In recent years, an enormous amount of research effort has been devoted to the study of immobilization methods and carrier materials for enhancement of the dark fermentation process. It is shown that immobilization has a complex multifactorial effect on the process of dark fermentation and opens up new technological possibilities, such as better acclimatization of hydrogen producers, a decrease in the lag phase, and an increase in biomass density, which provides greater resistance to inhibitory substances and shock loads. In addition, the use of carriers allows a wider variation of the main technological parameters, such as hydraulic retention time (HRT) and organic loading rate (OLR), and more flexible control. The chapter highlights the main immobilization methods, and their advantages and disadvantages. Parameters affecting attached growth systems, such as type of material, biofilm thickness, pH, substrate characteristics, are discussed. Particular attention is paid to materials that have a complex stimulating effect, such as conductive materials, as well as materials containing trace elements and nanoparticles that affect cell growth, metabolism, and enzyme activation. A comparative analysis of various types of biofilm reactors, their design, and operating modes is given. In conclusion, an assessment is given of the prospects for using immobilization to develop efficient, economical, and stable technologies for producing dark fermentative biohydrogen.

Among renewable energy sources, hydrogen and methane are gaseous fuels that have a higher energy density than petroleum-derived gasoline and diesel. In recent years, there has been increasing interest in converting existing anaerobic digestion systems to a two -stage process that produces hydrogen in the first stage and then methane in the second stage and is characterized by increased recovery of biofuels and bioenergy. In this study, an assessment of the energy recovery from two-stage mesophilic-thermophilic anaerobic digestion of cheese whey (CW) was carried out. After appropriate dilution, CW was fed at three COD levels of 6.8, 9.2 and 13.8 g O2/L to a mesophilic acidogenic reactor with a hy-draulic retention time (HRT) of 10 h. The acidogenic reactor effluent was then fed to three thermophilic methanogenic reactors, which operated at different HRTs: 72, 48, and 24 h. Polyurethane foam was used to immobilize the anaerobic acidogenic and methanogenic sludge. The heating value (HV) was determined according to the experimental method using a bomb calorimeter for modes with the highest methane content and with the highest hydrogen content, as well as a calculation method based on the content of combustible gases in biohythane. The obtained deviations of the calculated from the experimentally determined HV of biohythane (4.84-7.60%) may be due to the fact that the HV of biohythane is probably not equal to the sum of the HV of pure hydrogen and methane. While an increase in the hydrogen content in biohythane leads to a decrease in the deviation of the calculated HV of biohythane from the experimental one. The maximum energy production rate was 53.2 kJ/(L d) at a COD level of 13.8 g O2/L, HRT in an acidogenic reactor of 10 h, and HRT in a methanogenic reactor of 48 h. The maximum energy yield of 14.42 kJ/g COD was obtained at a COD level of 9.2 g O2/L, HRT in an acidogenic reactor of 10 h and HRT in a methanogenic reactor of 72 h. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Spatial separation into acidogenic and methanogenic stages is considered a viable option to ensure process stability, energy efficiency and the better control of key anaerobic digestion (AD) parameters. The elucidation of the optimal modes of two-stage AD for the maximization of the recovery of biofuels (H2 and CH4) is still an urgent task, the main optimization criteria being the highest energy yield (EY) and energy production rate (EPR). In this work, a response surface methodology was used for an optimization of energy production from the two-stage mesophilic–thermophilic AD of cheese whey (CW). Three dilution rates of CW, providing values of 10.9, 14.53 and 21.8 g for the chemical oxygen demand (COD)/L in the influent and three hydraulic retention times (HRTs) (1, 2 and 3 days) in methanogenic biofilters at a constant HRT in an acidogenic biofilter of 0.42 days, were tested to optimize the EY and EPR. The desirability approach produced combined optimum conditions as follows: the dilution rate of the CW provided 17.58 g COD/L (corresponding to OLR of 6.5 g COD/(L·day)) in the influent and a HRT in the methanogenic biofilter of 2.28 days, both of which provided a maximum EPR of 80.263 kJ/(L·day) and EY of 9.56 kJ/g COD, with an overall desirability value of 0.883.

