency at an optimum parameter of dosage (0.2g), contact time (10 min), and pH (8) with a 70.58% removal of methylene blue dye. An increase in dosage, contact time, and pH above the optimum parameter leads to a decrease in percentage removal. The adsorption capacity was achieved using adsorption isotherm models like Langmuir and Freundlich. Adsorption of methylene blue validated the Langmuir model with an R2 of 0.999 and a Qm of 11.83 mg/g. These results show that activated carbon prepared from Costus afer leaves constitutes an effective low-cost material for the adsorption of Methylene dye from wastewater.

Adsorptive performance of graphene oxide-activated carbon composite for simultaneous removal of diclofenac sodium and ibuprofen from aqueous solutions in batch mode

Adsorptive performance of graphene oxide-activated carbon composite for simultaneous removal of diclofenac sodium and ibuprofen from aqueous solutions in batch mode

An up-scaled biotechnological approach for phosphorus-depleted rye bran as animal feed

Side streams from the milling industry offer excellent nutritional properties for animal feed; yet their use is constrained by the elevated phosphorus (P) content, mainly in the form of phytate. Biotechnological P recovery fosters sustainable P management, transforming these streams into P-depleted animal feed through enzymatic hydrolysis. The enzymatic P mobilization not only enables P recovery from milling by-products but also supports the valorization of these streams into P-depleted animal feeds. Our study presents the scalability and applicability of the process and characterizes the resulting P-depleted rye bran as animal feed component. Batch mode investigations were conducted to mobilize P from 100 g to 37.1 kg of rye bran using bioreactors up to 400 L. P reductions of 89% to 92% (reducing from 12.7 gP/kg to 1.41–1.28 gP/kg) were achieved. In addition, High Performance Ion Chromatography (HPIC) analysis showed complete depletion of phytate. The successful recovery of the enzymatically mobilized P from the process wastewater by precipitation as struvite and calcium hydrogen phosphate is presented as well, achieving up to 99% removal efficiency. Our study demonstrates a versatile process that is easily adaptable, allowing for a seamless implementation on a larger scale.Graphical

Development of microbial desalination cells for the treatment of reverse osmosis reject water: A new benchtop approach

To address the growing global demand for usable water, there is an immediate necessity to enhance wastewater treatment systems. A continuous mode adaption of the conventional three-chamber microbial desalination cell (MDC) configuration was used, with gravity facilitating the flow of residential reject water for desalination. Initially, operating in batch mode with a 100 mL treatment volume, the single microbial desalination machine was expanded to 300 mL in continuous mode, capable of treating 5 L of home refuse water over 36 days. The batch mode MDC had a maximum current and power density of 3.81 µA/cm2 and 0.337 µW/cm2, resulting in 76 % desalination and 83.9 % COD eradication rates. Scaling up increased the MDC's performance, reaching a maximum of 0.45 µW/cm2 and 5.31 µA/cm2, which was 1.3 times greater than batch mode operation. The current work demonstrates the feasibility of microbial desalination cells and their novel approach for treating much higher quantities of reverse osmosis (R.O.) saline water in a comparable period of roughly 36 days. It emphasizes the actual limits when dealing with real-world wastewater samples, presenting a unique path for biotechnology by simultaneously generating bio-electricity and tackling future contaminants. Furthermore, incorporating desalination chambers with microbial fuel cells increases efficiency and opens up new options for enhanced wastewater treatment, resource recovery, and bioenergy generation. This pioneering strategy uses innovative membrane technologies and microbial optimization approaches to push the limits of desalination.

Autocalibration based on dilution of a single concentrated standard is used for the determination of silicate in sea water by the modified molybdenum blue method

The silicate (Si) molybdenum blue method was modified by combining oxalate and ascorbic acid into a single reagent and was used for determining Si in sea water samples. The first step of this automated assay protocol was designed to perform either a calibration by a single Si standard prepared in deionized (DI) water, or to dilute samples in the range of 0–160 μM Si to fit into 0–20 μM Si calibration range using a 20 cm flow cell. By designing the assay protocol to function in batch mode, the influence of salinity on calibration was eliminated, thus making the method suitable for analysis of samples collected in the open ocean, coastal areas, or rivers. Reproducibility and accuracy of this method were evaluated by analysis of certified sea water reference materials. Phosphate (P) does not interfere significantly if the Si:P ratio is 4:1 or larger. The limit of detection was 514 nM Si, r.s.d. 2.1 %, sampling frequency 40 s/h, reagent consumption 700 μL/sample, and using deionized water as the carrier solution.

