Dynamics of the microbiological indicators of fresh sludge from wastewater treatment plants with a concentration of CaO, 10% and 20%, and ash, −30% and 50%, and treated with quicklime, ash, and microbial fertilizer for a 50-day period of composting were studied. The influence of temperature, water content, and oxygen on the development of microbes was established in laboratory conditions. Microbiological analysis included the determination of non-pathogenic (non-spore-forming bacteria, bacilli, actinomycetes, micromycetes, bacteria digesting mineral nitrogen), and pathogenic (Salmonella, Listeria, Escherichia coli, Enterococcus, Clostridium perfringens) microorganisms. Of the beneficial microflora in the sludge before treating, the amount of non-spore-forming bacteria was the highest, followed by bacilli and micromycetes. It was found that actinomycetes were absent in the untreated sludge. Clostridium perfringens occupied a major share in the composition of the pathogenic microflora, followed by Escherichia coli, Enterococcus, and Listeria. The best results for decontamination of the sludge were obtained by adding 20% quicklime and 50% ash. Alkalization of the sludge after treatment led to the destruction of pathogenic microflora but also reduced the number of beneficial microorganisms. The decrease in pH during the study period determined the redevelopment of pathogenic microflora. Combined variants with lime or ash and microbial fertilizer showed better results for the development of non-pathogenic microflora and the destruction of pathogens.
Microbiological indexes have been studied in dynamics at lime treatment and independent planting of lavender (Lavandula angustifolia, variety “Hemus”) and sweet basil (Ocimum basilicum, variety “Genovese”) of fresh sludges from a purification plant, with concentrations of quicklime: 10%, 20% and 30% for a 40-day period of composting. The microbiological analysis includes determining of nonpathogenic (non-spore forming bacteria, bacilli, actynomycetes, micromycetes, bacteria, which assimilate mineral nitrogen) and pathogenic (Salmonella spp., Escherichia coli and coliforms, Enterococcus, Clostridium perfringens) microflora. Out of the beneficial microflora in the sludges the quantity of the non-spore forming bacteria is the biggest, and the lowest is of the actynomycetes. A basic share in the composition of the pathogenic microflora occupies Clostridium perfringens, followed by Escherichia coli and coliforms, and Enterococcus. Absence of Salmonella spp. was established in the studied sludges. The best results for the disinfection of the sludges displays the adding of 30% quicklime (followed by the variants with 20% and 30% lime), on 5-th day of the experiment setting. The pH decrease in the period of the study leads to a repeated development of pathogenic microflora. In the meantime the creation of an alkaline medium leads to decrease in the quantity of the beneficial microorganisms. The decrease of the moisture and the drying of the sludges for the study period display a weaker effect on the dynamics of the microflora in comparison with the pH increase impact. The planting of lavender and basil independently in the sludges samples from a purification plant has a beneficial effect (a little bit better with the lavender variants) for increase of the quantity of nonpathogenic microbes and pathogens frequency of occurrence decrease. The effect is intensified by increasing the plant development period.
Microbiological studies of forest soils are an important field of research due to the role of forest as carbon sinks and the main role of microorganisms in biogeochemical cycle and in the transformation of organic mass. Microbiological monitoring of soils in forest ecosystems is of key importance to achieve accurate and comparable data. This paper examines the interrelationship of soil microbial communities with different environmental characteristics. For the purpose of the study, the influence of soil type, the influence of some soil parameters, tree composition and altitude on microbial abundance were analyzed. Basic soil parameters were evaluated - content of organic carbon and pH in water extract. For the purpose of the study, 20 representative sample plots were laid out in the territory of Vitosha nature park. The sample plots are in Cambisols and Umbrisols. The microbiological abundance of soils was determined. The total microbial number varied from 5.59 to 6.60 CFU log10/g soil mass. Cambisols have a higher microbial abundance. The sample plots with higher microbial abundance are concentrate at altitudes between 1200 m a.s.l. and 1500 m a.s.l. The data were evaluated statistically. Of greatest importance in the study sample plots is altitude, followed by organic carbon content. Sample plots under mix vegetation have greater microbial abundance. Under coniferous vegetation, the participation of micromycetes in the microbial communities clearly stands out.
Polar soils under different vegetation cover from Livingston Island (Antarctica) were studied analyzing indicators of carbohydrates decomposition in soils: organic carbon, biomass carbon, total nitrogen, C:N ratio, cellulase, amylase, and invertase activity. The highest values of microbial biomass in soils were indicated for sites with vegetation cover while the lowest values in soils without vegetation, which correlate with the content of total organic carbon and the C:N ratio. The highest percentage of biomass carbon compared to the total organic biomass carbon is obtained for two sites with mosses, and the lowest in sites without vegetation, followed by the sites with lichens. Cellulase activity is highest in polar soils with moss cover. Amylase activity depends more strongly on the type of vegetation. The highest amylase activity is detected in soils under algae cover and the lowest in soils without vegetation. Invertase activity is limited by the extreme soil and climatic conditions of Antarctica. A very strong, positive correlation is found between total carbon and total nitrogen. The relationship between total carbon and the C:N ratio, as well as between biomass carbon and amylase activity, is moderate, and positive. The higher dependence of amylase activity from organic carbon with microbial origin correlates with higher values of the enzyme amylase compared to the enzyme cellulase. There is a strong (cellulase) and very strong (amylase) positive relationship between the activity of enzymes and the combination of factors: total carbon, total nitrogen, C: N ratio and biomass carbon.
A vegetation experiment was carried out with different amounts of vermiculite mixed with humus depot substrates, tailings pond and mine, in different proportions, and with an application of mineral fertilization and liming. Biomass carbon of microbial origin has the highest values after the addition of 10% vermiculite, simultaneous application of fertilization and liming, and alone fertilization, compared to controls, without ameliorants. The activity of the studied enzymes - cellulase, amylase, invertase and catalase increased with increasing concentration of vermiculite, as well as in the combined application of fertilization and liming. The values of microbial biomass carbon and enzymes are highest in the variants with substrates from the mine.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.