Reactor Contents Research Articles

Optimization of methane production from co-digestion of citrus agro-industrial waste in a two-stage system: Investigation of the effects of organic matter concentration and alkalinization

The essential oils in citrus waste poses challenges for the anaerobic digestion application to energy recovery from these wastes due to the potential to inhibit the bioprocess. The two-stage system is a practical alternative to overcome these limitations of anaerobic co-digestion of citrus peel waste and wastewater. This study proposes to overcome drawbacks associated with the use of these substrates in anaerobic digestion by separating the phases, performing parameters optimization of the methanogenic stage. To obtain optimized conditions for the methanogenic stage, the Rotational Central Composite Design (RCCD) and Response Surface Methodology (RSM) were applied, evaluating the effects of diluting the Fermentation Reactor Content (FRC) of the first stage (35.7%–100%) and alkalinization (up to 0.60 g sodium bicarbonate.gCOD−1), in methane production and organic matter removal. Values from 2100.4 to 6320.6 mLCH4.L−1 were obtained in the experimental design assays, with no inhibition identified by the high substrate concentration, nor by the limonene content (1.5–5.0 mg.L−1). Lower dilution of the fermentation reactor content (90%–100%) resulted in higher accumulated methane production, while the variation in the alkalinization did not imply significant effects on this response. The optimized condition for maximum production potential was obtained with 99.3% of fermentation reactor content and 0.58 gNaCHO3.gCOD−1, reaching a production of 6549.7 mLCH4.L−1, with organic matter removal (rCOD) of 87.1%, and 58.6% of reduction in solid waste content. For this condition, acetogenic metabolism predominance was observed, in the conversion of butyric acid and propionic acid into acetic acid. In the analysis of the microbial community of the optimized condition assay, a high relative abundance of hydrolytic and acidogenic bacteria (AUTHM297, Lachnospiraceae, and Hungateiclostridiaceae) was observed, as well as methanogenic archaea related to acetoclastic, hydrogenotrophic, and methylotrophic methanogenesis (Methanoregula, Methanolinea, Methanomassiliicoccus, Candidatus Methanomethylicus, and Methanofolis).

Kinetic and Thermodynamic Analysis of Chicken Manure Pyrolysis for Sustainable Waste Management in the Poultry Industry

This study explores the kinetics of the pyrolysis process applied to chicken manure as an environmentally sustainable waste management technique within the poultry industry. Pyrolysis, a thermochemical conversion method, involves the decomposition of organic materials in the absence of oxygen, yielding biochar, gases, and bio-oil. Experimental runs were conducted using a fixed-bed reactor, varying reactor temperature and heating rate settings. Pyrolytic conversion was determined by weighing the reactor contents before and after each run, allowing for the construction of pyrolytic conversion curves. Through the application of the Coats-Redfern method, the pyrolysis kinetics was determined. It was found that a second-order kinetics model exhibited better agreement with the experimental data than a first-order model, yielding coefficient of determination (R2) values ranging from 0.99 to 1.00, compared to 0.94 to 0.97 for the first-order model. The apparent activation energy (Ea) was estimated to fall within the range of 140.4 to 151.2 kJ/mol. Additionally, the pre-exponential factors (A) were found to be significantly high, on the order of 1010 min-1, suggesting a low pyrolytic reactivity. The calculated enthalpy of reaction (ΔH) ranged from 134.1 to 145 kJ/mol. Importantly, the energy barrier, represented by the difference between activation energy (Ea) and enthalpy of reaction (ΔH), was determined to be low at 7 kJ/mol. These findings indicate the potential for efficiently and sustainably valorizing chicken waste through pyrolysis. The outcomes of this study provide valuable insights into the kinetics and thermodynamics of chicken manure pyrolysis, supporting its adoption as an energy-efficient and environmentally sound waste management strategy within the poultry industry.