Iron particle-integrated anammox granules in baffled reactor: Enhanced settling property and nitrogen removal performance

This study evaluates iron particle-integrated anammox granules (IP-IAGs) to enhance wastewater treatment efficiency. The IP-IAGs resulted in notable improvements in settleability and nitrogen removal. The settling velocity of IP-IAGs increased by 17.91 % to 2.92 ± 0.20 cm/s, and the total nitrogen removal efficiency in batch mode improved by 6.82 %. These changes indicate enhanced biological activity for effective treatment. In continuous operation, the IP-IAGs reactor showed no accumulation of nitrite until 40 d, reaching a peak nitrogen removal rate (NRR) of 1.54 kg-N/m3·d and a nitrogen removal efficiency of 82.61 %. Furthermore, a partial nitritation-anammox reactor that treated anaerobic digestion effluent achieved a NRR of 1.41 ± 0.09 kg-N/m3·d, proving the applicability of IP-IAGs in real wastewater conditions. These results underscore the potential of IP-IAGs to enhance the efficiency and stability of anammox-based processes, marking a significant advancement in environmental engineering for wastewater treatment.

Adsorption of cephalexin from aqueous solutions by MIL-101 (Fe) metal–organic framework

Adsorption using metal–organic structures is one of the methods of eliminating antibiotics that has shown promising results so far. In this study, to remove the antibiotic cephalexin from water, metal–organic structure MIL-101(Fe) was used. After making the adsorbent, adsorption tests were carried out to remove cephalexin from the aqueous solution in batch mode. The effect of parameters, including initial adsorbent dosage, initial cephalexin concentration, pH, time, and temperature on the adsorption was investigated. Kinetic data showed that the cephalexin adsorption on MIL-101(Fe) followed the pseudo-second-order model. The cephalexin adsorption isotherm was consistent with Langmuir model, and the maximum absorption capacity at 45 °C was 16.44 mg/g. The thermodynamic parameters showed that the cephalexin adsorption on adsorbent is spontaneous, endothermic, and accompanied by an increase in entropy. Therefore, MIL-101(Fe) can be a promising adsorbent to remove cephalexin from aqueous solutions.

Optimization of continuous astaxanthin production by Haematococcus pluvialis in nitrogen-limited photobioreactor

The industrial production of astaxanthin from Haematococcus pluvialis is mainly operated following a two-stage cultivation strategy in photobioreactors (PBRs) operating in batch mode. This study provides a strategy for optimizing continuous astaxanthin production in a one-stage approach, by optimizing both astaxanthin accumulation and biomass productivity of H. pluvialis under nitrogen-limited condition. To achieve the good balance in culture conditions to maintain growth under nitrogen-limited conditions, while triggering significant astaxanthin accumulation in reddish vegetative cells, the role of light absorption, as represented by the mean rate of photon absorption (MRPA), and nitrate concentration was especially investigated. For that purpose, H. pluvialis cultures were grown in a flat-panel PBR with constant dilution rate D of 0.015 h−1, different photon flux densities PFDs ranging from 75 to 750 μmolhν·m−2·s−1 and different nitrogen concentration levels in the feeding medium [NO3−] of 1, 3 and 8.8 mM. A parabolic relationship between MRPA and astaxanthin production rate was obtained. This indicated that astaxanthin synthesis was limited by the MRPA, opening further optimization by adjusting incident light intensity, nitrogen concentration in the feeding medium or culture dilution rate. After optimization of operating conditions, we demonstrated that a large quantity of astaxanthin can be produced in continuous mode, following then a one-stage strategy which may be advantageous for industrial use. A maximum astaxanthin productivity of 1.27 ± 0.03 g·m−2·d−1 with an astaxanthin accumulation of 3.9 ± 0.2 % DW was reached for the culture featuring MRPA of 9000 μmolhν·kgx−1·s−1. The process was also proved reversible, allowing to tailor the biomass composition and physiological state (from green to red cells enriched in astaxanthin) by adjusting operating conditions, opening perspectives from an optimized coupling with downstream processing steps.

