Growth Rate Of Microorganisms Research Articles

The reduction of viscosity of heavy crude with micro-organisms

ABSTRACT This research investigates use of microorganisms (Pseudomonas aeruginosa, Bacillus subtilis and, Klebsiella spp) to reduce viscosity of heavy crude oil. It focuses on determination of abilities of microorganisms singly and in association to reduce viscosity of heavy crude oil, effects of secondary microbial injections and the significance in MEOR projects. At constant temperature of 29°C and within a 7-min investigative duration, microorganisms were injected twice into 9 Erlenmeyer flasks containing 50 ml sterile heavy crude oil (initial viscosity of 382cP) with changes in viscosities recorded 2 and 3 minutes after inoculations. The short investigative duration supports key assumptions of zero growth and death rates of microorganisms. The 10th flask without any microorganism served as control and was subject to the same environmental conditions as test flasks. Three minutes after initial inoculation of Klebsiella sp, Pseudomonas sp, and Bacillus sp into heavy crude, viscosities were reduced to 155 cP, 170 cP, and 188 cP, respectively; a reduction of more than 50% of original viscosity. With two bacteria mixtures (Pseudomonas sp + Klebsiella sp, Bacillus sp + Pseudomonas sp and Bacillus sp + Klebsiella sp), increase in average rate of change in viscosity were noted (3.00, 5.00 and 11.00 Cp/minutes, respectively), in all samples, except Pseudomonas sp + Klebsiella sp. The effect of second injection of microbes, were less effective (3.26–14.67%) and impacts on overall reductions were less. The correlation, r, after first and second inoculations were −1.00 and −0.98, respectively; a strong negative relationship between viscosities of heavy crude (Cp) and concentration of microbes.

Sonication treatment of pomegranate juice containing Saccharomyces cerevisiae and Byssochlamys fulva: Thermodynamic and predictive modeling after treatment and during shelf life.

The effect of ultrasound treatment (100 W, 30 kHz; 50 and 100% amplitudes) on inactivation of Saccharomyces cerevisiae and Byssochlamys fulva in pomegranate juice and shelf life of the juice during storage at different temperatures (5, 15 and 30 °C) for 30 days was modeled using predictive and thermodynamics models. The Baranyi and square root type models were implemented to determine the growth rate of microorganisms. It was predicted that the minimum growth temperature (Tmin) of B. fulva increased by increasing sonication amplitude, however, the Tmin of S. cerevisiae was not function of sonication amplitude. The predicted shelf life was shown to be in good agreement with the measured sensorial shelf life. Increasing the temperature from 5 to 35 °C, reduced the shelf life from 17.5 to 3.5 days for B. fulva and from 15 to 5 days for S. cerevisiae. Moreover, for B. fulva, the activation energy (Ea) decreased from 43.4 to 27.5 kJ/mol by increasing the amplitude, while no significant change was observed for S. cerevisiae. Besides, thermodynamics properties of the shelf life such as enthalpy (), entropy () and Gibbs free energy ( were proven to be suitable measures to determine the microbial spoilage reaction.

The survival investigation of sonicated soy sauce fermentation yeast strains using a spectrophotometer

The present work demonstrated a method to determine the growing activities of typical soy sauce fermentation yeasts under sonication stimulation in stress and/or enriched conditions. The yeast activities were determined using a programmed spectrophotometer which automatically records the optical density (OD) of the growth media. The increasing OD values were directly proportionally to the amount of yeast cells within the growth media. Spectrometry method provides a typical sigmoidal curve with the lag time, maximum growth rate, and average growth rate of microorganisms. Activities of two industrial yeast strains (Zygosaccharomyces spp. and Candida spp.) under sonication stimulations (0.5 cycles, 60 amplitude) at different salt contents (1, 3, and 5%), glucose contents (5, 10, and 15%), sonication durations (10, 20, and 30 min), and incubation temperatures (30 and 37°C) were investigated in a 24-h growth cycle model system by one-factor-at-a-time (OFAT) design. Overall, sonication treatment in the presence of salt was not lethal to yeast cells. The maximum growth rate of both yeast strains was significantly reduced (p < 0.05) when the sample was treated with 5% salt content coupled with sonication. However, when the sample was further enriched with glucose at 10%, it yielded significantly highest growth rate (0.1310 ± 0.0107 OD/h). Finally, 10 min sonication and 30°C incubation temperature were found to be better as compared to the other treatment combinations. Sonication did not exert any detrimental effect on investigated yeasts, and stimulated the growth when enrichment was appropriately provided.