Adapting R4 simplifications of Anaerobic Digestion Model No. 1 (ADM1-R4) for pump-mixed biogas production

Modification of the production chain in biogas generation is a common tactic used in this industry. However, the selection of appropriate reactor configuration and operational parameters is a crucial task. In such cases, mathematical modeling provides great support. Herein, we adapted a simplified version of the Anaerobic Digestion Model No. 1 to a system in which the mechanical stirrer was replaced with an external pump that recirculated the reactor content. Despite having conceptual similarities with continuous stirred-tank reactors, this system exhibited considerable differences in the vertical distribution inside the tank. The model was optimized by using a “genetic algorithm” and “fmincon” function to test both approaches. The new model showed very high accuracy with a mean error of 5.9–9.8%, depending on the mixing intensity, whereas the previous reference models reached 19.7% error. Therefore, compared to the previous models, the simplification of the ordinary differential equation in our new model did not significantly decrease accuracy; in fact, the precision was even higher than before in some cases. Finally, the new model was practically applied to demonstrate its implementation in realistic scenarios.

Neutral Hydrolysis of Post-Consumer Polyethylene Terephthalate Waste in Different Phases

Post-consumer polyethylene terephthalate (PET) was hydrolyzed in pure water over a wide range of temperatures (190–400 °C) and pressures (1–35 MPa) to produce terephthalic acid (TPA). Solid or molten PET was subjected to water as a saturated vapor, superheated vapor, saturated liquid, compressed liquid, and supercritical fluid. The highest TPA yields were observed for the hydrolysis of molten PET in saturated liquid water. Isothermal and non-isothermal hydrolysis of PET was also explored. Rapidly heating the reactor contents at about 5–10 °C/s (“fast” hydrolysis) led to high TPA yields, as did isothermal PET hydrolysis, but within 1 min instead of 30 min. Notably, these conditions resulted in the lowest environmental energy impact metric observed to date for uncatalyzed hydrolysis.

Dispensing Single Drops as Electrochemical Reactors

AbstractA strategy is proposed to generate single microdrops with femtoliter to microliter volumes as a liquid reactor and to guide them towards a reactive surface within a viscous carrier liquid. Reactions of the drop content with the surface are exemplified by exhaustive electrolysis of the reactor content, making use of an ion‐conducting pathway through the carrier liquid. The mechanisms by which the redox‐active species from the aqueous drop reach the electrode surface were established by a combination of time‐lapse microscopy of the drop shape, chronoamperometric recording of the single drop electrolysis, and modelling of the reaction‐transport problem, showing that partitioning over the liquid‐liquid interface must be a key step in this mechanism. The possibilities of reagent delivery and external triggering of a reaction are expanded by the possibility for controlled addition of further dissolved reactants to the liquid microreactor.

Thermal degradation of polyethylene in the presence of a non-acidic porous solid by a continuous flow reactor

Thermal degradation of polyethylene (PE) in the presence of a non-acidic porous solid (silicalite) was performed under atmospheric pressure in a continuous flow reactor, at 420 °C and feeding rate of 0–1.5 kg h−1. Conducting pyrolysis at steady state allowed observations on the behavior of polymers during thermal degradation. Based on collected information about reaction rates and the composition of pyrolysis products as well as of reactor content we could distinguish between the random and the chain-end scissions of polymer macromolecules and we showed that porous silicalite favored the later ones. Although silicalite had no acid reactive centers, it influenced the equilibrium attained at steady state and changed the composition of pyrolysis products. As a result, the rate of double bonds formation strongly increased with the silicalite amount; however the mass rate of pyrolysis was not significantly affected. The macroscopic mechanism for the thermal degradation of polymer explained why the amount of silicalite does not contribute to the improvement of the mass rate of volatilization.