New insights on antimony removal and recovery from water and wastewater using iron-coated cork granulates: Desorption on batch and fixed-bed column systems

This work investigated Sb adsorption–desorption using iron-coated cork granulates (ICG) in both batch and continuous modes to evaluate the materiaĺs adsorption and regeneration performance, as well as the possibility of antimony recovery. A fixed-bed column filled with ICG, demonstrated maximum adsorption capacities of 13 ± 2 mg g−1 and 10 ± 1 mg g−1 for Sb(III) and Sb(V), respectively, at pH 3. ICG was able to remove Sb within the WHO guideline of 20 μg/L at pH 6. Among the different classes of eluents tested for Sb(V) desorption, the acids achieved the highest desorption rates − 81 ± 9 % and 66 ± 8 % for HCl 1 M and ascorbic acid 0.1 M, respectively. The desorption kinetics showed that HCl 1 M reached equilibrium in 4 h, but ascorbic acid 0.1 M took 16 h. This work presents an ecological emerging solution for antimony removal and recovery from water and wastewater

High power illumination system for uniform, isotropic and real time controlled irradiance in photoactivated processes research

In the study of photocatalytic and photoactivated processes and devices a tight control on the illumination conditions is mandatory. The practical challenges in the determination of the necessary photonic quantities pose serious difficulties in the characterization of catalytic performance and reactor designs and configurations, compromising an effective comparison between different experiments.To overcome these limitations, we have designed and constructed a new illumination system based in the concept of the integrating sphere (IS). The system provides uniform and isotropic illumination on the sample, either in batch or continuous flow modes, being these characteristics independent of the sample geometry. It allows direct, non-contact and real time determination of the photonic quantities as well as versatile control on the irradiance values and its spectral characteristics. It can be also scaled up to admit samples of different sizes without affecting its operational behaviour.The performance of the IS system has been determined in comparison with a second illumination system, mounted on an optical bench, that provides quasi-parallel beam (QPB) nearly uniform illumination in tightly controlled conditions. System performance is studied using three sample geometries: a standard quartz cuvette, a thin straight tube and a microreactor by means of potassium ferrioxalate actinometry. Results indicate that the illumination geometry and the angular distribution of the incoming light greatly affect the absorption at the sample. The sample light absorption efficiency can be obtained with statistical uncertainties of about 3% and in very good agreement with theoretical estimations.

Synthetic greywater treatment using a scalable granular activated carbon bioelectrochemical reactor

Greywater reuse has emerged as a promising solution for addressing water shortages. However, greywater needs treatment before reuse to meet the required water quality standards. Conventional wastewater treatment technologies are unsuitable for recreating highly decentralized domestic greywater. This study evaluated bioelectrochemical reactors (BERs) with granular activated carbon (GAC) as a sustainable alternative for developing decentralized and low-cost biological treatment systems. BERs using GAC as the anode material and conventional GAC biofilters (BFs) for synthetic greywater treatment were operated in batch mode for 110days in two stages: (i) with polarized anodes at −150 mV vs. Ag/AgCl and (ii) as a microbial fuel cell with an external resistance of 1 kΩ. Anode polarization produced an electrosorption effect, increasing the ion removal of the BERs. Power production during the operation and cyclic voltammetry tests of the extracted granules revealed electrochemically active biofilm development on the BERs. Although low power density (0.193 ± 0.052 µW m−3) was observed in BERs, they showed a similar performance in sCOD removal (BER = 91.6–89.6 %; BF = 96.2–93.2 %) and turbidity removal (BER = 81–82 %; BF = 30–62 %) to BFs that used 50% aeration. Additionally, scanning electron microscopy of sampled granules showed higher biomass formation in BER granules than in BF granules, suggesting a higher contribution of sessile (vs. planktonic) cells to the treatment. Thus, the results highlight the synergistic removal effect of the GAC-based BER. The scalable design presented in this study represents a proof-of-concept for developing BERs to use in decentralized greywater treatment systems.

