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Additives Improving the Efficiency of Biogas Production as an Alternative Energy Source—A Review
Additives for anaerobic digestion (AD) can play a significant role in optimising the process by increasing biogas production, stabilising the system and improving digestate quality. The role of additives largely boils down to: (i) enhancing direct interspecies electron transfer (DIET) between microbial communities, resulting in improved syntrophic interactions and methane production rates (e.g. biochar, magnetite and carbon nanotubes), (ii) adsorption of toxic substances that may inhibit microbial activity (e.g. activated carbon, zeolites), (iii) improving microbial activity and increasing process stability (e.g. cobalt, nickel, iron, selenium), (iv) maintaining optimal pH levels for microbial activity (e.g. magnesium oxide), (v) reducing inhibition (the aforementioned adsorbents and conductive substances), (vi) accelerating the decomposition of complex organic materials into simpler compounds that are more easily digested by microorganisms, thereby increasing the rate of hydrolysis (enzymes, including cellulases, proteases and lipases). Through the aforementioned action, additives can significantly affect AD performance. The function of these materials varies, from enhancing microbial activity to maintaining optimal conditions and protecting the system from inhibitors. The choice of additives should be carefully tailored to the specific needs and conditions of the digester to maximise benefits and ensure sustainability. In light of these considerations, this paper characterizes the most commonly used additives and their combinations based on a comprehensive review of recent scientific publications, including a report on the results of conducted studies. The publication features chapters that describe: carbon-based conductive materials, metal oxide nanomaterials, trace metal and biological additives, including enzymes and microorganisms. It concludes with a chapter summarising reports on various additives and discussing their indications for functional systems with determined properties. A notable advantage of this work is the updated literature data, clear summaries, and a substantive description of the performance of the additives discussed.
Spatial and Temporal Variability of the Microbiological and Chemical Properties of Soils under Wheat and Oilseed Rape Cultivation
The size of the microbial biomass and the activity of soil enzymes are among the most sensitive indicators of agricultural land quality. The aim of this study was to determine the spatial and temporal variability of microbial biomass, the activity of dehydrogenase (DHA) enzyme and the concentration of micro- (Na, Mg and Ca) and macroelements (Cu, Zn, Mn and Fe) in the soil, collected from 37 measurement sites (depth 0–30 cm) in a 40-hectare field during two growing seasons (wheat and oilseed rape). The percentage of nitrogen (%N) in the wheat grain and rapeseeds was also determined. Mapping the spatial distribution of the microbial biomass, the level of DHA activity and the concentration of the selected elements was used to assess the soil productivity. All tested soil parameters exhibited temporal and spatial variability. The creation of raster maps showing the distribution of the tested parameters allowed the observation of a higher nitrogen content in wheat grains in the south-western part of the field, with high values of DHA activity, bacterial biomass and soil pH. In the case of oilseed rape, plants grown in the northern part of the field were characterized by a higher nitrogen content in the grain, where the soil was characterized by a higher content of fungal biomass. On the basis of the obtained research results, a positive, statistically significant correlation was also shown between the biomass of bacteria and the level of DHA in the soil under the cultivation of both wheat and rape. The cultivation of both crops had a significant impact on the size of the microbial biomass pool and on the DHA activity level but did not affect the concentration of the nutrients in the soil. High concentrations of the analyzed elements at the measuring points correlated with a greater %N content in the grain/seeds of the crops harvested at those locations in the field. The results conclude that the mapping of the physicochemical parameters, microbial biomass and activity on the field permits the development of an effective strategy for maintaining sustainable soil productivity through the appropriate management of agricultural practices and the better approximation of mineral fertilization.