Anaerobic digestion (AD) is a promising option to obtain renewable energy in the form of biogas and reduce the anthropogenic impact on the environment. In recent years there has been increasing interest in using pressurized digesters to improve the quality of biogas. However, maintaining high overpressure increases the requirements for the explosion safety of digesters. Consequently, there are natural limitations in the available technologies and facilities suitable for full-scale operation. In this work, we aimed to evaluate the possibility of using overpressure in the digester to improve the efficiency of codigestion of common municipal organic waste–sewage sludge and the organic fraction of municipal solid waste. Three levels of moderate excess pressure (100, 150 and 200 kPa) were used to meet requirements of existing block-modular anaerobic bioreactors based on railway tanks, which are widely utilized for AD in the Russian Federation. There was no significant change in methane content in biogas (65% ± 3%) at different values of overpressure, hydraulic retention time (HRT) and organic loading rate (OLR). The maximum methane and energy production rates (2.365 L/(L·day) and 94.27 kJ/(L·day), respectively) were obtained at an overpressure of 200 kPa, HRT of 5 days and OLR of 14 kg VS/(m3·day). However, the maximum methane yield (202.44 mL/g VS), energy yield (8.07 kJ/g VS) and volatile solids (VS) removal (63.21%) were recorded at an overpressure of 150 kPa, HRT of 7 days and OLR of 10.4 kg VS/(m3·day). The pressured conditions showed better performance in terms of AD stability at high OLRs.

The production of biohydrogen from industrial wastewater through the dark fermentation (DF) process has attracted increased interest in recent years. To implement a DF process on a large scale, a thorough knowledge of laboratory scale process control is required. The operating parameters and design features of the reactors have a great influence on the efficiency of the process. In this work, the possibility of continuous production of biohydrogen from confectionery wastewater was evaluated. The DF process was carried out at 37 +/- 1 degrees C in two different reactors: an upflow anaerobic filter (AF) and a fluidized bed reactor (AFB). Polyurethane foam (PU) was used to immobilize the biomass. The DF process was studied at four hydraulic retention times (HRT) (1.5, 2.5, 7.5 and 15 days) and the corresponding organic loading rates (OLR) (9.21, 6.12, 2.04 and 1.02 g CODinit/(L day)). The highest hydrogen yield (HY) (44.73 ml/g CODinit) and hydrogen production rate (HPR) (92.5 ml/(L day)) was observed in AFB at HRT of 7.5 days and 2.5 days, respectively. The highest concentration of hydrogen in biogas was 34% in AF and 36% in AFB at HRT of 7.5 days. In contrast to AF, the COD removal efficiency in AFB increased with increasing HRT. The pH of the effluent was low (3.95-4.38). However, due to the use of PU for biomass immobilization, it is possible that there were local zones in the reactor that were optimal for the functioning of not only acidogens, but also methanogens. This was evidenced by a rather high content of methane in biogas (2.5% in AF and 9.6% in AFB at HRT of 15 days). These results provide valuable data for optimizing the continuous DF of wastewater from confectionery and other food industries to produce biohydrogen or biohythane. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

The process of anaerobic fermentation of organic waste makes it possible to produce not only methane, but also hydrogen, which, when mixed, form a high-energy mixture - biohythane. The efficiency of biohythane production in a two-stage anaerobic fermentation process depends on many factors, including organic loading rate (OLR) and hydraulic retention time (HRT). It is known that the addition of an immobilizing support materials to anaerobic bioreactors improves the stability of their operation and increases the biogas yield. An important aspect is the nature of the immobilizing support material, which can perform not only the immobilization function, but also have a stimulating effect on the anaerobic digestion. Therefore, the selection of an appropriate immobilizing support material for a fixed bed bioreactor can ensure high efficiency and successful operation of the fermentation system. The aim of the work was to select the most effective immobilizing support material for a fixed-bed methanogenic reactor in a two-stage anaerobic digestion of cheese whey to produce biohythane. Polyurethane bed material, carbon felt, Raschig ring-type ceramic bed material, as well as a mixture of carbon felt and ceramic bed material were used in the work. The highest methane production rates (MPR) were obtained for the reactor with carbon bed material as an immobilizing support materials (753.9 ml/(L d)) and for the reactor with a mixture of ceramic bed material and carbon felt (763.5 ml/(L d )). The highest concentration of methane in biogas (68.8%) was recorded in the methanogenic reactor with coal felt. The average concentration of hydrogen in the biogas of the acidogenic reactor when using polyurethane bed material was 41.04%.