Simulation of Methane Gas Production Process from Animal Waste in a Discontinuous Bioreactor

Due to the importance of environmental protection and the need to use new energy and alternative to conventional fuels, renewable energy has received much attention. Due to this necessity, a discontinuous bioreactor producing methane gas from animal waste has been modeled and simulated in this research. Monod kinetics was used to express the relationship between the growth rate of microorganisms and substrate concentration. The fourth-order Rong Kuta numerical method solved the substrate consumption and production of microorganisms and methane gas. The effect of the initial concentration of microorganisms on methane production has also been investigated. The initial concentrations of substrate and microorganisms are 74.51 g/L and 61.1 g/L, respectively. The results of this study showed that the mathematical model deviates about 53.8% from the laboratory data. According to the presented model, the amount of methane produced after 70 days is equal to 29.10 g/L. The decomposition rate of the substrate and methane gas production depends on the substrate's residence time. Increasing the initial concentration of microorganisms produces methane gas in less time. The amount of methane produced is independent of the initial concentration of microorganisms. The model presented in this study can predict the time required to perform the reaction, optimal bioreactor performance, design of relevant process equipment, and increase the scale of equipment, such as storage tank and proper control to produce high purity methane more volume. Suitable in bioreactors.

Attachment and survival of bacteria on apples with the creation of a kinetic mathematical model.

The estimation of growth or inactivation of bacterial population in fruits during preservation and storage provides useful information for the improvement of the safety of fresh-cut fruits and vegetables. This paper addressed the attachment to the surface and the growth in the flesh of apple fruits of four bacterial cultures (Escherichia coli, Bacillus cereus, Staphylococcus aureus and Pseudomonas aeruginosa). The growth of the bacterial cultures in apple flesh was monitored at particular time intervals, and Gompertz parameters, i.e. maximum number of bacteria (Pm), the maximum growth rate of bacteria rp,m, and lag time tl, were used to determine the growth kinetics. After the immersion, the highest number of P. aeruginosa and the lowest number of B. cereus adhered to the apples. After washing and swabbing, E. coli was reduced from the surface of apples to the highest extent (by 3.34 log cfu g-1), while the number of B. cereus was reduced to the lowest extent (1.66 log cfu g-1). Fitted curves of the Gompertz model corresponded quite well to the measured values of the number of microorganisms with R2 = 0.92-0.98. The values of the standard error (0.17-0.37) and extremely low p values of the Fischer test (p < 0.0001) indicated strict dependence between the model predicted and the maximum population density. The predicted values of the maximum number of microorganisms (Pm) correspond almost exactly to the actual values. A similar conclusion can be drawn for the maximum growth rate of microorganisms (rp,m), with the measured value being slightly higher than predicted values.

Numerical Study on Microbial Depolymerization Process of Xenobiotic Polymer

This study demonstrates mathematical analysis of biodegradation processes of xenobiotic polymers. A model for microbial population is based on the fact that growth rate of microorganisms is proportional to the microbial population and consumption rate of parts of carbon sources. The model is paired with a model for weight distribution. Those models lead to inverse problems for a molecular factor and a time factor of degradation rate. Solution of the inverse problems allows us to simulate the biodegra-dation process.