Monitoring of seven industrial anaerobic digesters supplied with biochar

BackgroundRecent research articles indicate that direct interspecies electron transfer (DIET) is an alternative metabolic route for methanogenic archaea that improves microbial methane productivity. It has been shown that multiple conductive materials such as biochar can be supplemented to anaerobic digesters to increase the rate of DIET. However, the industrial applicability, as well as the impact of such supplements on taxonomic profiles, has not been sufficiently assessed to date.ResultsSeven industrial biogas plants were upgraded with a shock charge of 1.8 kg biochar per ton of reactor content and then 1.8 kg per ton were added to the substrate for one year. A joint analysis for all seven systems showed a decreasing trend for the concentration of acetic acid (p < 0.0001), propionic acid (p < 0.0001) and butyric acid (p = 0.0022), which was significant in all cases. Quantification of the cofactor F420 using fluorescence microscopy showed a reduction in methanogenic archaea by up to a power of ten. Methanogenic archaea could grow within the biochar, even if the number of cells was 4 times less than in the surrounding sludge. 16S-rRNA gene amplicon sequencing showed a higher microbial diversity in the biochar particles than in the sludge, as well as an accumulation of secondary fermenters and halotolerant bacteria. Taxonomic profiles indicate microbial electroactivity, and show the frequent occurrence of Methanoculleus, which has not been described in this context before.ConclusionsOur results shed light on the interplay between biochar particles and microbial communities in anaerobic digesters. Both the microbial diversity and the absolute frequency of the microorganisms involved were significantly changed between sludge samples and biochar particles. This is particularly important against the background of microbial process monitoring. In addition, it could be shown that biochar is suitable for reducing the content of inhibitory, volatile acids on an industrial scale.

Model development and control of an auto-refrigerated polystyrene polymerization reactor

Dynamic model development and control of an existing operating industrial continuous bulk free radical styrene polymerization process are carried out to evaluate the performance of auto-refrigerated CSTRs (continuous stirred tank reactors). One of the most difficult tasks in polymerization processes is to control the high viscosity reactor contents and heat removal. In this study, temperature control of an auto-refrigerated CSTR is carried out using an alternative control scheme which makes use of a vacuum system connected to the condenser and has not been addressed in the literature (i.e. to the best of our knowledge). The developed model is then verified using some experimental data of the real operating plant. To show the heat removal potential of this control scheme, a common control strategy used in some previous studies is also simulated. Simulation results show a faster dynamics and superior performance of the first control scheme which is already implemented in our operating plant. Besides, a nonlinear model predictive control (NMPC) is developed for the polymerization process under study to provide a better temperature control while satisfying the input/output and the heat exchanger capacity constraints on the heat removal. Then, a comparison has been also made with the conventional proportional-integral (PI) controller utilizing some common tuning rules. Some robustness and stability analyses of the control schemes investigated are also provided through some simulations. Simulation results clearly show the superiority of the NMPC strategy from all aspects.

Sampling and Analysis in Flow: The Keys to Smarter, More Controllable, and Sustainable Fine‐Chemical Manufacturing

AbstractProcess analytical technology (PAT) is a system designed to help chemists better understand and control manufacturing processes. PAT systems operate through the combination of analytical devices, reactor control elements, and mathematical models to ensure the quality of the final product through a quality by design (QbD) approach. The expansion of continuous manufacturing in the pharmaceutical and fine‐chemical industry requires the development of PAT tools suitable for continuous operation in the environment of flow reactors. This requires innovative approaches to sampling and analysis from flowing media to maintain the integrity of the reactor content and the analyte of interest. The following Review discusses examples of PAT tools implemented in flow chemistry for the preparation of small organic molecules, and applications of self‐optimization tools.

Sampling and Analysis in Flow: The Keys to Smarter, More Controllable, and Sustainable Fine-Chemical Manufacturing.