Pretreatment prior to anaerobic digestion is an effective option for increasing the biodegradability of organic waste. Vortex layer apparatus (VLA) is considered one of the promising types of equipment for pretreatment. In this work, confectionery wastewater (CW) was pretreated in VLA for 1 and 3 min before dark fermentative hydrogen production in anaerobic upflow biofilters. The pretreatment resulted in a slight increase in soluble chemical oxygen demand (COD), soluble sugars and acetic acid, and a decrease in the concentration of propionic, butyric and caproic acids. Due to the abrasion of steel needles in VLA, the concentration of iron in the pretreated CW increased by 2.57 times. Hydraulic retention time in anaerobic upflow biofilters was gradually reduced from 5.6 to 1.8 and 1.3 days, which corresponded to organic loading rate of 2.0, 6.3 and 8.8 kg COD/(m3 day). Although the highest hydrogen yield (96.2 ?? 8.1 ml/g COD) was obtained for non-pretreated CW, the pretreatment contributed to a significant increase in methane yield (39.2 ?? 2.5 ml/g COD), possibly due to higher iron content (1.8 ?? 0.3 mg/L). The highest energy production rate (4407 J/(L day)) was achieved after 3 min CW pretreatment. Thus, pretreatment in VLA can be a promising method for improving the biohythane production process. ?? 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Dark fermentation (DF) is a promising process for mitigating environmental pollution and producing “green” H2. However, wider implementation and scaling of this technology is hampered by insufficient process efficiency. In this work, for the first time, the effect of innovative pretreatment of cheese whey (CW) in a vortex layer apparatus (VLA) on characteristics and DF of CW was studied. Pretreatment in VLA resulted in a heating of the CW, slight increase in pH, volatile fatty acids, iron, and reduction in fat, sugar, and chemical oxygen demand (COD). The biochemical hydrogen potential test and analysis of H2 production kinetics confirmed the significant potential of using VLA in enhancement of dark fermentative H2 production. The maximum potential H2 yield (202.4 mL H2/g COD or 3.4 mol H2/mol hexose) was obtained after pretreatment in VLA for 45 s and was 45.8% higher than the control. The maximum H2 production rate after 5 and 45 s of pretreatment was 256.5 and 237.2 mL H2/g COD/d, respectively, which is 8.06 and 7.46 times higher than in the control. The lag phase was more than halved as a function of the pretreatment time. The pretreatment time positively correlated with the total final concentration of Fe2+ and Fe3+ and negatively with the lag phase, indicating a positive effect of pretreatment in VLA on the start of H2 production.

The paper studies the effect of pretreatment of highly concentrated wastewater from confectionery production in a vortex layer apparatus (VLA) on its physical and chemical properties, with the aim of its further use as a substrate for dark fermentation with the production of biohydrogen. Pretreatment in VLA resulted in a 2.6-fold increase in the iron content and 6.5% increase in soluble chemical oxygen demand after 3 minutes of exposure. After pretreatment in VLA, an increase in the content of acetic acid and a decrease in the contents of propionic, butyric and caproic acids were observed. An increase in the content of mono- and disaccharides was registered, and the effect of the VLA exposure time of confectionery wastewater on its physicochemical properties was studied. An increase in the concentration of iron and simple sugars in wastewater makes the use of VLA promising for improving the process of its subsequent dark fermentation.

This article presents the results of the start-up of continuous production of biohydrogen from cheese whey (CW) in an anaerobic filter (AF) and anaerobic fluidized bed (AFB) with a polyurethane carrier. Heat and acid pretreatments were used for the inactivation of hydrogen-scavengers in the inoculum (mesophilic and thermophilic anaerobic sludge). Acid pretreatment was effective for thermophilic anaerobic sludge to suppress methanogenic activity, and heat treatment was effective for mesophilic anaerobic sludge. Maximum specific yields of hydrogen, namely 178 mL/g chemical oxygen demand (COD) and 149 mL/g COD for AFB and AF, respectively, were obtained at the hydraulic retention time (HRT) of 4.5 days and organic load rate (OLR) of 6.61 kg COD/(m3 day). At the same time, the maximum hydrogen production rates of 1.28 and 1.9 NL/(L day) for AF and AFB, respectively, were obtained at the HRT of 2.02 days and OLR of 14.88 kg COD/(m3 day). At the phylum level, the dominant taxa were Firmicutes (65% in AF and 60% in AFB), and at the genus level, Lactobacillus (40% in AF and 43% in AFB) and Bifidobacterium (24% in AF and 30% in AFB).