Et ve et ürünlerinin üretimi ve saklanmasında antimikrobiyal ambalajlama sistemlerinin kullanımı

Many microbiological, enzymatic, physicochemical, and biochemical changes occur during the production and storage of fresh and processed meat products, which tend to deteriorate more easily by their nature. Nevertheless, consumers mainly prefer cost-effective foods that have a longer shelf life and minimally modified natural properties, can be easily prepared, and in which fewer additives are used. For these reasons, the food packaging industry has turned towards developing new applications with different functions that are not found in traditional packaging methods, such as antimicrobial packaging systems, especially for the protection and improvement of food quality and safety. In this type of packaging, in addition to improving food safety and quality, the shelf life of the product is extended by slowing down the growth rate of microorganisms. Thus, the existing growth of microorganisms during the transportation and storage of the product is also prevented. Therefore, the preservatives taken into the human body with foods are reduced, and the negative effects on health are also avoided. In these systems, the application of antimicrobial food packaging components to the packaging material can be performed by the addition of antimicrobial agents into the polymer, coating polymer surfaces with antimicrobial agents, immobilizing antimicrobial agents on the polymer, and using polymers with antimicrobial properties. In this review, antimicrobial packaging and application methods were generally explained, and innovative packaging systems and their use in meat and meat products were evaluated.

ГИДРОТЕРМАЛЬНЫЙ НАНОКРЕМНЕЗЕМ КАК СТИМУЛЯТОР РОСТА И РАЗВИТИЯ РАСТЕНИЙ ОДНОЛЕТНИХ ВИДОВКЛЕВЕРА И АМАРАНТА

The article considers the results of application of scientific-research practical technique on new pre-treatment of seeds of plants of annual types of clover and amaranth of fodder with growth stimulator hydrothermal nanosilicon (GNA) in combination with sulfur-containing mineral water. Earlier, numerous tests showed the effectiveness of the use of GNA to increase the yield and growth rate of agricultural plants: amaranth, zucchini, onions, spring wheat, sugar beets, etc. Silica nanoparticles increase the growth rate of microorganisms, including pathogenic ones, which allows reducing the time for diagnosing antibiotic resistance of pathogen microbes. Hydrothermal nanosilicon has high biochemical activity, high penetration rate into plant seeds, high sorption capacity due to silica particle size and their surface area up to 500 cm2/g. There are no toxic substances in the prepared working solution of the plant growth stimulator, which makes the proposed pre-treatment more environmentally friendly and bioavailable for seeds, in particular, to endosperm and intensify the germination process. The essence of the studied procedure was that the seeds of clover and amaranth were soaked in a 0,005% solution of hydrothermal nanosilicon dissolved with sulfur-containing mineral water during exposure for 30-40 minutes before sowing, as a result of which the efficiency of the stimulator was increased, the possibilities of hydrothermal nanosilicon were expanded, which made it possible to reduce the costs of pre-treatment of seeds. The obtained data make it possible to conclude that nanosilicon of hydrothermal origin in combination with hydrogen sulfide mineral water is a stimulator of plant development at the germination stage and can be used to reduce labour intensity and costs for pre-treatment of seeds, increase efficiency and expand the field of application in the technology of production of biomass of clover and amaranth in field-agro-production of North Ossetia.

Arrhenius Plot Analysis of the Temperature Effect on the Biodegradation Rate of 2-chloro-4-nitrophenol

Several models are available to determine the effect of temperature on the growth rate of microorganisms on substrates. An example is Arrhenius model, which is very popular because it has few parameters. For the first time, a discontinuous chevron-like graph of apparent activation energy based on the Arrhenius plot on the growth of 2-chloro-4-nitrophenol by Cupriavidus sp. is reported. The plot of ln mm against 1/T shows a discontinuous chevron-like graph for the entire investigated temperature range with an inflection at 27.75°C. This indicates that the existence of 2 activation energies for growth on 2-chloro-4-nitrophenol ranges from 20 to 40°C. Furthermore, a regression analysis from 20–25°C and 30–40°C results in activation energies of 88.71 kJmol-1 and 75.16kJ mol-1, respectively. This is probably the first time a Chevron-like graph was observed for the Arrhenius plot on the effect of temperature on the growth rate of 2-chloro-4-nitrophenol.