Process analytical technology (PAT) is a system designed to help chemists better understand and control manufacturing processes. PAT systems operate through the combination of analytical devices, reactor control elements, and mathematical models to ensure the quality of the final product through a quality by design (QbD) approach. The expansion of continuous manufacturing in the pharmaceutical and fine-chemical industry requires the development of PAT tools suitable for continuous operation in the environment of flow reactors. This requires innovative approaches to sampling and analysis from flowing media to maintain the integrity of the reactor content and the analyte of interest. The following Review discusses examples of PAT tools implemented in flow chemistry for the preparation of small organic molecules, and applications of self-optimization tools.

An ambient pressure method for synthesizing NaY zeolite

Abstract Zeolites are vital industrial materials applied widely in the field of heterogeneous catalysis. Porous zeolites are essentially synthesized in the presence of soft or hard templates in processes such as hydrothermal, solvothermal, and ionothermal synthesis. Herein, we demonstrated a facile ambient pressure technique to synthesize NaY zeolite using a glass tube as a reactor and a fluid sealant to create a physical barrier between the reactor contents and the atmosphere. The synthesized zeolite Y was characterized by XRD, SEM, TEM, UV-Raman, N2 sorption, MAS NMR, and XRF spectroscopy. In comparison to the traditional hydrothermal synthesis routes, the avoidance of high-pressure synthesis apparatus not only reduces safety risks but also significantly improves the yield of zeolite products with a crystallinity of 52% and Si/Al = 3.51. Furthermore, the process is leaner, efficient, and reduces costs. Optimum conditions realized for the synthesis of highly crystalline zeolite Y were 90 °C and 18 h crystallization temperature and period respectively, using 1-dodecanol as a sealant. Subsequently, PEG6000 emerged the best among organic templates investigated to improve porosity while maintaining high crystallinity of the zeolite.

Effect of static magnetic field on microbial community during anaerobic digestion

Dairy wastewater is characterized by high concentration of organic compounds and is commonly used for energy production. Methods for enhancement of biogas production include application of magnetizers on the digester to induce static magnetic field (SMF). The study aimed at investigation of Bacteria and Archaea communities during anaerobic digestion of model dairy wastewater exposed to SMF. Magnetic field caused a significant increase in methane production to 373.2 mL/g VS compared to 200.2 mL/g VS in a control reactor and methane content to 56.8% compared to 49.1% in a control reactor. In both reactors, the biomass was dominated by Trichococcus sp. The relative abundance of lactic acid bacteria was of about 10% higher in the reactor exposed to SMF. This higher number of Lactobacillales resulted from a higher acetate production, which additionally caused enhanced growth of Methanosarcinacaea in the reactor exposed to SMF. SMF also stimulated the growth of hydrogenotrophic methanogens.

Optimization of mixing in a Chinese dome digester for tropical regions

Optimization of mixing in a Chinese dome digester for tropical regions

Caproicibacter fermentans gen. nov., sp. nov., a new caproate-producing bacterium and emended description of the genus Caproiciproducens.

A strictly anaerobic bacterial strain designated EA1T was isolated from an enrichment culture inoculated with biogas reactor content. Cells of strain EA1T are spore-forming rods (1-3×0.4-0.8 µm) and stain Gram-negative, albeit they possess a Gram-positive type of cell-wall ultrastructure. Growth of strain EA1T was observed at 30 and 37 °C and within a pH range of pH 5-9. The major components recovered in the fatty acid fraction were C14:0, C16:0, C16:0 DMA (dimethyl acetal) and C16:1 ω7c. Strain EA1T fermented several mono- and disaccharides. Metabolic end products from fructose were acetate, butyrate, caproate and lactate. Furthermore, ethanol, CO2 and H2 were identified as products. The genome consists of a chromosome (3.9 Mbp) with 3797 predicted protein-encoding genes and a G+C content of 51.25 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain EA1T represents a novel taxon within the family Oscillospiraceae. The most closely related type strains of EA1T, based on 16S rRNA gene sequence identity, are Caproiciproducens galactitolivorans BS-1T (94.9 %), [Clostridium] leptum DSM 753T (93.8 %), [Clostridium] sporosphaeroides DSM 1294T (91.7 %) and Ruminococcus bromii ATCC 27255T (91.0 %). Further phenotypic characteristics of strain EA1T differentiate it from related, validly described bacterial species. Strain EA1T represents a novel genus and novel species within the family Oscillospiraceae. The proposed name is Caproicibacter fermentans gen. nov., sp. nov. The type strain is EA1T (DSM 107079T=JCM 33110T).