Производство биоводорода (H) из возобновляемых источников энергии (отходов производства и потребления) является перспективным направлением развития энергетической отрасли промышленности. H считается уникальным энергоносителем с высоким выходом энергии (122 кДж/г). Представленная работа посвящена изучению процесса запуска непрерывной анаэробной ферментации молочной сыворотки в мезофильных условиях с получением водород содержащего биогаз в реакторах двух типов: с неподвижной загрузкой (затопленный биофильтр - anaerobic filter, AF) и подвижной загрузкой (аппарат с кипящим слоем загрузки - fluidized bed loading, AFB). Инактивацию метаногенов проводили термическим методом (30 мин, 90°С). На начальной стадии процесса оптимальным является режим с гидравлическим временем удерживания (hydraulic retention time, HRT) 12-14 сут, нагрузкой по органическому веществу (organic loading rate, OLR) 1,88-2,25 кг ХПК/(м·сут). Данный режим позволяет начать работу со стабильной генерацией биогаза с содержанием водорода в нем 15,9% (для AF) и 11,4% (для АFB) и поддержанием рН среды 5,72. В реакторе AF-типа общее количество образовавшегося за 17 сут темновой анаэробной ферментации биогаза было больше, чем в реакторе с AFB-типа. Содержание масляной кислоты превышало содержание уксусной кислоты в обоих реакторах. Production of biohydrogen (H) from renewable energy sources (production and consumption waste) is an upcoming trend in energy industry. H is considered as a unique energy carrier with a high energy yield (122 kJ/g). The paper presents the results of investigating the start-up stage of the process of continuous dark fermentation of milk whey under mesophilic conditions with the production of hydrogen-containing biogas in two types of reactors: with a fixed feed (flooded biofilter - anaerobic filter, AF) and with a movable load (apparatus with fluidized bed loading - AFB). Methanogens are inactivated by the thermal method (90°C, 30 min). At the initial stage of the process, the optimal regime is achieved with hydraulic retention time of 12-14 days, and organic loading rate of 1.88-2.25 kg COD/(m·day). This mode makes it possible to run the process with a stable biogas generation with hydrogen content of 15.9% (for AF) and 11.4% (for AFB) and maintaining the pH of the medium at 5.72. The total amount of biogas formed over 17 days of dark anaerobic fermentation processing in the AF-type reactor was greater than in the AFB-type reactor. The butyric acid content exceeded the acetic acid content in both types of reactors.

Pretreatment of the organic fraction of municipal solid waste ( OFMSW ) is a necessary step to accelerate the process of anaerobic digestion in order to avoid rapid acidification and inhibition of methanogenesis. This work shows for the first time the effect of pretreatment in a vortex-layer apparatus ( VLA ) on the physicochemical properties and characteristics of the anaerobic thermophilic, two-phase fermentation of OFMSW. Pretreatment in a VLA led to a decrease in the amount of fat, an increase in pH, a slight increase in the amount of protein in dry matter, and a change in the density and dry matter content. OFMSW processing in a VLA for 2 min increased the specific yield of biogas and methane by 11.6 and 15.8%, respectively.

Quantum dots are nanoparticles, which due to their unique physical and chemical (first of all optical) properties, are promising in biology and medicine. There are many ways for quantum dots synthesis, both in the form of nanoislands self-forming on the surfaces, which can be used as single-photon emitters in electronics for storing information, and in the form of colloidal quantum dots for diagnostic and therapeutic purposes in living systems. The paper describes the main methods of quantum dots synthesis and summarizes medical and biological ways of their use. The main emphasis is laid on the ways of quantum dots surface modification. Influence of the size and form of nanoparticles, charge on the surfaces of quantum dots, and cover type on the efficiency of internalization by cells and cell compartments is shown. The main mechanisms of penetration are considered.

For biomedical applications, it is important to know, which kinds of blood cells can capture quantum dots (QDs). The maximum accumulation of QDs was found for the monocyte fraction of leukocytes, the minimum binding of QDs was observed for lymphocytes. It was found that CdSe/ZnS-MPA QDs are actively absorbed by the cells and have more expressed toxicity. The classical mechanism of the phagocytosis of QDs was revealed for neutrophils, when the QDs are located in phagolysosomes. The capture of QDs by neutrophil granulocytes has resulted in a destruction of certain types of QDs. The interaction of the neutrophils with the QDs has resulted in the death of the cells by one of the following cell death mechanisms: necrosis, apoptosis, autophagy, NETos, or mummification. The aggregation of the QDs manifested as an increase of the hydrodynamic diameter of the QDs was found to occur under the influence of serum and under the influence of blood cells (lymphocytes and neutrophils) in a serum-free medium.