The use of probiotics in the cultivation of turkeys

The specific microclimate of poultry premises contributes to the accumulation of microflora, which may contain pathogenic and opportunistic microorganisms. The concentration of microorganisms in poultry houses increases over time and reduces the resistance of the bird. Researchers have reported very high growth rates of mesophilic aerobic microorganisms, which include most pathogenic bacteria, namely: gram-positive cocci (staphylococci, enterococci) and gram-negative bacteria of the family Enterobacteriaceae (Escherichia coli, Salmonella spp., Salmonella spp.). Proteus spp., Klebsiella spp., and Pseudomonas spp. The goal of our research was to investigate and compare the effectiveness of two probiotics for turkeys, one of which contains recombinant strains of lactic acid microorganisms of intestinal intestinal symbionts, and the other based on a mixture of biologically active substances based on natural components of organo-mineral origin. The task of our work: 1. To study the microflora of the gastrointestinal tract during the use of probiotics after the use of antiparasitic drugs in nematode invasion of turkeys. 2. Compare the growth of young animals with the use of probiotics and provide suggestions on the prospects for the most effective use of probiotics in the cultivation of turkeys. 3. Investigate changes in the physicochemical properties of turkey meat when using probiotics and compare them with controls. To conduct the experiment, three experimental groups of turkeys cross Hybrid converter, 14 days old, each with 10 heads. The first and second experimental groups were given an antiparasitic drug containing levamisole hydrochloride at a dose of 5 ml per 5 liters of water once. After that, probiotics were used for each experimental group of birds. Two types of probiotics were used in the experiments: the first contains recombinant strains of lactic acid microorganisms of intestinal intestinal symbionts: Bifidobacterium bifidum, Bacillus thermophilus, Bacillus coagulance, Bacillus subtilis. Has antimicrobial, antiviral and antioxidant activity; the second preparation contains a mixture of biologically active substances, based on natural ingredients of organo-mineral origin, which includes organic substances – fulvic and humic acids. The third group (control) used only the above antiparasitic drug. After the experiment, at the age of 78 days, poultry was slaughtered and studies of the effect of probiotics on weight, physicochemical parameters of meat. When testing turkeys for helminths. As a result of research, helminths were identified, which were attributed to the causative agent of heterakidosis - Heeterakis gallibarum. After that, it was decided to carry out deworming with levamisole hydrochloride. After a course of treatment, it was found that no deaths were observed in the first experimental group; in the second experimental group, one head died, and in the third control group, which did not use probiotics, the death was two heads. The use of probiotics due to competition reduces the level of total bacterial contamination and coliform bacteria in the experimental groups. And the level of lactic acid bacteria in the experimental groups was higher than in the control. The use of probiotics had a positive effect on weight gain of experimental turkeys, compared with the control group, where probiotics were not used. The difference in the first experimental group compared with the control averaged 618 g, and in the second group – 198 g. Post-mortem examination of turkey carcasses showed that the indicators of the experimental and control groups differ. In terms of external organoleptic characteristics, the meat obtained from the slaughter of experimental birds does not differ from the meat of poultry in the control group. Conclusions and prospects for further research. The use of probiotics based on lactic acid bacteria proved to be the most effective and ensured the complete preservation of livestock. Due to competition, it reduced the level of coliform bacteria by an average of 6.67 % in the experimental groups; the level of lactic acid bacteria in the experimental groups was 4.89 % higher than in the control. The use of probiotics increased the weight gain of poultry by 3.28 %. No significant effect on the organoleptic and physicochemical properties of meat was observed.In the future it is planned to study the microflora of turkey slaughter products.

Kinetics of Anaerobic Digestion of Unripe Plantain Peels

This study was carried out to investigate the biogas production obtained from anaerobic digestion of unripe plantain peels (PP) and the kinetics of the digestion process. 400 g of dried and shredded unripe plantain peels were mixed with 200 ml of water and put into 1 L digester and observed for biogas for hydraulic retention time (HRT) of 15 days by the method of downwards displacement. The cumulative biogas volume obtained after digestion was 285 ml. The COD removal efficiency of 72.5% was achieved. The kinetics of PP digestion was evaluated using first order, Monod, Contois and, Grau second-order models. Results showed that the kinetics of anaerobic digestion of PP followed the first-order model with a constant (K) of 0.095 day-1. Monod kinetics was evaluated and the maximum rate of substrate utilization (K), the half velocity constant (KS), endogenous decay coefficient (Kd), biomass growth yield (Y) and, maximum specific microorganism growth rate (µmax) obtained were 0.7615 day-1, 16.20 mg/l, 0.0047 day-1, 0.0112 mgVSS mgCOD-1 and, 0.009 day-1 respectively. These results revealed that inoculation would be required to increase the rate and volume of biogas production. Both first-order and Monod models gave a high coefficient of determination indicating that first order and Monod models can be used to model the digestion of PP. Contois model gave values of µmax and β as 0.011 day-1 and 0.644 mgCOD mgVSS-1 respectively. The result obtained has shown that the digestion of PP did not follow second-order kinetics.