Biofilm Formation and Genetic Diversity of Microbial Communities in Anaerobic Batch Reactor with Polylactide (PLA) Addition
In this paper, an anaerobic digestion (AD) study was conducted on confectionery waste with granular polylactide (PLA) as a cell carrier. Digested sewage sludge (SS) served as the inoculum and buffering agent of systems. This article shows the results of the analyses of the key experimental properties of PLA, i.e., morphological characteristics of the microstructure, chemical composition and thermal stability of the biopolymer. The evaluation of quantitative and qualitative changes in the genetic diversity of bacterial communities, performed using the state-of-the-art next generation sequencing (NGS) technique, revealed that the material significantly enhanced bacterial proliferation; however, it does not change microbiome biodiversity, as also confirmed via statistical analysis. More intense microbial proliferation (compared to the control sample, without PLA and not digested, CW–control, CW–confectionery waste) may be indicative of the dual role of the biopolymer—support and medium. Actinobacteria (34.87%) were the most abundant cluster in the CW–control, while the most dominant cluster in digested samples was firmicutes: in the sample without the addition of the carrier (CW–dig.) it was 68.27%, and in the sample with the addition of the carrier (CW + PLA) it was only 26.45%, comparable to the control sample (CW–control)—19.45%. Interestingly, the number of proteobacteria decreased in the CW–dig. sample (17.47%), but increased in the CW + PLA sample (39.82%) compared to the CW–control sample (32.70%). The analysis of biofilm formation dynamics using the BioFlux microfluidic system shows a significantly faster growth of the biofilm surface area for the CW + PLA sample. This information was complemented by observations of the morphological characteristics of the microorganisms using fluorescence microscopy. The images of the CW + PLA sample showed carrier sections covered with microbial consortia.
Nośniki w fermentacji metanowej bioodpadów: ujęcie procesowo–mikrobiologiczne na przykładzie wybranych układów
Additives Improving the Efficiency of Biogas Production as an Alternative Energy Source - A Review
Additives for anaerobic digestion (AD) can play a significant role in optimizing the process by increasing biogas production, stabilizing the system, and improving digestate quality. The role of additives largely boils down to, among others, enhancing direct interspecies electron transfer (DIET) between microbial communities, resulting in improved syntrophic interactions, adsorption of toxic substances that may inhibit microbial activity, improving microbial activity, and increasing process stability and accelerating the decomposition of complex organic materials, thereby increasing the rate of hydrolysis. Through the aforementioned action, additives can significantly affect AD performance. The function of these materials varies, from enhancing microbial activity to maintaining optimal conditions and protecting the system from inhibitors. The choice of additives should be carefully tailored to the specific needs and conditions of the digester to maximize benefits and ensure sustainability. In light of these considerations, this paper characterizes the most commonly used additives and their combinations based on a comprehensive review of recent scientific publications, including a report on the results of conducted studies. The publication features chapters that describe carbon-based conductive materials, metal oxide nanomaterials, trace metal, and biological additives, including enzymes and microorganisms. It concludes with the chapters summarising reports on various additives and discussing their functional properties, as well as advantages and disadvantages. The presented review is a substantive and concise analysis of the latest knowledge on additives for the AD process. The application of additives in AD is characterized by great potential; hence, the subject matter is very current and future-oriented.
Quantitative and Qualitative Changes in the Genetic Diversity of Bacterial Communities in Anaerobic Bioreactors with the Diatomaceous Earth/Peat Cell Carrier
This paper analyses the impact of the diatomaceous earth/peat (DEP; 3:1) microbial carrier on changes in the bacterial microbiome and the development of biofilm in the anaerobic digestion (AD) of confectionery waste, combined with digested sewage sludge as inoculum. The physicochemical properties of the carrier material are presented, with particular focus on its morphological and dispersion characteristics, as well as adsorption and thermal properties. In this respect, the DEP system was found to be a suitable carrier for both mesophilic and thermophilic AD. The evaluation of quantitative and qualitative changes in the genetic diversity of bacterial communities, carried out using next-generation sequencing (NGS), showed that the material has a modifying effect on the bacterial microbiome. While Actinobacteria was the most abundant cluster in the WF-control sample (WF—waste wafers), Firmicutes was the dominant cluster in the digested samples without the carrier (WF-dig.; dig.—digested) and with the carrier (WF + DEP). The same was true for the count of Proteobacteria, which decreased twofold during biodegradation in favor of Synergistetes. The Syntrophomonas cluster was identified as the most abundant genus in the two samples, particularly in WF + DEP. This information was supplemented by observations of morphological features of microorganisms carried out using fluorescence microscopy. The biodegradation process itself had a significant impact on changes in the microbiome of samples taken from anaerobic bioreactors, reducing its biodiversity. As demonstrated by the results of this innovative method, namely the BioFlux microfluidic flow system, the decrease in the number of taxa in the digested samples and the addition of DEP contributed to the microbial adhesion in the microfluidic system and the formation of a stable biofilm.