Differences in the oxygen-dependent reactions of neutrophil granulocytes (NGs) depending on the nature of the agent affecting the cells were revealed. In vitro magnetite nanoparticles (MNPs) cause suppression of the NADPH–oxidase activity of NGs, which manifests itself in falling rates of reactions (NBT test) both with the effect of MNPs on NGs alone and a combined effect (MNPs and zymosan), as well as in the reduction of the index of activation (IA) and functional reserve of neutrophils (FRN). However, the introduction of MNPs dose-dependently stimulates the activity of myeloperoxidase (MPO). Gram-positive ( S. aureus 2879 M) and gram-negative ( E. coli 321) bacteria caused a respiratory burst of neutrophils, which manifested itself in a significant increase in the number of NBT-positive cells in single and combined influences (bacteria and zymosan). The lack of differences in the reaction of cells on opsonized and nonopsonized bacteria and the decrease in IA and FRN suggest that NGs are at the maximum level of functionality. Both strains of bacteria caused activation of the MPO.

In the process of paper production a large amount of solid and liquid wastes is appearing. The purpose of the work was the development of a complex technology of water use for enterprises of the pulp and paper industry. Wastewater treatment was carried out by two-step technology, which includes biological method in anaerobic and aerobic conditions. After two-step technology of treatment the COD of wastewater decreased on 95 %. Therefore the wastewater after treating in MBR may be reused in a technological process. This paper explores the possibility of using anaerobic co-digestion of the pulp and paper industry solid wastes with blood from a slaughter house to enhance the potential of methane production. In two weeks of experiments the decrease of cellulose content in the sludge/waste mixture constituted 28%, and in the sludge/waste/blood mixture 60%. The biomethane quantity in the sludge/waste/blood mixture was more than in sludge/waste mixture on 33%. The researches have proved that the water recirculation technology at a pulp and paper mill may be realized by means of biological and baromembrane methods.

In recent years, membrane technologies combining advantages of biological treatment and membrane filtration have been well advanced in the world practice. In Western Europe there are fifteen biomembrane facilities, which are used for purifying wastewaters of pharmaceutical industries. Out of which, fourteen plants use submersible units and one external membrane modules. The capacity of these stations varies from 50 to 1500 m(3)/day.This technology is not applied at Russian chemical and pharmaceutical enterprises.The article presents the results of laboratory and pilot tests on water treatment in a membrane bioreactor with a submerged membrane module. Wastewater of a large pharmaceutical enterprise producing more than one hundred products was used for researches.The plant has its own facilities of physical-chemical wastewater treatment with an average capacity of 144 m(3)/d, and the treated water is discharge in to the city sewage system. The wastewater treatment plant consists of a two-days balancing tank, a grease catcher, a bubble-type mixer, where reagents are fed to, and a settling tank. A long-term exploitation of that kind of a treatment plant showed high efficiency and reliability of the applied technology. But as the plant's capacity grew, and new products were introduced, the volumes and quality of wastewater were changing. New tasks appeared: to work out a new ecologically safe MBR-technology, to improve the current methods of wastewater treatment at the plant.The automated pilot installation worked 24 hours a day during four months. After the period of active sludge adaptation, its condition and quality of treated water were monitored.The membrane module of the pilot installation included flat PVDF polymer membranes with total surface area 7 m(2), and pore size of membrane surface 200 mn. Daily flaw of the pharmaceutical enterprise wastewaters after a grease trap constituted 1 m3/day. Average time of wastewater treatment in the installation was 24 hours, amount of sludge varied from 8 g/1 to 14 g/l. COD varied within the range from 71% to 93%.The experiment has proved that the industrial wastewater of the given pharmaceutical enterprise may be treated efficiently in a membrane bioreactor, it is not toxic and meets entirely requirements for treated wastewaters discharged into a city sewage network.

The effects of quantum dots CdSe/ZnS-mercaptopropionic acid, (CdSe/CdZnS)ZnS-polyT, and CdSeCdSZnS/polyT/SiO 2 -NH 2 on human erythrocytes were studied. The nanomaterials reduced signifi cantly the erythrocyte sedimentation rate and modified the erythrocyte membrane resistance to induced (acid and hypo-osmotic) hemolysis. Evaluation of the erythrocyte morphology by atomic force microscopy in the control and after exposure to quantum dots showed significant differences in erythrocyte size and changes in their morphology as a result of exposure to the nanomaterials.