Effect of Photosynthetic Microorganism on Lime Plant Growing and Fruiting

Lime plant has an absolute requirement of nutrients for growing. The microbial application can facilitate in addressing limited access to chemical fertilizer concern. Moreover, the photosynthetic microorganism community can contribute together in nutrient availability for plant growing and fruiting. The objectives of this research were analyzed the growth rate of photosynthetic microorganism in a fermented juice within three months. A fermented juice was analyzed in terms of MLSS, COD, and nutrient. The efficiencies of fermented juice of lime plant growing, and fruiting was also investigated. The lime plant growth rate was collected in terms of plant height, and fruiting. The experimental results showed that the concentration of microbes in a fermented juice was maintained approximately 1,063 ± 135 mg/L on average (n=5). The photosynthetic microorganism concentration and nutrients concentration in fermented juice was a significant promotion of productivity of lime plant growing and fruiting.

Control of Specific Growth Rate in Fed-Batch Bioprocesses: Novel Controller Design for Improved Noise Management

Accurate control of the specific growth rate (µ) of microorganisms is dependent on the ability to quantify the evolution of biomass reliably in real time. Biomass concentration can be monitored online using various tools and methods, but the obtained signal is often very noisy and unstable, leading to inaccuracies in the estimation of μ. Furthermore, controlling the growth rate is challenging as the process evolves nonlinearly and is subject to unpredictable disturbances originating from the culture’s metabolism. In this work, a novel feedforward-feedback controller logic is presented to counter the problem of noise and oscillations in the control variable and to address the exponential growth dynamics more effectively. The controller was tested on fed-batch cultures of Kluyveromyces marxianus, during which μ was estimated in real time from online biomass concentration measurements obtained with dielectric spectroscopy. It is shown that the specific growth rate can be maintained at different setpoint values with an average root mean square control error of 23 ± 6%.

Improvement of methods of the influence on microbiological indicators of raw milk

Improving the quality and safety of milk and dairy products requires professional work on the technology and culture of production, improving the operating conditions of equipment and improving methods for influencing microbiological indicators. A method of electromagnetic influence on the microbial cell control system is proposed that allows reducing the growth rate of microorganisms, optimizing the quality and safety of milk and increasing the shelf life of products. The object of the study was the milk of cows of Kholmogorskaya breed, which were housed at loose (group 1) and tie barn (group 2) methods. It has been found that the method of housing animals does not affect the physical and chemical parameters of the milk under study, which meet the requirements for raw materials. Density, freezing point, acidity, and somatic cell content in milk have been affected by the season of the year. Changes in the quantitative composition of sanitary-indicative microorganisms of raw milk depend both on the method of housing and milking cows, and on the season of the year. The highest contamination of milk with microflora has been observed in the case of cows housing in tie barn. The maximum number of microorganisms has been observed in the summer with different methods of housing. There were no Salmonella in the milk of experimental groups of cows. Yeast and fungi have been registered in all milk samples. The influence of electromagnetic radiation on the development of certain types of microorganisms has been established. The largest number of Quantity of Mesophilic Aerobic and Facultative Anaerobic Microorganisms (QMAFAnM) was in raw milk without additional effects and amounted to 486 289 CFU/cm[sup]3[/sup] . When exposed to electromagnetic pulses the number of yeast and mold fungi has been decreased by 9 or more times.