Czy mikrobiologiczne bioherbicydy mogą być alternatywą dla chemicznych środków ochrony stosowanych w uprawie buraka cukrowego?
Influence of plant growth-promoting bacteria and green manures on the degreeof weed infestation in Triticum spelta in organic farming
Sustainable Methods of Soybean Cultivation in Poland
Many countries in Europe are struggling with a shortage of feed protein; moreover, efforts are being made to limit the import of post-extraction soybean meal, most often from GMO crops. To achieve the above assumptions, varietal progress is necessary and, above all, breeding work should aim at greater adaptation to regional conditions. This study was designed to evaluate the potential for growing Ukrainian soybean ‘Annushka’ in the southeastern Baltic Sea area, in accordance with the application of mineral nitrogen fertilizer and the inoculation of seeds with Bradyrhizobium japonicum. Soybean ‘Annushka’ yielded 0.98–1.68 t ha−1 in the conditions of central Poland. Our experiments have shown significant variations in seed, protein, and fat yields over the years. The maximum amounts of these characteristics were recorded in 2017. Nitrogen fertilization combined with seed inoculation with B. japonicum has proven to be an important factor in improving soybean yields; however, it slightly modified the content of organic compounds in seeds. Improvement in seed and protein yields relative to the control amounted, respectively, to Nitragina + 30 kg N ha−1 (58.8%; 72.6%), HiStick® Soy + 30 kg N ha−1 (57.6%; 68.3%), and Nitroflora + 60 kg N ha−1 (57.6%; 71.9%).
Efektywna stabilizacja pofermentu z biogazowni rolniczej z wykorzystaniem biowęgla i mikroorganizmów promujących wzrost roślin
Nośnik diatomit/torf w intensyfikacji fermentacji metanowej odpadów organicznych: efektywność i stabilność procesu oraz zmiany mikrobiomu
Enhancing Soil Microbial Activity and Spelt (Triticum spelta L.) Yield in Organic Farming Through Biofertilizer and Green Manure Applications
Fungi of the Trichoderma Genus: Future Perspectives of Benefits in Sustainable Agriculture
The negative impact of chemical pesticides on the environment and human health has contributed to the introduction of legal regulations that ensure the reduction in the use of agrochemicals in favor of biological products. The existing review of the literature, including our research, clearly shows that the ideal biocontrol agents are Trichoderma fungi. The production of antibiotics, lytic enzymes degrading the cell walls of plant pathogens, or inducing a defense response in plants are just some of the features supporting the wide use of these microorganisms in sustainable agriculture. It is estimated that currently about 60% of biofungicides used to eliminate fungal pathogens are produced based on Trichoderma sp. strains.
Eco-Friendly and Effective Diatomaceous Earth/Peat (DEP) Microbial Carriers in the Anaerobic Biodegradation of Food Waste Products
This article aims to present the results of research on anaerobic digestion (AD) of waste wafers (WF-control) and co-substrate system—waste wafers and cheese (WFC-control), combined with digested sewage sludge. The aim of this study was to assess the physicochemical parameters of the diatomaceous earth/peat (DEP; 3:1) carrier material and to verify its impact on the enzymatic activity and the process performance. The experiment was conducted in a laboratory, in a periodical mode of operation of bioreactors, under mesophilic conditions. The results of analyses of morphological-dispersive, spectroscopic, adsorption, thermal, and microbiological properties confirmed that the tested carrier material can be an excellent option to implement in biotechnological processes, especially in anaerobic digestion. As part of the experiment, the substrates, feedstock, and fermenting slurry were subjected to the analysis for standard process parameters. Monitoring of the course of AD was performed by measuring the values of key parameters for the recognition of the stability of the process: pH, VFA/TA ratio (volatile fatty acids/total alkalinity), the content of NH4+, and dehydrogenase activity, as an indicator of the intensity of respiratory metabolism of microorganisms. No significant signals of destabilization of the AD process were registered. The highest dehydrogenase activity, in the course of the process, was maintained in the WFC + DEP system. The microbial carrier DEP, used for the first time in the anaerobic digestion, had a positive effect on the yield of methane production. As a result, an increase in the volume of produced biogas was obtained for samples fermented with DEP carrier material for WF + DEP by 13.18% to a cumulative methane yield of 411.04 m3 Mg−1 VS, while for WFC + DEP by 12.85% to 473.91 m3 Mg−1 VS.