Comparison of atmospheric pressure and gas-pressurized torrefaction of municipal sewage sludge: Properties of solid products

Gas-pressurized (GP) and atmospheric (AP) torrefaction of municipal sewage sludge were carried out under pure nitrogen and 9%-oxygen nitrogen atmosphere, in order to investigate the effects of reactor and oxygen content on the physicochemical properties, combustion/pyrolysis characteristics and heavy metal availability of solid products. Compared with the solid products from AP torrefaction, the GP torrefied sludge had higher ash content, lower H/C ratio and better hydrophobicity. The oxidative torrefaction produced torrefied sludge of similar properties (except for higher heating value) as normally torrefied sludge in AP and GP, respectively. The activation energy (Ea) required for torrefied sewage sludge (TSS) pyrolysis was 23.56–37.07 kJ/mol by the Coats–Redfern method. Comprehensive combustion characteristics of GP torrefied sewage sludge obtained at torrefaction temperature of 200 °C were much higher than those obtained at torrefaction temperature of 300 °C. Interestingly, GP torrefaction can significantly promote the transformation of heavy metals (e.g. Pb, Zn and Cd) into the residual fraction. The secondary interaction between volatiles and solids in GP torrefaction via gas-pressure-induced deoxygenation behavior dominated the difference of derived-solid products from GP torrefaction and AP torrefaction.

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).&#x0D; 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.&#x0D; 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.&#x0D; 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 .&#x0D; 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.

Impact of Leachate in the Soil Vellalore, Coimbatore

As a consequence of increasing urbanisation and industrialization two major effects have occurred. They are resource exploitation and waste generation. In this view, the present work has been undertaken to study problems of open dumping of MSW at Vellalore disposal site of Coimbatore city. The objectives of the present study are monitor and assess the problems of principle solid waste on land and to investigate the feasibility of energy recover from MSW. Physical and chemical characterization of MSW collected from the disposal site showed that the solid waste has 68.95% of biodegradable fraction with relatively higher percentage of moisture content and 72% of volatile solids contents. Hence, methanation process of MSW can be carried out to recover energy. Leachate characterisation study concludes the that the concentration of Total Organic Carbon, Ammonia nitrogen, volatile solids, pH , electrical conductivity were high in fresh leachate and decreased due to the decomposition of MSW. Soil quality study of Vellalore site showed that the soil texture and colour has been altered to a depth of 60cm.To manage the solid waste problem, high solids anaerobic digestion process was carried out in the laboratory in a batch reactor, which showed that the factor pH was found to be significant in the production of biogas. The concentration of volatile solids, Total carbon, Total nitrogen, due to the decomposition of the reactor contents, which has utilized in the production of gas. During the experimental study a cumulative volume of 3.2 litres of gas was obtained in a period of 120 days from 8 litres volume of the initially loaded MSW.

Virus disinfection for biotechnology applications: Different effectiveness on surface versus in suspension