Effect of presence of hydrophilic volatile organic compounds on removal of hydrophobic n-hexane in biotrickling filters

Hydrophilic VOCs (volatile organic compounds) were applied to explore their positive influence on the elimination of the single hydrophobic VOC in biotrickling filters (BTFs). Comparison experiments were carried to evaluate the effect of 4-methyl-2-pentanone and toluene on the performance of BTFs for n-hexane removal. The results showed that the existence of 4-methyl-2-pentanone improved the removal performance of BTFs at short gas empty bed contact time (EBRT) of 15 s and low temperature of 10 °C. The degradation of n-hexane in the presence of 4-methyl-2-pentanone was slightly enhanced with a loading ratio of 6:1. When the mixing ratio was greater than 4, toluene significantly promoted the biodegradation of n-hexane with toluene loading rate less than 10 g m−3 h−1. Additionally, The promotion effect was not only reflected in the contents of proteins and polysaccharides, but also in the growth rates of microorganisms in biofilms. This work discussed the detailed effect between n-hexane and hydrophilic VOCs in BTFs, which would contribute to develop a more economical method to improve the removal performance of hydrophobic VOCs in BTFs.

A New Remote Sensing-Based System for the Monitoring and Analysis of Growth and Gas Exchange Rates of Photosynthetic Microorganisms Under Simulated Non-Terrestrial Conditions.

Oxygenic photosynthetic microorganisms are a focal point of research in the context of human space exploration. As part of the bioregenerative life-support systems, they could have a key role in the production of breathable O2, edible biomasses and in the regeneration of CO2 rich-atmospheres and wastewaters produced by astronauts. The test of the organism’s response to simulated physico-chemical parameters of planetary bodies could also provide important information about their habitability potential. It is believed that the success of future planetary and space missions will require innovative technologies, developed on the base of preliminary experiments in custom-made laboratory facilities. In this context, simulation chambers will play a pivotal role by allowing the growth of the microorganisms under controlled conditions and the evaluation in real-time of their biomass productivity and impact on atmosphere composition. We here present a system capable of addressing these requirements with high replicability and low costs. The setup is composed by three main parts: 1) a Star Light Simulator, able to generate different light intensities and spectra, including those of non-solar stars; 2) an Atmosphere Simulator Chamber where cultures of photosynthetic microorganisms can be exposed to different gas compositions; 3) a reflectivity detection system to measure from remote the Normalized Difference Vegetation Indexes (NDVI). Such a setup allows us to monitor photosynthetic microorganism’s growth and gas exchange performances under selected conditions of light quality and intensity, temperature, pressure, and atmospheres simulating non-terrestrial environments. All parameters are detected by remote sensing techniques, thus without interfering with the experiments and altering the environmental conditions set. We validated the setup by growing cyanobacteria liquid cultures under different light intensities of solar illumination, collecting data on their growth rate, photosynthetic activity, and gas exchange capacity. We utilized the reflectivity detection system to measure the reflection spectra of the growing cultures, obtaining their relative NDVI that was shown to correlate with optical density, chlorophyll content, and dry weight, demonstrating the potential application of this index as a proxy of growth.

Development of a novel probiotic milk product with enhanced antioxidant properties using mango peel as a fermentation substrate

Abstract Mango peel is an agroindustrial waste with excellent nutritional value and a considerable content of bioactive compounds that can be used as a source of antioxidants. Additionally, biotransformation processes by kefir fermentation increase the interest in obtaining products from agroindustrial wastes with good biological properties. In this context, this work aimed to evaluate the effects of milk supplementation with mango peels on the growth rates of kefir microorganisms during fermentation as well as the antioxidant properties of the obtained fermented products. The results were comparatively evaluated between fermented samples in the presence of mango peels (KMP) and in their absence (KC). Significant increases (p ≤ 0.05) in antioxidant activities for KMP were observed for all methods, as follows: 113% for DPPH-radical scavenging (10 h of fermentation), 153% for the Ferric Reducing Antioxidant Power (FRAP) assay (8 h of fermentation), 21% for ABTS-radical scavenging (6 h of fermentation) and 43% for Total Reducing Capacity (Folin-Ciocalteu method) (8 h of fermentation) compared to those of KC fermented samples. According to microbiological analyses, the KMP samples allowed microbial growth of up to 3-fold higher than the growth of KC samples, reaching counts of up to 108 CFU/mL for lactic acid bacteria. According to the results, the products obtained from the fermentation process using milk combined with mango peels as the substrate presented improved antioxidant properties and a potential probiotic property.