Periodic on-off operations of the self-cycling ethanol fermentation process: Stability analysis and optimal operation strategies

Fuel ethanol is highlighted for being renewable and carbon neutral, but a multi-scale challenge exists that hampers its role as a future energy substitute, and with the breakthrough of cellulose pretreatment and enzyme hydrolysis technology, fermentation itself has become one of the main limiting factors for process enhancement. To tackle the problem, this paper studies periodic operation strategies to improve process performance and avoid possible instabilities. Firstly, superiority by periodic operation over the corresponding steady-state operation is verified. Then, to settle the problem of possible instabilities under impulsive control, stability of state-impulsive control is conducted and for the studied case, any self-cycling fermentation starts from batch mode with 50 % discharge-and-refill portion exhibits superior repeatability property, which allows continuous fermentation to operate under very slow overall dilution rate to cope with the extreme slow fermentation rate. Finally, on-off operation problem is formulated that is governed by a multidimensional nonlinear system, affine to the manipulated variable that is under the isoperimetric constraint; with the use of Pontryagin maximum principle, the optimal synthesis of the optimal strategies under integral constraint is computed out, and a practically plausible on-off operation strategy for ethanol fermentation is formulated with guaranteed periodic stability and optimality.

Polypyrrole-encapsulated metal oxide nanocomposite for adsorptive abatement of anionic dye from dye laden wastewater: Cost analysis and scale up design

The present work demonstrates the fabrication of an organometallic material i.e. polypyrrole-encapsulated zinc oxide (PPy@ZnO) nanocomposite for adsorptive elimination of Eriochrome black-T (EBT) dye from water. The specific surface area and pore volume of the PPy@ZnO nanocomposite were observed to be 28.726 m2/g and 0.086 cc/g, respectively. At optimum experimental conditions of solution pH; 4.0, PPy@ZnO nanocomposite dose: 1.0 g/L, contact time: 30 min and initial EBT dye concentration: 50 mg/L, maximum EBT dye removal efficiency of ∼94±1.86% was obtained. The pseudo-second-order kinetic and Langmuir isotherm model provides the best fit for the adsorption experiments, with maximum EBT dye adsorption capacity of 277.78 mg/g. The prominent adsorption mechanisms include the hydrogen bonding, π–π interactions, and electrostatic attraction. The adsorption study is spontaneous (ΔG° < 0) and endothermic (ΔH° > 0, ΔS° > 0) in nature as indicated by the thermodynamics study. The reduction in EBT dye removal efficiency was insignificant (∼10±0.94%) in surface water as compared to other real water samples. Monovalent anions (i.e., NO3–and Cl–) have minimal impact on EBT removal efficiency with reduction in removal efficiencies in the range of 4.0±1.54% to ∼11.0±1.93%. Regeneration study suggests an overall ∼20±1.45% decrease in the EBT dye removal efficiency after 5th cycle of regeneration. Response surface methodology suggests the maximum adsorption efficacy of 95±1.68% at initial EBT dye concentration of 35 mg/L, PPy@ZnO dose of 0.85 g/L and contact time of 40 min. The estimated synthesis cost of PPy@ZnO nanocomposite was determined to be ∼117 USD/kg. Batch mode scale-up design suggests a minimum of 87.48 g of PPy@ZnO nanocomposite needs to be applied to treat 50 mg/L of EBT dye loaded wastewater (50 L volume) with 95% dye removal efficiency.

NA-ALGINATE BEADS OF CALCIUM / IRON-LAYERED DOUBLE HYDROXIDE FOR TREATING WATER CONTAMINATED WITH AMOXICILLIN ANTIBIOTIC

The objective of this study was to prepare an adsorbent material from eggshells of chicken banished to the ambient as wastes to satisfy the ecological requirements of sustainable. The preparation process based on the extraction of calcium ions from eggshells and these ions must be reacted with iron to form nanoparticles of (Ca/Fe)-layered double hydroxides (LDHs) which immobilized as Na-alginate beads. Molar ration of calcium to iron, pH and dosage of LDH nanoparticles must be equal to 1, 12 and 5 g/100 mL to ensure that the prepared beads have highest ability to remove of Amoxicillin (AMOX) antibiotic with removal efficiency equal to 32% for operational conditions of Co=100 mg/L, beads dosage=0.5 g/50 mL, speed=200 rpm, pH=7 for 3 hrs. To increase this efficiency to ≥ 90%, best conditions must be time 90 min, pH 7, and beads mass 1.2 g/ 50 mL for Co 100 mg/L at 200 rpm in the batch mode. The Pseudo second order has high capability in the description of such tests with coefficient of determination (R2) ≥ 0.9924 and sum of squared error (SSE) ≤ 0.1287. Hence, the sorption of AMOX onto beads is governed by the chemisorption process. The reflections of XRD analysis proved the presence of (Ca/Fe)-LDH nanoparticles with size of 13.49 nm, calcium hydroxide (Ca(OH)2) and calcium carbonate (CaCO3)