Virus contamination events in cell culture-based biotechnology processes have occurred and have had a dramatic impact on the supply of life-saving drugs, and thus on the wellbeing of patients. Cleanup requires effective and robust virucidal decontamination procedures for both the liquid reactor content before discharge, as well as facility surfaces to prevent recurrence. Beyond rare contamination events, it is important to implement virucidal disinfection for change-over procedures as effective preventive measure in routine biomanufacturing. Knowledge of the virus inactivation capacity of commonly used disinfectants is therefore important. However, available virus inactivation data often refer to studies performed in suspension only, and not, as often more relevant, to virus inactivation on surfaces. In this study three liquid disinfectants, based on sodium hypochlorite, glutaraldehyde, or hydrogen peroxide/peroxyacetic acid, as well as one gaseous hydrogen peroxide-based disinfectant were investigated for inactivation of lipid enveloped and non-lipid enveloped model viruses, using suspension (for the liquid disinfectants) and carrier assay designs for their virucidal efficacy on surface. The results of these side-by-side investigations demonstrate that depending on the type of application, i.e. routine surface disinfection or decontamination of e.g. a contaminated bioreactor content, the most effective choice of disinfectant may be remarkably different.

Characteristics of MEG Removal from Industrial Wastewater by Sequencing Batch Reactor (SBR)

Background: MEG is extensively applied in the sour gas industry as a hydrate inhibitor. It is toxic in oral drinking and serious injury or death may result from swallowing of pure ethylene glycol and poses a potential hazard to the environment through impact soil. Glycols are harmful to aquatic life. There is little information about the digestion of MEG in the aerobic reactor. Therefore, the feasibility of MEG removal in the aerobic reactor was investigated. Materials and method: Biodegradation of MEG was done in an aerobic SBR reactor with the capacity of 2000 cc and sanitary wastewater as primarily required microorganisms. The experiments were done in the three stages. In stages 1 and 2, 500cc of reactor content was drawn-off and solutions contain 500 cc of 0.073 (wt %) of MEG (for the first stage) and 0.201 (wt %) of MEG (for the second stage) were added to the reactor. In stage 3, 500 cc of wastewater of MEG removal unit in the 2nd refinery of South Pars Gas Company, Iran with a concentration of 4.021 (wt %) of MEG was added to 1500 cc of reactor content. The feed of stage 1 was pure MEG that was diluted in demineralized water but Feed of stage 2 was a dilution of industrial feed of stage 3. Results: In stage 1, after four days, the removal efficiency of more than 80% was obtained. In stage 2 after six days, the efficiency of 20% was obtained. In stage 3, after seven days, more than 70 percent of MEG removal was obtained. Conclusion: by increasing residence time, the removal efficiency of the reactor could be increased acceptably. Therefore, the MEG solution of more than 4 (wt %) of MEG can be treated biologically.

Retention marker excretion suggests incomplete digesta mixing across the order primates

The digestive tract of animals, and the patterns how passage markers are excreted from them, have been fruitfully compared to chemical reactor models from engineering science. An important characteristic of idealized reactor models is the smoothness of the curves plotting marker concentrations in outflow (i.e., faeces) over time, which is the result of the assumed complete mixing of the marker with the reactor contents. Published excretion patterns from passage experiments in non-primate mammals appear to indicate a high degree of digesta mixing. In order to assess whether marker excretion graphs from primates differ from ideal outflow graphs, we performed passage experiments in eight individuals of three foregut-fermenting species (Pygathrix nemaeus, Trachypithecus auratus and Semnopithecus vetulus), and added them to available marker excretion curves from the literature. In the resulting collection, 23 out of a total of 25 patterns in foregut fermenters (21 individuals of 10 species from 7 studies), and 13 out of 15 in hindgut fermenters (9 individuals of 2 species from 2 studies), showed an irregular, ‘spiky’ pattern. We consider this proportion to be too high to be explained by experimental errors, and suggest that this may indicate a taxon-wide characteristic of particularly incomplete digesta mixing, acknowledging that further data from less related primate species are required for corroboration. Our hypothesis is in accordance with previous findings of a comparatively low degree of ‘digesta washing’ (differential retention of particulate and fluid digesta) in primates. Together with literature findings that suggest a low chewing efficiency in primates compared to other mammals, these observations indicate that in contrast to other herbivores, the success of the primate order is not derived from particularly elaborate adaptations of their ingestive and digestive physiology.