Predicting the effects of integrating mineral wastes in anaerobic digestion of OFMSW using first-order and Gompertz models from biomethane potential assays

Previous studies found mineral wastes (MW; incineration bottom ash (IBA), cement based waste (CBW), Fly ash (FA) and boiler ash (BA) are a promising resource for the macro-/micronutrients necessary for anaerobic digestion (AD) processes. The current study used first-order and modified Gompertz models from BMP assays to investigate the effects of integrating MW on the AD of OFMSW at 37 °C. Results from the first-order model showed a 45% increase in the specific growth rate of microorganisms (μ) in the MW- supplemented BMP compared to the control. Gompertz model results indicated that the IBA, CBW, FA and BA BMP amended assays obtained the highest K values (45–54 mL CH4 g VS−1 d−1) than the control (K ∼ 31 mL CH4 g VS−1 d−1), with no significant adverse effects of co-digestion of OFMSW with MW on the length of the lag phase (λ) in BMP assays (λ = 1.89 ± 0.07 days for IBA, CBW and BA amended assays compared to 1.5 ± 0.01 days for the control). However, FA amended assays had a greater λ value (3.66 ± 0.1 days). The MW provided both alkalinity and released several trace elements at concentrations within the optimal ranges for methanogenic archaea.

Enhancement of performance and biodegradability kinetics of aerobic-anaerobic sludge digestion

The excess sludge problem from a wastewater treatment plant is a great concerned due to the high cost of sludge management accounting for about 20% to 50% of the total operating cost. Therefore, sludge reduction is critical. Currently, aerobic and/or anaerobic sludge digestions are widely used in the industries for treating the excess sludge. The objective of this research was to study the effects of aeration rate and temperature on the excess sludge reduction by using the aerobic-anaerobic digestion system in the laboratory. The aeration rates of 1.0, 0.5, and 0.1 volume air per volume slurry per minute (vvm) at the room temperature and the thermophilic temperature (55 ± 2°C) were investigated. The results showed that the highest removal efficiency of aerobic sludge digestion was obtained at the thermophilic temperature and aeration rate of 1.0 vvm. The removal efficiency of organic matter in terms of COD, total solids (TS) and volatile solids (VS) were 34.76%, 33.01% and 43.45%, respectively. Consequently, the highest specific growth rate of microorganisms was 0.39 per hour and the substrate removal rate was 0.55 milligram CODremoved per milligram VSS per hour. Furthermore, slowly biodegradable organic matter was hydrolyzed to readily biodegradable organic matter and inert soluble organic matter. When the sludge effluent from aerobic sludge digestion was feed to the anaerobic sludge digestion, the removal efficiency of organic matter in terms of COD, TS and VS were increased by 25%, 17% and 28%, respectively. Moreover, the obtained methane production rate in the anaerobic sludge digestion was approximate 0.234 m3/kg COD removed.

An anaerobic membrane bioreactor using a hollow fiber membrane and biogas agitation

Many biomass disposal demonstration projects are based on anaerobic digestion. However, the excessively slow anaerobic microorganism growth rate is a drawback because a decreased anaerobic microorganism population limits methane fermentation's efficiency. To ensure operation at higher loads, this study used an anaerobic membrane bioreactor (AnMBR) for maintaining anaerobic microorganisms’ growth, and this article introduces a series of improvements to address the reactor's shortcomings. Finally, we chose to mix-the internal biogas and conducted the experiment using a hollow fiber AnMBR.•Introducing the design of a highly efficient and compact anaerobic membrane bioreactor (AnMBR).•Introducing the initial OLR and the changes of HRT, SRT, TS, and flux of the permeate in the AnMBR after gradually increasing the load.•Monitoring decomposition characteristics in the gas meter connection.