A novel integrated membrane bioreactor-stirred tank bioreactor system for simultaneous biodegradation of bisphenol A contaminated wastewater and biopolyol production: An approach towards circular bioeconomy

The present work examined the biodegradation of bisphenol A (BPA) under batch and continuous modes using hydrocarbonoclastic bacterium, Pseudomonas aeruginosa PR3. The strain showed great biodegradation potential under batch shake flask and stirred tank reactor. Bacterial growth was considerably inhibited at initial BPA concentrations > 50 mg/L. Further, membrane bioreactor (MBR) for BPA biodegradation was also evaluated under different inlet BPA concentration and hydraulic retention time (HRT) and the maximum BPA removal efficiency of 94.4 % was attained with an influent BPA concentration of 25 mg/L at 5 d of HRT. MBR also showed better performance under shock loading conditions. Identification of BPA biodegraded pathways was also performed using liquid chromatography-mass spectrometry, elucidating the different metabolites and end products formed. A subsequent enhancement in BPA removal efficieny was also observed owing to the microfiltration system of MBR that was applied to separate bacterial biomass from effluent. The maximum removal efficiency was further enhanced to 98.5 % under the same operational schedule. As the strain has the ability to produce extracellular diol synthase enzyme which transforms oleic acid into the biopolyol 7,10-dihydroxy-8(E)-octadecenoic acid, the effluent containing the enzymes was supplemented with 1 % (v/v) oleic acid under whole cell and cell-free approaches. Cell-free technique showed an enhanced bioconversion efficiency in comparison to the traditional whole cell approach. Further, the produced biopolyol was characterized using Fourier transform infrared spectroscopy, thermogravimetry, differential scanning calorimetry, and 1H nuclear magnetic resonance analyses and also depicted the antibacterial activity.

Bioremoval of lead ion from the aquatic environment using lignocellulosic (Zea mays), thermodynamics modeling, and MC simulation

AbstractLead (Pb+2) ions considered a crucial neurotoxic heavy metal result in serious troubles in the live biological environment including poisoning, and liver and kidney shortage, in addition to anemia, hepatitis, encephalopathy, and renal syndrome. In the current study, the biomass of Zea mays (ZMS) was prepared as a biosorbent for the elimination of Pb+2 ions from the aquatic environment in batch mode relevant to contact time, pH solution, biosorbent dose, and temperature. The Zea mays biomass was characterized using an SEM microscope coupled with EDX, FTIR, XRD, and BET surface area analysis to investigate the modification of chemical structure for the biosorption system. According to the biosorption experiments, the supreme biosorbent capability of ZMS approaches 16.9 mg/g for 180 min at pH = 5.5. The evaluation of kinetics analysis reveals that the (Pb+2) biosorption by ZMS was better described with pseudo-second-order kinetics. In addition, the nonlinear regression of Freundlich, Langmuir, Temkin, and Elovich isothermal models was modeled to the equilibrium data, and it was deduced that the Langmuir isotherm provides a better fit than Langmuir based on the correlation coefficient values. The thermodynamic factors were calculated for this biosorption process in which the lead ions are sequestered by the ZMS. According to these factors, it was elucidated that the (Pb+2) ions biosorption onto the Zeamays sponge is exothermic and spontaneous. In addition, Monte Carlo (MC) simulations were conducted to screen the adsorption competence of pigments and ligands in Zea mays for Pb+2 ions adsorption. The outputs of experimental and simulation studies proved the potentiality of Zea mays sponge (ZMS) as a promising biosorbent for eliminating heavy metallic elements from aqueous media.